Abstract:
A hand held-type apparatus for fracturing a gate or riser from a casting subsequent to a foundry pouring process. The apparatus operates off of a driven piston assembly, which upon a stroke of such causes a hammer end of the piston assembly to extend from the apparatus and contact the casting, thereby causing the fracturing of the gate or riser from the casting. The apparatus also includes an assembly for decelerating the driven piston assembly upon a stroke of such, as well as an apparatus for isolating the linear motion of the apparatus from the operator thereof.

Description:
FIELD OF THE INVENTION 
     The present invention relates to equipment used in the foundry industry, and more particularly to the specific equipment used to fracture a riser or flashing from a casting subsequent to the foundry pouring process. Even more particularly, the present invention relates to a hand held single stroke foundry impactor for fracturing a riser from cast products. With even greater particularity, the present invention relates to a hand held foundry impactor having an apparatus for decelerating and absorbing the excess kinetic energy of the impacting rod and piston assembly within the impactor upon a miss or partial miss of the target riser or flashing. Further yet, the present invention relates to a hand held foundry impactor having an apparatus for absorbing the linear kinetic energy of the impactor such that a single operator is able to efficiently and safely operate the impactor without being subjected to the forces generated by the impacting of a cast product by the impactor. 
     BACKGROUND OF THE INVENTION 
     The foundry industry has long been accustomed to the processes associated with the removal of excess cast material from cast products. In the typical foundry operation, the pouring of molten cast into molds inevitably leaves an excess portion of cast material extending from the cast product subsequent to the cooling of the molten material. This excess portion, often termed a neck or riser, is formed as a result of molten cast remaining in the pour hole of the mold during the pouring and cooling process. Once the exterior mold is removed from the cast product, the cast material previously remaining in the mold pour hole becomes riser extending from the cast product. This riser must be removed from the casting in order to yield a finished cast product. 
     Currently, the foundry industry generally relies upon extremely dated, crude, and inefficient technology to remove the excess cast material formed when molten cast is poured into a mold. According to industry custom and practice, foundry operations typically utilize a process following the pouring of a cast product which essentially comprises the steps of removing the entire cast product from the surrounding mold and manually impacting the unwanted excess cast material until fracturing occurs, such that the excess cast material is able to be removed. This manual impacting operation is commonly performed by a worker with crude manual labor implements such as a heavy mallet or sledge hammer. Using these human operated heavy mallets and sledges to impact casting riser often results in near or complete misses of the riser and the subsequent damaging of the casting itself. Additionally, attempting to fracture a riser from a casting with a sledge or mallet will often require many blows at a high level of risk to both the worker and the integrity of the casting. 
     A minority of foundry operations employ manually operated explosive powder driven hammers to fracture a riser from the casting. Although technologically more advanced than mallets and sledge hammers, these explosive powder driven hammers are subject to many of the same problems and limitations associated with the manual sledge and mallet operations. Manually operated explosive powder driven hammers are known to damage the main body of the cast products upon a near or complete miss of the riser intended to be fractured, as the intended fracturing force is then absorbed by the body of the casting causing damage. The explosive powder driven hammers are additionally subject to a limitation and disadvantage in that they are unable to control the level of force generated for each individual impacting, and often impact with excessive force causing damage to the body of the casting. The impacting force delivered by an explosive powder driven hammer is predetermined by the size of the explosive powder casing inserted within the hammer prior to impacting, which is a standard shell casing size and not variable. Explosive powder impacting hammers are additionally cumbersome, inconvenient, and unreliable for foundry use. Manual operation of an explosive powder impactor requires the exchange of a new explosive powder shell after every attempted impact or firing. Explosive powder impacts also require frequent maintenance tear-downs due to the extreme pressures and stresses upon the impactor components. In addition to the above-mentioned methods of fracturing, there are also additional uses of both hydraulic wedges and cutting torches in the industry to remove riser. The use of torches and wedges, although probably predominate in the industry, is nonetheless a very time consuming and inefficient method or process for removing a riser from a cast product. Therefore, there is a well-found need in the foundry industry for an apparatus capable of accurately and efficiently fracturing excess cast material from castings using only a single operator. 
