US2290256A - Pneumatic tool - Google Patents

Description

July 21, 1942. H, 'SOUTER 2,290;256

PNEUMATIC TOOL Filed N07. 4, 1940 2 Sheets-Sheet l I i Z5 Z4 1 7. 1.

; I I INVENTOR.

' I q ")%HNEYS.

July 21, 1942. ou- 1 2,290,256

PNEUMATIC TOOL Filed Nov. 4, 1940 2 Sheets-SheetZ INVENTOR' 52/56/76 Sou/er Patented July 21, 1942 TED STATES PATENT OFFICE PNEUMATIC TOOL Eugene H. Souter, Independence, M0.

Application November 4, 1940, Serial No. 364,256

Claims.

This invention relates to pneumatic tools and particularly air actuated equipment in the nature of means for imparting efifective blows to a part of the tool for the purpose of piercing sheet metal or the like, forming heads on rivets, or otherwise treating the work where speed of movement of the tool part, rather than the amount of power, constitutes the desirable quality.

This invention has for one of its primary aims the provision of a pneumatic tool that is portable in character, compact, and capable of being actuated through the employment of compressed air at normal commercial pressures.

A further object of the invention is to provide a pneumatic tool of the aforementioned character that is particularly useful in piercing sheet metal from one side thereof and without the employment of cooperating means on the other side whereby clean-cut holes of desired diameter may be created in sheet metal, such as automobile body stock, with speed and accuracy.

Another object of the instant invention is to provide a pneumatic tool with unique elements for releasably holding a freely movable hammer at one end of its path of travel, to cause a quick release of said hammer when the air pressure behind the same is raised to a predetermined point.

Some of the most important objects of this invention are embodied in the unique details shown in the accompanying drawings and therefore, the following specification will further indicate additional aims. In said drawings:

Figure 1 is a side elevational View of a pneumatic tool made in accordance with the present invention.

Fig. 2 is an enlarged condensed longitudinal central sectional view through the tool taken on line IIII of Fig. 1.

Fig. 3 is a transverse sectional view through the tool taken on line III-III of Fig. 2.

Fig. 4 is a similar view taken on line IVIV of Fig. 2.

Fig. 5 is a longitudinal condensed sectional view through a pneumatic tool made to embody a modified form of the invention.

Fig. 6 is a transverse sectional View through the tool shown in Fig. 5 taken on line VIVI of Fig. 5.

Fig. 7 is a similar view taken on line VIIVII of Fig. 5.

A portable, compact, effective and inexpensive pneumatic tool capable of being operated'by air passing through the conventional compressed air hose, is desirable where the operator wishes to aifix parts to the sheet metal body of an automobile. Particularly it is desired to form openings through the fire wall of the automobile body from a place beneath the hood and to the end that metal screws or the like may be inserted from one side without the necessity of entering the passenger compartment of the automobile. The tool is also capable of employment in all sheet metal fabrication both in the factory and field applications.

The pneumatic tool illustrated in the accompanying drawings is capable of piercing comparatively heavy gauge sheet metal without producing an objectionableburr on one side thereof.

The preferred manner of constructing the tool is illustrated in Figs. 1 to 4 inclusive, wherein the numerals l0 and I2 designate outer and inner telescoped tubes between which is provided an air chamber or clearance pocket I4. Inner tube 12 has ports l6 provided near one end thereof and ports l8 formed through its wall at a slightly greater distance from the end of tube l2 than ports I6.

Exhaust ports 20 place tube 12 in communication with the atmosphere for the purpose of allowing the escape of air as hammer 22 moves longitudinally along tube l2 toward punch 24.

Punch 24 mounted in cavity 26 of tip 28 is free to reciprocate. Head 30 on punch 24 limits the length of the path of travel in one direction by striking cellulose bushing 32 in tip 28, while stop 34 engages head 30 when punch 24 is moved inwardly.

An air intake port 36 places air chamber 14 in communication with hose 38 when the tool is made in accordance with one form of the invention and as illustrated in Figs. 1 and 2.

A finger operated valve controls the passage of air from tube 38 to chamber Hi. This valve comprises a hollow body 411 wherein thimble-shaped element 42 is reciprocably mounted and held at one end of a path of travel by spring 44. This hollow element 42 has an opening 46 and an opening 48 provided in the wall thereof, which openings are in ofiset relation for the purpose of placing air chamber M in communication with the atmosphere when element 42 is in the normal position, shown in Fig. 2, and in communication with hose 38 when the operator has depressed head 50.

A hole 52 in the side of hollow body 40 is in register with opening 48 to release air from chamber I4. When head 50 is depressed, opening 46 is in register with lateral passage 54 to place chamber I4 in communication with hose 38.

