US2397871A - Cycle controlling device - Google Patents

Description

Api'il 2, 1946.

w. R. KovAcs 2,397,871

CYCLE CONTROLLING DEVICE Filed Feb. 8, 1943 INVENTOR WILL/AM {a KOVACJ ATTORNEY Patented Apr. 2, 1946 CYCLE CONTROLLING DEVICE William R. Kovacs, Cleveland, Ohio, asslgnor to The Cleveland Pneumatic Tool Company, Cleveland, Ohio, a corporation of Ohio Application February 8, 1943, Serial No. 475,093

Claims.

The present invention relates broadly to fluid actuated tools, but more particularly to fluid actuated riveting hammers of the type used for HD- setting rivets. Still more particularly, this invention deals with an improved cycle control or timing device for fluid actuated riveting hammers.

The primary object of the invention is to provide an improved mechanism for automatically controlling the cycle of operation of a riveting hammer to an extent whereby fluid under pressure will be gradually supplied until a predetermined maximum has beenreached to accelerate the hammer for upsetting the rivet, and the maximum pressure maintained for a predetermined interval of time before termination of the cycle.

Another object of the invention resides in the provision of an improved cycle control or timing device having the above characteristics which is designed to accurately producerivet bucktails of uniform height and diameter. In accordance with the present invention, the riveting cycle is pre-set and ceases automatically when the rivet has been upset, thereby avoiding the possibility of damage to the sheet and reducing to a minimum the number of rejects or damaged rivets.

A further object of the invention is to provide a mechanism of this type which can be attached to, or incorporated in, the handle of a fluid actuated riveting hammer with but slight modification of the tool.

Other objects and advantages more or less ancillary to the foregoing reside in the specific construction and aggroupment of the elements peculiar to this structure, as will become apparent from a more complete examination of this specification.

In the drawing which illustrates the invention:

Fig. 1 is a side elevational view of a riveting hammer with the improved cycle control mechanism attached to the handle thereof, the handle and attachment being in section to show details of construction.

Fig. 2 is a view of a portion of the handle shown in Fig. 1 with the parts in another position.

Fig. 3 is a view similar to Fig. 2 with the parts in still another position.

Fig. 4 is a perspective view of the slidable cylinder through which the pressure fluid flows, the same being removed from its housing.

Referring to the drawing for a more detailed description thereof, a fluid actuated riveting hammer is generally designated by the reference numeral I8 and includes a cylinder II having a piston (not shown) reciprocable therein and accylindrical shaped bore I6 which bore extends I tive on a rivet set I 2 which is operatively mounted within the front end of the cylinder II and secured in position by a suitable retainer I3. To the cylinder It is threaded, Or'OtherWise affixed, a handle I4 provided in its upper end with a passage I5 which leads into the cylinder II for admitting motive fluid, such as compressed air, therein to effect reciprocation of the piston and thereby cause rapidly recurring impacts to be delivered to the rivet set I2. The outer end of the passage I5 communicates with a relatively large outwardly through the end of the handle as clearly shown in Fig. 1 of the drawing.

A depressable trigger I! is slidably mounted in the handle I4 and is preferably positioned adjacent the connecting end of said handle for convenience of the operator handling the tool. A lever I8 has one end is pivotally attached to the inner end of the trigger II bya pin and slot connection and said lever is pivotally connected at 20 to the handle I4. A cam-like portion M is formed integral with the lever l8 and is normally in engagement with the upper end of a slidable supported rod 22 for a purpose to be hereinafter more fully described.

The outlet end of the bore I6 is interiorly threaded as indicated at 23 for receiving the threaded end 24 of a housing 25, said housing enclosing the cycle controlling mechanism about to be described. As shown in Fig. 1 of the drawing, the housing 25 depends from the handle I4 and the rod 22 extends downwardly through the bore I6 and into said housing. The upper end of the rod 22 passes through a bushing 26 provided in the handle I4 while the lower end of said rod carries a valve 21 which is normally urged into con tact with its seat 28 by means of a compression spring 29. The housing 25 is adapted to be connected with a motive fluid supply conduit (not shown) through the threaded end 30, and for convenience of operation, the threaded end 30 is pref erably disposed so as to be in alignment with the bore 56 and threaded end 23. The threaded end 313 communicates with a recess 3I in which is housed the compression spring 29.

The housing 25 is also formed with a cylindrical bore 32 which communicates with the bore I6 and threaded end 24 through the passage 33, and mounted for slidable movement within the bore 32, is a hollow cylinder or plunger 34 formed with a bottom wall 35 and sleeve 36 of integral construction. The cylinder 34 is formed with an opening 31 and, as more particularly shown in Fig. 4 of the drawing, said opening is of substan- 2 asaaevi tially the same size throughout the major portion of its length, but one wall thereof inclines inwardly toward the upper end of said cylinder to form a restricted opening 38 for a purpose to be hereinafter described.

