Patent Publication Number: US-6983674-B1

Title: Device and method for delivering an impact

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to impacting devices and methods, and in particular, to a moving weight that provides a secondary impact. 
   2. Description of Related Art 
   Impact devices such as hammers, axes, icebreakers, scrapers, and the like deliver a blow by swinging, pushing, or otherwise thrusting the device against an object. Upon impact the kinetic energy of the device is rapidly transferred to the object for the purpose of driving a nail, fragmenting ice, splitting wood, etc. This type of impact is not always the most effective means of energy transfer. 
   In FIG. 1 of U.S. Pat. No. 4,314,593 when a hammer  16  strikes an object, auxiliary hammer  28  overcomes a ball detent, swings free, and impacts the back of hammer  16  causing a second impact. 
   German Patent 232,168 shows a sledge hammer with a hinged appendage. 
   In U.S. Pat. No. 1,341,373 a center punch  7 / 8  may be placed against a target. Trigger  30  may then be squeezed to raise hammer  23  before releasing it so that leaf spring  25  can drive hammer  23  against anvil  9 . 
   In FIG. 2 of U.S. Pat. No. 4,458,415 a hammer  15  can slide along rod  14  to deliver an impact against stop  17  and thereby deliver a blow through ice-chopping blade  12 . In the embodiment of  FIG. 3 , when hammer  15   a  strikes stop  17 , spring-biased auxiliary hammer  22  continues to travel and provides a second impact. This reference describes using the device for chopping ice, cutting through asphalt, or for tools for stripping worn shingles from a roof. See also U.S. Pat. No. 3,568,657. 
   In U.S. Pat. No. 3,601,204 a steel ball  23  initially rests in conical seat  14  until the housing arm (mounted on pivot  26 ) hits extension  27 . Thereafter ball  23  hits the inside end of rod  18 , which in turn impacts the type palette  32 . 
   In U.S. Pat. No. 911,591 a projectile is shown making an initial impact in FIG. 5 followed by a secondary impact from ball J. 
   Accordingly, there is a need for an improved impact device that is able to transfer energy in a more effective way. 
   SUMMARY OF THE INVENTION 
   In accordance with the illustrative embodiments demonstrating features and advantages of the present invention, there is provided an impact device including a handle attached to an impact head that has a guideway. A weight is reciprocatably mounted on the head and can move along the guideway between a first position and a second position in response to motion of the head. 
   In accordance with another aspect of the invention, there is provided an impact device including an impact head attached to a handle. A weight is mounted on the head to reciprocate between a first position and a second position in response to motion of the head. Also included is a yielding member mounted at the impact head. The weight can recoil against the yielding member in response to motion of the head. 
   In accordance with yet another aspect of the invention, a method is provided for impacting an object through the use of a weight reciprocatably mounted on an impact head. The method includes the step of moving the impact head to bring the weight to a first position. Another step is hitting the object with the impact head in a manner to move the weight in a straight line from the first position to a second position. 
   In accordance with still yet another aspect of the invention, a method is provided for impacting an object through the use of a yielding member and a weight reciprocatably mounted on an impact head. The method includes the step of moving the impact head to bring the weight to a first position. Another step is hitting the object with the impact head in a manner to move the weight to a second position. The weight recoils against the yielding member at either the first position or the second position. 
   By employing apparatus and methods of the foregoing type, an improved impact technique is achieved. In one preferred embodiment, a hammer, axe and the like have an annular weight slidably mounted on a shaft that acts as a guideway. In one embodiment an optional helical compression spring is fitted on a guideway shaft behind the sliding annular weight. With this arrangement a user can rhythmically swing a hammer so the sliding annular weight will retract at the start of the forward motion, rebound off the compression spring and then slide forward to provide a secondary impact immediately after the primary impact caused when the main body of the hammer strikes the target object. 
   In some embodiments the sliding weight will be near the forward end of a hammer head, while in other embodiments the sliding weight will be at the back end. Also, in some embodiments a nail-removing claw will be located behind the guideway supporting the sliding weight. In still other embodiments the impact device may have two striking surfaces on opposite sides of the sliding weight so the device can be swung in two different directions in order to be used in two different modes. In particular, if the impact device employs a compression spring the device can be used where the secondary impact is applied either in a first mode directly or in a second indirect mode through the compression spring. 
