Hand held apparatus for fracturing risers from castings

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'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.