US3232177A

US3232177A - Pneumatic percussion tool

Info

Publication number: US3232177A
Application number: US388488A
Authority: US
Inventors: Robert L Sandvig
Original assignee: Jaeger Machine Co
Current assignee: Jaeger Machine Co
Priority date: 1964-08-10
Filing date: 1964-08-10
Publication date: 1966-02-01
Anticipated expiration: 1983-02-01
Also published as: ES315534A1; DE1503170A1; GB1041780A; BE667314A; LU49172A1; SE300956B; CH445409A

Description

Feb. 1, 1966 R. L. SANDVIG 3,232,177

PNEUMATIC PERCUSSION TOOL Filed Aug. 10, 1964 4 Sheets-Sheet 1 /l d V v INVENTOR ROBERT L. SANDV/G BY MAHONEY,MILLER 8. RAMBO ATTORNEYS.

Feb. 1, 1966 R. L. SANDVIG 3,232,177

PNEUMATIC PERCUSSION TOOL Filed Aug. 10, 1964 4 Sheets-Sheet 2 I INVENTOR. 25 ROBERT L. SANDVIG E2 5 MAHONEY, MILLER & RAMBO ATTORNEYS.

- Feb. 1, 1966 INVENTQR. ROBERT L. SANDVIG BY MA I NEY. MILLER & RAMBO ATTORNEYS.

Feb. 1, 1966 R. SANDVIG 3,232,177

ed Aug. 10, 1964 4 Sheets-Sheet 4.

NNNNN TOR. 5 5 ROBERT L. SANDVIG BY MAHONEY, MILLER & RAMBO ATTORNEYS.

United States Patent 3,232,177 PNEUMATKC PERCUSSiGN T001.

Robert L. Sandvig, Columbus, Ohio, assignor to The Jaeger Machine Company, Qolumbus, Ohio, a corporation of Uhio Filed Aug. 10, 1964, Ser. No. 388,488 Claims. (Cl. 9131'7) This invention relates to a pneumatic percussion tool. It has to do, more particularly, with the pneumatic pressure system and valve control system for obtaining and controlling the reciprocation of a piston in the cylinder of a pneumatic tool.

With conventional pneumatic percussion tools, the automatic reversing valve, which controls reciprocation of the piston in the cylinder, is shifted by pressure increases at the outer end of the piston or from the direction of hammer movement in the cylinder. The reversing valve provided according to the present invention is automatically shifted by pre-calculated pressure differentials. Furthermore, the ambient air is exhausted from the lower or outer end of the cylinder during the percussion stroke of the piston. This unique arrangement results in the piston striking a harder blow than is possible with prior art pneumatic percussion tools.

In the accompanying drawings, the preferred embodiment of this invention is shown and in these drawings:

FIGURE 1 is an axial sectional view of a pneumatic percussion tool embodying this invention.

FIGURE 2 is an enlarged axial sectional view through the cylinder of the tool at the location of the reversing valve and showing the valve in the piston-down position.

FIGURE 3 is a similar view but showing the valve in the piston-up position.

FIGURE 4 is a transverse sectional view taken along line 44 of FIGURE 2.

FIGURE 5 is a similar view but taken along line 5-5 of FIGURE 2.

FIGURE 6 is a detail of the valve in section taken substantially along line 6-6 of FIGURE 4.

FIGURE 7 is an enlarged transverse sectional View taken along line 77 of FIGURE 1.

FIGURE 8 is an enlarged transverse sectional view taken along line 8& of FIGURE 1.

With reference to the drawings, the present invention is shown embodied in a pneumatic tool of the demolition type but is not limited thereto. This tool is indicated as comprising generally a case or cylinder 16 which has a piston hammer 11 reciprocably mounted therein to strike an axially movable anvil block 12 that is adapted to engage the inner end of a workpiece or tool member 13 that is also slidably mounted in the cylinder at the outer end thereof which is the forward or lower end thereof. A novel valve arrangement for controlling this tool is provided according to this invention and is illustrated generally at 14 at the opposite or inner end of the cylinder which is the rear or upper end thereof.

