A changeover apparatus for changing between workpiece supports for a machining machine. The changeover apparatus has a base frame with a carrier apparatus for the workpiece supports, which are vertically movable by the carrier apparatus, with the result that one of the workpiece supports can be transferred into a working plane in which the workpiece support is moved from the carrier apparatus into the machining machine and guided out therefrom. A lifting apparatus acts between the base frame and the carrier apparatus and by way of which the carrier apparatus can be vertically moved relative to the base frame for one workpiece support to take up a first lifting position or a further lifting position in the working plane. The lifting apparatus contains a slotted guide, which movably actuates the carrier apparatus with the workpiece supports together between the first lifting position and the further lifting position.

The invention relates to a handling system (1000) comprising a handling device (100) that has a carrier device (20) and a handling means (30) which is carried by the carrier device (20), intended for handling workpiece pallets (101, 101a, 101b), and comprises an exchange device (40) having at least two receiving spaces (41a, 41b) designed for receiving workpiece pallets (101, 101a; 101b), and the handling means (30) being designed to move the exchange device (40) relative to the carrier device (20) in a first movement direction X in such a way that both receiving spaces (41a, 41b) are moved together, characterized in that the handling means (30) is also designed to decouple a workpiece pallet (101a, 101b) which is handled by the handling means (30) and received in one of the at least two receiving spaces (41a, 41b) from the exchange device (40) via at least one decoupling device (42a, 42b) in such a way that the decoupled workpiece pallet (101a; 101b) substantially retains its position relative to the carrier device (20) during a movement of the exchange device (40) in the first movement direction X.

A machining center is provided, which can complete replacement of processed works on stock shelves in a work storage section with unprocessed works within a time period significantly shorter than those in conventional techniques and improve the efficiency of an entire processing process. In the machining center, a cover surrounding the work storage section includes an opening portion where rear surface regions of the stock shelves are exposed, a stock shelf access door that closes the opening portion and is driven to be opened and closed, a locking device for the stock shelf access door, a unlocking mechanism that is operable from the outer side of the cover to unlock the locking device, and a door opening/closing detection device that detects an opened or closed state of the stock shelf access door. A control unit of a CNC device includes an interlocking function of disabling the unlocking mechanism while an automatic pallet changer is driven, and a safety control function of prohibiting, based on a detection signal from the door opening/closing detection device, a drive unit of the automatic pallet changer from being driven while the stock shelf access door is in the opened state.