When the latter condition exists, opening 48 is offset from 52 to close the same.

Hammer 22 is of hardened metal and equipped with a stem 56 to enter bore 58 of stop 34 and a head 60 joined to the body by a neck 62.

Inclined annular surfaces 64 and 66 in spaced relation adjacent to head 60, increase the surface area of hammer 22 to a desirable extent, and their location is important as will be fully hereinafter set down.

Section 60 in connection with inner tube I2 and outer tube I6, has an outer annular shoulder thereon against which one end of spring 12 rests, while the other end of said spring engages the bottom of a thimble-shaped handle 14 provided with a counter bore 16 extending inwardly from the outer face on its axis. A stem 18 flanged at one end as at 80 receives the threaded portion of bolt 82 and is held to handle 14 by a nut 84 disposed in counterbore 16. The flange 80 of stem 13 is disposed in section 68 and normally behind an internal annular rib 86.

Packing 90 held in place by screwthreaded plug 92 precludes leakage around stem 18. The head of bolt 82 is confined within holder 94 on the outer face of which is provided an annular shoulder 96 against which bears one end of spring 88, the other end of said spring engaging the flange 80.

Diametrically opposed balls 98 carried by holder 94 are radially movable only when they are opposite either annular groove I60 or I02. These balls 98 rest behind head 66 of hammer 22, as shown in Fig. 2, to preclude its movement toward punch 24 until the operator has depressed handle 3.

14, and if a valve such as illustrated in Fig. 2 is employed, until said valve is opened to allow air from hose 38 to pass into chamber I4.

When handle 14 is so depressed against the force of spring 12. stem 13 will move inwardly and permit holder 64 with balls 98 and hammer 22 to move to a position where balls 98 will move radially outwardl into groove I02 a distance sufiicient to release head 60. Hammer 22 follows balls 98 because grooves 61 in hammer 22, being in communication with ports I6 and I8, admit sufiicient air into the chamber of section 68 to maintain the head of hammer 22 against balls 98. Air under pressure in chamber I4 will now immediately exert force against hammer 22 to move it longitudinally along inner tube I2 toward punch 24. As hammer 22 so moves, inclined surface 64 will reach a point opposite ports I6 and inclined surface 66 will move inwardly to a place where air entering ports I8 will exert additional force. Manifestly, the full pressure of air in chamber I4 will be exerted against hammer Has it passes beyond both ports I6 and I8, whereupon the complete force of air passing through ports I6 and I8 from chamber I4 will be exerted upon the hammer to instantaneously drive the same against punch 24 at great velocity.

Stop 34 is made of cellulose material, or some material that will withstand the blow of hammer 22 after it has performed the work of driving punch 24 through the material, or when hammer 22 is released without punch 24 being in engagement with work.

As hammer 22 travels along inner tube I2 air therefrom will be exhausted through ports 20.

In the form of tool just described and illustrated in Figs. 1 to 4 inclusive, hammer 22 is returned to the normal or set position, shown in Fig. 2, by the action of gravity. The tool ismerely positioned so that handle 14 is the lower most part thereof, whereupon hammer 22 will slide longitudinally along tube I2, strike balls 98 and thereby compress spring 88 to move holder 94 a distance sufficient to register balls 98 with groove I00. When balls 98 move outwardly into this groove, head 60 of hammer 22 will move beyond the same and before it can return spring 88, will move holder 94 to the position shown in Fig. 2 where balls 98 are again projected inwardly behind head 60.

In the illustrated embodiment of the pneumatic tool shown in Figs. 5, 6 and '7, the parts are similar to a great extent, but the additional feature of rendering the tool automatic is present. In this form, compressed air is employed to return the hammer to the set or normal position.

Referring to the specific details of this modified form, the numerals II 0 and H2 designate outer and inner tubes between which air chamber or clearance pocket H4 is created. Tip IIB operably supporting punch H8 and stop I20 is as before described, and ports I22 through the wall of inner tube II2 allows air to pass thereto from chamber II4. Exhaust port I24 places inner tube H2 in communication with the atmosphere under certain conditions, as will be hereinafter described.

Hammer I26 is freely movable in inner tube I I2 and the means for releasably retaining hammer I26 at one end of its path of travel, comprises the section I28 having annular grooves I30 and I32 which receive balls I34 operably mounted in a loosely fitting holder I36. Spring I38 lies between holder I36 and stem I40 and the latter carries bolt I42, the head of which limits the movement of holder I36 in one direction.

