US3223182A

US3223182A - Powered impact tools

Info

Publication number: US3223182A
Application number: US444510A
Authority: US
Inventors: Mikiya Toshio
Original assignee: Nitto Kohki Co Ltd
Current assignee: Nitto Kohki Co Ltd
Priority date: 1962-08-07
Filing date: 1965-03-26
Publication date: 1965-12-14
Anticipated expiration: 1982-12-14
Also published as: GB979744A; CH406097A; DE1286980B

Description

Dec. 14, 1965 Tosi-uo MIKIYA POWERED IMPACT TOOLS 5 Sheets-Sheet 1 Filed March 26, 1965 POWERED IMPACT TOOLS INVENTOR rdff//a M/,f//1/4 Dec. 14, 1965 Tosi-no MlKlYA POWERED IMPACT TOOLS 5 Sheets-Sheet 5 Filed March 26, 1965 N l: 1 Mm/2.1

v INVENTOR raf/Wa /W/A//y 3,223,182 POWERED IMPACT TOOLS Toshio Mikiya, Tokyo, Japan, assigner to Nitto Kohki Co., Ltd., Tokyo, Japan, a corporation of Japan Filed Mar. 26, 1965, Ser. No, 444,510

Claims priority, application Japan, Aug. 7, 1962,

37/ 32,572 4 Claims. (Cl. 173-114) This application is a continuation-in-part of copending application Serial No. 250,858 tiled on January 1l, 1963, now abandoned.

This invention relates to powered impacted tools actuated by compressed air, for driving perforated needles, chisels and other tool elements and, more particularly, to pneumatic chisels having improved mechanism fo-r supporting and imparting impact blows to the chisel elements Iof such a device.

While the following specification is principally directed to the structure of pneumatic chisels incorporating the present invention, it will be understood that the invention is applicable to other powered impact tools incorporating other tool elements for effecting desired work functions.

In conventional pneumatic chisels, the chisel elements are driven forward by the force of compressed air and returned to normal position by the force of a spring that has been` compressed by the forward movement of the chisel elements. Consequently, the power for driving the chisel elements is partly consumed for com-pressing the returnspring, resulting in the loss of impact energy. Moreover, such a mechanical spring is apt to be damaged or to deteriorate rather quickly since it is subjected to repeated compression and release, with high frequency.

In certain types of pneumatic chisels, the impact blows of a hammer piston are transmitted directly to the chisel elements, so that the chisel must be manually and firmly pressed against the work surface. The operation of such chisel requires bodily strength. Moreover, ordinary pneumatic chisels do not work satisfactorily `on `curved or uneven surfaces.

One of the objects of the present invention, therefore, is to permit the construction of a pneumatic chisel in which the well-known chisel return-spring is eliminated.

It is another object of the invention tio provide an improved pneumatic chisel comprising an air cylinder having a hammering piston, a throttle-anvil and a second piston which elements pneumatically cooperate with one another for imparting impact blows to a bundle of chisel elements.

It is a still further `object of the invention to improve the construction o-f the chisel elements, or the bundle o-f needles of a pneumatic chisel, as regards the manner of support thereof, so that the needles are projected like bullets from the second piston.

A further object of the invention is to provide an improved driving and return device for pneumatic chisels which permits easy operation and which, when the ch-isels are pointed at a curved or uneven surface, positively adapts itself to such surface without having to press the chisel to direct the bundle of needles onto the work surface.

For other objects and for a better understanding of the invention, reference may be had to the following detailed description taken in connection with the accompanying drawings, in which:

FIGURE l is a longitudinal sectional view of a preferred embodiment of the powered impact tool of the present invention, showing the hammer-piston and needle or chisel elements in their forward projected positions.

FIGURE 2 is a view similar to FIGURE 1, illustrating the positions of the respective elements of the tool immediately after actuation thereof;

te States Patent O ice FIGURES 3 and 4 are partial longitudinal sectional views corresponding to FIGURES l and 2 deleting, however, illustration of the valve mechanism of the tool, and showing the orientation of the elements of the device in successive stages of the operation thereof; and

FIGURE 5 is a view similar to FIGURE 4, showing the device :acting against a curved work surface.

