Can someone requests further modification after the revised deadline in an IEEE conference? If one has an accepted paper in the conference and he already submitted the revised version. Suppose that the deadline for submitting the revised papers has been finished last week for example. Is it possible to send a mail to the conference in order to request some further changes? In other words, can this be acceptable by the IEEE conference?

Any help will be very appreciated!
Contact the program chairs immediately. There is a moment in the publication process where changes are no longer possible, but this moment is not necessarily the deadline for revised papers.

Regarding the acceptability of such a request: Conference organizers are humans, too, so they will understand that people make errors and/or suboptimal choices. In addition, they might have an active interest in publishing the revised version: For example, a critical error that made it through the review process may reflect poorly on the conference and its organizers.