Run Excel Macro daily on new file

I am trying to find a solution for this scenario.  We have a batch process from a vendor that delivers a new file in csv format every night.  Column E in this file contains numeric values with a minus sign included for negative values, and this minus sign must be removed before we can pass the file to another process.  I need to automate and schedule the process.

I can automate changing the file from csv to xlsx, and the following macro works for removing the minus sign as intended, but I am struggling with how to run the macro on a new file each night and save the results.    Thanks  

Sub ChgSign()
Columns(5).Select
For Each Cell In Selection
    If Cell.Value < 0 Then
        Cell.Value = -Cell.Value
    End If
Next Cell
End Sub