US3336840A - Fluid operated tool - Google Patents

Description

Amt WW R. H. ALEXANDER FLUID OPERATED TOOL Filed March 22, 1965 R a m 2 w 7 9 N O a M w W A mama f I 1 ATTORNEYS United States Patent 0 3,336,840 FLUID OPERATED TOOL Robert H. Alexander, Dayton, Ohio, assiguor to Roclrwell Manufacturing Company, Pittsburgh, Pa, a corporation of Pennsylvania Filed Mar. 22, 1965, Ser. No. 441,749 7 Claims. (Cl. 9138) ABSTRACT OF THE DISCLOSURE A power impacting tool having a fluid operated driving motor and a compact fluid actuated automatic timing mechanism incorporating a tubular conduit member extending within a chamber formed within the tool, a manually controlled start valve and a stop valve mounted on said conduit member, and an adjustable needle valve for controlling the flow of fluid to actuate the stop valve.

Summary of the invention This invention relates to improvements for fluid operated tools such as a portable pneumatic impact tool for tightening threaded or riveted fasteners, and more particularly, to an improved fluid actuated timing mechanism for automatically controlling the time of operation of the tool so that it may be used successively on a series of identical fasteners.

It is the ultimate desire in connecting the two members with a plurality or series of fasteners such as bolts, screws or rivets to have a substantially uniform tension in the fasteners which results in an overall uniform connecting force between the members joined together. As it is practically impossible to determine the exact tension in a threaded fastener, usually the tightening torque is controlled since this torque is a good indication of the tension in the fastener.

It has been found, however, that due to slight variations in the surface of the member being fastened and in the threaded fasteners themselves, the friction between the fasteners and the member will vary substantially which results in corresponding variations in tension even though each fastener is tightened with the same maximum torque. To minimize this variation in tension within a series of threaded fasteners, it has been determined that if each fastener is tightened by a substantially constant amount of energy, the resulting tension within the series of fasteners will be substantially more uniform even though a variation in maximum tightening torque results among the fasteners. The desirability of employing a constant input of energy into the tightening of a series of fasteners is mentioned in applicants copending application Ser. No. 69,756, filed Nov. 16, 1960, now Patent No. 3,195,702.

The total amount of energy required to tighten a threaded fastener by a fluid actuated rotary impact tool is influenced by several factors. The primary factors are the rotational speed of the hammer at impact, the moment of inertia of the hammer, the time period of impacting, the spring rate of the tool components receiving the impacting blows, and the actual spring rate of the fastener assembly itself. It has been determined, however, that it is impractical to provide for a variable moment of the inertia of the hammer in a small portable tool. Furthermore, it has been found that a change in hammer speed provides for fine control within a given speed range, but does not serve as a good control for providing a wide range in the output of energy.

As the spring rate of the fastener assembly is fixed for any particular fastener this factor does not provide a variable control over the energy output best suited for tightening the fastener. Thus it has been resolved that the output of energy of the impacting tool for tightening a threaded fastener is best controlled by providing an accurate con trol over the time which the tool operates and by varying the spring rate of the tool components between the impacting hammer member and the fastener.

As such, the present invention is directed to a fluid operated impact tool which includes an improved fluid actuated timing mechanism which can be precisely adjusted so that the time period of impact can be selected along with the spring rate of an interchangeable tool component to provide the optimum total output of energy best suited for tightening a particular fastener. Also, the speed of the fluid operated motor can be adjusted to provide a fine control over the output of energy Within a given energy range.

Accordingly, it is a primary object of the present invention to provide an improved and compact fluid actuated automatic timing mechanism which can be mounted on a portable fluid operated impacting tool while maintaining the overall compactness of the tool.

It is a further object of the invention to provide a portable impacting tool with an adjustable automatic timing mechanism which can be set to cooperate with an interchangeable tool component having a predetermined spring rate to provide a precise energy output best suited for tightening a series of threaded fasteners.