The case or cylinder 1% may be made as an ordinary casting. It preferably comprises the main section 15 and an outer axially aligned guide or front head section 16 which are suitably connected. The section 16 has a guide sleeve or front head bushing 17 removably mounted therein for receiving and guiding the tool 13, the sleeve 17 having a shoulder 18 for cooperating with a similar shoulder on the section 16 to prevent outward displacement of the sleeve. Directly behind the sleeve 17 is an anvil lock seat guide or collar 19 in which the anvil block 12 is axially movable. This member 19 is removably mounted in the rear or inner end of the cylinder section 16 and the forward or outer end of the main section 15 of the cylinder. The collar 19 has an inner tapered seat 23 3,232,177 Patented Feb. 1, 1966 which cooperates with a similar tapered shoulder on the anvil block 12 and is provided with an exterior shoulder 24 which cooperates with a similar shoulder on the member 16.

The main section 15 of the cylinder has a cylindrical socket in which a separate removable bushing or liner 25 of tubular form is disposed. This liner 25 can be slipped into the socket from the forward or inner open end of the cylinder section 15. The section 15 can be mounted on a handle portion 2 0 of the tool casing by an attaching flange 26 at its inner or rear end and cooperating bolts 27 or in any other suitable manner. The removable liner 25 fits snugly into the socket in the cylinder section 15 and its outer or forward end abuts the rear end of the guide collar 19. The piston hammer 11 fits snugly in the liner 25 for axial sliding movement.

As previously indicated, the cylinder section 15 may be a simple casting being of suitable tough cast metal since it need not be a hard and wear-resistant metal. The liner 25 is made of wear-resistant material, preferably hardened steel. Cast into the inner cylindrical socket wall of the section 15 are the necessary air-directing grooves or pets sages. In this instance, they are shown as being four grooves 39 (FIGURES 4-8) formed at angularly spaced positions and extending longitudinally in the socket wall surface. Before the liner 25 is hardened, it is provided with a pair of annular inwardly opening grooves or

recesses

31 and 32 on its inner surface. These annular recesses are spaced axially apart a distance slightly less than the axial extent of the piston hammer 11 and the recess 31 is spaced axially above the lower end of the cylinder chamber, as indicated in FIGURE 1. At the recess 31 (FIGURES l and 8), the liner is provided with a group of radial bores 33 corresponding in number and angular position to the four grooves 23%. At the recess 32, the liner is provided with a group of radial bores 34, for example six, the bores being angularly spaced in a predetermined manner. These bores also will be formed before the liner 25 is hardened. The respective bores 33, as indicated, communicate with the grooves 39, as shown in FIGURE 7. To insure that the tubular liner 25 will be positioned in the cylindrical receiving socket so that the bores and grooves thereof will be in angular align merit, a locating dowel pin 29 (FIGURES l5) is inserted at the inner or rear end of the cylinder section 15 and cooperates with radial aligned locating notches formed respectively in the outer surface of the liner and the inner surface of the cylinder section at their adjacent ends. Thus, the liner 25 will be located in a predetermined fixed angular position within the cylinder section 15. The six bores 34 communicate with corresponding radial bores 35 (FIGURE 7) in the wall of the cylinder section 15. The aligning

bores

34 and 35 and the aligning bores and

grooves

33 and 38, form part of the pneumatic system which actuates the piston hammer 11 and which is controlled by means including the reversing valve 14 previously mentioned.

Compressed air is supplied to the tool through a line 35 which is connected to the cylinder section 15 at a swivel connection 37. Flow of air into the cylinder is controlled by a throttle valve which comprises a spring plunger 38 reciprocably mounted in the handle 29. This plunger 38 is actuated by a trigger 39 which engages the outer end of the plunger 38, the plunger being normally held in its outer position by a spring 40. In this position, the valve plunger 38 closes a passageway 41 leading from the line 36 to the valve 14. The trigger 39 is pivoted to the handle 20 at 42 and is stopped in an outwardly swung position by the transverse stop pin 43 which extends through an enlarged opening 44 therein.

The handle 20 also has formed therein a reservoir or oil chamber 45 for lubricating oil which may be filled through a filler bore 46 normally closed by a removable plug (not shown). Oil under certain pressure conditions created by the valve 14 will seep from the chamber 45 through a porous plug 47 into a chamber 48 formed in the front face of the handle 2&9. This plug may be made of porous bronze.

