I take imipramine 4 pain but it makes me fall asleep, will this symptom go away after a couple weeks?

Likely yes. It is likely that the sedation will improve with time.
Probably not. Although Imipramine has been shown to be quite helpful, it's use is usually limited to night-time use due to sedation, and this effect usually doesn't get much better. Many people find that a single dose before bed helps with sleep and still helps with the pain during the day....Even after the sedation wears off.