This invention relates generally to assembly of explosive devices. More particularly, the present invention relates to an apparatus and method for the assembly of blast initiation devices.
It is common practice in blasting operations to initiate the detonation of one or more main explosive charges by transmitting an initiation signal to the charges through initiation signal transmission lines. There are various conventional forms of signal transmission lines, e.g., detonating cord, shock tube, low velocity signal tube, etc. It is often necessary to transfer an initiation signal from a first transmission line to a second transmission line or a plurality of second transmission lines, such as when long distances are involved or when multiple main charges must be initiated. It may also be necessary to amplify the initiation signal from the first line to accomplish the initiation signal transfer to a second line or a plurality of second lines. This may be accomplished by using the initiation signal to initiate a detonator mounted to the first line and disposed in signal transfer relation to the second transmission line or lines. Typically, this is accomplished with a connector device. The connector device includes a body portion having a channel holding the detonator cap and an engaging member for holding one or more signal receiving transmission lines in signal transfer relationship to the detonator cap. The end of the signal transmission line opposing the connector block may be connected to an initiator for initiating a signal in the transmission line or, alternatively, may be connected to another detonator.
An object of the invention is to provide an improved method and apparatus for the assembly of blast initiation devices.
Another object of the invention is to provide an improved method and apparatus for the assembly of blast initiation devices which may be efficiently utilized by a single operator.
Other objects and advantages of the invention will become apparent from the drawings and the specification.
Briefly stated, the invention in a preferred form is a new and improved method for assembly of a blast initiation device. The invention also encompasses an apparatus for use with the method. The apparatus in preferred form is an inventive single operator workstation.
The workstation comprises a tagger device for fixing an identification tag to a predetermined length of a transmission line. A crimp device is located on the workstation. The workstation operator loads a detonator within an aperture in the crimp device, inserts a bushing within the detonator and places the end of the transmission line within the bushing. Actuation of the crimp device crimps the outside of the detonator at a predetermined location and to a predetermined depth to securely fasten the transmission line and bushing to the detonator. In a preferred embodiment, the crimp device comprises a dual crimp head with two apertures. The workstation operator loads a desired detonator in each aperture of the dual crimp head. A bushing is inserted within each detonator and both ends of the transmission line are inserted within a respective bushing and held adjacent an explosive charge within the detonator. Actuation of the dual crimp head crimps each of the detonators at a predetermined location and to a predetermined depth substantially simultaneously. The detonator crimping operation creates a cannelure at least partially around the circumference of the detonator.
The operator places a connector block over one crimped detonator. The workstation includes a blocker device adjacent the cap crimp device. The connector/detonator/transmission line subassembly is placed in the blocker device. The blocker device drives a locking member into the connector block. The locking member includes spaced legs, each of which is driven into an opposing side of the detonator cannelure. The blocker device fixes the position of the detonator/transmission line within the connector block. It should be realized that the inventive workstation is arranged so that a single operator can safely and expediently operate all of the above devices and handle the high explosive components to create an assembled blast initiation device.
Preferably, the workstation is adjacent a feeder to provide a supply of predetermined lengths of coiled transmission line to the operator and includes feeders or holders to provide the operator with a ready supply of detonator, bushings and connector blocks. Naturally, the component feeders are designed and located so that explosive components, such as detonators while available for quick access by the operator are also safely contained. The workstation is preferably located adjacent a bundler. The bundler receives a predetermined number of blast initiator assemblies; bands the predetermined number of assemblies together; and transfers the banded assemblies to a pack-out station.
In use of a preferred embodiment of the inventive workstation, an operator loads a desired detonator in each of the two crimp head apertures. A bushing is placed within each of the detonators. The operator receives a predetermined length of coiled transmission line and attaches a tag with the tagger device adjacent one end of the line. The operator inserts each end of the transmission line into a respective bushing/detonator subassembly so that the end of the transmission line is adjacent the explosive charge in the detonator. Actuation of the crimp head causes a crimp to be formed in the metal housing of the detonator, securing the detonator through the bushing to the transmission line. The operator removes from the crimp head aperture one end of the transmission line with the now attached detonator and places the attached detonator within the bore of a connector block. The connector block/detonator/transmission line subassembly is placed in a blocker device. The blocker device drives a locking member through the connector block so that the locking member legs are driven into the cannelure formed during the detonator crimp operation. This operation locks the detonator to the connector block. The operator removes the locked connector block/detonator/transmission line subassembly from the blocker and the opposing crimped detonator/transmission line end from the crimp head aperture. The operator places the assembled blast initiator device in a bundler. When a predetermined number of initiator devices have been placed in a bundler, the operator actuates the bundler to band the predetermined number of devices together into a bundle and to transfer the bundled devices to a pack-out station for subsequent packaging.