Keep TCP orientation when using object frame in vision system

I'm using integrated vision to locate and pick up parts. Location of part is given to robot by moving the object frame like this:  wCam.oframe:=camTarget.cframe; and then robot is moved to that position with Offs command: MoveL pPickObject,vFast,fine,tGripper\WObj:=wCam;

The problem is that as the parts I'm picking are round there is no need to rotate the tool when picking them up so how can I make it so that the tool won't rotate? I want to keep it in specific angle to minimize change of collision.