The powered impact tool hereof comprises an air cylinder including first and second cylindrical segments which are coupled to one another and which contain longitudinally extending air conduits formed in their walls and having valve means for controlling the iiow of compressed air thereto. A hammer piston is slidably mounted in the iirst cylindrical segment. Mechanism is provided for introducing compressed air from the air conduits peripherally of such piston and for exhausting air from behind it to move the piston from a rst to a second position, and mechanism is provided for introducing compressed air behind the piston to return it from the second to the rst position.

A tool holder is slidably mounted in the second cylindrical segment of the air cylinder, having a chamber formed in and extending longitudinally thereof. Further mechanism is provided for introducing compressed air from the air conduits into such chamber to move it from a rst position to a second position, for interrupting the flow lof compressed air when the tool holder is disposed intermediate such positions and for exhausting the air from a chamber when the tool holder reaches the second position.

A plurality of tool elements are slidably received in the tool holder extending longitudinally yof and protruding from the air cylinder, such elements being movable from a first position seated in the tool holder, when it is disposed in its iirst position, to a second position out of seating engagement with the tool holder, and being movable from the second position back to such first position.

Slidably mounted in the second cylinder segment intermediate the hammer piston and the tool holder is an anvil, which is movable by the too-l elements from a iirst position abutting the too-l holder to a second position spaced therefrom, and which is movable from such second position to its first position by the hammer piston. The anvil, during movement from its second to its first position, strikes the tool elements and projects them longitudinally relative to the tool holder to effect the desired work functions.

Referring to the drawing, the powered impact tool or pneumatic chisel illustrated comprises a rear cylinder 1 and a front cylinder 2 joined by a closure member 3.

Suitable packing rings

4 and 5 are located at the juncture portions of the respective cylinders 1 and 2.

'Iihe rear cylinder 1 is internally threaded at 6 (see FIG- URES l and 2) to receive a lcylinder head 7 having a valve element 8. The latter element may be depressed by a manually operable lever 9 pivotally connected to the cylinder head 7 at 10. The valve includes a valve chamber 12 having a seat to -which the element 8 is normally urged by a spring 13 and a plug 14 threaded into the cylinder head 7. The valve chamber communicates with a nipple 11, which may be secured to an air hose or the like.

Extending longitudinally through the wall of the rear cylinder 1 are

air supply conduits

15, 15. Such conduits communicate with a longitudinal air conduit 16 in the wall of the front cylinder 2 through an annular chamber 17 dened at the juncture of the respective cylinders and sealed by the packing ring 4. The air conduits 15, 15 additionally communicate with the valve chamber 12 at a port 18 through an annular space 19 formed at the juncture of the cylinder head 7 and the rear cylinder 1. Packing ring 20 is provided between the cylinder head 7 and the inner walls of the cylinder 1 for preventing escape of the compressed air from the annular space 19.

Mounted slidably within a chamber 21 defined in the rear cylinder is a hammer-piston 22 having an internal bore 23 opening at one end into the rear cylinder chamber 21. The hammer-piston includes a cylindrical portion 24 projecting forwardly from, and of reduced diameter with respect to, a cylindrical root portion 25 thereof.

The cylinder chamber 21 in which the hammer-piston 22 is received is provided with aforward axial bore 26 and a main cylinder bore 28, separated by a step portion 33. When the hammer-piston 22 is disposed in the rearward position of its stroke, with the reduced cylinder portion 24 extending into a main cylinder bore 28, an annular space 27 is defined therebetween (see FIGURES 2 and 3). The hammer-piston is provided with ports 29 in the lower end of bore 23 thereof for communicating with such annular space 27 which is, in turn, connected through ports 30 to the air `supply conduits -15, 15.

The rear cylinder 1 is also provided with an enlarged forward axial bore 31 communicating with an exhaust port 32 formed in the wall of the front cylinder 2. When the ham-mer-piston is disposed in the forward portion of its stroke, with the inlet ports 30 closed by the root portion 25 thereof, the ports 29 of the bore 23 communicate with the atmosphere through bore 31 and exhaust port 32.

