US3335805A - Pneumatic hammer and counterbalanced suspension therefor - Google Patents

Pneumatic hammer and counterbalanced suspension therefor Download PDF

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Publication number
US3335805A
US3335805A US434958A US43495865A US3335805A US 3335805 A US3335805 A US 3335805A US 434958 A US434958 A US 434958A US 43495865 A US43495865 A US 43495865A US 3335805 A US3335805 A US 3335805A
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United States
Prior art keywords
piston
hammer
auxiliary
hammerhead
guide sleeve
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Expired - Lifetime
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US434958A
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English (en)
Inventor
Diez Adolf
Heim Josef
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Karl Schmidt GmbH
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Karl Schmidt GmbH
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D31/00—Cutting-off surplus material, e.g. gates; Cleaning and working on castings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25D—PERCUSSIVE TOOLS
    • B25D11/00—Portable percussive tools with electromotor or other motor drive
    • B25D11/06—Means for driving the impulse member
    • B25D11/066—Means for driving the impulse member using centrifugal or rotary impact elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25D—PERCUSSIVE TOOLS
    • B25D17/00—Details of, or accessories for, portable power-driven percussive tools
    • B25D17/28—Supports; Devices for holding power-driven percussive tools in working position
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25D—PERCUSSIVE TOOLS
    • B25D9/00—Portable percussive tools with fluid-pressure drive, i.e. driven directly by fluids, e.g. having several percussive tool bits operated simultaneously
    • B25D9/14—Control devices for the reciprocating piston

