US3359777A

US3359777A - Hand tool

Info

Publication number: US3359777A
Application number: US471570A
Authority: US
Inventors: William H Lee
Original assignee: ELGEN Manufacturing CORP
Current assignee: ELGEN Manufacturing CORP
Priority date: 1965-07-13
Filing date: 1965-07-13
Publication date: 1967-12-26
Anticipated expiration: 1984-12-26

Description

Dec. 2 1967' w. H- LEE 3,359,777

HAND TOOL 4 Sheets-Sheet 1 INVENTOR 7-7- Wz'ZZz'am H. L66

BY w

ATTORNEY W. H. LEE

Dec. 26, 1967 HAND TOOL Filed July 1a,

4 Sheets-Sheet mm xh INVENTOR i/l/z'Zlz'arrz H Z66 ATTORNEY W. H. LEE

HAND TOOL Dec. ,26, 1967 Filed July 15, 1965 4 Sheets-Sheet INVENTOR Wz'ZZz'am Lee "Elva ATTORNEY W. Hv LEE Dec. 26, 1967 HAND TOOL 4 Sheets-Sheet Filed July 13,

l l I I l l J INVENTOR ATTORNEY WiZZz'am H Z66 United States Patent 3,359,777 HAND TOOL William H. Lee, Mount Vernon, N.Y., assignor to Elgen Manufacturing Corporation, a corporation of New York Filed July 13, 1965, Ser. No. 471,570 14 Claims. (Cl. 72-391) ABSTRACT OF THE DISCLOSURE An electrically powered blind rivet pulling or setting tool is provided in which an electric motor powers a rotary cam with the electrical power being disconnected after the rivet has been set so that the inertia is dissipated by the continued movement of the motor and the cam with the current off. The continued movement of the cam actuates a reversing mechanism to reversely power the motor and the cam for an instant to cause the cam to rotate toward an appropriate initial position. The cam is' rotated by means of a worm gear acting through a ratchet wheel with a spring-biased pawl interengaging the two for forward rotation. The motor disconnecting and reversing means are carried by a switch plate which is held inoperative while the rivet is set, and means which respond to the completion of the setting action is used to shift the switch plate to an operative position. The cam is formed with a step and aleaf spring with a stop is used to catch the step of the cam to hold it in an appropriate initial position when the cam is reversely rotated. Friction means are used to transmit the reverse rotation of the motor to the cam. The cam acts to pivot an operating lever, and latch means are provided to hold the lever when the cam has depressed the same until a trigger is operated to release the lever during the reverse rotation of the cam. Also, a 'threadedly mounted nosepiece is employed to carry a rivet mandrel-receiving die so that the position of the die can be adjusted to regulate the spreading action of a separator used to spread the rivet setting jaws when these jaws are in their projected position.

The present invention relates to electrically operated hand tools for pulling or setting blind rivets.

Hand-powered tools for setting blind rivets are Well known, but power requirements, especially for the larger diameter rivets, are excessive and auxiliary power is essential. v

' Most commonly, pneumatic power is used, but appropriate sources of compressed air are frequently unavailable or difiiculty available, so that pneumatic tools are of only limited value. Also, and since the setting of a blind rivet normally involves the application of progressively increasing force until the rivet mandrel snaps to suddenly release the built-up force, pneumatic rivet setting tools have been complicated and expensive in order to accommodate and dissipate the suddenly released force.

Electrically operated hand tools for setting blind rivets are also known, but these, despite the obvious advantage of the almost universal availability and convenience of electrical power, have received only limited acceptance. This is because the available electrically operated tools for setting blind rivets have been subject to various disadvantages such as: excessive size and weight; excessive cost, excessive maintenance; etc.

The present invention provides electrically operated hand tools of simplified structure and enhanced operating effectiveness, whereby many of the aforesaid disadvantages are mitigated and a superior and more useful tool is provided.

3,359,777 Patented Dec. 26, 1967 'ice In accordance with the invention, the rivet-setting power is supplied by an electric motor which operates a rotary cam so that, when the rivet mandrel has snapped and the high point of the rotary cam is passed, the inertia of the motor can be dissipated, at least in part, by the continued movement of the motor and cam while no electricity is supplied to the motor. When the cam is still moving with part of the inertial force dissipated, a reversing mechanism is actuated to cause the electric motor to power the cam in a reverse direction to cause the cam to return to an initial position from which the powering or rivet-pulling cycle can begin by placing the rivet-pulling jaws in a position where they can be opened to receive a rivet mandrel and to enable the motor to be operated for a period of time before full rivet-pulling power is required to enable the motor to develop power adequate to the task.