It is another object of the invention to provide an impacting tool as outlined above with an improved fluid actuated timing mechanism which is simple in construction and dependable in operation and, in addition, may be quickly assembled into the handle of the tool.

Still another object is to provide an improved fluid operated automatic timing mechanism for a fluid operated tool wherein the timing mechanism can be easily and conveniently adjusted to change the precise period of automatic operation of the tool or to convert to manual operation.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawing and the appended claims.

In the drawing:

FIG. 1 is a side view in part section of a typical fluid operated rotary impacting tool including the improved timing mechanism in accordance with the invention;

FIG. 2 is an enlarged sectional view of the tool handle and showing the assembled relationship of the timing mechanism; and

FIG. 3 is an enlarged sectional view of the combined valves for controlling the period of automatic operation of the timing mechanism.

Referring to the drawing which illustrates a preferred embodiment of the present invention, the fluid operated rotary impacting tool shown in FIG. 1 is illustrative of a typical fluid operated tool which can employ a fluid operated timing mechanism in accordance with the invention. Generally, this tool includes a housing In having a handle 12 depending downwardly from one end. Enclosed within the housing 10 at the rear is a fluid operated motor 16 which preferably is of a sliding vane type well known in the art. Extending forwardly from the motor 16 and formed as part of the drive shaft 19 is a drive pinion 21. Surrounding the drive pinion 21 is a planetary reducing gear system 23 which is driven by the drive pinion 21.

The planet gears of the system 23 are mounted on a cage 27 which is preferably formed as the rear portion of the spindle 3t} which includes a rear hub rotatably mounted Within a ball bearing 33 retained by the housing 10. Mounted directly ahead of the cage 27 is a thrust bearing 38 which has a forward race carried within a stationary retaining member 41 and serves to oppose the biasing force exerted by a compression spring 44.

The forward end of the compression spring 44 is retained within a cylindrical bore 46 formed within an elongated cylindrical hammer member 48. The forward end of the hammer member 48 is provided with a plurality of striking lugs 58 which are adapted to engage interlockingly with a corresponding plurality of lugs formed on the rear portion of an anvil member 58.

A thrust bearing 60 is retained within the forward portion of the housing and serves to oppose the forward axial force exerted against the anvil member 58. The anvil member 58 is rotatably supported within a cylindrical bearing 63 and includes a tubular connecting portion 65 on which is slidably mounted a coupling 67 adapted to retain releasably the driving end 69 of a torsion connecting bar 70 by a suitable hexagonal shaped socket connection 72.

The forward end of the interchangeable torsion bar 70 is provided with a suitable square drive stud 74- on which is mounted the desired element (not shown) for tightening the fastener such as a socket or a screwdriver head. The torsion bar 70 is selected according to the diameter D of its elongated intermediate portion which provides the optimum spring rate for tightening a particular fastener and thus prevents over-torquing of the fastener during any given time period. That is, a smaller diameter D provides for a lower spring rate between the anvil member 58 and the head of the fastener and a larger diameter increases the spring rate.

The general operation of the impaction tool shown in FIG. 1 is described in more detail in the above mentioned copending application. Other constructions and operations of rotary impact tools, however, are well known in the art and it is to be understood that the particular construction of the impacting tool shown in FIG. 1 forms no part of the present invention. In fact, the improved fluid actuated timing mechanism of the invention can easily be adapted for use on any fluid operated tool when it is desirable to provide precise automatic control over the time period of operation.

