A Chicopee man is free on bail after allegedly punching a 5 year old child in the head at Look Park in Northampton.  Police say the incident happened Saturday, with Brian Gawron punching the child, shoving him to the ground, and threatening the boy's mother.  Witnesses say the child was upset throughout the day at the park, and the 28-year old Gawron and the child's mother got into an argument which led to the incident.  He was takeninto custody later in Easthampton.  Yesterday Gawron pleaded not  guilty to charges of assault and battery on a child with injury, dometic assault and intimidation of a witness.