Definitions

  • This invention relates in general to pneumatic power tools, and more particularly to a pneumatically powered hammer and counterbalanced suspension therefor which is suitable for heavy duty use in foundries, as for example, for knocking-off risers and feedheads on castings.
  • the pneumatic hammer of the instant invention by reason of its high momentum hammerhead, is ideally suited for removing risers and feedheads from castings.
  • a spiral spring counterbalance device By suspending the pneumatic hammer from a jib crane or travelling hoist by means of a spiral spring counterbalance device according to the invention, said hammer can be easily moved and positioned almost eifortlessly as needed, thereby increasing the overall efficiency of riser and feedhead removal operations.
  • the spiral spring counterbalance serves to take up the dead Weight of the pneumatic hammer which is preferably suspended at its center of gravity, and permits it to be selectively positioned at a desired height.
  • a pair of longitudinally olfset handles one of which can be hollow and serve as a pressurized air inlet, are provided.
  • the pneumatic hammer of the instant invention comprises a casing having a piston guide sleeve which is open at its forward end, a hammerhead piston slidably disposed within said guide sleeve, and controllable valve means for selectively pressurizing the guide sleeve to forcibly drive the hammerhead piston forward from an initial retracted position therein to deliver a hammer blow, and controllable means for restoring the hammerhead piston to its initial retracted position in the guide sleeve after a hammer blow has been delivered.
  • the guide sleeve which is open at its forward end so as to permit the hammerhead portion of the piston to extend outward therefrom, as when delivering a hammer blow, is provided with a stop, such as an annular shoulder, to limit the forward travel of the piston so that it performs as a pneumatic hammer, rather than as a projectile shot from an air gun.
  • a primary valve comparable in size to the guide sleeve is used for selectively admitting pressurized air into the guide sleeve to drive the piston.
  • the primary valve is arranged in the pneumatic hammer according to the invention so as to be normally closed, and is opened for delivering a hammer blow. Since by using a primary valve having a size of the same order of magnitude as the guide sleeve and piston, a relatively large valve opening force is required.
  • This valve opening force 3,335,805 Patented Aug. 15, 1967 is supplied by an auxiliary pneumatic actuator operatively connected to the primary valve.
  • a control valve which is manually operated, and is in flow connection with a source of pressurized air and the auxiliary pneumatic actuator, is provided for selectively pressurizing and venting said. actuator.
  • the control valve When the control valve is in the configuration for pressurizing the auxiliary actuator, the primary valve is opened, whereas when said control valve is in the venting configuration, the primary valve is restored to its closed position.
  • control valve is placed in the pressurizing configuration, and to retract the hammerhead piston, said control valve is placed in its venting configuration.
  • a restoring spring is preferably provided in the control valve for maintaining said valve in a normally venting configuration, thereby also maintaining the primary valve in a normally closed position.
  • the pneumatic hammer of the invention must, for practical reasons, be supplied with pressurizedair from a conventional source, preferably a constant pressure source, via a conventional flexible pneumatic line, which of practical necessity, has a much smaller cross sectional area than the guide sleeve. If such a pneumatic line were used directly for supplying the pressurized air to the guide sleeve, it would take longer to supply said sleeve with a volume of air corresponding to the hammerhead piston displacement, than would be required by using the comparatively large primary air chamber and primary valve according to the invention.
  • the pneumatic hammer of the instant invention will be used intermittently rather than continuously as in a vibrator type hammer, there will be suflicient time between hammer strokes to refill the primary air chamber.
  • the pneumatic hammer of the instant invention can also be used continuously, i.e., to provide consecutive hammer blows as fast as the hammerhead piston can be retracted for repeat bolws, but with somewhat lower average hammer blow rate.
  • the basic pneumatic hammer of the instant invention can be modified by the inclusion of an intermediate hammerhead which is slidably mounted within the forward portion of the guide sleeve so as to have a limited axial travel therein when struck by the hammerhead piston.
  • the hammerhead piston never actually comes in contact with the workpiece, but delivers hammer blows thereto via the intermediate hammerhead.
  • the guide sleeve is protected against the entry of chips, metal fragments, and other foreign matter which could result in jamming of the hammerhead piston.
  • the forward end of the guide sleeve can be provided with an outwardly beveled opening for preventing the penetration of foreign matter which could cause jamming.
  • an object of the invention to provide a pneumatic hammer which is capable of controllably delivering hammer blows of s ufiicient impact to remove risers, feedheads, and other metal projections from large castings.
  • Another object of the invention is to provide a pneumatic hammer as aforesaid which can be conveniently operated from a conventional pressurized air source.
  • Another and further object of the invention is to provide a pneumatic hammer as aforesaid which is relatively free from jamming by chips, metal fragments, and other foreign matter.
  • Still another and further object of the invention is to provide a counterbalanced suspension device for the aforesaid pneumatic hammer which will enable it to be moved and positioned with little effort.