     SUMMARY OF THE INVENTION 
     As a result of the aforementioned need in the foundry industry, it is the object of the present invention to provide a hand held foundry impactor capable of accurately, safely, and efficiently fracturing a riser or excess cast material from a casting. It is a further object of the present invention to provide a hand held single stroke foundry impactor capable of being efficiently and safely operated by a single operator. It is yet a further object of the present invention to provide a hand held single stroke foundry impactor having an apparatus for absorbing the residual kinetic energy of the impactor piston and rod assembly upon a stroke of such. It is still a further object of the present invention to provide a hand held single stroke foundry impactor having a shock absorption assembly attached thereto for isolating the force generated by the impactor from the operator upon actuation of the impactor. Other features, objects, advantages, and methods of use of the present invention will become apparent from a thorough reading of the following description as well as a study of the appended drawings and diagrams. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The apparatus embodying features of the invention are illustrated in the enclosed drawings which form a portion of this disclosure and wherein: 
     FIG. 1 is a perspective view of the hand held impactor; 
     FIG. 2 is a perspective view of the hand held impactor positioned proximate a riser to be fractured from a cast product; 
     FIG. 3 is a detail of the impactor in the ready to fire position; 
     FIG. 4 is a schematic of the impactor valving system; 
     FIG. 5 is a detail of the impactor with the hammer end partially extended; 
     FIG. 6 is a detail of the impactor assembly having the hammer end fully extended with the volume of air in the deceleration chamber partially compressed; 
     FIG. 7 is a cutaway of the impactor showing the cushion piston in both the normal and compressed positions; 
     FIG. 8 is a detail of the shock absorption assembly; and 
     FIG. 9 is a perspective view of the deceleration piston. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings for a better understanding of the principles of operation and structure of the invention, it will be seen that FIG. 1 shows a perspective view of hand held foundry impactor  10 . Generally speaking, impactor  10  is often suspended from an overhead structure via sling  50 , such that nearly all of the impactor  10  weight is supported by the respective overhead structure. Further, in operation, impactor  10  is generally positioned proximate a casting  11  having a riser  12  extending therefrom, as shown in FIG. 2, such that the longitudinal axis of impactor  10  is aligned with riser  12  to be fractured from casting  11 . Subsequent to alignment of impactor  10  with riser  12 , the operator activates impactor  10 , such that riser  12  is impacted and fractured from casting  11  via contact with the impacting end  17  of a force transferring rod  16  as it extends from snout  32 . 
     With particularity, the internal operational components of hand held impactor  10  are clearly illustrated in FIG.  3 . Hand held impactor  10  comprises an elongated outer casing  13  having a concentric inner bore formed therein defining an elongated power barrel  14 . Further, a substantially hollow outer sleeve defining an air reservoir  35  is concentrically positioned about the same axis as power barrel  14  and is in fluid communication with a pressurized air supply. Power barrel  14  contains an elongated piston assembly  15  slidably mounted therein for actuated longitudinal movement within power barrel  14  upon selective pressurization of power barrel  14 , which will be further discussed herein. The upper portion  20  of piston assembly  15  is of sufficient diameter to slidably engage the interior walls of power barrel  14 , while the lower portion  21  of piston assembly  15  is of a sufficiently smaller diameter, such that lower portion  21  is not in contact with the interior walls of power barrel  14  upon longitudinal movement of piston assembly  15 . Piston assembly  15  further includes an elongated force transferring rod  16  extending therefrom along the longitudinal axis of piston assembly  15  proximate the terminating end of lower portion  21 . Force transferring rod includes a longitudinally displaceable terminating impacting end  17  for impacting a riser to be fractured from a casting upon a longitudinal stroke of piston assembly  15  within power barrel  14 . 