Stem I40 is secured at one end to cap I44 by nut I46. Cap I44 has diametrically opposed slots I48 through which pass radial stubs I50 integral with ring I52 in screwthreaded engagement with section I28. Spring I54 lies between ring I52 and the closed end of cap I44 whereby upon rotation of the latter, ring I52 will move longitudinally along the screwthreaded portion of holder I28 to vary the tension of spring I54. Stem I40 has the annular flange I56 at one end thereof resting behind internal annular rib I58 of section I28 and packing I60 held in place by a nut I62, renders the joint at this point airtight.

Hammer I26 in this form, is precisely the same as illustrated in Fig. 2 in that its two inclined surfaces I64 and I66 are spaced apart and adjacent to head I60.

Manually operable means to cause hammer I26 to travel through inner tube II2 forms an integral part of the tool embodying the modification illustrated in Figs. 5 to '7 inclusive. This means includes a grip I10 mounted on outer tube II 0 and having a bore I12 for the reception of a piston I14. An annular groove I16 in piston I14 is always in communication with inlet port I 18 through which air under pressure from hose I is admitted.

A spring I82 operably coiled about a portion of piston I14 is compressed when the operator moves trigger I84 against the force of spring I02. Inlet port I86 formed through the wall of outer tube III] is in communication with bore I12.

In the normal or set position the parts of the pneumatic tool are as clearly seen in Fig. 5.

Air from hose I82 is admitted through inlet port I10, annular groove I16 and into inner tube IIZ through port I24 and relatively small way I88.

When trigger I84 is pulled, annular groove I'I6 will place into communication, ports I18 and I86 and open the port I24. Air under pressure will immediately enter air chamber H4, pass into inner tube I I2 through ports I22, thence through grooves I23 in hammer I26 to a place in section I28 behind inclined faces I64 and I66 of hammer I26 to move holder and balls I36 and I34 respectively downwardly, as viewed in Fig. 5, against the force exerted by spring I54. When annular groove I36 is reached, balls I34 will move radially to release hammer I26. The force of air passing into inner tube I I2, as just described, will immediately and instantaneously drive hammer I26 through the length of tube H2 and against punch H3. When the operator releases trigger I84, piston I14 will return to the position shown in Fig. and air entering port I24 will move hammer I26 back to the point of beginning with sufficient force to compress spring I33 and move balls I3 outwardly into groove I32.

The inertia of hammer I26 combined with the force of air entering way I88 and port I24 is sufficient to reset the parts but spring I38 is strong enough to maintain holder I36 in the normal position until desired pressure is reached depending upon the position of ring I52.

To insure unretarded movement of the hammer I26, port I24 exhausts air from tube II2 as the hammer is forced toward punch H8. While hammer I26 is being moved back to the normal position, air escapes from within inner tube H2 by way of ports I22 and I86, it being important that piston I14 not completely close port I86 when trigger I85 is normally set.

The adjustments permitted by the form of cap I44 and associated parts, will allow the operator to meet any conditions with respect to air pressure. This adjustment enables the operator to set the tension of spring I54 for releasing hammer I26 at various air pressures depending upon the force of blow necessary to perform a particular duty.

The materials from which this pneumatic tool are made should be strong enough to withstand the forces exerted by the movement of hammer 22 or I26, as the case may be, but because diameters are relatively small and the high velocity of the hammer is the actuating factor and the force of such velocity is directed against the work engaging elements 24 or IIS, as the case may be, the materials may be light in weight.

A tool made in accordance with the foregoing specification has been used to punch a clean hole e gin. in diameter in sheet steel up to .070 in. in thickness with an air pressure of 150 lbs. per sq. in. The hammer was in. in diameter, weighed 4% oz. and the travel was 12 in.

Air storage capacity in chambers I4 and H4, as the case may be, should be a minimum of twice the displacement of the respective hammers as they move the full length of their path of travel. The ports permitting entrance of air from the air chambers of the tool should be sufficiently large to provide instantaneous equali zation of pressure between the inner tube and the air chamber wherein a volume of air is maintained.

Deviations from these figures might be made so long as the relative proportions are maintained.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. A pneumatic tool of the character described comprising telescoped inner and outer tubes forming a double walled barrel having an air chamber between said tubes; a freely movable hammer reciprocably carried by the inner tube, said inner tube havin intake ports at one end thereof for admitting air thereto from the chamber; and means releasably retaining the hammer in a set position at said one end of the inner tube, said ports being sufficiently large to provide instantaneous equalization of pressure between the inner tube and air chamber during the travel of the hammer.

2. A pneumatic tool of the character described comprising telescoped inner and outer tubes forming a, double walled barrel having an air chamber between said tubes; a freely movable hammer reciprocably carried by the inner tube; a work-engaging member at one end of the inner tube disposed to be struck by the hammer, said inner tube having intake ports at th other end thereof for admittin air thereto from the chamber; and a latch retaining the hammer in a set position at said other end of the inner tube including a structure for releasing the hammer when a predetermined pressure is reached in the cylinder.

