This invention relates to a fastener installation tool and more particularly to a key and a key holder for the fastener installation tool.
Threaded fasteners are frequently used in loose and interference fit applications in which it is difficult to work from both sides of workpieces to be secured together. In such applications, it has been the practice to use a fastener installation tool having a key which is inserted into a broached recess of a fastener to hold the fastener stationary while a non-circular threaded nut is threaded on the fastener with the installation tool. When the nut is threaded on the fastener with the tool and the fastener is restrained against rotation by the key to secure the workpieces together in a fastened joint, the fastener is set.
In the prior art, springs were used to prevent the key from rotating relative to the fastener during installation of the nut. Oftentimes, the spring would fatigue and fail during the installation process which requires replacement of the spring in a time consuming process. Because the spring fatigues, the spring was typically manufactured from large diameter spring stock which makes it difficult for an operator of the installation tool to keep the key engaged in the recess of the fastener during the installation process. Without proper engagement of the key with the recess of the fastener, the nut will not thread on the fastener in a reliable manner. Unreliable installations are not acceptable in mission critical applications. Also, a problem that exists with this type of fastener installation tool is the tendency of the key to twist or otherwise deform. Additionally, changing the key after damage or to a different sized key is a relatively slow procedure when a spring made from a large diameter spring stock is used to prevent the key from rotating relative to the fastener during installation of the nut.
It is an object of the invention to provide a key for a fastener installation tool that has an improved key holder that provides resistance to twisting deformation or bending of the key.
It is another object of the invention to provide a key for a fastener installation tool that can be quickly changed to replace a damaged key or a different size.
It is an additional object of the invention to provide a key holder for a fastener installation tool that provides anti-rotation to the key of the fastener installation tool.
These objects of the invention are achieved by providing a fastener installation tool of the type used for installing a threaded nut with a non-circular external surface onto a threaded fastener of the type having a non-circular recess in an end of the fastener that matingly engages with a male member that has a complementary shaped non-circular tip end to the non-circular recess. In general, the fastener installation tool has a head, a gear, a socket, a key, a key holder and a spring. The gear is disposed within the head, is rotatably operable and has a non-circular bore. The socket has a non-circular seat configured to matingly engage the non-circular nut that has a complementary shaped non-circular external shape to the non-circular seat. The socket also has a shaft with a non-circular external surface and a tubular bore internal surface. The shaft matingly engages within the bore of the gear having a complementary shaped non-circular shape to the non-circular external surface of the shaft. The key has a shank with a non-circular external surface and a tip end with a non-circular external surface. The shank of the key is disposed within the tubular bore of the shaft. The tip end of the key is configured to matingly engage with a complementary shaped non-circular recess in the fastener of the type having the non-circular recess in the end of the fastener. The key holder has a non-circular aperture that matingly engages the shank of the key having a complementary shaped non-circular shape to the non-circular aperture. The key holder is attached to the exterior surface of the head. The spring has one end of the spring attached to the key and another end of the spring attached to the head. Also, the key, key holder and spring described in this paragraph are available as a kit for retrofitting a fastener installation tool that has a head, a gear and a socket of the type described in this paragraph.
With reference to
With reference to
The key 16 additionally has a bore 52 located adjacent to an end opposite to the tip end 40. One end of the spring 22 is disposed within the bore 52 and another end of the spring 22 is secured to the head 14 with fasteners. The spring 22 operates to bias the key 16 along a longitudinal axis of the shaft 38 of the socket 20. In an alternative embodiment, one end of the spring 22 could be secured within a slotted groove (not shown) disposed in an end of the key 16 opposite to the tip end 40 and another end of the spring 22 could be secured to the head 14 with fasteners. Other approaches to securing the spring 22 to the key 16 could be used as well.
In the prior art, a large gauge spring was typically used to provide a key with anti-rotation of the key relative to the fastener, to bias the key along a longitudinal axis of the shaft of the socket. Conversely, the key holder 18 of the instant invention which provides anti-rotation of the key 16 relative to the fastener 24 during installation of the fastener 24 allows the use of a spring 22 with a smaller gauge that is only used to bias the key 16 along a longitudinal axis of the shaft 38 of the socket 20 and retain the key 16. Use of a spring 22 with a smaller gauge facilitates replacement and removal of the key 16 without the need of additional tools needed to manipulate a spring made from large diameter spring stock.
The exterior surface of the shaft 38 of the socket 20 has a non-circular shape that is disposed in a slip fit within a non-circular bore of a gear 56 so the socket 20 rotates with the gear 56 during actuation of the fastener installation tool 10. The socket 20 also has non-circular seat 58 that is adapted to receive a complementary shaped non-circular threaded nut 44 to be secured to the threaded fastener 24. While a standard threaded nut 44 is shown in
As shown in
As shown in
In operation, the installer typically starts rotation of the nut 44 onto the threaded shank 64 of the fastener 24. Upon initial engagement, the tip end 40 is received into the recess 42, whereas the nut 44 is received into the seat 58. In this regard, the biasing spring 22 positions the tip end 40 to protrude axially beyond the nut 44 and seat 58.
When initial engagement between the tip end 40 and the recess 42 occurs, the fastener installation tool 10 is actuated to rotatably drive the socket 20. This rotatably advances the nut 44 onto the threaded shank 64. During this motion, the key 16 retains the shank 64 against rotation relative to workpiece 30, workpiece 32 and the socket 20. Nut 44 advancement is accompanied by the key 16 retracting within the head 14, until the nut 44 reaches the final installed position. Once the nut 44 reaches the final installed position, installation of the fastener 24 is complete.
Having described the presently preferred embodiments of the invention, it is to be understood that the invention may be otherwise embodied within various functional equivalents within the scope of the appended claims.