     Coaxially affixed to casing  13  immediately adjacent head end  19  of power barrel  14  is a deceleration chamber  23 . Deceleration chamber  23  comprises a longitudinally continuous outer wall forming a substantially cylindrical inner chamber aligned with the longitudinal axis of power barrel  14 . Slidably positioned within deceleration chamber  23  is an annularly shaped deceleration piston  22 , which cooperatively receives force transferring rod  16  therethrough. Deceleration chamber  23  includes a first open end  24  in fluid communication with head end  19  of power barrel  14 , and a second substantially closed end  25  having only a coaxially positioned longitudinally aligned bore  26  formed therein for cooperatively and concentrically receiving force transferring rod  16  therethrough to impactor snout  32 . Open end  24  of deceleration chamber  23  is rigidly mounted to head end  19  of power barrel  14  along the same longitudinal axis as power barrel  14 . Snout  32  is rigidly mounted to closed end  25  of deceleration chamber  23  along the longitudinal axis of power barrel  14  and operates both to communicate force transferring rod  16  and impacting end  17  to the exterior of impactor  10 , and to align impacting end  17  with the target riser  12  to be fractured from a casting  11 . Snout  32  is generally of a conical shape and contains a substantially hollow interior portion for communicating force transferring rod  16  therethrough to the exterior of impactor  10 . 
     A deceleration chamber pressurization valve  27  is positioned proximate closed end  25  of deceleration chamber  23 . Pressurization valve  27  is a selectively actuated bi-directional valve in fluid communication with both a pressurized air supply and the ambient atmosphere. Valve  27  operates to selectively pressurize deceleration chamber  23 , such that deceleration piston  22  is urged to slide to a position proximate open end  24  of deceleration chamber  23  in preparation for engaging piston assembly  15  upon completion of an impacting stroke. Further, the pressurization of deceleration chamber  23  firmly biases deceleration piston  22  towards power barrel  14 , thus operating to resist and decelerate the longitudinal motion of piston assembly  15  upon engagement of such. Alternatively, valve  26  also serves to selectively depressurize deceleration chamber  23  to atmospheric pressure during maintenance periods, such that any excess oil or unwanted particles that may hinder proper operation of deceleration piston  20  can be purged or allowed to escape from deceleration chamber  23 . 
     Specifically, deceleration piston  22 , as shown in FIG. 9, comprises a circular disk shaped member having an axial bore  28  formed therein for slidably receiving force transferring rod  16  therethrough; thus, deceleration piston  22  is generally annular in shape. Power barrel side  29  of deceleration piston  22  includes an axially formed recess  30  in the form of a partial bore of sufficiently larger diameter than axial bore  28  to accommodate lower portion  21  of piston assembly  15  upon engagement of piston assembly  15  by deceleration piston  22 . Opposite power barrel side  29  of deceleration piston  22  is deceleration chamber side  31  of deceleration piston  22 , which is generally planar in form. Further, inasmuch as longitudinally aligned bore  26  on closed end  25  and axial bore  28  both slidably receive force transferring rod  16  therethrough, the diameter of these particular bores is also slightly larger than that of force transferring rod  16 , thereby allowing for rod  16  to slide within the respective bores. Furthermore, inasmuch as deceleration piston  22  is continually engaging and absorbing the kinetic energy of piston assembly  15 , deceleration piston  22  must be manufactured from a structurally resilient material capable of continually absorbing the forces associated with contacting piston assembly  15  without critical failure. As such, deceleration piston  22  is generally manufactured from a structurally sound non-metallic material. 
     In order to maintain pressurization of deceleration chamber  23  and the resulting biasing force of deceleration piston  22  during operation of impactor  10 , deceleration piston  22  is equipped with two sets of pressure seals, which are generally known in the art. First pressure seal  37  is positioned about the outer circumference of deceleration piston  22  in similar fashion to a common ring seal type arrangement, such that a seal is formed between the outer circumference of deceleration piston  22  and the interior wall of deceleration chamber  23 . Second pressure seal  38  is positioned about the circumference of axial bore  28  of deceleration piston  22 , again in similar fashion to ring type seals, such that a seal is formed between axial bore  28  and the outer surface of force transferring rod  16 . Although not located on deceleration piston  22 , a third pressure seal  39  located between longitudinally aligned bore  26  in closed end  25  of deceleration chamber  23  and force transferring rod  16  completes the pressurization seals of deceleration chamber  23  by sealing chamber  23  from the exterior of impactor  10 . The presence of these pressure seals allows for the selective pressurization of deceleration chamber  23 , such that deceleration piston  22  is firmly biased against longitudinal movement. 