Referring to FIGS. 1 and 2, air is supplied to the motor 16 from a suitable supply source connected by a supply hose 75 to the fitting 79 which is integrally formed on the lower end of a tubular or cylindrical conduit member 80 extending upwardly into a cylindrical chamber 81 formed in the handle 12. The conduit member 80 is retained within the handle 12 by a threaded connection 82 at the lower end of the chamber 81. As shown in FIG. 2, the tubular conduit member 80 is formed with a lower portion 83 having a slightly greater diameter than the upper portion 84 to define an annular external shoulder 86. Formed within the fitting 79 is an inlet chamber 87 which is partly defined by an annular shoulder 88. This shoulder forms the seat for a normally closed main control valve 90 which includes an O-ring 91 mounted on the lower end of a start rod 92 extending through the central chamber 93 defined by the tubular conduit member 81).

As shown, the O-ring 91 is spaced between the flanges 94 and 95 rigidly mounted on the lower end portion of the start rod 92 and is held in sealing contact with the shoulder 88 by a compression spring 96 adjustably supported by an annular retainer plug 99 threadably mounted within the fitting 79.

The axial movement of the start rod 92 and thus the opening of the normally closed main control valve 90 is controlled by the actuation of a generally cylindrical trigger 100 slidably carried within a cylindrical chamber 104 formed in the upper portion of the handle 12. As shown, the trigger 100 is retained and prevented from rotating by a cross pin 106 extending within a slot 108 formed within the outer surface of the trigger 100. A slidable pin 110 and compression spring 112 carried within the trigger 100 serve to bias the trigger normally outwardly as shown in FIG. 2.

The lower inward end portion of the trigger is provided with a cam surface 114 which is adapted to engage the upper end of the actuating rod 92 and force the rod downwardly when the trigger 100 is depressed to open the control valve 90. The release of the trigger 101 operates to close the control valve 90 as the O-ring 91 carried by the start rod 92 is forced upwardly to seat against the shoulder 88 by the force exerted by the spring 96.

Intermediately spaced within the upper portion 84 of the tubular conduit member 80 is an integrally formed diverter wall 118 which separates a pair of diametrically opposed lower ports 128 formed within the upper portion 84 from a series of similarly formed upper ports 122. Surrounding the upper portion 84 of the conduit member 80 and the ports 120 and 122 is a cylindrical control or valve member 125 having an internal cylindrical relief chamber 128 formed thereon for providing fluid communication between the ports 120 and 122 externally of the conduit member 80. The lower portion of the valve member 125 is provided with an internal O-ring 133 which serves to provide an air tight seal with the outer surface of the conduit member 80 and a slightly larger O-ring 135 which forms an air tight seal with the inner surface of the cylindrical bore defining the chamber 81.

The annular shoulder 86 formed on the conduit member 80 serves as a bottom stop for the valve member 125 which is normally biased downwardly by a compression spring 144 extending between the washer 145 mounted within the upper end of the chamber 81 and an annular shoulder 146 formed on the valve member 125. As mentioned above, the cylindrical chamber 128 formed within the valve member 125 serves to connect the ports 120 with the ports 122 whereby the air flowing into the lower portion of the chamber 93 when the control valve 90 is opened flows through the ports and into the upper portion of the chamber 93 defined within the upper portion 84 of the conduit member 80. From here the air flows out the ports 149 formed in the upper portion 84 to a speed control valve 150 mounted within the passageway 152 which connects the ports 149 to the fluid operated motor 16.

Mounted within a chamber (FIG. 3) formed within the lower portion of the handle 12 is a time control valve assembly 161 which is constructed within a fitting 165 threadably connected within the chamber 160 and includes a needle member 167 adapted to be adjustably positioned in relation to a restricted seat portion 170 by adjusting the threaded head portion 172 positioned at the end of the handle 12 with a suitable screwdriver. O-rings 173, 174 and 175 provide an air tight seal between the fitting 165 and the handle 12 and head portion 172, respectively. Preferably, the valve 161 is constructed to provide an effective time range for the tool of between 0 and 5 seconds.