   In other embodiments the reciprocating weight mechanism is adjustable. For example, the length of travel of a reciprocating weight can be adjusted by adjusting the exposed length of a shaft that supports the reciprocating weight. Alternatively, the position of an outer stop on a shaft supporting the weight can be adjusted. In still other embodiments, the impact device can be provided with a variety of replaceable springs and support shafts to allow alteration of the characteristics of the weight mechanism. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above brief description as well as other objects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of presently preferred but nonetheless illustrative embodiments in accordance with the present invention when taken in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is side view of an impact device in accordance with principles of the present invention; 
       FIG. 2  is a longitudinal sectional view of a fragment of the device of  FIG. 1  that supports the moveable weight; 
       FIG. 3  is a longitudinal sectional view of the fragment of  FIG. 2  fitted with a spring cover, and with its moveable weight repositioned; 
       FIG. 4  is a longitudinal sectional view of a fragment of a device that is an alternate to that of  FIG. 3 ; 
       FIG. 5  is a longitudinal sectional view of a fragment of a device that is an alternate to that of  FIGS. 3 and 4 ; 
       FIG. 6  is a longitudinal sectional view of a fragment of a device that is an alternate to that of  FIGS. 3–5 ; 
       FIG. 7  is a detailed side view of an impact device that is an alternate to that shown in  FIG. 1 ; 
       FIG. 8  is a detailed side view of an impact device that is an alternate to that shown in  FIG. 1 ; and 
       FIG. 9  is a detailed side view of an impact device that is an alternate to that shown in  FIG. 1 . 
       FIG. 10  is a detailed elevational view of an impact device that is an alternate to that shown in  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIGS. 1 and 2 , the illustrated impact device has a hammer head  10 , also referred to as an impact head. A handle  12  is attached below impact head  10  in alignment with the central region  14  of head  10 . The forward end of impact head  10  is formed into a primary outer striker  16  having a shape similar to those found in conventional hammers. Extending backwardly from central region  14  is a shaft  18  acting as a guideway for weight  20 . Weight  20  is a metal annulus having a weight of between 5 to 250 grams, although the actual weight will be chosen depending upon the impact desired when following the motions described hereinafter. 
   Guideway  18  may be a cylindrical shaft having a length of between 1.5 to 6.0 inches (3.8 to 15.2 cm), although the actual length will be chosen depending upon the desired characteristics and timing of the secondary impact to be described presently. The forward end of guideway  18  has a flanged stop  22  acting as an impact surface for weight  20 . The aft end of guideway  18  has a flanged stop  24 . 
   A helical compression spring  26  is mounted between stop  24  and weight  20  to act as a yielding member against which weight  20  can recoil or rebound. Accordingly, weight  20  is free to move in a straight path between a first position where spring  26  is fully or partially compressed to a second position against stop  22 . When uncompressed, spring  26  preferably occupies 20% to 60% of the length of guideway  18 . Also, spring  26  preferably has a spring constant and overall configuration that permits about 2% to 30% compression of the spring when weight  20  rests statically against the spring with guideway  18  vertical. Alternatively, spring  26  may be configured to compress about 50% to 95% when the user rhythmically swings the device when, for example, driving a nail. Accordingly, spring  26  will be tailored to accommodate the vigor and rhythm of individual users. 
   A bifurcated structure  28  projecting backwardly behind stop  24  acts as a nail-removing claw and has a configuration similar to that found on conventional claw hammers. 
   Referring to  FIG. 3 , the device of  FIG. 2  is fitted with a flexible sleeve  30  shown herein as an elastomeric bellows having an outer lip  32  designed to fit around stop  24  and an inner lip  34  designed to fit between spring  26  and a thrust washer  36 . 
   Referring to  FIG. 4 , the illustrated, modified guideway is an alternative that shown in  FIG. 2 . Components corresponding to those previously illustrated in  FIGS. 1 and 2  bear the same reference numeral but increased by 100. Instead of a shaft-type guideway, impact head  110  has a tubular guideway  118  threaded onto threaded stub  110 A. Mounted in the distal end of the tunnel  118 A of guideway  118  is a helical compression spring  126 . A spherical weight  120  is mounted in the proximal end of tunnel  118 A. A thrust disk  138  is slidably mounted between spring  126  and weight  120 . Similar to the previous embodiment, the end of guideway  118  is fitted with nail-removing claw  128 . 
