Convert .csv file

Hello,
Iam having the ".csv" file with the file type "Unicode Text(*.txt)" and it is having tab seperated . I want to change it's type as "CSV (Comma delimited) (*.csv)" . Can u please give me the batch file to do this (because i have 1000 csv files and I need to change the format every day) .

Please help on this ASAP .

Thanks in Advance .