  • FIG. 1 is a longitudinal view, partly in section, of a pneumatic hammer according to a preferred embodiment of the invention.
  • FIG. 2 is a side elevation view of the pneumatic hammer of FIG. 1 suspended by means of a spiral spring counterbalance device according to the invention.
  • FIG. 3 is a longitudinal view, partly in section, of a portion of a pneumatic hammer constructed in accordance with another embodiment of the invention.
  • FIG. 4 is a longitudinal view, partly in section, of a portion of a pneumatic hammer constructed in accordance with another and further embodiment of the invention.
  • FIG. 5 is a side view, partly in section, showing the details of the spiral spring counterbalance device illustrated in FIG. 2.
  • the pneumatic hammer H is preferably constructed with an assembled casing having a main body 11 and a cap member 12 fastened thereto.
  • the main body 11 is generally hollow, and is provided with a pair of adjoining stepped cylindrical bores 13 and 14 which define a primary pressurized air chamber a and a hammerhead piston guide sleeve g, respectively.
  • a hammerhead piston f is slidably disposed within the sleeve g with a clearance of about 0.5 mm. and is provided with a forwardly disposed hammerhead portion 15 which is somewhat smaller in diameter than the forward end opening 16 of said sleeve g, so that said hammerhead portion 15 can be extended through and beyond said forward end opening 16 as when delivering a hammer blow.
  • a shoulder stop 17 is provided at the forward end of said sleeve g.
  • a ring 18 of resilient material is preferably provided ahead of the stop 17 to cushion the impact of the piston 15 at the end of each hammer stroke.
  • the interior of the cap member 12 is generally hollow, and is provided with a cylindrical bore 19 in which an auxiliary piston c is slidably disposed.
  • the cap member 12 and piston 0 function as an auxiliary pneumatic actuator 20 which is operatively connected via a hollow rod d to a primary valve e.
  • a pair of longitudinally offset handles 24 and 25 are provided, which can be integrally formed with the main body 11, if desired, or made separately.
  • the handle 25 is shown as being integrally constructed with the main body 11, and is provided with a central passage 26 which opens into the primary air chamber a, and a female threaded portion 27 for connection to a source of compressed air (not shown) by a conventional line or hose (not shown).
  • a control valve b which is flow connected to the source of compressed air (not shown) via a passage 28-, and is also flow connected with the auxiliary actuator 20 via the passage 29 which is open at the surface 23, is provided for selectively pressurizing and venting the actuator 20.
  • the valve b which is constructed so as to be manually operable, is preferably provided with a spring 30 for maintaining it in a normally venting configuration. With valve b in the venting configuration, a spring i maintains the piston c in the position shown in FIG. 1.
  • the hollow rod d which passes through the closure member 21 with a slidable sealing fit, is connected to piston c, and to the primary valve e, and is of such a length that when the actuator 20 is vented, the primary valve e is pressed into sealing engagement with the shoulder 31 provided in the body 11 at the forward end of the air chamber a.
  • the piston c, and valve e are provided with passages 32 and 33 respectively, which together with the hollow portion of the rod 0., form a continuous open passage 34 extending from the working portion 35 of the sleeve g to the exhaust portion 36 of the bore 19, so as to enable said working portion 35 which is pressurized for driving the hammerhead piston f, to be vented through the hollow rod d after a hammer blow has been delivered.
  • a spring k connected at one end to the piston f, and at the other end to the cap member 12, is provided for restoring the piston f to the initial retracted position shown in FIG. 1 after a hammer blow has been delivered.
  • the operation of the pneumatic hammer H is best explained by considering its working parts to be in an initial configuration as shown in FIG. 1 with the handle 25 being connected to a source of compressed air (not shown) and the control valve b being in the vent position. Under these conditions, pressurized air will fill the chamber a and be confined therein by the closure member 21 and primary valve e.
  • the control valve b When the control valve b is placed in the pressurize position, compressed air from the aforesaid source will flow through passages 28, 29, and said valve b, and act upon the auxiliary piston c, urging it rearward overcoming the influence of the spring i and in sealing engagement against a resilient disc seal member 37, which seals the vent passage 34 to prevent the escape of pressurized air needed for driving the hammerhead piston 1.
  • any air in the region 36 is expelled via the ports 1 extending through the cap member 12, along with any pressurized air which might initially flow through passage 34 before piston c can be sealed by the disc 37, since the opening of the primary valve e occurs simultaneously with the rearward movement of the auxiliary piston c.
  • the dimensions of the piston 0, rod d and sealing disc 37 are preferably selected so as to minimize this initial loss of pressurized air when the piston c begins to open valve e.
  • vent holes are provided; ust in case the opening 16 should be pressed against an obstructing surface (not shown).
  • the aforesaid sequence of events can be repeated as desired for consecutive hammer blows.
  • FIG. 4 illustrates an alternate sleeve g construction which may be incorporated into the embodiment of FIG. 1, if desired.
  • An outwardly beveled portion s is provided at the forward end opening 16 of the sleeve g to prevent the entrance of metal chips and other foreign matter which might jam the piston f.
  • the beveled portion s cooperates with the oppositely beveled hammerhead portion 15 so that when the latter is driven forward, there is an annular wedge clearance zone for ejection of any chips or foreign matter which might be present at the end 16.
