Patent ID: 8978728
Filing Date: 2015-03-17
Classification: B29D

Abstract:
1. An expandable and contractable band building drum, comprising: a plurality of first and a plurality of second segments formed separately in a peripheral direction and positioned alternately with respect to one another in the peripheral direction, guide means for guiding the plural first and plural second respective segments into respective expanding and contracting movements in a diametrical direction and for restricting movements in an axial direction relative to a drum shaft, wherein the plural first segments are connected to and expandably and contractably supported by a first expanding/contracting means provided on the drum shaft and the plural second segments are connected to and expandably and contractably supported by a second expanding/contracting means, respectively; and wherein the first expanding/contracting means and the second expanding/contracting means are configured to be individually controllable to detach a band after having been built, the first segments are configured to be controllable to diametrically contract toward one another while the second segments are configured to be controllable to be in the diametrically expanded state, the first segments thereafter are temporarily, controllable to be configured to an original diametrically expanded state while the second segments are controllable to be configured in the diametrically expanded state, next, the second segments are configured to be controllable to contract in diameter while the first segments remain in the diametrically expanded state, thereafter, the first and the second respective segments are controllable to be configured to be in a diametrically contracted state, wherein the first and second expanding/contracting means comprise means for utilizing a movement in the axial direction by a cylinder mechanism on a drum shaft and a link mechanism, and further comprising a first and a second cylinder mechanism respectively including a first cylinder and a second cylinder maintaining an airtight state relative to the drum shaft and slidable in the axial direction, and a first piston portion and a second piston portion respectively fixed to the drum shaft in the two cylinders, wherein the two cylinders are slideable in the axial direction by operations of charging and discharging air to and from inner spaces of the two cylinders as the first and second expanding/contracting means, wherein the first segments and the second segments are connected to the first cylinder and the second cylinder, respectively, by way of link members, such that the first and second segments are expandable and contractable in response to movement of the cylinders in the axial direction, further wherein a connection fulcrum of the link member connected to the second segment with the second cylinder is disposed on a diametrically inner side of a connection fulcrum of the link member connected to the first segments with the first cylinder, such that the second segments are diametrically contractable to a position at which the diameter of the second segments are smaller than the diameter of the first segments, and wherein the first and the second cylinders are aligned to be spaced apart from each other in the axial direction of the drum shaft, the first cylinder is extended with a first cylinder portion slidably fitted to an outer periphery of the second cylinder at an end portion thereof on a side opposed to the second cylinder, the first cylinder portion and the first respective segments are connected to each other by way of a first link member at two portions in the drum shaft direction, both ends of the second cylinder are extended with second cylinder portions respectively each having a diameter smaller than that of the second cylinder and slidably fitted, to the drum shaft, the second respective cylinder portions and the second, respective segments are connected to each other respectively by way of a second link member, and the second link member connected to the second cylinder portion on a side opposed to the first cylinder is connected to the second respective segments by way of a notch formed at the first cylinder portion.