Conventionally, there are transport devices that, on a production line, transport a workpiece and cause a machine tool at a transport destination to apply predetermined processing to the workpiece. JP 2011-93032A (FIG. 11) discloses a pallet transport device that transports a plurality of pallets having workpieces placed thereon by circulating the pallets on a track-like path composed of two linear portions and two curved line portions that connect between the linear portions.
This transport device includes first and second pallet rails that extend in parallel to each other, first and second pallet moving mechanisms that move the pallets guided to the first and second pallet rails along the first and second pallet rails, and pallet transfer mechanisms that transfer the pallets on a semicircular path from an end portion of the first or second pallet rail to an end portion the second or first pallet rail.
In the pallet transport device configured in the foregoing manner, pallets that have been moved by the first or second pallet moving mechanism along the first or second pallet rail are transferred by the pallet transfer mechanisms on a semicircular path from the end portion of the first or second pallet rail to the end portion of the second or first pallet rail. The transferred pallets are moved again by the second or first pallet moving mechanism along the second or first pallet rail. In this way, conventional circulation-type pallet transport devices circulate and transport a plurality of pallets on a track-like path.