     During a stroke of impactor  10 , piston assembly  15  is longitudinally displaced within power bore  11  through the selective introduction of fluid pressure into power barrel  14  via a system of selectively actuated valves. Generally speaking, piston assembly  15  is urged to longitudinally travel from blind end  18  of power barrel  14  towards the head end  19  via fluid pressurization of blind end  18  of power barrel  14 . This longitudinal movement concomitantly acts to extend impacting end  17  of force transferring rod  16  beyond the exterior of casing  13  through snout  32 , such that casting  11  may be impacted and riser  12  fractured therefrom. In order to return piston assembly  15  to blind end  18  of power barrel  14  in preparation for subsequent impacting strokes, head end  19  of power barrel  14  is pressurized such that piston assembly  15  is urged to longitudinally return to blind end  18 . 
     With particularity, the system of valves utilized to selectively introduce fluid pressure to power barrel  14  for the purpose of selectively imparting longitudinal motion to piston assembly  15  is schematically shown in FIG.  4 . Two valves, the main fire/return exhaust valve  33  and the high fire valve  34 , are positioned in the blind end  18  of power barrel  13 . The main fire/return exhaust valve  33  operates to both pressurize the upper portion of power barrel  14  in a normal firing mode, as well as to vent blind end  18  of power barrel  14  to atmospheric pressure during longitudinal movement of piston assembly  15  towards blind end  18  in the return portion of the stroke. High fire valve  34  operates only to cooperatively pressurize blind end  18  of power barrel  14  with main fire/return exhaust valve  33  at a much faster rate when impactor  10  is operated in a high fire mode. High fire  34  and main fire/return exhaust  33  valves are in fluid communication with pressurized air reservoir  35 , which is used to pressurize power barrel  14  such that piston assembly  15  is urged to rapidly slide within power barrel  14 . A third valve positioned upon impactor  10  is the exhaust and return valve  36 , which is positioned proximate the head end  19  of power barrel  13 . Exhaust and return valve  36  is also in fluid communication with reservoir  35 , and operates to both pressurize the lower portion of power barrel  14  to urge piston assembly  15  to return to the blind end  18  of power barrel  14  upon completion of an impacting stroke, as well as to vent the head end  19  of power barrel  14  to atmospheric pressure during the impacting stroke. Venting of head end  19  to atmospheric pressure by exhaust and return valve  36  serves to increase the output power of the impactor, as the resistive force on the piston assembly as a result of air pressure is minimized when valve  36  is vented to atmospheric pressure. 
     The exterior of casing  13  of impactor  10  includes a shock absorption assembly  40  mounted thereto for the operator of impactor  10  to grip and control the apparatus from. Shock absorption assembly  40  serves to isolate the operator from any longitudinal movement of impactor  10  upon contact with a casting. Shock absorption assembly  40  includes a pair of elongated rail members  41  rigidly mounted to impactor casing  11  along the longitudinal axis of such and in parallel relation to each other. Rail members  41  are mounted to casing  13  at first  44  and second  45  terminating ends, as well as at the midpoint  43 , thus, rail members  41  are rigidly mounted to casing  13  at three specific locations. An operator handle assembly  42  is slidably attached to rail members  41  at two points; the first point being between the midpoint mount  43  and a first terminating  44  end of rail members  41 , and the second point being between the midpoint  43  and a second terminating end  45  of rail members  41 . This mounting configuration allows handle assembly  42  to slidably travel along rail members  41  between the midpoint mount  43  and the terminating end mounts. The operator grips handle assembly  42  at a first handle  47  positioned proximate the rear of impactor  10  with one hand, while concurrently gripping handle assembly  42  at a second handle  48  positioned proximate the middle casing  13 . Second handle  42  also includes a thumb trigger  49  for initiating the impacting stroke of impactor  10 . Handle assembly  42  is additionally biased to a rest position by a pair of opposing biasing springs  46  positioned proximate rail members  41 . As a result of this biasing, handle assembly  42  is able to slidably absorb a substantial portion of the linear kick back of impactor  10  upon an impacting stroke, and as such, motion of the impactor  10  is damped or isolated from the operator by biasing springs  46 . 
