A shock-absorbing bolt for a crossbow comprises a shaft, a forward flange, and a shock-absorbing mechanism coupled to the shaft or the forward flange. The forward flange is coupled to a forward end of the shaft and has a forward surface with a transverse area that is greater than about three times l
A shock-absorbing bolt for a crossbow comprises a shaft, a forward flange, and a shock-absorbing mechanism coupled to the shaft or the forward flange. The forward flange is coupled to a forward end of the shaft and has a forward surface with a transverse area that is greater than about three times larger than a transverse area of the shaft. A tapered tip can be attached to and protrude from the forward surface of the forward flange. The shock-absorbing mechanism is arranged so that, upon acceleration or deceleration of the bolt, kinetic energy of the bolt is dissipated by viscoelastic, viscous, or frictional forces within the bolt.
대표청구항▼
1. An article comprising a shock-absorbing bolt for a crossbow, wherein the bolt comprises: (a) a rearward, outer shaft;(b) a forward, inner shaft slidably received in a forward end of the outer shaft, wherein the inner shaft or the outer shaft is arranged to limit forward movement of the inner shaf
1. An article comprising a shock-absorbing bolt for a crossbow, wherein the bolt comprises: (a) a rearward, outer shaft;(b) a forward, inner shaft slidably received in a forward end of the outer shaft, wherein the inner shaft or the outer shaft is arranged to limit forward movement of the inner shaft relative to the outer shaft and to retain a rearward portion of the inner shaft within the forward end of the outer shaft;(c) a forward flange attached to a forward end of the inner shaft, which forward flange has a forward surface with a transverse area that is greater than about three times larger than a transverse area of the outer shaft;(d) a rearward washer slidable along the inner shaft with the inner shaft passing through a hole in the rearward washer, wherein the outer shaft limits rearward movement of the rearward washer along the inner shaft;(e) a forward washer positioned between the forward flange and the rearward washer with the inner shaft passing through a hole in the forward washer; and(f) a viscoelastic shock absorber slidable along the inner shaft between the forward and rearward washers with the inner shaft passing through a hole in the shock absorber. 2. The article of claim 1 wherein the outer shaft comprises an insert received and retained within the forward end of the outer shaft, the inner shaft extends through and is slidable within the insert, and the inner shaft includes a retainer attached to a rearward end of the inner shaft, which retainer is arranged to prevent entry of the retainer into a rearward end of the insert, thereby limiting forward movement of the inner shaft relative to the outer shaft. 3. The article of claim 1 wherein the bolt further comprises a tapered tip attached to and protruding from the forward surface of the forward flange. 4. The article of claim 1 wherein the forward washer is attached to the inner shaft or the forward flange so as to substantially prevent movement of the forward washer along the inner shaft. 5. The article of claim 1 wherein the forward washer is slidable along the inner shaft, and the forward flange limits forward movement of the forward washer along the inner shaft. 6. The article of claim 1 wherein (i) a rearward surface of the forward washer is concave and a forward surface of the rearward washer is concave, and (ii) the concave washer surfaces are arranged to limit transverse expansion of the shock absorber upon longitudinal compression thereof between the forward and rearward washers upon relative movement of the washers toward one another along the inner shaft. 7. The article of claim 1 wherein the elastomeric shock absorber comprises a polyurethane viscoelastic polymer. 8. The article of claim 1 wherein the forward flange, the forward washer, and the rearward washer comprise metal. 9. The article of claim 1 wherein mass of the bolt is greater than about 1000 grains. 10. An article comprising a shock-absorbing bolt for a crossbow, wherein the bolt comprises: (a) a shaft;(b) a forward flange attached to a forward end of the shaft, which forward flange has a forward surface with a transverse area that is greater than about three times larger than a transverse area of the shaft;(c) a rearward washer slidable along the shaft with the shaft passing through a hole in the rearward washer;(d) a forward washer positioned between the forward flange and the rearward washer;(e) a viscoelastic shock absorber slidable along the shaft between the forward and rearward washers with the shaft passing through a hole in the shock absorber; and(f) a retainer attached to the shaft and positioned to limit rearward movement of the rearward washer along the shaft. 11. The article of claim 10 wherein the bolt further comprises a tapered tip attached to and protruding from the forward surface of the forward flange. 12. The article of claim 10 wherein the forward washer is attached to the shaft or the forward flange so as to substantially prevent movement of the forward washer along the shaft. 13. The article of claim 10 wherein the forward washer is slidable along the shaft, and the forward flange limits forward movement of the forward washer along the shaft. 14. The article of claim 10 wherein (i) a rearward surface of the forward washer is concave and a forward surface of the rearward washer is concave, and (ii) the concave washer surfaces are arranged to limit transverse expansion of the shock absorber upon longitudinal compression thereof between the forward and rearward washers upon relative movement of the washers toward one another along the shaft. 15. The article of claim 10 wherein the bolt further comprises an elastomeric washer positioned between the rearward flange and the retainer. 16. The article of claim 10 wherein the elastomeric shock absorber comprises a polyurethane viscoelastic polymer. 17. The article of claim 10 wherein the forward flange, the forward washer, and the rearward washer comprise metal. 18. The article of claim 10 wherein mass of the bolt is greater than about 1000 grains. 19. An article comprising a shock-absorbing bolt for a crossbow, wherein the bolt comprises: (a) a shaft;(b) a forward flange coupled to a forward end of the shaft, which forward flange has a forward surface with a transverse area that is greater than about three times larger than a transverse area of the shaft;(c) a shock-absorbing mechanism coupled to the shaft or the forward flange, which mechanism is arranged so that, upon acceleration or deceleration of the bolt, kinetic energy of the bolt is dissipated by viscoelastic, viscous, or frictional forces within the bolt; and(d) a tapered tip attached to and protruding from the forward surface of the forward flange. 20. The article of claim 19 wherein: (i) the shock-absorbing mechanism includes a hollow cylinder, a piston reciprocally movable within the cylinder and dividing the cylinder into first and second chambers, a fluid in the first and second chambers, and one or more channels or orifices arranged to permit restricted fluid flow between the first and second chambers;(ii) the shock-absorbing mechanism is arranged so that acceleration or deceleration of the bolt results in movement of the piston within the cylinder and concomitant viscous flow of the fluid between the first and second chambers through the one or more channels or orifices, thereby dissipating at least a portion of the kinetic energy of the bolt. 21. The method of claim 19 wherein: (i) the shock-absorbing mechanism includes a viscoelastic member and at least one movable member;(ii) the shock-absorbing mechanism is arranged so that acceleration or deceleration of the bolt results in movement of the movable member that deforms the viscoelastic member, thereby dissipating at least a portion of the kinetic energy of the bolt.
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