   Referring to the illustrated, modified impact device of  FIG. 5 , components corresponding to those previously illustrated in  FIGS. 1 and 2  bear the same reference numerals but increased by 200. Specifically, impact head  210  has a modified guideway shaft  218 , bordered on its forward end by flange  224  and its aft end with a flange  224 . A cup-shaped weight  220  is slidably mounted on shaft  218 . Weight  220  has a proximal lip  220 A that engages flange  224  and captures weight  220  on shaft  218 . 
   Referring to the illustrated, modified impact device of  FIG. 6 , components corresponding to those previously illustrated in  FIGS. 1 and 2  bear the same reference numerals but increased by 300. Specifically, guideway  318  is fitted into the bore  310 A of impact head  310 . The depth of insertion of guideway  318  is maintained by screwing set screw  340  in flange  324  against guideway  318 . In some embodiments, guideway  318  may be a threaded shaft that is screwed into bore  310 A, which would then be threaded as well. 
   The distal end of guideway shaft  318  is fitted with a stop  324 . While this stop could be an integral terminal flange, in this embodiment stop  324  is a thrust washer backed by a hex nut  324 A. Much like before, an annular weight  320  is slidably mounted on guideway shaft  318 . A helical compression spring  326  is mounted between weight  320  and stop  324 . 
   In this arrangement the exposed length of guideway shaft  318  can be adjusted by changing its depth of insertion by using set screw  340 . Also, guideway length can be adjusted by turning hex nut  324 A to adjust the position of stop  324 . Adjustments can also be made by replacing the guideway and therefore guideway  318  may be considered a substitute guideway in this embodiment. Also, hex nut  324 A and thrust washer  324  may be temporarily removed so that spring  326  can be replaced to change the device&#39;s recoil or rebound characteristics. 
   Referring to the illustrated, modified impact device of  FIG. 7 , components corresponding to those previously illustrated in  FIGS. 1 and 2  bear the same reference numerals but increased by 400. A significant difference with this embodiment is the location of the annular weight  420  on the forward side of impact body device  410 . On the other hand, the central portion  414  and claw  428  of impact device  410  are similar to the configuration found on conventional claw-type hammers. The forward end of impact device  410  has a guideway  418  in the form of a shaft on which annular weight  420  is slidably mounted between helical compression spring  426  and primary outer striker  416 . 
   Referring to the illustrated, modified impact device of  FIG. 8 , components corresponding to those previously illustrated in  FIGS. 1 and 2  bear the same reference numerals but increased by 500. In this embodiment impact device  510  has two striking surfaces: primary outer striker  516  and secondary outer striker  542 . Guideway  518  is located between secondary outer striker  542  and the central portion  514  of impact device  510 . The previously mentioned helical spring has been replaced with an annular elastomeric element  526  that may be made of a rubber-like material, a foam, or a yielding plastic material. 
   It will be appreciated that the foregoing reciprocating weight technology can be employed in a number of environments where it is desirable to provide a strong thrust or impact. Such force may be useful with brooms, scrapers, pry bars, shingle-removing bars, etc. 
   Referring to  FIG. 9 , the foregoing reciprocating weight technology is applied to an axe head  610  having a cutting-edge  616 . As before, components corresponding to those previously illustrated in  FIGS. 1 and 2  bear the same reference numerals but increased, now by 600. Specifically, a guideway shaft  618  extends backwardly from the aft end of ax head  610 . Annular weight  620  is slidably mounted on guideway  618  next to helical compression spring  626 , all of which are captured on guideway  618  by its outer stop  624 . 
   Referring to  FIG. 10 , the foregoing reciprocating weight technology is applied to an icebreaker. Once again, components corresponding to those previously illustrated in  FIGS. 1 and 2  bear the same reference numerals but increased, now by 700. Unlike a hammer or an ax, handle  712  is in alignment with guideway  718  and may be a simple extension of the handle. In particular, guideway  718  is bordered on one side by flanged stop  724 , and on the opposite side by stop plate  724 . Annular weight  720  is slidably mounted on guideway  718 . A helical compression spring  726  is mounted around guideway  718  between weight  720  and stop  724 . 