The front cylinder 2 has an anvil 34 and a second piston or tool holder 35 slidable therein, respectively. The tool holder, which is heavier than the anvil 34, carries a number of needles 36 which are movable with respect thereto and include enlargements 37 on their rear ends preventin-g disengagement of the needles from the holder 35.

The tool holder 35 has a hollow reduced cylindrical extension 38, the interior of which communicates with the atmosphere and which is slidably received in a neck portion 39 of the front cylinder 2. Above the neck portion,

air passages

40, 40 are provided extending longitudinally through the walls of the tool holder. When the tool holder is disposed in the forward portion of its stroke (FIGURE 1) each of these air passages 16 of the front cylinder 2 and is seated, at its opposite end, on a shoulder portion 42 of the front cylinder adjacent the neck portion 39 thereof. When, on the other hand, the tool holder 35 is disposed in the rearward portion of its stroke (FIGURE 3) the

air passages

40, 40 do not communicate with passage 16 but communicate instead with the atmosphere through

ports

43, 43 defined in the walls of extension 38 of the tool holder.

The front cylinder 2 has an opening 44 through which air may be exhausted from the space between anvil 34 and the tool holder 35 to the atmosphere` Additionally, a cover sleeve 45 is preferably provided for covering the opening 44 and the above-mentioned exhaust port 32 to protect the operator from the high pressure exhaust.

In operation, the lever 9 is depressed against the Valve spring 13 (compare FIGURES l and 2) in order to feed compressed air into the

air supply conduits

15, and 16 of the rear and front cylinders 1 and 2. The compressed air supplied through inlet ports 30 is fed over the periphery of root portion 25 of piston 22 into the annular region adjacent step portion 33 of the cylinder chamber 21. The resulting air pressure forces the hammer-piston 22 rearwardly, or upwardly (viewing FIGURE 1), into the successive positions illustrated in FIGURES 2 and 3 of the drawings. It will be noted that, while the compressed air introduced through ports 30 is similarly fed to the portion of cylinder chamber 21 to the rear (above, viewing FIG- URE l) of the hammer-piston, no counter-pressure is produced since the air is exhausted to the atmosphere through the piston bore 23, ports 29 and exhaust port 32.

The compressed air is simultaneously fed into

air passages

40, 40 through port 41 from supply conduit 16, forcing the tool holder 35, the needles 36 and the adjacent anvil 34 rearward from the position shown in FIGURE 1 4- to that illustrated in FIGURE 2. Shortly after initiating movement of the tool holder 35 the

air passages

40, 40 are displaced out of communication with port 41 connected to the supply conduit 16, `cutting off flow of compressed air to

passages

40, 40 and terminating the rearward movement of the tool holder when it reaches the position illustrated in FIGURE 3. The anvil 35 and needles 36 are, as illustrated in FIGURES 2 and 3, simultaneously displaced from the heavier tool holder 35, after the initial rearward thrust thereof, by the force of inertia.

When the hammer-piston 22 and tool holder 35 reach the end-s of their rearward strokes (FIGURE 3) the forward strokes are automatically initiated. Thus, when the hammer-piston reaches the end of its stroke the ports 29 thereof communicate with annular space 27, permitting the flow of compressed air from

supply conduits

15, 15 through ports 30, space 27, ports 29 and bore 23 into the rear cylinder chamber 21. Continued flow of the compressed air stream initiates the forward, or downward (viewing FIGURE 3), stroke of the piston 22 against the anvil 34 which, in turn, imparts an impact blow to the needles 36 (FIGURES 4). The several needles 36 are thus driven forward to elfe-ct chiseling of the work surface.

Towards the end of the forward stroke of the anvil 34 (between the positions illustrated in FIGURES 4 and l), the anvil strikes the tool holder 35, displacing the tool holder so that the

ports

43, 43 of the cylindrical extension 38 thereof are closed by the neck portion 39 of the 'front cylinder 2. Sufficient air is thereby trapped in the space above the shoulder portion 42 of the front cylinder 2 to provide an air cushion the effect of which is not, however, so large that is signicantly decreases the working force or power of the needles 36.

