IMPROVEDBOLT CUTTER BACKGROUND
This invention relates to an improved bolt cutting device of the type comprising two jaws in face to face relationship which are pivotally connected together and each having an end adapted for connection to a handle. Each of the jaws includes a bevelled cutting edge arranged to rotate toward and away from each other but not beyond each other in the same plane of rotation. Operation of the handles causes the jaws to move between open and closed positions thereby severing the bolt or similar elongate member placed therein.
These jaw assemblies are common with bolt cutting devices wherein each of the jaws is mounted for rotation around its respective pivot pin or bolt. The pivot bolts are carried on a pair of straps, one strap on each flat side of the jaw pair. The handles are normally adjustable to permit the jaws to be adjusted to the correct position wherein there is a small clearance between the cutting edges of the jaws in the closed position.
Bolt cutting devices employing the jaw assemblies described above comprise a relatively large number of components which renders the assembly relatively complicated in terms of manufacturing and assembly. The improved bolt cutter of the present invention overcomes the deficiencies of the prior art and provides a bolt cutter of less weight to ease manipulation and less parts to reduce maintenance requirements.
An example of a prior bolt cutter is the B. B. Brunosson U.S. Patent No. 3,906,631 which shows a jaw assembly for a bolt cutting device with a single pivot for the jaws.
The M. Blanc U. S. Patent No. 3,949,473 discloses a bolt cutter with each jaw pivoted about its respective pin and mounted between parallel plates.
U. S. Patent No. 4,058,893 to A. Z. Boyajian discloses a bolt cutter with one stationary jaw and a movable jaw actuated through a roller cam arrangement by one of the handles. The A. Z. Boyajian U. S. Patent No. 4,249,308 discloses another bolt cutter with one stationary jaw and one movable jaw actuated by a cam roller and cam groove arranged to enable the cam groove to change its contour and thereby change the mechanical advantage.
U. S. Patent No. 4,569,132 to R. A. Hill discloses a compound-action scroll snip which uses a plurality of washers as a friction reducing means between pivoting members. U. S. Patent No. 5,058,272 to G. J. Steube discloses a hydraulically powered bolt and cable cutter utilizing a scissor mechanism to actuate the cutter jaws. SUMMARY
The improved bolt cutter includes a pair of jaws rotatable about a common axis with a pair of handles rotatably interconnected with the jaws. Each handle includes a boss which pivots about a common axis to operate the jaws between open and closed positions. An adjustment means to
compensate for wear of the jaws and maintain the jaws in substantially face to face contact in the closed position includes a pair of eccentric bushings disposed between the handle bosses on a common axis. The eccentric bushings include a plurality of protrusions which engage complementary recesses on the handle bosses to prevent rotation of the eccentric bushings with respect to the pair of handles when the handles are operated.
An object of the present invention is to provide an improved bolt cutter which minimizes the number of components to reduce maintenance requirements.
Another object of the present invention is to provide an improved bolt cutter of less weight to ease manipulation. BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and advantages of the present invention are set forth below and further made clear by reference to the drawings, wherein:
Figure 1 is an plan view of a prior bolt cutter with each jaw pivoting about its respective pivot pin. Figure 2 is an exploded view of the improved bolt cutter of the present invention.
Figure 3 is a plan view of the improved bolt cutter of the present invention.
Figure 4 is a cross-sectional view of the cutter head of Figure 3 taken along lines 4-4.
Figure 5 is a plan view of the underside of the eccentric bushing showing the offset of the bore with respect to the centerline of the bushing. Figure 6 is a cross-sectional view of the eccentric bushing of Figure 5 taken along lines 6-
6. DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to Figure 1, a prior bolt cutter, denoted generally by numeral 10, is shown with the jaws closed. Jaws 12 and 14 are maintained in opposed relationship by flat plates or straps 16. Jaws 12 and 14 each pivot about their respective pivot bolts 18 and 20 when actuated by handles 22 and 24. Handles 22 and 24 are pivotally connected to jaws 12 and 14 by bolts 26 and 28 and are rotatable about pivot pin 30 on a common pivot axis. Compensation for the wear of jaws 12 and 14 is by means of adjustment bolt 32 in handle 24.
The improved bolt cutter, denoted generally by numeral 40, is shown in Figure 2 in an exploded view. Bolt cutter 40 includes cutter head 42 comprised of left jaw 44 and right jaw 46 which are interchangeable. Jaws 44 and 46 include beveled cutting edges 48 and 50 and are secured in opposing relationship by jaw bolt 52 with thread locking compound, such as Loctite thereon, washers 53 and locking jaw nut 54. Handles 56 and 58 are interchangeable elongate members of a generally I shaped cross section formed of a suitable material as cast aluminum or
a zinc aluminum alloy. One end of handles 56 and 58 is enlarged with raised lip or stop 60 formed thereon to control the position of handles 56 and 58 in the closed position.
Adjacent stop 60 on each handle 56 and 58 are center pivot hole 62 and handle hole 64. Handle holes 64 have wear bushings 65 positioned therein and are formed of a suitable wear resistant material as steel. As seen more clearly in Figures 3 and 4, the rear portion of jaws 44 and 46 have holes 47 drilled therethrough to receive handle bolts 66 with thread locking compound, such as Loctite thereon, which are closely received in steel bushing 65 in handle holes 64 to secure jaws 44 and 46 to handles 56 and 58 with lock nuts 67 and washers 67a. The side of center pivot hole 62 opposite handle stops 60 has a plurality of hemispherical recesses 68 formed therein and evenly spaced circumferentially. Center pivot bushings 70 have complementary protrusions 72 formed thereon and an eccentrically drilled hole 74 therein as seen in greater detail in Figures 5 and 6.
Center pivot bushings 70 are assembled to handles 56 and 58 as shown in Figures 2, 3 and 4 and secured therein by bolt 76 which is cross-drilled to receive locking pin 79 after castellated nut 78 is threaded thereon. In this position, protrusions 72 of center pivot bushings 70 engage complementary recesses 68 of handles 56 and 58 to prevent rotation of center pivot bushings 70 with respect to handles 56 and 58. Cushion grips 80 are installed on the rear portion of handles 56 and 58. During initial assembly and subsequent use, the optimum positioning of cutting edges 48 and 50 is obtained as follows. With locking pin 79 removed, castellated nut 78 is loosened slightly on bolt 76 to allow center pivot bushings 70 to be moved away from handles 56 and 58 thereby disengaging protrusions 72 from recesses 68. This allows center pivot bushings 70 to be rotated which shifts the position of eccentric hole 74 to change the relative position between handles 56 and 58 and thereby adjust the gap between cutting edges 48 and 50. Castellated nut 78 is then retightened on bolt 76 and pin 79 reinstalled to prevent rotation of center pivot bushings 70 with respect to handles 56 and 58 as previously described.
The construction of our improved bolt cutter and the methods of its application will be readily understood from the foregoing description and it will be seen we have provided an improved bolt cutter which minimizes the number of components to reduce maintenance requirements and provide an improved bolt cutter of less weight to ease manipulation. Furthermore, while the invention has been shown and described with respect to certain preferred embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalent alterations and modifications, and is limited only by the scope of the appended claims.