Also mounted within the bore 32, there is a stem 39 which carries a valve 48 on its upper end for controlling the passage of fluid from the bore 32 into the passage 33. Supported on the lower end of the stem 39 which projects through an orifice 51 in the end wall of the housing 25 is a lever 4!, the same being attached thereto by means of the nut 42. A washer 43 is provided for spacing the rotated by the lever 4| and, as will hereinafter appear, the cylinder 34 -is rotated when the position of the opening 31 is to be changed. As will also hereinafter appear, entrance of air under pressure through the opening 31 of the cylinder 34 will move said cylinder downwardly on the stem 39, the cylinder being guided through engagement of the pin 44 within the slot 45. The

be upset and the operator depresses the trigger I1 for urging the rod 22 outwardly through the action oi the lever it to unseat the valve 31, said valve being displaced from its seat against the pressure of the spring 3|. Air under pressure then enters the passage 54 and flows into the cylinder 34 through the opening 31. By referring to Fig. 3 of the drawing it will be noted that the valve 21 is in open position while the valve 40 is in closed position and therefore the pressure of the air entering the cylinder 34 will urge said cylinder downwardly on the stem 39 until the lower end of the sleeve 38 contacts the stem '39, adjacent its lower end, supports a piston 46 and said piston is formed with a depending portion 41 of a reduced diameter through which passes a pin 48 for locking the piston to the stem 39. Thus, the piston 46 is supported on the lower end of the stem 39 for movement therewith in a longitudinal as well as a rotary direction. The end wall '49 01' the housing 25 is formed with a cup-shaped valve seat 50 through which the stem 39 projects, and is adapted to support therein the tapered end 5| of the piston 46 during one phase of the cycle. By this construction, the reduced end of the piston 46 acts as a valve for preventing the escape of motive fluid through the orific 51, said orifice acting as a vent for the lower end of the bore 32, communication therewith being provided through the recess 53. A second vent 52 is formed substantially intermediate the ends of the bore 32 whereby said bore may be additionally vented at the termination of the cycle. Interposed between the upper face of the piston 46 andthe bottom wall of the cylinder 34, there is a spring 58 which normally maintains said cylinder in the upper end of the bore 32. A similar spring 59 is interposed between the bottom face of the piston 46 and the bottom wall 49 for maintaining said piston in its normal posi tion shown in Figs. 1 and 3.

A horizontally extendingpassage 54 is formed above the valv 21 and communicates with the vertical bore 32. With the valve 21 in open position, air under pressure is admitted through the inlet 30 and flows through the passage 54 and opening 31 of the cylinder 34. A restricted passage communicates with the passage 54 adjacent its discharge end and the lower end of the passage 55 communicates with the bore 32 adjacent its lower end. The upper end of the passage 55 is controlled by means of a needle valve or the. like 66, while the discharge end thereof is controlled by the piston 46.

In the operation of the device, with the parts in the position shown in Fig. 1 of the drawing, the rivet set is positioned adjacent th rivet to mination' of the cycle.

upper face of the piston 46. The cylinder 34 continues to move downwardly on the stem 38 and forces the piston 46 downwardly until the tapered end 5| thereof is seated on its seat 60. As clearly shown in Fig. 2 of the drawing, downward'movement of the cylinder 34 will collapse the spring 58 and likewise downward movement of the piston 46 will collapse the spring 68. During the downward movement of the cylinder 34, the stem 39 remains stationary until contact is made withthe piston 46 and as said piston is forced downwardly, the stem 39 will be similarly moved to unseat the valve 40, thereby allowing the air to be discharged through the passage 33 into the bore I6 and passage 5 for action on the hammer. At this phase of the cycle, the parts are all in the position and in the relation shown in Fig. 2 and it will be observed that the restricted opening 38 of the cylinder 34 is then disposed substantially opposite to the passage 54. Since the lower end of the restricted passage 66 has been uncovered by movement of the piston 46, a certain amount of air under pressure will be discharged in the area between the bottomwall 35 of the cylinder 34 and the upper face of the piston 46 and the pressure therein is gradually built up until the cylinder 34' is caused to move upwardly on the stem 39. The pressure of air on the face of the piston 46 will maintain said piston in its Fig. 2 position until the cylinder 34 has returned to its normal position at which time the air within the bore 32 will be vented through the outlet 52 whereupon the pressure of the spring 59 will be sumcient to return the piston 46 to its normal position to close the discharge end of the passage 55. Of course, upward movement of the piston 46 will cause the stem 39 to be moved upwardly to seat the valve 40 and thereby shut oil? the flow of air to the hammer.

A feature of th present invention provides for the gradual flow of air under pressure to the hammer until a maximum pressure has beenreached and the maximum pressure maintained for a predetermined interval of time before ter- The restrictedu opening 38 of the cylinder 34, with said cylinder in the Fig. 2 position, will cause a gradual feeding of air under pressure to the hammer until said cylinder begins to rise on the stem 39 in the manner previously described. As the cylinder rises the opening 38 will move upwardly beyond the passage 54 and gradually increase in size until the full opening 31 is opposite the passage 54 at which time maximum pressure is being fed to the hammer and that pressure will be maintained until the piston 46 moves from the Fig. 2 to the Fig. 3 position for closing the valve 40.

