US2120992A - Pneumatic tool - Google Patents

Description

June 21, 193 8..

' E. J. SEIDEN PNEUMATIC TOOL:

Filed Aug. 29, 1935 V IIIIIIIIIIA Q Elma/WM Elmer- J. fie/den Patented June 21, 1938 UNITE-D STATES PATENT OFFICE V PNEUMATIC TOOL v Elmer J; Seide'n, Jackson, Mich. Application August29, 1935, Serial No. 38,398

7 Claims. (01. 1 21-3 The present invention relates to improvements in pneumatic tools and .the like. While the in-. vention has general application, it has particular reference to pneumatic hammers forcontouring sheet metal over a dolly .or form.

Primary objects of my improvements are, first,

to provide a pneumatic hammer which may be used in .a manner ,similar to the, conventional hand hammer for contouring sheet metal; sec- 0nd, to provide a pneumatic hammer in which reciprocation of the working head is initiated out of engagement with the workandthe intensity and rapidity of the blow may beregulated; and third, to provide a compact, inexpensive, durable pneumatic hand hammer.

Other objects and advantages of the invention residing in the arrangement, combination, and construction of parts will-appear from a consideration of the following description and the annexed claims.

In the accompanying drawing, wherein ,a preferred form of the invention is illustrated,

Fig. 1 is a longitudinal cross-sectional view of the tool and Figs. 2 and 3 are fragmental diagrammatic cross-sectional views showing the piston and hammer head in different positions.

Referring to the drawing, the invention in pneumatic, tools is disclosed in connection with a hammer adapted to be held in either or both hands of the operator. While it is-not my purpose to limit the invention to a tool for a particular use, the'illustratedhammer is particularly-constructed tobe used inrepairand refinishing shops for straighteningthe fenders and bodies of automobiles. Although pneumatic hammers have heretofore been used in such work, they have not been fully satisfactory, with the result that at the present time a manually swung hammer is the generally accepted form of-tool for obtaining satisfactory work. According to the present invention a compact,,reaclily handable ham mer I8 is provided by casting the handle l2;and body [4 as an integral unit, the hammer being capable of delivering controlled blows of great rapidity to one side of the sheet metal being reformed .over a dolly held in the operators hand and applied to the votherside of the metal. Within the body I4 is machined a bore 16 to receive the piston l8, carrying the hammerhead ,20. As

shown, the hammer head 28 is supported by a shaft 22 threaded at-23 intothe wall 24 of the otherwise hollow piston .18. The shaft-22 and head 20 maybe machined from a single piece of metal; vor connecte d,;in any suitable manner, de-

pending generaliy upon the characteristics of the head '28 desired. For repairing automobile fenders and;bodies a soft steel head'is found most desirable, as it produces a smoother finish and reduces the rebound following the metal to metal blows of the head. A relatively heavy coil sprin 2 2B is housed withinthe piston l8 and held under compression by a collar '28 threaded. at 29 into the outer end of the body I4. Preferably, the shaft 22 is freely embraced by the collar 28, whereby the hammer head 28 and rod 22 are entirely free from any guiding or aligning action by the collar 28. The spring 28 normally urges the piston l8 against the inner .end 21 of the bore l6. a i 5 Compressed air is admitted into the conduit 29 defined in the handle l2 and passes through a drilledhole38past the manuallycontrolled valve 32, through the conduit 34, past the adjustment valve 36, and hence into the bore 16 past the g piston actuated valve "38. From the bore IS the air is exhausted through the portMl in the wall 24 and communicating ports Hand in the shaft 22 and collar 28. To describe in detail the valve mechanism for regulating the passage of compressed air just describedthevalve 32 comprises a rod 46 which is actuated bya lever 48 to remove the valve from its seat 50 against the tension of the spring 52. When the lever 48 is re.-