  • This beveled portion s has been found to be superior to the cylindrical counterpart of FIG. 1 in this regard.
  • a plurality of small vent holes r which can be covered with a screen, if desired, have been substituted for the larger holes h in FIG. 1, to further aid in eliminating the hazard of piston jamming by foreign matter.
  • the number of holes r can be selected to provide a suitable total venting area, and their size can be selected so as to exclude a chip or foreign particle above a given size.
  • FIG. 3 illustrates an alternate embodiment of the pneumatic hammer H of FIG. 1, wherein an intermediate hammer 0, which is slidably disposed within the sleeve 3 to be driven by the impact of the hammerhead piston j", is used for delivering hammer blows.
  • the remainder of the pneumatic hammer H can be the same as that shown in FIG. 1.
  • the intermediate hammer o is mounted between a snap ring p and the cushion ring 18 or shoulder 17 of the cushion ring 18 is omitted, and is generally free to slidably travel therebetween. Dirt or broken pieces of metal, chips, etc., are prevented from entering through the open end 16 of the sleeve g by reason of the close fit between the outside diameter of the intermediate hammer and the diameter of the opening 16.
  • a plurality of small vent holes r are provided, for proper venting ahead of both the piston and the intermediate hammer 0.
  • FIG. 3 offers an additional advantage in that when the hammerhead piston f strikes the intermediate hammer 0 and the latter moves forward, the air trapped between the shoulder 38 of said hammer 0 and the wall 14 of the sleeve g, i.e., in the annular region q, is compressed, thereby providing damping of the movement of said intermediate hammer 0. After a hammer blow has been struck, this compressed air in the region q will cause the hammer 0 to rebound slightly.
  • FIG. 2 illustrates generally, a manner in which a spiral spring counterbalance device in can be used to aid in the positioning of the pneumatic hammer H.
  • a jib crane It provides support for the counterbalance device m, the hammer H, and its associated air pressure line 39 as well.
  • the housing (see detail in FIG. of the counterbalance m is in turn suspended by a cable 42 which is attached to a travelling hook 43 on the jib crane n.
  • FIG. 5 shows in detail a typical spiral spring counterbalance device m according to the invention, which can be used for suspending the pneumatic hammer H as illustrated in FIG. 2.
  • the counterbalance device m comprises a housing 44, an axle 45 mounted to said housing 44, a cable reel 46 rotatably mounted to the axle 45, and a spiral spring 6 47 attached at its inner end 48 to the axle 45, and at its outer end 49 to the reel 46.
  • An eye 50 which can be either integral with, or fastened to the housing 44, is provided for suspending the counterbalance device In by the cable 42, as in FIG. 2.
  • a pair of guides 51 are provided on the housing 44 for guiding the passage of the cable 41 as it is reeled in or paid out from the reel 46.
  • the spiral spring 47 provides a restoring force which tends to reel in the cable 41 onto the reel 46 until a length of cable 41 is wound thereupon which results in said spring 47 being in its equilibrium configuration. As the cable 41 is paid out, the spring 47 resists the unwinding action of the reel 46, so that when said cable 41 is connected to support the hammer H as in FIG. 2, the device In provides a counterbalance type of suspension to take up the dead weight of the hammer H, thereby facilitating its manipulation.
  • the various parts of the pneumatic hammer H with the exception of sealing parts such as the disc 37, or cushioning parts as the ring 18, which are preferably made of a resilient material such. as rubber or a plastic can be made of a metal, such as aluminum or steel.
  • the hammerhead piston f, and also the intermediate hammer 0 can be weighted with a heavy metal such as lead, which can be encased within the interior of the piston f and/ or hammer 0.
  • a pneumatic hammer H can be designed to provide hammer blows of a selected energy level, with the application of merely routine engineering calculations.
  • a sufiiciently high operating pressure a relatively light hammerhead piston f can be used to deliver hammer blows of selected intensity.
  • a pneumatic hammer which comprises a hollow casing defining a guide sleeve open at its forward end, a primary air. chamber disposed for communication with a source of pressurized air, and an auxiliary air chamber, a hammerhead piston slidably disposed within said guide sleeve for movement relative thereto from a retracted position to an extended position for delivering a hammer blow, a first resilient means connected to said casing and to said hammerhead piston to urge same toward its retracted position, a normally closed primary valve disposed for movement into an open state to admit pressurized air from said primary chamber in to said guide sleeve behind the hammerhead piston to accelerate same against the effect of said first resilient means toward said extended position, an auxiliary piston slidably disposed within said auxiliary air chamber, a hollow rod connectng said primary valve and auxiliary piston together for movement in unison, said auxiliary piston and primary valve each having an open passage communicating with the hollow portion of said rod for venting said guide slee
  • the pneumatic hammer according to claim 1 includ ing an intermediate hammer slidably disposed within said guide sleeve ahead of the hammerhead piston and adapted to be struck thereby for delivering a hammer blow.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Percussive Tools And Related Accessories (AREA)
  • Separation By Low-Temperature Treatments (AREA)
US434958A 1964-03-06 1965-02-24 Pneumatic hammer and counterbalanced suspension therefor Expired - Lifetime US3335805A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DESCH34760A DE1215313B (de) 1964-03-06 1964-03-06 Pressluftschlaggeraet zur allgemeinen Verwendung in Giessereibetrieben

