Cylindrical grinding machines are basically used for
producing work pieces with non circular or cylindrical contours and on
increasingly basis. Hence it was very important for monitoring on route or
process and measurements in-process as surface or shape is not circular but
also its shape is cylindrical.
The cylindrical grinding machine i.e. CGM faces a
no. of various types of disturbances for example; temperature drifts, tool
wear, path control deviations and much more factors and due to these factors
there will be losses in productivity as well as there will be dimensional
deviations also in work piece.
In order to achieve the right quality there are various types of tools for
monitoring the correct operation and these monitoring tools can help in order
to amend the process of grinding.
Measurement controls could also be utilized in order to compensate for the most
various types of disturbances during process of cylindrical grinding. This is
done by the concept of measuring & positioning the tools during process of
machining in remote way or in the way of automation. Now these days the
measurement controls tools are used widely and also well established.
These are very - very important in case of securing
high for an efficient as well as for robust manufacturing processes. It could
be concluded that the intelligent monitoring facilities in CNC cylindrical
grinding processes will play very important role.
The modern cylindrical grinding machine of these
days could also be utilized for the higher precision grinding process of
non-circular or cylindrical contours and for this purpose the cylindrical
grinding machine has path control continuous in the X- & C-axes, for
example in case of for eccentric grinding.
Objective
- We have to search, understand and to implement the following techniques in cylindrical grinding machines for better productivity.
- Parameters which must be measured on the cylindrical ground components for ensuring geometrical and dimensional accuracy.
- Show how our experience and knowledge, on Cylindrical grinding process, could be utilized in order to predict the behaviour of grinding and securing optimum operating processes- parameters.
- List of instruments for monitoring the process during cylindrical grinding.
- Different types of sensors used for efficient operation of cylindrical grinding machine.
- Importance of sensors for cylindrical grinding machine.
- Location of sensors for efficient operation CGM.
- Feedback or compensation system for CGM sensors
Fig: 1 cylindrical grinding machine
Parameter which must be measured on the cylindrical ground
Cylindrical grinding process is a process of giving
final finishing of product or component required for smoother surfaces as well
as with close tolerances. We must understand that in case of cylindrical
grinding process a very small size of chips will be produced. It is mostly used
in industrial areas.
The bigger operating I/P parameters which influences
the output response of the surface - roughness are as mentioned below.
- Machine parameter
- Process parameter
- Grinding wheel parameter
- Work piece parameter
- Static tests, such as local reproducibility, repeatability, reproducibility over
- Measuring range
- Slope limit as well as point to point inspection
- Dynamic tests inspection of scanning probing error on sphere
There will be some important input processed parameters
also and these are as Feed rate, Cutting Speed and depth of cut.
This knowledge is basically in the form of empirical
models and physical models that will describe different characteristic of
cylindrical grinding process. Taguchi method now utilized that integrates these
empirical models and physical models to replicate what happens during the
process of cylindrical grinding processes.
Anticipation from the simulation is analyzed further b y calibration along with
actual data’s. There are various factors those are involved for securing the
optimal values such as grinding wheel Chemical composition, Abrasive, feed
rate, Cutting Speed and Depth of Cut. Surface finish is very important output
feedback in production w. r. t quality & quantity.
List of instruments for process monitoring of cylindrical work piece diameter and surface finish
There are some important facilities are provided to
be control or monitor the operation during grinding operation.
The distance measurement sensor is installed on
wheel head in cylindrical grinding machine and it could be automatically put in
place for measuring, as alternative to the wheel head, otherwise it was located
in rear portion of cabin.
Chromatic confocal distance sensor was selected in
order to measure the head. The sensor employs one polychromatic point-source.
As chromatic aberration will be used, each focal-point relates to a particular
wavelength or the distance between the sensor and the surface of the work
piece, corresponds to a particular wavelength.
A spectrometer is basically
utilised for measuring the wavelength of reflected light and the most important
and considerable advantage of such type of principle of measuring over other
various types of principles is it’s insensitivity to various surfaces along
with various reflectivity and noted also that it is also beneficial for shiny
surfaces.
As sensor is
fixed on wheel head, it will move along the direction of X-axis just like
grinding wheel. It only requires a smaller measuring range of the order of 1 mm
for highly precision measuring over a big working distance.
The optical sensor is
also utilized for this purpose and this type of sensor will be
completely integrated with the CNC unit of Cylindrical grinding machine.
It will allow information from sensor, the X-, Z and C- axes to be noted as
well as linked simultaneously.
List of sensors used for intelligent operation of CGM and their importance
There are various types of sensors used in
cylindrical grinding machine for different purpose, let us understand each
sensor and its importance in efficient working of cylindrical grinding machine
Contact displacement sensors
This type of sensors
are used for measuring outer diameter of cylindrical work piece such as ingot.
Fig2: Contact displacement sensors
Optical sensor
The optical sensor is also utilized for
this purpose and this type of sensor will be completely integrated with
the CNC unit of Cylindrical grinding machine. It will allow information from
sensor, the X-, Z and C- axes to be noted as well as linked simultaneously.
Fig3: optical sensors
Distance measurement sensor
The distance measurement sensor is installed for
controlling or monitoring the operation during grinding operation.
Fig4: Simulator of
arrangements coordinates transformations and tests
Proximities sensors
This type of sensors are basically used for
detecting metal parts & objects
Location of sensors
Location of sensors, we may understand in above
figure the location of sensors, for location of optical sensors we may refer
following figure for better understanding.
Conclusion
We have concluded that it is really possible and
quite beneficial for using optical sensors in cylindrical grinding machines;
however it is not easy to measure directly during operation of grinding. With
new possibility of monitoring the process of grinding, such type of metrology
will lead for additional values for the complete manufacturing process.
We also concluded that we will have ability for detecting contour- errors and
to rejecting work pieces those are not in allowable range of tolerance as well
as we will also have opportunities for securing useful knowledge about
cylindrical grinding machine.
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