Modern industrial facilities can include a number of hazardous areas that should only be accessed when certain safe conditions within the areas are met. These can include areas in which potentially dangerous automated machinery is running. Such areas are typically enclosed within protective structures (e.g., safety cages) having one or more lockable access doors or gates. To ensure that these access doors cannot be opened during unsafe operating conditions, many access doors incorporate electrically actuated locking mechanisms that can be either manually or automatically engaged. Solenoid-driven bolt-actuated safety locks represent one example of such a controllable door lock. These solenoid-driven locks can comprise a locking mechanism (often mounted on the door frame) having a linearly actuating bolt that either advances or retracts when the associated solenoid is energized, and a receptacle (mounted on the door itself) having an opening that receives the bolt when advanced, thereby locking the door.
Bolt-actuated locks such as those described above require accurate alignment between the bolt and the receptacle before the lock can be successfully engaged. However, there are a number of mechanical factors that can hinder proper alignment of the bolt and receptacle. For hinged doors, the swinging of the door on its hinge allows free travel in two directions. Although door frames typically incorporate some type of door stopping mechanism to stop the door at a generally aligned location when in the closed position, the door is still not prevented from drifting to an open position prior to engagement without force being applied against the door manually by an operator. Additionally, excessive door sagging or warping can lead to misalignment in other directions. Sliding safety doors are also prone to lock misalignment, since such doors are susceptible to sideways movement perpendicular to the plane of the door frame. These problems can be particularly troublesome in the industrial settings described above, since the safety gates and doors employed in such environments are sometimes constructed from relatively flexible metal caging or transparent plastic material to allow visibility into the automated processes being executed within the enclosed areas. Since such safety gates lack the rigidity of some other types of doors, accurate lock alignment is rendered more difficult. Moreover, there are a number of general design inefficiencies inherent in typical safety door locking systems, such as the use of separate devices to achieve door stopping, door alignment, and lock alignment.
Bolt actuated locks can also suffer from integrity issues even after the bolt is engaged with the receptacle. Since the stroke of the bolt used to lock the door can be relatively short, such locks can conceivably be bypassed by exerting enough force on the door in the direction of the bolt's stroke to slip the receptacle off the bolt and disengage the lock.
Given the problems described above, there is a need for a safety lock design that ensures consistent and accurate alignment between the locking bolt and the receptacle in all six directions without the need for manual trial-and-error positioning by an operator. It would also be beneficial to improve the overall integrity of bolt-actuated locks such that the lock cannot be bypassed by slipping the receptacle off the end of the bolt while in the locked position.