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US3335805A true US3335805A (en) 1967-08-15

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US434958A Expired - Lifetime US3335805A (en) 1964-03-06 1965-02-24 Pneumatic hammer and counterbalanced suspension therefor

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US (1) US3335805A (US20110009641A1-20110113-C00256.png)
BE (1) BE660582A (US20110009641A1-20110113-C00256.png)
DE (1) DE1215313B (US20110009641A1-20110113-C00256.png)
GB (1) GB1024138A (US20110009641A1-20110113-C00256.png)
LU (1) LU48082A1 (US20110009641A1-20110113-C00256.png)
NL (1) NL6502806A (US20110009641A1-20110113-C00256.png)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090151587A1 (en) * 2007-12-18 2009-06-18 Raytheon Utd Inc. Device and method for controlled breaching of reinforced concrete
US20160356208A1 (en) * 2014-02-11 2016-12-08 Borgwarner Inc. Corrosion resistant pneumatic actuator
US10814468B2 (en) 2017-10-20 2020-10-27 Milwaukee Electric Tool Corporation Percussion tool
US10926393B2 (en) 2018-01-26 2021-02-23 Milwaukee Electric Tool Corporation Percussion tool
US11571796B2 (en) 2018-04-04 2023-02-07 Milwaukee Electric Tool Corporation Rotary hammer

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NO870246L (no) * 1987-01-21 1988-07-22 August Sandstad Loepbrekker.

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US730839A (en) * 1903-01-21 1903-06-09 Christen J Peterson Fire-escape.
US1065339A (en) * 1912-05-31 1913-06-24 Benjamin Brazelle Single-acting engine.
US2722918A (en) * 1951-03-02 1955-11-08 James F Kimball Air impact hammer
US2734488A (en) * 1956-02-14 Portable internal-combustion
US2854953A (en) * 1955-10-17 1958-10-07 Lloyd M Osborne Fluid-actuated fastener-applying machine
US2998148A (en) * 1959-02-02 1961-08-29 Jr Edmond E Himel Sea transfer device
US3094901A (en) * 1958-05-02 1963-06-25 Fastener Corp Pneumatically operated tacker

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2734488A (en) * 1956-02-14 Portable internal-combustion
US730839A (en) * 1903-01-21 1903-06-09 Christen J Peterson Fire-escape.
US1065339A (en) * 1912-05-31 1913-06-24 Benjamin Brazelle Single-acting engine.
US2722918A (en) * 1951-03-02 1955-11-08 James F Kimball Air impact hammer
US2854953A (en) * 1955-10-17 1958-10-07 Lloyd M Osborne Fluid-actuated fastener-applying machine
US3094901A (en) * 1958-05-02 1963-06-25 Fastener Corp Pneumatically operated tacker
US2998148A (en) * 1959-02-02 1961-08-29 Jr Edmond E Himel Sea transfer device

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090151587A1 (en) * 2007-12-18 2009-06-18 Raytheon Utd Inc. Device and method for controlled breaching of reinforced concrete
US7814822B2 (en) * 2007-12-18 2010-10-19 Raytheon Utd Inc. Device and method for controlled breaching of reinforced concrete
US20110030539A1 (en) * 2007-12-18 2011-02-10 Mike Brennan Device and Method for Controlled Breaching of Reinforced Concrete
US8342069B2 (en) * 2007-12-18 2013-01-01 Raytheon Company Device and method for controlled breaching of reinforced concrete
US20160356208A1 (en) * 2014-02-11 2016-12-08 Borgwarner Inc. Corrosion resistant pneumatic actuator
US10215087B2 (en) * 2014-02-11 2019-02-26 Borgwarner Inc. Corrosion resistant pneumatic actuator
US10814468B2 (en) 2017-10-20 2020-10-27 Milwaukee Electric Tool Corporation Percussion tool
US11633843B2 (en) 2017-10-20 2023-04-25 Milwaukee Electric Tool Corporation Percussion tool
US10926393B2 (en) 2018-01-26 2021-02-23 Milwaukee Electric Tool Corporation Percussion tool
US11059155B2 (en) 2018-01-26 2021-07-13 Milwaukee Electric Tool Corporation Percussion tool
US11141850B2 (en) 2018-01-26 2021-10-12 Milwaukee Electric Tool Corporation Percussion tool
US11203105B2 (en) 2018-01-26 2021-12-21 Milwaukee Electric Tool Corporation Percussion tool
US11759935B2 (en) 2018-01-26 2023-09-19 Milwaukee Electric Tool Corporation Percussion tool
US11865687B2 (en) 2018-01-26 2024-01-09 Milwaukee Electric Tool Corporation Percussion tool
US11571796B2 (en) 2018-04-04 2023-02-07 Milwaukee Electric Tool Corporation Rotary hammer

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Publication number Publication date
LU48082A1 (US20110009641A1-20110113-C00256.png) 1965-04-26
BE660582A (US20110009641A1-20110113-C00256.png) 1965-07-01
NL6502806A (US20110009641A1-20110113-C00256.png) 1965-09-07
DE1215313B (de) 1966-04-28
GB1024138A (en) 1966-03-30

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