The reversing valve 14 is of novel construction and functions in accordance with this invention to control the reciprocation of the piston hammer 13. This valve 14- includes a tubular chest t) which is formed as a separate sleeve or bushing and is disposed at the rear or inner end of the cylinder section behind the liner in axially spaced relationship thereto (FIGURES 1-3 and 6). The interior of the chest 5% communicates with the air passages or grooves in the cylinder section 15 by means of four radial bores 51 (FIGURES 4 and 6) extending from an annular chamber 52 outwardly through the tubular wall of the chest 50 and aligned with the grooves St? in the cylinder surface when the chest is properly positioned and set in the cylinder section 15. The dowel pin 2% also locates the tubular chest so angularly within the cylinder section 15 cooperating with an aligning notch in the exterior of the chest as shown in FIGURES 2 and 3. It will be noted that the chamber 43 is directly behind the valve cage 5t? and that the compressed air inlet passageway 41 communicates therewith. Another annular chamber 53 is provided by a recess below the chamber 52 and is vented by a vent bore 54 (FIGURE 5) extending radially outwardly through the valve chest 5th and the cylinder section 15.

The automatic valve member of the valve 14 is in the form of an annular piston 55 (FIGURES 2 and 3) which is mounted for its axial movement on the concentric stem of a valve guide as which includes a peripheral flange that is disposed between the adjacent ends of the chest 50 and the liner 25, the flange being provided with a notch for receiving the dowel pin 29. The valve member 55 is provided with bores 58 extending axially therethrough and with. an annular groove 5h around its periphery. The flange 57 of the valve guide 56 is provided with bores 61 extending axially therethrough. The upper or outer end of the chest 5% is flat and substantially closed but is provided with the inlet bores 49.

A spring-pressed plunger 6% is axially mounted in the handle 20 in concentric relationship with the stem of the guide 56 and engages the outer end thereof. The plunger is normally urged inwardly by a compression spring 63 which has its inner end disposed within the hollow plunger 6t and its outer end in engagement with the outer end of a socket 64 in the handle 20 in which the plunger is mounted for axial sliding movement. The spring-pressed plunger normally urges the guide 56 into contact with the outer end of the liner 25.

In the operation of this. tool, compressed air for actuating the tool is admitted by opening the normally closed valve 33. Assuming the piston 11 is down, the valve 114 will be in the condition shown in FIGURE 2. Therefore, the admitted air will enter into the valve cage 59 through the bores 49 into the chamber 56a above the valve member 55 and the lower face of this member will be seated on the flange of the valve guide 56 seating at the lower valve face 55:: and thereby closing the valve ports 58 and preventing flow of compressed air therethrough which would otherwise reach the cylinder chamber 110: above the piston 11, through the ports 61. The admitted compressed air does flow from the chamber 50a out through the bores 5i, through the valve cage wall, and into the longitudinal grooves 3% (FIGURE 4) of the cylinder section 15 and will emerge from those grooves through the bores 33 at the annular recess 31 (FIGURE 1) of the cylinder liner 25, into the space 1112 below the piston 11. The build-up in volume of air below the piston 11 will thrust it upwardly at high velocity compressing the air in the chamber Ila above the piston 11 and causing this compressed air to be forced through the ports 61 into the chamber Bil b around the lower end of the valve member 55'. The bores 58 of the valve member are closed at this time. The face areas 55a, 55b, and 55c of the valve 55' are all equal. Therefore, when the air pressure in the lower chamber 5% exceeds the air pressure in the supply line 36 and the upper chamber 50a, the valve member 55 shifts upwardly (FIGURE 3) seating at the upper valve face 55c to prevent compressed air from the line 36 from reaching the grooves Pt! through the radial valve cage bores 51, this occurring toward the end of the upstroke of the piston 11. As the piston 11 nears the extent of its upstroke the exhaust bores 34 are exposed to exhaust the compressed air from the lower cylinder chamber lllb. The compressed air from the line .36 now flows through the chamber Stia and from it through the bores 53 into the upper end of the chamber lia thrusting the piston hammer 11 into its downstroke or percussion stroke. This downstrolre continues until the upper end of the piston clears the exhaust groove 32 (FIGURE 1) and exhaust bores 34 and the piston hammer It strikes the anvil 12;. and drives the tool 13 downwardly. The ambient air in front of the hammer piston 11 in the forward or lower chamber 11b passes outwardly through the radial bores 33, until these bores are covered by the piston, into and through the grooves 3t? and from the upper ends of the grooves through the bores 51 into the annular groove 52 (FIGURE 3) and then into the communicating annular space 55 around the valve and finally out to the amosphere through the vent bore 54 (FIGURE 5) which communicates with the chamber 59. As indicated, in the downward stroke of the piston it will move below the bores 33 and compress air in the cylinder chamber below the piston which will serve as a piston cushioning and returning force. Simultaneously, with the hammer piston 11 striking the anvil I2, compressed air is exhausted from the chamber Ila above the piston through the