A passageway 177 (FIG. 3) formed within the handle 12 and an aligned passageway 178 (FIG. 2) formed within the fitting 79 connect the internal chamber 93 defined within the conduit member 80 with the portion of the chamber 160 spaced above the fitting 165. Thus the air under pressure within the chamber 93 can pass to the chamber 183 formed within the fitting 165 to the chamber 184 surrounding the needle member 167. Depending on the relative setting of needle member 167 to the seat 170, a controlled flow of air passes through the passageways 185 and 186 (FIG. 3) into the chamber 187 formed within the handle 12.

Another passageway 192 (FIG. 3) connects the chamber 187 to the lower portion of the chamber 81 spaced under the valve member 125. A combined check valve 195 employs the upper end of the fitting 165 as a seat and includes a stem 196 and O-ring 197 which is biased normally downwardly or closed by a compression spring 198. Thus, when the air pressure in the chamber 184 is greater than the pressure in the chamber 160, the check valve 195 provides for a reverse flow of air.

In operation, when the rotary impact tool is placed in position with a suitable connecting element mounted on the stud 74 for engaging the head of the fastener, and the trigger 100 is depressed causing the main control valve 90 to open, air flows to the motor 16 through the chamber 93, ports 120 and 122 and the speed control valve 150. Simultaneously with the opening of the control valve 90, the pressurized air fiows through the passageways 178, 177 and 183 and through the time control valve 161 to the chamber 81.

The rate of flow through the valve 161 is controlled by adjusting the needle 167 in relation to the seat 170. As the pressure within the chamber 81 continues to increase, the valve member 125 is forced upwardly against the biasing force exerted by the spring 144 until the inner cylindrical surface of the lower portion of the valve member 125 begins to close the lower ports 120 which begins to stop the flow of air to the motor 16.

To prevent a gradual cut-ofi of air flow through the ports 121] by the slow upward movement of the valve member 125, a relief port 199 (FIG. 2) is formed in the conduit member 80 and opens the chamber 81 to the chamber 93 as soon as the valve member 125 begins to close the lower ports 120. In this manner, pressure within the chamber 81 is suddenly increased to the same pressure as in chamber 93 causing the valve member 125 to jump upwardly until the top end of the valve member 125 engages the resilient washer 145. To prevent the upward movement of the valve member 125 from compressing the air within the upper portion of the chamber 81 enclosing the spring 144, an exhaust port 200 is provided in the handle 12.

When the motor 16 stops at the end of the cycle and the operator releases the trigger 100, the control valve 90 closes in response to the trigger actuation. To release the air compressed within the chamber 81 so that the valve member 125 can immediately return to its normal downward position, a slot 205 is formed in the exterior surface of the actuating rod 92 at a position corresponding to the diverter wall 118. This slot 205 enables the air to flow between the diverter member 118 and the actuating rod 9 2 after the trigger 100 is released and the actuating rod returns upward to its normal position as shown in FIG. 2.

Thus, air within the chamber 81 can escape back through the passageways 192, 186 and 185, through the check valve 195 and into the chamber 93 defined within the conduit member 80. The slot 2% then enables this small volume of air to flow from the chamber 93 to the passageway 152 connected with the motor 16. When the air pressure within the chamber 81 is released in this manner, the valve member 125 returns quickly to its normal position on the shoulder 86 as a result of the downward force exerted by the spring 144. The timing mechanism is then ready for another cycle.

From the drawing and the above description, it can be seen that the automatic timing mechanism in accordance with the invention provides several distinct advantages and features for a rotary fluid operated impacting tool. Primarily, the fluid actuated timing mechanism of the invention is basically simple and compact in construction which provides not only for dependable service but enables the mechanism to be easily assembled into the handle of the impacting tool without enlarging its overall size.

Furthermore, the time for pressurizing the chamber 81 to operate the valve member 125 can be easily and conveniently controlled at the bottom of the handle 12 by adjusting the needle member 167 of the time control valve 161. As a result, when this precise control of the period of operation of the timing mechanism is combined with the variable speed provided by the speed control valve 150 and the variable spring rate provided by the interchangeable torsion bar 70, the impacting tool can be adjusted to provide the precise output of energy which produces the desired uniform tension in a. series of fasteners.

