A yarn-clamping device for clamping a yarn layer, this yarn-clamping device comprising: - a support member forming a support surface extending along a longitudinal axis; - a clamping bar including a toothed surface and a clamping surface which faces the support surface along a transverse axis perpendicular to the longitudinal axis; - a first pressing rail provided with a first complementary toothed surface shaped for cooperating with the toothed surface of the clamping bar; and - a first drive unit for moving the first pressing rail between a released position and a holding position, along the longitudinal axis with respect to the toothed surface of the clamping bar, so that its first complementary toothed surface cooperates with the toothed surface of the clamping bar to move the clamping surface, in a direction parallel to the transverse axis, between a first open position, where yarns of the yarn layer are releasable between the support surface and the clamping surface, and a second closed position, where the clamping surface and the support surface cooperate, with the yarns in-between; characterized in that - the yarn-clamping device also comprises a second pressing rail provided with a second complementary toothed surface shaped for cooperating with the toothed surface of the clamping bar; - the yarn-clamping device also comprises a second drive unit for moving the second pressing rail between a released position and a holding position, along the longitudinal axis, with respect to the toothed surface of the clamping bar, so that the second complementary toothed surface cooperates with the toothed surface of the clamping bar to move the clamping surface, in the direction parallel to the transverse axis, between the first open position and the second closed position; - the first complementary toothed surface faces a first longitudinal portion (128P1) of the toothed surface of the clamping bar and the second complementary toothed surface faces a second longitudinal portion (128P2) of the toothed surface of the clamping bar; - the first and second complementary toothed surfaces (146, 148) of the first and second pressing rails (112, 114) are adjacent along the longitudinal axis; and - the first and second complementary toothed surfaces (146, 148) of the first and second pressing rails (112, 114) are moved, from their respective released positions to their respective holding positions, by the first and second drive units (132, 134) in the same longitudinal direction (A2, A5), for moving the clamping surface from its first open position to its second closed position. - a support member forming a support surface extending along a longitudinal axis; - a clamping bar including a toothed surface and a clamping surface which faces the support surface along a transverse axis perpendicular to the longitudinal axis; - a first pressing rail provided with a first complementary toothed surface shaped for cooperating with the toothed surface of the clamping bar; and - a first drive unit for moving the first pressing rail between a released position and a holding position, along the longitudinal axis with respect to the toothed surface of the clamping bar, so that its first complementary toothed surface cooperates with the toothed surface of the clamping bar to move the clamping surface, in a direction parallel to the transverse axis, between a first open position, where yarns of the yarn layer are releasable between the support surface and the clamping surface, and a second closed position, where the clamping surface and the support surface cooperate, with the yarns in-between; - the yarn-clamping device also comprises a second pressing rail provided with a second complementary toothed surface shaped for cooperating with the toothed surface of the clamping bar; - the yarn-clamping device also comprises a second drive unit for moving the second pressing rail between a released position and a holding position, along the longitudinal axis, with respect to the toothed surface of the clamping bar, so that the second complementary toothed surface cooperates with the toothed surface of the clamping bar to move the clamping surface, in the direction parallel to the transverse axis, between the first open position and the second closed position; - the first complementary toothed surface faces a first longitudinal portion (128P1) of the toothed surface of the clamping bar and the second complementary toothed surface faces a second longitudinal portion (128P2) of the toothed surface of the clamping bar; - the first and second complementary toothed surfaces (146, 148) of the first and second pressing rails (112, 114) are adjacent along the longitudinal axis; and - the first and second complementary toothed surfaces (146, 148) of the first and second pressing rails (112, 114) are moved, from their respective released positions to their respective holding positions, by the first and second drive units (132, 134) in the same longitudinal direction (A2, A5), for moving the clamping surface from its first open position to its second closed position.