ports

3 and 35, exposed by downward movement of the piston, and due to the pressure drop in the lower valve chamber Stib through the ports 61, the pressure in the upper valve chamber 56a exceeds that in the lower valve chamber and causes the valve member 5'5 to shift automatically again to the lower position shown in FIGURE 2 where it seats at the lower seal 55a thereby completing the percussion cycle.

Lubricating oil is contained in the chamber 45 and at ambient pressure is contained by the porous plug 4-7 due to capillary action. When the valve 33 is opened, however, compressed air enters into the chamber 48 and from that chamber through the plug 4-7 pressurizing the chamber 45. However, when the valve 35 is again closed, the oil passes through the plug 47 into the chamber 48 until the pressure in the chambers 48 and 45 is equalized. Thus, there will be a limited controlled flow of lubricating oil into the chamber 43 and the associated valve parts.

It will be apparent that with this valve arrangement the valve member 55 is shifted by precalculated pressure differentials. Ambient air is exhausted from the lower or forward end of the cylinder during the percussion stroke of the piston. This arrangement differs from prior art tools where the air ahead of the hammer piston is compressed and is relied upon to shift the valve. With the arrangement of this invention, it is possible to obtain a greater precussive blow than with prior art arrangements.

The piston is moved axially in opposite directions under control of the reversing valve which also comprises the axially movable and axially aligned valve member. This member has the ports extending axially therethrough and the connections of the valve cage to the cylinder are such that the valve is moved axially in the same direction as the axial movement of the piston. The valve member shifts downwardly as the piston 11 moves downwardly (FIGURE 2) to bring about the upstroke of the piston whenever the upper chamber of the cylinder decompr'esses. It shifts upwardly as the piston 11 moves upwardly (FIGURE 3) to bring about the downstroke of the piston whenever the upper chamber of the cylinder is pressurized sutficiently by such upward movement of the piston. During the downstroke or percussive stroke of the piston hammer, the air below it is not compressed but is allowed to escape to the atmosphere.

As previously indicated, this valve arrangement is not limited to the tool described having the specific cylinder and piston arrangement. For example, the valve may be used in a structure where the piston and tool are rotated as disclosed in the copending application of Robert L. Sandvig, directed to Tool Retainer for a Pneumatic Hammer, Ser. No. 388,487, filed August 10, 1964.

According to the provisions of the patent statutes, the principles of this invention have been explained and have been illustrated and described in what is now considered to represent the best embodiment. However, it is to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

