Mechanical locking of floor panels with vertical folding

A set of essentially identical floor panels each comprising a front face and a rear face, and long and short edges provided with first and second connectors, the connectors are integrated with the floor panels and configured to connect adjacent edges in a vertical direction and in a horizontal direction, the front and rear faces being parallel to the horizontal direction, the first connector comprises a locking strip with an upwardly directed locking element, projecting toward a front face of one floor panel, at an edge of the one floor panel and a downwardly open locking groove, opening toward a rear face of another floor panel, at an adjacent edge of the another floor panel for connecting the adjacent edges in the horizontal direction and perpendicular to the adjacent edges, the second connector comprises a tongue at the edge of the one floor panel, extending in the horizontal direction and perpendicular to the edge, and a tongue groove opening in the horizontal direction in the adjacent edge of the another floor panel for connecting the adjacent edges in the vertical direction, the connectors at the long edges are configured to be locked with angling and the connectors at the short edge are configured to be locked with vertical folding, whereby a long edge of a new panel in a second row is configured to be connected to a long edge of a first panel in a first row by angling, whereby a short edge of the new panel and a short edge of a second panel in the second row are configured to be connected with the same angle motion wherein the tongue at the short edges comprise a separate material and is being arranged in a connection groove and said tongue has a flexible part configured to be displaced in the horizontal direction during the folding and to cooperate with the tongue groove of an adjacent short edge for locking the floor panels together in the vertical direction, whereby the first and second connectors on the long edges comprise friction means which increase the friction along the long edges when the upper parts of said edges are pressed against each other in an angle with only two contact points between the first and second connectors.