Stretching unit as well as method for reducing non-uniform temperatures and air flows in a film stretching unit

A stretching unit for stretching a film, comprising an oven and a compensation device,

• wherein the oven comprises a vertical direction (H), a transverse direction (Q) and a drawing direction (R),
• wherein the compensation device comprises an air conveyor, a first compensation opening and a second compensation opening, wherein the first compensation opening and the second compensation opening open into the oven on opposing sides of a central plane (M) of the oven in the vertical and drawing directions (H, R),
• wherein the air conveyor is located in terms of flow between the first compensation opening and the second compensation opening,
• wherein the compensation device is configured to remove a volume of air from the oven through one of the compensation openings and to feed the removed volume of air into the oven through the other one of the compensation openings,
• wherein the first compensation opening is flow-connected to the air conveyor via a first pipe and the second compensation opening is flow-connected to the air conveyor via a second pipe,
• wherein the compensation device comprises a first hinged box that is flow-connected to the outlet side of the air conveyor and a second hinged box that is flow-connected to the intake side of the air conveyor,
• wherein the first pipe and the second pipe each branch into two branches and in each case one branch is flow-connected to the first hinged box and the corresponding other branch to the second hinged box.