When the hammer-piston 22 reaches the end of its forward stroke the ports 29 are placed in communication with exhaust port 32 through bore 31, thereby exhausting the air from bore 23 of the piston and permitting the return stroke to commence as described above. Additionally, when the tool holder 35 reaches the end of its forward stroke the air passages 40 come into registry with port 41 communicating with air supply conduit 16, effecting the return stroke of the holder, the needles 36 and the anvil 34. It will be noted that, while the anvil 34 acts dynamically on the needles 36 during the forward stroke of the device, it imposes no positive force opposing the rearward stroke of the tool holder 35 or needles 36, since both axial ends of the anvil are exposed to atmospheric pressure through

exhaust ports

32 and 44.

It will thus be noted that the plurality of needles 36 are thus actuated repeatedly with high speed toward the desired work surface, as long as the operating lever 9 is depressed.

The pneumatic chisel of the invention is of light weight, easily handled and has many uses. Some of such uses are shot peening for metal surfaces, chiseling out pipe channels, de-rusting and de-scaling, roughing up and cleaning concrete and masonry, etc., cleaning weld seams, roughing up for metalizing, cleaning casings, de-furring boilers, stripping paint, bitumen, etc., removing plaster, etc.

For certain uses of the pneumatic chisel, the

needles

36, 36 should not be pressed against the working surface. It is preferred to hold the chisel firmly at a proper distance from the work surface, so that the floating needles act on the work surface like bullets. In this manner, as shown in FIGURE 5, the device may be utilized to act on curved or uneven surfaces.

It will be understood that various changes may be made in the embodiment of the powered impact tool described hereinabove without departing from the scope of the present invention; accordingly, it is intended that the preceding description and the accompanying drawings are illustrative and should not be considered in a limiting sense,

pressed air, which comprises.:

(a) an air cylinder comprising first and second cylindrical segments coupled to one another;

(b) air conduits formed in the walls of said air cylinder and extending longitudinally thereof;

(c) valve means connected to said air conduits for controlling the flow of compressed air thereto;

(d) a hammer-piston slidably mounted in said first cylindrical segment;

(e) means for introducing compressed air from said air conduits peripherally of said piston and means for exhausting air from behind said piston when the piston is disposed in a first position, to effect movement thereof to a second position;

(f) means for introducing compressed air from said air conduits behind said piston when it is disposed in said second position, to return the piston to said first position;

(g) a tool holder slidably mounted in said second cylindrical segment;

(h) a chamber, formed in and extending longitudinally of said tool holder;

(i) means for introducing compressed air from said air conduits into said chamber to move the tool holder from a first position to a second position;

(j) means for interrupting the flow of compressed air from said air conduits into said chamber when the tool holder is disposed intermediate the first and second positions thereof; Y

(k) means for exhausting the air from said chamber when the tool holder is disposed at said second position;

(l) a plurality of tool elements slidably received in said tool holder and extending longitudinally of and protruding from said air cylinder, said elements being movable from a first position seated in the tool holder, when it is disposed in its first position, to a second position out of seating engagement with said tool holder, and being movable from said second position back to said first position;

(m) an anvil slidably mounted in said second cylindrical segment intermediate the hammer-piston and the tool hol-der, said anvil being movable by said tool elements from a first position abutting said tool holder to a second position spaced therefrom, and being movable from the second position to said first position by said hammer-piston; said anvil, during movement from its second to its first position, striking said tool elements and projecting them longitudinally relative to said tool holder.