     Upon initiation of impactor  10  by the operator&#39;s actuation of thumb trigger  49 , the aforementioned valves begin a specific sequence, which causes impactor  10  to stroke and impact a riser  12 . Assuming that piston assembly  15  is located proximate blind end  18  of power barrel  14  in the ready to fire position commonly known as top dead center, the impacting sequence begins with the opening of exhaust and return valve  36 , such that head end  19  of power barrel  14  is vented to atmospheric pressure. Immediately after venting head end  19 , in normal fire mode, main fire/return exhaust valve  33  is opened for a predetermined period of time, such that the volume of pressurized air in reservoir  35  becomes in fluid communication with blind end  18  of power barrel  14 . This pressurizes the blind end  18  of power barrel  14 , and therefore rapidly urges piston assembly  15  to longitudinally travel towards head end  19  of power barrel  14 . This motion acts to longitudinally extend impacting end  17  of force transferring rod  16  outside snout  32  for contact with riser  12 . If the impactor is operated in the high power firing mode, which offers a greater impacting force for larger risers and such, essentially the same valve sequence is utilized. However, in the high fire mode, high fire valve  34  is simultaneously opened with main fire valve  33 . The simultaneous opening of high fire  34  and main fire  33  valves operates to pressurize blind end  18  of power barrel  14  at a much faster rate, thus imparting a substantially greater force to piston assembly  15  and impacting end  17 . 
     Proximate the end of the impacting stroke, lower portion  21  of piston assembly  15  contacts deceleration piston  22  and is received within recess  30 . Thereafter, deceleration piston  22  and piston assembly  15  begin to concomitantly travel longitudinally within deceleration chamber  23 . However, as the components longitudinally travel, the volume of air in deceleration chamber  23  is proportionally compressed by deceleration piston  22 , which results in an increased force resisting further longitudinal motion. Therefore, the concomitant longitudinal motion of deceleration piston  22  and piston assembly  15  is quickly decreased to a stop as a result of the proportionally increasing resistive force. Subsequent to completing the impacting stroke, piston assembly  15  must be returned to the top dead center position in preparation for another firing. Therefore, main fire/return exhaust valve  33  is positioned such that power barrel  14  is no longer being pressurized and piston assembly  15  is no longer being urged towards head end  19  of power barrel  14 . In order to urge piston assembly  15  towards blind end  18  of power barrel  14 , exhaust and return valve  33  is positioned such that the head end  19  of power barrel  14  is in communication with reservoir  35 , which pressurizes head end of power barrel  14 . This pressurization urges piston assembly to travel towards blind end  18  of power barrel  14  to the top dead center position. When piston assembly  15  reaches the top dead center position, impactor  10  is ready for another impacting stroke. 
     As a result of deceleration piston  22  continuously receiving and absorbing the kinetic energy of piston assembly  15  and force transferring rod  16  upon a stroke of impactor  10 , it is critical that deceleration piston  22  be manufactured of a material capable of continually absorbing such kinetic energy while maintaining structural integrity. Thus, rigid metallic compounds commonly utilized to construct piston assemblies, such as iron and aluminum compounds, are to be avoided, as the potential for metal fatigue and fracture as a result of continuous impacting is high. Therefore, in the preferred embodiment, deceleration piston  22  is manufactured from a non-metallic compound. Particularly, it is contemplated within the scope of the present invention to manufacture deceleration piston  22  from nylon, a family of high-strength, resilient synthetic polymers, the molecules of which contain the recurring amide group CONH, or equivalents. The use of these compounds dramatically increases the ability of deceleration piston  22  to resist fracturing due to continuous high energy impacts with piston assembly  15 , and therefore the life span of deceleration piston  22  and the impactor as a whole is dramatically increased. Specifically, it is contemplated that a nylon compound be utilized to manufacture deceleration piston  22 , as such compounds offer the high material strength properties of the previously utilized metallic compounds without the tendency to fracture and cause critical failure of the apparatus  10 . With even greater particularity, the preferred embodiment illustrated herein utilizes a heat stabilized type six polyamide resin nylon compound for the manufacture of the deceleration piston  22 , as this material offers substantial structural strength capable of absorbing thousands of impacts with piston assembly without fracturing or otherwise causing a critical failure of the impactor  10 . 
     It is to be understood that the form of the invention shown is a preferred embodiment thereof and that various changes and modifications may be made therein without departing from the spirit of the invention or scope as defined in the following claims.