Having tilfllS described this invention, what is claimed 1. A pneumatic percussion tool comprising a cylinder; a piston hammer reciprocably mounted in the cylinder; selectively actuated means for supplying compressed air to the cylinder; means for automatically controlling the supply of com-pressed air to the cylinder in accordance with actuation of said selectively actuated means, said last-named means comprising a reversing valve; said cylinder having air passages which communicate therewith at a point spaced from the forwardmost end of the cylinder and which commuicate with said reversing valve; said cylinder having vent passages intermediate its length communicating with the atmosphere; said vent passages and said air passages communicating with the cylinder at locations spaced apart axially of the cylinder a distance slightly less than the axial extent of said piston; said reversing valve comprising a tubular cage mounted in axial alignment with the cylinder at the rear end thereof and having a concentric valve guide positioned therewithin; a sleeve-like valve member mounted within said tubular cage and around said valve guide for axial movement; said valve cage having at its rear end inlet 'ports which lead into a first rear annular chamber formed therein, said inlet .ports being connected to said selectively actuated air-supplying means, said first chamber being provided with air-passages which communicate with said cylinder air-passages, said valve cage being provided with a second annular chamber intermediate its ends which is vented, said valve cage being provided with a third annular forward chamber communicating by axial passages with the rear end of said cylinder, said valve member being provided with passages leading axially therethrou-gh; said valve member when in its forward position with the piston in its forward position having said third chamber connected to the rear end of the cylinder, with said first chamber connected to said inlet ports so as to permit fiow of air into said first chamber upon actuation of said selectively actuated means and then into said cylinder air passages to reach the space in said cylinder ahead of the piston through said cylinder air passages, the space in said cylinder behind the piston communicating with atmosphere through said cylinder vent passages; air pressure supplied ahead of the piston by said selectively actuated means causing the piston to move rearwardly in the cylinder to thereby close the vent passages of the cylinder and to move the valve member rearwardly to thereby connect the source of supply of compressed air through said valve inlet ports and said valve member ports through said third chamber to said rear end of the cylinder, to interrupt flow from said inlet ports to said first chamber and the connected cylinder air passages and to connect the first chamber with the vented second chamber to thereby vent said cylinder air passageways and the space in the cylinder ahead of the piston to permit subsequent forward movement of the piston during actuation of said selectively actuated means, said space ahead of the piston venting continuously during the forward stroke of the piston until said cylinder air passages are closed as the piston nears the extent of its forward movement.

2. A pneumatic percussion tool according to claim 1 including means for supplying lubricating oil to the valve cage for lubricating movement of said valve member therein, said means comprising a chamber for oil communicating with said valve cage through a porous plug which permits passage of oil from said oil chamber to said cage.

3. A pneumatic percussion tool comprising a cylinder; a piston hammer reciprocably mounted in the cylinder; selectively actuated means for supplying compressed air to the cylinder; means for automatically controlling the supply of compressed air to the cylinder in accordance with actuation of said selectively actuated means, said last-named means comprising a reversing valve; said cylinder having air passages which communicate therewith at a point adjacent the forwardmost end of the cylinder and which communicate with said reversing valve; said cylinder having vent passages intermediate its length communicating with the atmosphere; said vent passages and said air passages communicating with the cylinder at 10- cations spaced apart axially of the cylinder; said reversing valve comprising a tubular cage mounted in axial alignment with the cylinder at the rear end thereof; a concentric sleeve-like valve member mounted within said tubular cage for axial movement; said valve cage having at its rear end inlet ports which lead into a first rear annular chamber formed therein, said inlet ports being connected to said selectively actuated air-supplying means, said first chamber being provided with air-passages which communicate with said cylinder air-passages, said valve cage being provided with a second annular chamber intermediate its ends, which is vented, said valve cage being provided with a third annular forward chamber communicating iby passages with the rear end of said cylinder, said valve member being provided with passages leading therethrough; said valve member when in its forward position with the piston in its forward position having said third chamber connected to the rear end of the cylinder, with said first chamber connected to said inlet ports so as to permit flow of air into said first chamber upon actuation of said selectively actuated means and then into said cylinder air passages to reach the space in said cylinder ahead of the piston through said cylinder air passages, the space in said cylinder behind the piston communicating with atmosphere through said cylinder vent passages; air pressure supplied ahead of the piston by said selectively actuated means causing the piston to move rearwardly in the cylinder to thereby close the vent passages of the cylinder and to move the valve member rearwardly to thereby connect the source of supply of compressed air through said valve inlet ports and said valve member ports through said third chamber to said rear end of the cylinder, to interrupt flow from said inlet ports to said first chamber and the connected cylinder air passages and to connect the first chamber with the vented second chamber to thereby vent said cylinder air passageways and the space in the cylinder ahead of the piston to permit subsequent forward movement of the piston during actuation of said selectively actuated means, said space ahead of the piston venting continuously during the forward stroke of the piston until said cylinder air passages are closed as the piston nears the extent of its forward movement.