2. The powered impact tool as set forth in claim 1, in

which said tool holder includes a first hollow cylindrical segment defining a plurality of seats for receiving said tool elements for slidable movement relative thereto, said segment providing an annular chamber extending longitudinally of the tool hol-der in the walls thereof and communicating at one end with a port extending through the walls of the tool holder;

a second hollow cylindrical extension segment formed integrally with said first segment, the hollow interiors of said segments communicating with one another and said second segment defining annular ports for connecting said hollow interiors with said annular chamber when the tool holder is disposed in the second position thereof;

and in which the second cylindrical segment slidably mounting the tool holder includes a first, expanded bore in which the first cylindrical segment of the tool holder is mounted, said bore including means for communicating with the port in said first segment when the tool holder is disposed in its first position, for connecting said chamber with said air conduits;

a second, restricted bore in which the cylindrical extension of the tool holder is slidably mounted, said second bore defining a port connecting the hollow interior of the tool holder with the atmosphere.

3. The powered impact tool as set forth in claim 1, in

which said hammer-piston includes and in which the first cylindrical segment in which said hammer-piston is slidably mounted denes a first bore slidably mounting the root segment of the hammer-piston, the walls of said bore defining ports extending -therethrough and communicating with said air con-duits;

a second bore slidably mounting the second segment of the hammer-piston;

expanded bore communicating with the atmosphere and communicating, in turn, with the ports defined in the walls of the second cylindrical segment of the hammer-piston, when the piston is disposed in its first position; and

a step portion intermediate said bores, said step portion communicating with the ports defined in the walls of said first bore when the hammer piston is disposed in said first position.

4. A powered impact tool to be activated by compressed air, which comprises:

(d) a hammer-piston 4slidably mounted in said rst cylindrical segment for movement between a first and a -second position, said hammer-piston comprising:

( 1) a first cylindrical root segment,

(2) a second cylindrical segment integral with said root segment and having a relatively restricted diameter with respect thereto, said segments defining a bore extending longitudinally of the piston and communicating at one end with the back of the piston adjacent to the root segment and at the opposite end with ports defined in the walls of said restricted cylindrical segment;

(e) the first cylindrical segment of the air cylinder providing:

(1) a first bore slidably mounting the root segment of the hammer-piston, the walls of said bore defining ports extending therethrough and communicating with said air conduits;

(2) a second bore slidably mounting the second segment of the hammer-piston;

(3) an expanded bore communicating with the atmosphere and communicating, in turn, with the ports defined in the Walls of the second cylindrical segment of the hammer-piston, when the piston is disposed in its first position; and

(4) a step portion intermediate said first .and second bores, said step portion communicating with the ports defined in the walls of said first bore when the hammer-piston is disposed in said first position;

(f) a tool holder slidably mounted in the second cylindrical segment of the air cylinder for movement between a first and second position, said tool holder including:

(1) a first hollow cylindrical segment defining a plurality of seats for receiving the tool elements defined hereinafter for slidable movement relative thereto, said segment vproviding an annular chamber extending longitudinally of the tool holder in the walls thereof and communicating at one end with a port extending through the walls of the tool holder;

(2) a second hollow cylindrical extension segment formed integrally with said first segment, the hollow interior regions of said segments communicating with one another and said second segment defining annular ports for connecting `said interior regions with said annular chamber when the tool holder is disposed in the second position thereof;

(g) the second cylindrical segment of the air cylinder providing:

(1) a first expanded bore in which the first cylin- (h) a plurality of tool elements slidably received in said tool holder and extending longitudinally of and protruding from said air cylinder, said elements being movable from a first position seated in the tool holder when i-t is disposed in its rst position, to a second position out of seating engagement with said tool holder, and being movable from said second position back to said first position; and

(i) an anvil slidably mounted in said second cylindrical segment intermediate the hammer-piston and the References Cited by the Applicant' UNITED STATES PATENTS drical segment of the tool holder is mounted, 842655 1/1907 Halfdsoeg' said bore including means for communicating 1076I246 10/1913 Smlth with the port in said first segment when the 25 1,583,288 5/1926 Gflmantool holder is disposed in its first position, for 1,747,164 2/1930 DltSOn et aL connecting said chamber with said air conduits; 2,356,314 8/1944 Gray et al- (2) and a second, restricted bore in which the y 2,613,647 10/ 1952 Curtis.

cylindrical extension of the tool holder is slid- 2,672,129 3/1954 Fischer. ably mounted, said second bore defining ya port 3()y 2,672,677 3/ 1954 Von Arx.

connecting the hollow interior of the tool holder with the atmosphere; MILTON KAUFMAN, Primary Examiner.