3. A pneumatic tool of the character described comprising telescoped inner and outer tubes forming a double walled barrel having an air chamber between said tubes; a freely movable hammer reciprocably carried by the inner tube; a work-engaging member at one end of the inner tube disposed to be struck by the hammer, said inner tube having intake ports at the other end thereof for admitting air thereto from the chamber; and spring retained means for releasably holding the hammer in a. set position at said other end of the inner tube, the spring in said retaining means being strong enough to overcome the pressure of air against the hammer.

4. A pneumatic tool of the character described comprising telescoped inner and outer tubes forming a double walled barrel having an air chamber between said tubes; a freely movable hammer reciprocably carried by the inner tube; a work-engaging member at one end of the inner tube disposed to be struck by the hammer, said inner tube having intake ports at the other end thereof for admitting air thereto from the chamber; and spring retained means for releasably holding the hammer in a set position at said other end of the inner tube, the spring in said retaining means being strong enough to overcome the pressure of air against the hammer, said holding means having elements securing the hammer against the action of the air until after the force of the spring has been overcome.

5. A pneumatic tool of the character described comprising telescoped inner and outer tubes forming a double walled barrel having an air chamber between said tubes; a freely movable hammer reciprocably carried by the inner tube; a work-engaging member at one end of the inner tube disposed to be struck by the hammer, said inner tube having intake ports at the other end thereof for admitting air thereto from the chamber; and means retaining the hammer in a set position at said other end of the inner tube comprising an internally grooved section, a holder provided with radially movable balls, and a head on the hammer engagable by the balls.

6. A pneumatic tool of the character described comprising telescoped inner and outer tubes forming a double walled barrel having an air chamber between said tubes; a freely movable hammer reciprocably carried by the inner tube; a work-engaging member at one end of the inner tube disposed to be struck by the hammer, said inner tube having intake ports at the other end thereof for admitting air thereto from the chamher; and means retaining the hammer in a set position at said other end of the inner tube comprising a section having a cam face, a holder provided with radially movable balls, a head on the hammer engageable by the balls, and a spring to yieldably maintain the balls in positions on the cam face to engage the head.

7. A pneumatic tool of the character described comprising telescoped inner and outer tubes forming a double walled barrel having an air chamber between said tubes; a freely movable hammer reciprocably carried by the inner tube; a work-engaging member at one end of the inner tube disposed to be struck by the hammer, said inner tube having intake ports at the other end thereof for admitting air thereto from the chamber; and means retaining the hammer in a set position at said other end of the inner tube comprising a section having a pair of spaced apart, annular, internal grooves, a holder provided with radially movable balls shiftable across the grooves, a head on the hammer engageable by the balls when in positions other than in the grooves, and pressure responsive means for moving the balls into one of the grooves to release the hammer from the set position.

8. A pneumatic tool of the character described comprising telescoped inner and outer tubes forming a double walled barrel having an air chamber between said tubes; a freely movable hammer reciprocably carried by the inner tube; a work-engaging member at one end of the inner tube disposed to be struck by the hammer, said inner tube having intake ports at the other end thereof for admitting air thereto from the chamher; and means retaining the hammer in a set position at said other end of the inner tube comprising a section having a pair of spaced apart, annular, internal grooves, a holder, provided with radially movable balls, shiftable across the grooves, a head on the hammer engageable by the balls when in positions other than in the grooves, and pressure responsive means for moving the balls into one of the grooves to release th hammer from the set position, said pressure responsive means being shiftable by movement of the hammer thereagainst to force the balls into the other groove during the setting operation.

9. A pneumatic tool of the character described comprising a housing having a cylinder and a clearance pocket formed therein; a piston freely operating in the cylinder; a valve for admitting motive fluid to the clearance pocket; a pressure operated latch reciprocably mounted in the cylinder at one end thereof for releasably holding the piston against movement; and means for releasing the piston upon movement of the latch toward one end of its path of travel, said latch being moved to the releasing position by a predetermined pressure in the cylinder, said cylinder and the clearance pocket being interconnected adjacent the latch.

10. A pneumatic tool of the character described comprising a housing having a cylinder and a clearance pocket formed therein; a piston freely operating in the cylinder; a valve for admitting motive fluid to the clearance pocket; a pressure operated latch reciprocably mounted in the cylinder at one end thereof for releasably holding the piston against movement; and means for releasing the piston upon movement of the latch toward one end of its path of travel, said latch and piston being simultaneously moved to a position, where the piston is released for travel along, by a predetermined pressure in the cylinder, said cylinder and the clearance pocket being interconnected adjacent the latch.

EUGENE H. SOUTER.

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