leased, the air pressure and spring 52 act jointly h to close the valve 32, shutting off the flow of air. The adjustment valve 36 takes the form of a conical pointed screw, which through axial adjustment regulates the air passing through the con-.- duit 34. Itis to be understood that both the valves 32 and 36 may take innumerable forms and their specific construction forms no part of the present invention. The construction and function of the valve 38, however, do constitute an important'feature of the present invention, and the. valve 38comprises a head portion ,54 disposed-,between-stem portions 56 and 58. A seat 68 for the head ti l is defined in the body .l4, the head 54 beingguided to its seat by the stem portion 58, which is in turn guided within a re- 4 movable sleeve 62 threaded into the .body [,4 at 64. A spring 65 normally tends to urge the valve 38 to a closed position. The forwardly extending stem portion 56 extends through the port .66 in the end 21 ,of the bore l6, and the end 18 thereof engages the endof the piston l8 and closes the exhaust port 48in the wall 24 when the piston is at the inner .endof its strokeas viewed in Fig. 1 The operation of the tool heretofore described follows: With the 11,001 vconnected to a suitable source of air pressure, prior to opening the valve 32 by actuating the stem 46 through movement of the lever 48, the spring 26 will position the piston l8 against the end 21 of the bore I6, holding the valve 38 open, as shown in Fig. 1. When the lever 48 is depressed, air is directed against the piston l8 which moves toward the other end of its stroke. The exhaust port 40 in the piston 18 is held closed by the head 10 which follows the initial movement of the piston due to the action of the spring 65, as shown in Fig. 2. Movement of the valve 38 is, however, arrested prior to the end of the stroke of the piston l8 through engagement with the seat 60 shutting off the air being directed against the piston, as shown in Fig. 3. Relative movement between the end H! of the valve 38 and the piston I8 results in the exhaust port being opened and the pressure reduced behind the piston. The momentum of the piston I8 is cushioned by the spring 26 at the end of its outward stroke and returned to the inner end of its stroke by the spring 26 upon the reduction of air pressure resulting from opening the exhaust port 40. Movement of the piston toward the end 21 closes the exhaust port 40 and opens the valve 38, resulting in the cycle of operation being automatically repeated. The incoming compressed air, as well as the air trapped between the piston and end 21 of the bore I6, upon closing of the exhaust port 40 cushions the piston at the end of its inner stroke. In operation, the hammer head 20 and piston l8 are vibrated at a high rate of speed within the bore 16 as long as the lever 48 is depressed. Through regulation of the valve 32 more or less air is directed against the piston l8, and it is possible in this manner to vary the rapidity and intensity of the'blows of the hammer. This ability to regulate the hammer blows, coupled with the fact that the hammer head is capable of vibration out of contact with the work, makes the use of the same in connection with metal finishing exceedingly successful. 1

Having described my invention, what I claim and desire to protect by Letters Patent is:

' 1. In a pneumatic hammer, an integral body and handle portion, a bore defined in said body portion, a piston reciprocatably mounted in said bore, a hammer head, means connecting said head and piston for reciprocating as a unit, a collar connected to one end of said bore through which said means extends, a spring interposed between said collar and piston, valve mechanism for directing compressed air against one end of said piston imparting movement to said head and compressing said spring, and exhaust mecha nism, including passages defined in said piston, for exhausting the air directed against said piston, whereby the same is returned by said spring.

2. In a pneumatic hammer, a body and handle portion, a bore defined in said body portion, a reciprocating hammer structure comprising a head and piston, said piston being disposed within and said head without said bore, a collar structure disposed between said head and piston and located at one end of said bore, a spring interposed between said collar and piston, said spring being compressed when said piston moves toward one end of its stroke and actingto return said piston to the other end of a stroke, and valve mechanism, including a movable inlet valve structure and a passage in said hammer structure closed by said valve structure during periods of air inlet, for intermittently admitting and exhausting compressed air in one end of said bore.

3. In a fluid pressure tool, a cylinder, a piston located in said cylinder, operating structure associated with said piston, valve mechanism actuated by movement of said piston for admitting fluid pressure into said cylinder, exhaust mechanism, including passages in said piston, regulated by movement of said piston relatively to said valve mechanism for exhausting fluid pressure in said cylinder, and mechanical means for automatically returning said piston to its initial position following the exhausting of fluid pressure.

4. In a fluid pressure tool, a body portion defining a cylinder, a piston supported in said cylinder for reciprocating movement, an inlet valve, continuously urged in a closing direction, engaging with said piston and adapted to be held open directly by said piston at one end of its stroke, exhaust means associated with said piston, means closing said exhaust means at said end of the piston stroke, movement of said piston from one end of its stroke to the other acting to open said exhaust means and close said inlet, and automatic means actuated by movement of said piston from one end of its stroke to the other for returning said piston to its initial position opening said inlet and closing said exhaust.

5. In a fluid pressure tool, a vibratory member, an inlet valve, mechanical means normally urging said inlet valve to a closed position, said member in one position directly holding said inlet valve open and in another position permitting said inlet valve to be closed by said means, an exhaust port associated with said member and closed with said member in a position opening said inlet valve, and means compressed upon movement of said member from said position for returning the same following the opening of said exhaust valve.

6. In a fluid pressure tool, a vibratory mem ber, an air inlet valve, means normally urging said valve in a closing direction, said valve being held open directly by said member when it is in one position, a source of fluid pressure, manually operating means for connecting said inlet valve to said source of fluid pressure, means for regu-- lating the amount of flow of fluid pressure to said inlet valve, an exhaust port, said port being opened upon movement of said member from said position, permitting said inlet valve to be closed by said means, and, means for returning said member to its initial position opening said air inlet and closing said exhaust port.

7. A pneumatic hammer characterized by the fact that the operating member thereof is capable of vibration out of contact with the work piece, comprising a member supported for vibratory movement, spring mechanism tending to urge said member to its initial position, said spring being placed under compression upon movement of said member out of its initial position, and an air inlet valve directly held open by said member in its initial position, means for closing said valve upon movement of said member out of its initial position, exhaust mechanism opened upon movement of said piston out of its initial position with the closing of said inlet, said spring mechanism upon the closing of said inlet and the opening of said exhaust acting to return said member to its initial position, directly closing said exhaust and opening said inlet for repetition of the cycle of operation.

ELMER J. SEIDEN.

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