4. A pneumatic tool com-prising a cylinder; a piston reciprocably mounted in the cylinder; selectively actuated means for supplying compressed air to the cylinder; means for automatically controlling the supply of compressed air to the cylinder in accordance with actuation of said selectively actuated means, said last-named means comprising a reversing valve; said cylinder having air passages which communicate therewith at a forward point along the cylinder and which communicate with said reversing valve; said cylinder having vent passages axially behind said cylinder air passages communicating with the atmosphere; said reversing valve comprising a valve member mounted within said cage for reciprocal movement; said valve cage having inlet ports which lead into a first chamber formed therein, said inlet ports being connected to said selectively actuated airsu-pplying means, said first chamber being provided with air-passages which communicate with said cylinder airpas'sages, said valve cage being provided with a second chamber which is vented, said valve cage being provided with a third chamber communicating by passages with the rear end of said cylinder, said valve member being provided with passages leading thereth-rough; said valve member when in one position with the piston in its forward position having said third chamber connected to the rear end of the cylinder, with said first chamber connected to said inlet ports so as to permit flow of air into said first chamber upon actuation of said selectively actuated means and then into said cylinder air passages to reach the space in said cylinder ahead of the piston through said cylinder air passages, the space in said cylinder behind the piston communicating with atmosphere through said cylinder vent passages; air pressure supplied ahead of the piston by said selectively actuated means causing the piston to move rearwardly in the cylinder to thereby close the vent passages of the cylinder and to move the valve member to thereby connect the source of supply of compressed air through said valve inlet ports and said valve member ports through said third chamber to said rear end of the cylinder, to interrupt flow from said inlet ports to said first chamber and the connected cylinder air passages and to connect the first chamber with the vented second chamber to thereby vent said cylinder air passageways and the space in the cylinder ahead of the piston to permit subsequent forward movement of the piston during actuation of said selectively actuated means, said space ahead of the piston venting continuously during the forward stroke of the piston (until said cylinder air passages are closed as the piston nears the extent of its forward movement.

5. A pneumatic tool comprising a cylinder; a piston reciprocably mounted in the cylinder; a source of supply of compressed air for the cylinder, means for automatically controlling the supply of compressed air to the cylinder from said source and including a reversing valve; said cylinder having air passages which communicate therewith and with said reversing valve; said cylinder having vent passages axially spaced from said cylinder air passages communicating with the atmosphere; said reversing valve comprising a cage; a valve member mounted within said cage for reciprocal movement; said valve cage having inlet ports which lead into a first chamber formed therein, said first chamber being provided with air-passages which communicate with said cylinder air-passages, said valve cage being provided with a second chamber which is vented, said valve cage being provided with a third chamber communicating by passages with the rear end of said cylinder, said valve memher being provided with passages leading therethrough; said valve member when in one position with the piston in its forward position having said third chamber connected to the rear end of the cylinder, with said first chamber connected to said inlet ports so as to permit flow of air into said first chamber from said compressed air source and then into said cylinder air passages to reach the space in said cylinder ahead of the piston through said cylinder air passages, the space in said cylinder behind the piston communicating with atmosphere through said cylinder vent passages; air pressure supplied ahead of the piston causing the piston to move rearwardly in the cylinder to thereby close the vent passages of the cylinder and to move the valve member to thereby connect the source of supply of compressed air through said valve inlet ports and said valve member ports through said third chamber to said rear end of the cylinder, to interrupt flow from said inlet ports to said first chamber and the connected cylinder air passages and to connect the first chamber with the vented second chamber to thereby vent said cylinder air passageways and the space in the cylinder ahead of the piston to permit subsequent forward movement of the piston during supply of compressed air from said source, said space ahead of the piston venting continuously during the forward stroke of the piston until said cylinder air passages are closed as the piston nears the extent of its forward movement.

References Cited by the Examiner UNITED STATES PATENTS 2,164,970 7/1939 Van Sittert et a1. 91-556 2,254,695 9/ 1941 Fuehrer 91-239 2,613,646 10/1952 Gillerstnum 91-3l7 3,038,447 6/1962 OFlarrell 9l-317 SAMUEL LEVINE, Primary Examiner.

P. E. MASLOUSKY, Assistant Examiner.

Claims

1. A PNEUMATIC PERCUSSION TOOL COMPRISING A CYLINDER;