Britain's Chris Hoy collected his 10th world track championship title when he won the keirin race on Thursday.
Australia, who claimed two golds on the opening day of the championship on Wednesday, added another two when they took the women's team sprint and the women's team pursuit.
Taylor Phinney of the United States won the men's individual pursuit for the second year in a row and Denmark's Alex Rasmussen won the men's scratch race to give the hosts their first gold of the championships.
Hoy suffered a serious crash at the same Ballerup track 13 months ago and missed last year's world championships as a result.
‘I'm over the moon,’ he told the BBC. ‘The year hadn't gone well but to win that just feels amazing.
‘Whilst it wasn't in my mind, to come back here at the venue where I had a nasty crash last year, to make amends for that is very special indeed.’