The feature of simplified construction and assembly of the timing mechanism further enables the conduit member 80, valve member 125, spring 144, valve 90, and actuating rod 92 to be all assembled as a unit'into the chamber 81 formed within the handle 12. Similarly, the combined time control valve 161 and check valve 195 can be easily assembled as a unit into the chamber This construction has been found to provide for an economical assembly as Well as enabling the tool to be used without the timing mechanism simply by closing the time control valve 161.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing fromthe scope of the invention which is defined in the appended claims.

What is claimed is:

1. In a portable power impacting tool having a pneumatically operated rotary motor, an improved air actuated automatic timing mechanism for precisely controlling the operation of the tool to produce substantially the same output of energy during each repetitive operation of the tool, said timing mechanism including a tubular conduit member positioned within a chamber formed in said tool and defining a main air passage connected to said motor, a main control valve adapted to start the flow of air through said passage, a stop valve adapted to stop the flow of air through said passage and including a valve member surrounding said conduit member and slidably mounted within said chamber, said valve member being operable between a normally open position where air flows through said passage to said motor and a closed position where the flow is stopped, spring means biasing said valve member in said normally open position, means defining a passageway connecting said main air passage following said main control valve to said chamber, a time control valve in said passageway and including means for conveniently adjusting the rate of flow therethrough so that air metered through said time control valve will progressively increase the pressure in said chamber to move said valve member against said spring means and to close said stop valve, and a check valve adapted to release the pressure in said chamber when said main control valve is closed so that said stop valve returns to its normally open position in preparation for another operation of said tool.

2. In a portable power impacting toolhaving a pneumatically operated rotary motor and including a handle extending therefrom, an improved compact air actuated timing mechanism for precisely controlling the operation of the tool to produce substantially the same output of energy during each repetitive operation of the tool, said timing mehcanism including means defining a chamber in said handle, a tubular conduit member positioned Within said chamber and defining a main air passage connected to said motor, means defining a set of spaced apart ports in said conduit member, means in said conduit member for separating said ports, a main control valve positioned near the outer end of said handle and adapted to start the flow of air through said passage, trigger means operably connected for manually operating said main control valve, a stop valve mounted within said handle and adapted to stop the flow of air through said passage and including a cylindrical valve member surrounding said conduit member and slidably mounted within said chamber, said valve member defining an internal chamber connecting said ports and being operable between a normally open position where air flows through said passage, said ports and said internal chamber to said motor and a closed position where said valve member blocks the flow through said ports, spring means biasing said valve member in said normally open position, means defining a passageway connecting said main air passage following said main control valve to said chamber in said handle, a time control valve in said passageway and having means for conveniently adjusting the rate of flow therethrough so that air metered through said time control valve will progressively increase the pressure in said chamber within said handle at a predetermined rate to move said valve member against said spring means and to close said stop valve, and a check valve for releasing the pressure in said chamber when said main control valve is closed so that said stop valve returns to its normally open position in preparation for another operation of said tool.

3. A power impacting tool including an automatic timing mechanism as defined in claim 2, wherein said time control valve and said check valve are combined in one fitting for simplifying the construction and assembly of said valves Within said handle.

4. A power impacting tool including an automatic timing mechanism as defined in claim 2, including an actuating rod extending from said trigger means through said conduit member for operating said main control valve and having a relief passage formed therein adjacent said means separating said ports to release air pressure in said chamber formed within said handle when said main control valve is closed.

5. A power impacting tool including an automatic timing mechanism as defined in claim 2, including means for quickly activating said valve member when it begins to block the fiow of air through said ports to prevent a gradual cut-ofi of the air supplied to said motor.