Claims

1. A POWERED IMPACT TOOL TO BE ACTIVATED BY COMPRESSED AIR, WHICH COMPRISES: (A) AN AIR CYLINDER COMPRISING FIRST AND SECOND CYLINDRICAL SEGMENTS COUPLED TO ONE ANOTHER; (B) AIR CONDUITS FORMED IN THE WALLS OF SAID AIR CYLINDER AND EXTENDING LONGITUDINALLY THEREOF; (C) VALVE MEANS CONNECTED TO SAID AIR CONDUITS FOR CONTROLLING THE FLOW OF COMPRESSED AIR THERETO; (D) A HAMMER-PISTON SLIDABLY MOUNTED IN SAID FIRST CYLINDRICAL SEGMENT; (E) MEANS FOR INTRODUCING COMPRESSED AIR FROM SAID AIR CONDUITS PERIPHERALLY OF SAID PISTON AND MEANS FOR EXHAUSTING AIR FROM BEHIND SAID PISTON WHEN THE PISTON IS DISPOSED IN A FIRST POSITION, TO EFFECT MOVEMENT THEREOF TO A SECOND POSITION; (F) MEANS FOR INTRODUCING COMPRESSED AIR FROM SAID AIR CONDUITS BEHIND SAID PISTON WHEN IT IS DISPOSED IN SAID SECOND POSITION, TO RETURN THE PISTON TO SAID FIRST POSITION; (G) A TOOL HOLDER SLIDABLY MOUNTED IN SAID SECOND CYLINDRICAL SEGMENT; (H) A CHAMBER, FORMED IN AND EXTENDING LONGITUDINALLY OF SAID TOOL HOLDER; (I) MEANS FOR INTRODUCING COMPRESSED AIR FROM SAID AIR CONDUITS INTO SAID CHAMBER TO MOVE THE TOOL HOLDER FROM A FIRST POSITION TO A SECOND POSITION; (J) MEANS FOR INTERRUPTING THE FLOW OF COMPRESSED AIR FROM SAID AIR CONDUITS INTO SAID CHAMBER WHEN THE TOOL HOLDER IS DISPOSED INTERMEDIATE THE FIRST AND SECOND POSITIONS THEREOF; (K) MEANS FOR EXHAUSTING THE AIR FROM SAID CHAMBER WHEN THE TOOL HOLDER IS DISPOSED AT SAID SECOND POSITION; (L) A PLURALITY OF TOOL ELEMENTS SLIDABLY RECEIVED IN SAID TOOL HOLDER AND EXTENDING LONGITUDINALLY OF AND PROTRUDING FROM SAID AIR CYLINDER, SAID ELEMENTS BEING MOVABLE FROM A FIRST POSITION SEATED IN THE TOOL HOLDER, WHEN IT IS DISPOSED IN ITS FIRST POSITION, TO A SECOND POSITION OUT OF SEATING ENGAGEMENT WITH SAID TOOL HOLDER, AND BEING MOVABLE FROM SAID SECOND POSITION BACK TO SAID FIRST POSITION; (M) AN ANVIL SLIDABLY MOUNTED IN SAID SECOND CYLINDRICAL SEGMENT INTERMEDIATE THE HAMMER-PISTON AND THE TOOL HOLDER, SAID ANVIL BEING MOVABLE BY SAID TOOL ELEMENTS FROM A FIRST POSITION ABUTTING SAID TOOL HOLDER TO A SECOND POSITION SPACED THEREFROM, AND BEING MOVABLE FROM THE SECOND POSITION TO SAID FIRST POSITION BY SAID HAMMER-PISTON; SAID ANVIL, DURING MOVEMENT FROM ITS SECOND TO ITS FIRST POSITION, STRIKING SAID TOOL ELEMENTS AND PROJECTING THEM LONGITUDINALLY RELATIVE TO SAID TOOL HOLDER.