Adaptive Cooling Phase 1

ADAPTIVE COOLING SYSTEM FOR VMC SPINDLE Guided by: Dr. B. Giriraj Senior lecturer Department of Mechanical Engineering

A.P. Arun R. No. 07MI31 ME CIM

FLOW OF PRESENTATION Problem definition Literature survey Objective Proposed solution Methodology Conclusion and further work

PROBLEM DEFINITION High-speed machining has become the mainstream of metal cutting. To achieve this goal, the rotational speed of the spindle must be increased. Thermally induced errors are significant factors affecting machine-tool accuracy. These thermal errors have been reported to be about 70% of the total positioning errors in machine tools[8] According to the data of FAG (Germany), with the installation of high-precision bearings in the spindle assemblies of the machine tools, the temperature of the spindle bearings should not exceed 50–60° (temperature rise of 30–40°C), while for the very-high-precision machines the temperature should not exceed 30–40°C(temperature rise of 10–20°C). During continuous running of machine with normal cooling system the spindle was over cooled causing significant shrink in the spindle. The resultant distortions are revealed in the motion of spindle relative to the machine frame. Equipment Operating for worst condition continuously, or cycling it on and off, is a sub optimal solution in most cooling applications.

LITERATURE SURVEY SPINDLE THERMAL DISPLACEMENT [1] Zone-Ching Lin ,et al., The building of spindle thermal displacement model of high speed machine center, International Journal of Advanced Manufacturing Technology, 2007, Vol :34, Page No. 556–566 [2] S.-M. Kim ,et al., Spindle Housing Design Parameter Optimization Considering Thermo-Elastic Behaviour International Journal of Advanced Manufacturing Technology, 2005, Vol: 25, Page No. 1061–1070 [3] S.-M. Kim, et al., Effect of Bearing Surroundings on the High-Speed Spindle-Bearing Compliance, International Journal of Advanced Manufacturing Technology, 2002, Vol:19, Page No.551–557 [4] V Prabhu Raja, et al., Prediction of Thermal Deflection at Spindle Nosetool Holder Interface in HSM ,2001 [5] Hayato YOSHIOKA, et al., Minimising thermal deformation of aerostatic spindle system by temperature control of supply air, JSME International Journal, 2006,series C, Vol. 49, Page No. 2

BEARING EFFECTS ON SPINDLE [6] S.-M. Kim, et al., Effect of Bearing Surroundings on the High-Speed Spindle-Bearing Compliance, International Journal of Advanced Manufacturing Technology, 2002, Vol:19, Page No.551–557

[7] Hongqi Li, et al., Analysis of bearing configuration effects on high speed spindles using an integrated dynamic thermo-mechanical spindle model, International Journal of Machine Tools & Manufacture, 2004, Vol:44, Page No.347–364 BRICATION OF SPINDLE

[8] Cheng-Hsien Wu, et al., A parametric study on oil/air lubrication of a high-speed

ndle, Precision Engineering, 2005, Vol:29, Page No.162–167

REAL TIME SPINDLE HEALTH MONITORING [9] H. J. Pahk et al., Thermal Error Measurement and Real Time Compensation System for the CNCMachine Tools Incorporating the Spindle Thermal Error and the Feed AxisThermal Error,International Journal of Advanced Manufacturing Technology , 2002, Vol:20, Page No.487–494 [10] Li Zhang, et al., Design of a Real-time Spindle Health Monitoring and Diagnosis

OBJECTIV E The objective of this project is to minimize the thermal distortion of spindle using adaptive cooling system. To accomplish this objective the specific sub-objectives of this project were as follows • Identification of sources of heat, which results in spindle distortion. •

To develop a adaptive cooling system using graphical programming Software (LabVIEW).

•

To test adaptive cooling system for improvement.

VERTICAL MACHINING CENTER CNC milling machine which has the following specification Machine

: 3-axis vertical CNC milling

Power

: 5 KW

Speed

: Integrated motorized spindle that can rotate up to 40,000 rpm

Bearings used in the spindle Front bearing type Rear end bearing type

7914X2TAU (bore diameter 70mm) 7912X2TAU (bore diameter 60mm)

SPINDLE HEAT SOURCE • • • •

Bearings of spindle shaft Electric motor Cutting process External heat sources (Ambient air, Electrical lighting ,Sunlight ,People ,Other machines…) The resultant distortions are revealed in the motion of the spindle relative to the machine frame.

PROPOSED SOLUTION To develop an adaptive cooling system for the HSM spindle number of materials were referred based on that the following ideas were generated. The first step is to control the flow rate of the coolant by automating the flow control valve based on the spindle temperature with the help of LabVIEW software. So that the equipment will be controlled to operate at whatever condition necessary to satisfy the need of the moment.

coolant system normally starts with the help of thermostat but it has a disadvantage that it takes some time to switch on the cooler, this time gap is because of the thermal expansion of the bimetallic strip in the thermostat, in-between this time gap the spindle distortion may takes place. To avoid this and for immediate response an on/off relay is going to be used which will be automated by LabVIEW software based on the coolant temperature coming as outlet from the spindle .

We can also automate the fan for condenser, where it should be controlled to operate at whatever speed necessary to satisfy the need of the moment based on the coolant temperature with the same LabVIEW software

BENEFITS • • • • • •

minimize spindle distortion Energy Savings Increased Fan Life Automatic Compensation for Changes in Cooling Noise Reduction Other System Dependant Benefits

METHODOLOGY • Study of vertical machining center has to be done and process parameter has to be studied. • Experiments are to be carried out by using a 3-axis Vertical CNC milling machine for mapping temperature rise. • Based on the experimental data and predetermined threshold values of spindle temperature , the coolant temperature and flow rate are to be altered using real time adaptive cooling system to maintain spindle temperature to achieve high precision. • The LabVIEW program will be used to receive temperature from thermocouple and using a feedback control, the coolant temperature and flow rate are to be controlled. • In order to establish an adaptive cooling system the flow control valve, relay and condenser fan were to be automated using LabVIEW. • The thermocouples are to be interface through the input port of the Data Acquisition Card (DAQ). •

Temperature will be acquired from DAQ through Analog input.

• Temperature value is then compared with the predefined threshold value and if there is any change, a voltage signal of the range 0-10 v will be made available in the output port of the DAQ. • Using this output voltage, the flow control valve, condenser fan and relay will be controlled automatically to maintain the flow rate, temperature and to on/off the coolant system. • Finally the improvement has to be made according to the previous test and analyzed data.

Methodology – Adaptive Cooling System Start Program load cycle Mathematical model

Predict the temperature variation Spindle health condition monitoring

Spindle health diagnosis

Spindle optimal operation

End

CNC program

CONCLUSION AND FURTHER WORK

In order to achieve the objective of the project literature survey were taken based on that solutions were proposed and methodology were developed to Implement the proposed solution Further work in this project is to find the relationship between heat developed and spindle deformation , based on that a graphical program is to be created in LabVIEW software. Then this adaptive cooling system will be implemented for the vertical machining center spindle. Finally the system is to be tested for improvement.

REFERENCES www.machinerylubrication.com

http://www.ahrinternational.com/bearing_materials_table.h http://www.ansys.com/events/proceedings/ http://www.yampanet.com/Technology/technology.htm

http://www.wipo.int/pctdb/en/wo.jsp?IA=WO2007019304&D

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