The'lever 4| forms the means for controlling the size of th opening 31 that is exposed to the passage 54 and the size of the opening governs the amount of pressure being supplied to the hammer. As is understood, the larger the size of the opening the larger the volume of pressure to be supplied and conversely the smaller the size of the opening the smaller the volume of pressure that will be supplied to the hammer. If desired, a suitable gauge can be attached to the outer wall of the housing 25 and the upturned end 60 of the lever 4| will point to the gauge and serve as an indicator for denoting the size of the opening as th stem 39 and cylinder 34 are rotated under the action of the lever 4!.

The upper end of the restricted passage 55 is controlled by a needle valve or the like 56 and is adjusted by the operator. Restricting the inlet opening to the passage 55 will delay the action of the cylinder 34 providing a longer time cycle and conversely an unrestricted opening will increase the flow of air through said passage to speed up the time cycle.

From the above description when taken in connection with the accompanying drawing, it will be readily apparent that there has been provided an improved mechanism for automatically controlling the cycle of operation of a riveting hammer to an extent whereby pressure will be gradually applied until a predetermined maximum has been reached to accelerate the hammer and the maximum pressure maintained for a predetermined interval of time before termination of the cycle. The width of the opening 31, 38 governs the amount of pressure to be fed to the hammer the reduced end 38 providing for gradually building up the pressure to the hammer. The entire operation is automatic and is beyond the control of the operator after the trigger has been depressed. In view of the fact that the riveting cycle is pre-set through the medium of the handle 4| and needle valve 56, and will cease automatically when the rivet has been upset, there is very little possibilit of damage to the sheet as well as a reduction to a minimum of the number of rejects or damaged rivets. Moreover it will be seen that a riveting tool or hammer embodying the control means herein disclosed can be used for rapidl driving a series of individual rivets in succession, and that since the riveting operation is automatically controlled and terminated all of the rivets of the series will be subjected to substantiall the same riveting operation and will be upset to substantially an identical extent.

Although the foregoing description is necessarily or a detailed character, in order to com;- pletely set forth the invention, it is to be understood that the specific terminology is not intended to be restrictive or confining and it is to be further understood that'various rearrangements of parts and modifications of structural detail may be resorted to without departing from the scopepr spirit of the invention as herein claimed.

I claim:

1. In mechanism of the character described, a housing having a bore with a valve seat at one end thereof, a stem in said bore carrying a'valve cooperating with said seat, a spring active upon said stem for biasing it toward valve closing position, a piston fixed upon said stem movable in said bore, a plunger in said bore between said valve and said piston slidable on said stem, said housing having an intake for pressure fluid communicating with said bore functioning to exert pressure on said piston for opening the valve, and functioning thereafter to exert pressure between said piston and said plunger for gradually moving the plunger away from the piston, and y means controlled by the latter movement of the plunger for relieving the pressure on said piston and thereby permitting said spring to shift the valve to closed position.

2. In mechanism of the character described, a housing having a bore with a valve seat at one end thereof, a stem in said bore carrying a valve cooperating with said seat, a spring active upon said stem for biasing it toward valve closing position, a piston fixed'upon said stem movable in said bore, a plunger in said bore between said valve and said piston slidable on said stem, said housing having an intake for pressure fluid communicating with said bore functioning to exert pressure against the valve side of said plunger, and against the valve side of said piston for opening the valve, and functioning thereafter to exert pressure between said piston and said plunger for gradually moving the plunger away from the piston, and means controlled by the latter movement of the plunger for relieving the pressure on said piston and thereby permitting said spring to shift the valve to closed position.

3. In mechanism of the character described, a

'housing having a bore with a valve seat at one end thereof, a stem in said bore carrying a valve cooperating with said seat, a spring active upon said stem for biasing it toward valve closing position, a piston fixed upon said stem movable in said bore, a plunger in said bore between said valve and said piston slidable on said stem, said housing having an intake for pressure fluid with a relatively large port communicating with said bore on the valve side or said plunger and a relatively small port communicating with the bore on the opposite side of the plunger, said plunger being effective in response to flow through said larger port for shifting said stem to open the valve, flow through said smaller port entering the space between said piston and said plunger for holding the piston in valve open position and graduall moving the plunger away from the piston, and means controlled by said plunger in its latter movement for relieving the pressure on said piston and permitting said spring to shift the valve to closed position.

4. The mechanism defined in claim 3 characterized in that said piston, in its position corresponding with closed valve position, covers and blocks said smaller port and uncovers it in valve open position.

5. The mechanism defined in claim 1 characterized in that spring means are provided for assisting the movement of said plunger away from said piston.. I

. WIIJ'JAM R. KOVACS.

Images