6. In a portable power impacting tool having a pneumatically operated rotary motor, an improved air actuated automatic timing mechanism for precisely controlling the operation of the tool to produce substantially the same output of energy during each repetitive operation of the tool, said timing mechanism including means defining a chamber within said tool, a conduit member extending within said chamber and defining a main air passage connected to said motor, a main control valve operable for starting the flow of air through said passage, a stop valve adapted to stop the fiow of air through said passage and including a valve member disposed within said chamber and slidably mounted on said conduit member, said valve member being operable between a normally open position where air flows through said passage to said motor and a closed position where the flow is stopped, means defining a passageway connecting said main air passage to said chamber, a time control valve in said passageway and including means for conveniently adjusting the rate of fiow therethrough so that air metered through said time control valve will progressively increase the pressure in said chamber to move said valve member for closing said stop valve, and means for releasing the pressure in said chamber when said main control valve is closed.

7. A power impacting tool including an automatic timing mechanism as defined in claim 6, wherein said means defining said passageway connecting said main air passage to said chamber include means defining a chamber which is substantially larger than the remaining portion of said passageway and is effective to delay the movement of said valve member towards said closed position.

References Cited UNITED STATES PATENTS 2,104,468 1/1938 Osborn 173169 2,349,548 5/1944 Haberstump 173169 X 2,397,103 3/1946 Haberstump et al. 9138 X 2,405,172 8/1946 Yanchenko 91-38 X 2,543,979 3/1951 Maurer 173-12 3,006,446 10/1961 Harrison et al 17393.6 3,131,554 5/1964 Hornschuch et a1. 17393 MARTIN P. SCHWADRON, Primary Examiner.

G. N. BAUM, Assistant Examiner.

Claims (1)

1. 6. IN A PORTABLE POWER IMPACTING TOOL HAVING A PNEUMATICALLY OPERATED ROTARY MOTOR, AN IMPROVED AIR ACTUATED AUTOMATIC TIMING MECHANISM FOR PRECISELY CONTROLLING THE OPERATION OF THE TOOL TO PRODUCE SUBSTANTIALLY THE SAME OUTPUT OF ENERGY DURING EACH REPETITIVE OPERATION OF THE TOOL, SAID TIMING MECHANISM INCLUDING MEANS DEFINING A CHAMBER WITHIN SAID TOOL, A CONDUIT MEMBER EXTENDING WITHIN SAID CHAMBER AND DEFINING A MAIN AIR PASSAGE CONNECTED TO SAID MOTOR, A MAIN CONTROL VALVE OPERABLE FOR STARTING THE FLOW OF AIR THROUGH SAID PASSAGE, A STOP VALVE ADAPTED TO STOP THE FLOW OF AIR THROUGH SAID PASSAGE AND INCLUDING A VALVE MEMBER DISPOSED WITHIN SAID CHAMBER AND SLIDABLY MOUNTED ON SAID CONDUIT MEMBER, SAID VALVE MEMBER BEING OPERABLE BETWEEN A NORMALLY OPEN POSITION WHERE AIR FLOWS THROUGH SAID PASSAGE TO SAID MOTOR AND A CLOSED POSITION WHERE THE FLOW IS STOPED, MEANS DEFINING A PASSAGEWAY CONNECTING SAID MAIN AIR PASSAGE TO SAID CHAMBER, A TIME CONTROL VALVE IN SAID PASSAGEWAY AND INCLUDING MEANS FOR CONVENIENTLY ADJUSTING THE RATE OF FLOW THERETHROUGH SO THAT AIR METERED THROUGH SAID TIME CONTROL VALVE WILL PROGRESSIVELY INCREASE THE PRESSURE IN SAID CHAMBER TO MOVE SAID VALVE MEMBER FOR CLOSING SAID STOP VALVE, AND MEANS FOR RELEASING THE PRESSURE IN SAID CHAMBER WHEN SAID MAIN CONTROL VALVE IS CLOSED.

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