   To facilitate an understanding of the principles associated with the foregoing apparatus, its operation will be briefly described. Referring to  FIGS. 1 and 2 , a user may grasp handle  12  in the usual fashion, swing device  10  back and then swing it forward so that striker  16  hits a target such as a nail. It is important to note that during the backswing weight  20  gathers kinetic energy while it stays against stop  22  and accelerates backwardly. 
   When device  10  reverses direction at the conclusion of the backswing, weight  20  will move from the second position shown in phantom in  FIG. 1  to a first position bearing against spring  26 . Depending upon the vigor of the backswing and forward swing, weight  20  will compress spring  26  accordingly. Compression of spring  26  will continue so long as device  10  is moving forward with significant acceleration. This acceleration may decline because of the user&#39;s swinging style or because the striker  16  hits its target, for example, a nail. 
   In any event, weight  20  will now be driven forward by the potential energy stored in spring  26 , which will add to the momentum already achieved by the weight during the forward swing of device  10 . Therefore, weight  20  will hit the impact surface provided by stop  22  to provide a secondary impulse that is conveyed through central region  14  to striker  16 . 
   The user may now immediately swing the impact device  10  back to repeat the foregoing process. It will be appreciated that the user can develop a rhythm so that weight  20  effectively bounces rhythmically between its two extreme positions. 
   The foregoing device delivers more energy than a conventional hammer because the kinetic energy imparted to the weight  20  during the backswing is stored in the compression spring  26  and then later used to accelerate the weight and produce an enhanced secondary impact. 
   Also, a secondary impact can be beneficial for certain tasks. In particular, driving an implement into a relatively soft material involves not only breaking an opening for the implement, but overcoming viscous and frictional forces that slow the progress of the implement. These viscous or frictional forces can be overcome by effectively extending the time over which the driving forces occur by means of the rapidly following secondary impact described above. 
   It will be appreciated that the other embodiments operate in a substantially similar manner. In particular, ball  120  ( FIG. 4 ) can rebound off spring  126  and then roll, slide or fly through tunnel  118 A to create a secondary impact at stub  110 . In addition, weight  420  ( FIG. 7 ) will operate in a similar fashion, rebounding off spring  426  before providing a secondary impact on striker  416 . 
   Referring to  FIG. 8 , when a blow is delivered by striker  516 , this embodiment will operate in a similar fashion with weight  520  rebounding off of elastomeric member  526  before hitting impact device  510  to provide a secondary impact. The operation will be different, however, when a user strikes a blow using striker  542 . In that case, weight  520  will tend to remain against the main body of device  510  during the forward swing (or depending on the dynamics, experience a hard bounce and achieve a relative forward motion). 
   When striker  542  hits its target, device  510  will rapidly decelerate and weight  520  will fly forward and impact elastomeric member  526 . Because yielding member  526  is involved, the impulse delivered by weight  520  will be spread out over time, instead of being applied as a short-lived, sharp impulse. This spread-out impulse can be very effective in certain applications. Also, in some applications the user may not want to deliver a sharp blow. For example, when driving a nail into a finished wall in order to hang a picture, one does not want to accidentally drive the nail flush and it is therefore desirable to moderate the blows so that the depth of insertion of the nail can be carefully controlled. 
   It will be noted that a spring is not employed in every embodiment. In particular, the embodiment of  FIG. 5  has no spring. Instead, weight  220  will extend during the forward swing to the position shown in  FIG. 5 . Upon impact, weight  220  will slide on guideway  218  until lip  220 A impacts stop  222  to provide a secondary impact. 
   The operation of the icebreaker of  FIG. 10  is essentially the same as described before, except that the user does not swing the device but thrusts it longitudinally. 
   It is appreciated that various modifications may be implemented with respect to the above described, preferred embodiments. In particular, the illustrated guideway can be made of metal, plastics, or other materials. Also the cross-section of the guideway can be circular, square, polygonal, oval, etc. In some embodiments the guideway may provide a curved path for the weight. While the motion of the weight is shown aligned with the striker, in other embodiments the path of the weight may be aligned differently. While the yielding members is shown mounted on the guideway, in other embodiments, the yielding member can be attached to the weight itself. Furthermore, the various shapes, dimensions and relative positions of illustrated components can be altered in other embodiments depending on the desired size, force, reliability, strength, etc. 
   Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.