As may be evident from the foregoing, structure must be provided to cause the motor to be continuously powered during the full pulling stroke and then, when this pulling stroke has been completed, to bring switches into the path of the rotating cam to turn off the electrical power and then to turn on a reversing surge of power. To this end, the required switches are actuated by means which are responsive to the change in the position of the pulling jaws or some means which move therewith, such as the main operating lever. Preferably, the operating lever at the bottom of its rivet-pulling stroke moves a switch plate into a position in which a cam member carried by the main shaft is engaged.

In the preferred practice of the invention, the motor drives a worm gear which is free running on the main shaft and the power is transmitted to the cam by a ratchet wheel which is secured to the main shaft and which is positively driven in a forward direction by pawls carried by the worm gear to cause a rivet pulling action. When the motor is reversed, the worm gear is driven in the opposite direction and the pawls become disengaged from the ratchet wheel so that the cam is rotated by friction until it is physically stopped by means which need only have sufiicient strength to overcome the friction. This stop mechanism is desirably constituted by a spring element which flexes out of the way when the cam is rotated in a forward direction, but which catches the step of the operating cam when the cam rotation is reversed to hold the cam in a position in which the operating lever is opposite a low point on the cam.

As a feature of the invention, the operating jaws are held in a retracted position until the reverse movement of the operating cam is accompanied by the release of the holding means. In preferred construction, a latch is used to hold the operating lever in the position which it is forced to assume by the operating cam and means responsive to the release of the main actuating trigger are used to released the latch so that spring pressure can return the operating lever and the operating jaws to a forward mandrel-receiving position. Since the nose dies are more easily changed when the operation jaws are in a retracted position, the fact that they remain retracted unless the main trigger is released is a distinct advantage.

Other and further features of the invention will become apparent from the description which follows taken in conjunction with the accompanying illustrative drawings in which:

FIG. 1 is a side elevation of an illustrative hand rivet FIG. 2 is an enlarged fragmentary view partly in section of the hand tool of FIG. 1;

FIG. 3 is an enlarged fragmentary side elevation of FIG. 1 with the side cover plate removed;

FIG. 4 is a vertical section taken on the line 4--4 of FIG. 2;

FIG. 5 is a vertical section taken on the line 55 of FIG. 2;

FIG. 6 is a vertical section taken on the line 6-6 of FIG. 4;

FIG. 7 is a horizontal section taken on the line 77 of FIG. 3;

FIG. 8 is a perspective view of the release plate and its associate-latch, shown in phantom lines;

FIG. 9 is a perspective view of the spring cam stock;

FIG. 10 is a perspective view of the operating lever;

FIG. 11 is a perspective view of the operating lever latch;

FIG. 12 is a perspective View of one of the blind rivet gripping members; and

FIG. 13 is a schematic diagram of the electrical circuit of the hand rivet gun.

Referring to FIG. 1, there is shown an overall view of an electrically operated hand tool for setting blind rivets, the tool being constructed in accordance with the invention. The tool is formed to include an electric motor housing 10, a central actuating section 11, a pulling head assembly 12, and a handle 13. The handle 13 carries a trigger 14 which serves to close an electrical circuit permitting electric current to flow from the electric cord 15 to energize the system. The electric motor housing 10 includes vents 16 formed at the forward end thereof to permit air to fiow into the housing and cool the same when the tool is in use.

As a feature of the invention, a hold-button 17 is located on the handle immediately behind the trigger 14 and functions to hold the trigger in a depressed or engaged position when so desired. Another feature is a friction device 18 which is operated by manipulating lever 19 to control the grip exerted on the mandrel of the blind rivet when this rivet is not being actively pulled. The operation of the foregoing will be discussed in greater detail hereinafter.

Referring to FIG. 2, there is shown a reversible electric motor 20 enclosed by the electric motor housing 10. Extending from the forward end of the motor 20 is a drive shaft 21 which carries vanes 22, the vanes functioning to pull air through the vents 16 and onto the motor 20 to cool the same. The drive shaft 21 is splined at 23 whereby the reduction gears 24 are powered to drive the powering gear 25. The gear 25 is integral with a worm 26 which is in engagement with a worm gear 27, so that, when motor 20 is operated, the worm gear 27 is rotated. Worm gear 27 is freely mounted for rotation about the main drive shaft 28.

As will be seen in FIG. 4, the main drive shaft 28 carries a ratchet wheel 29 fixedly secured thereto, the previously noted freely mounted worm gear 27 an operating cam 30, and a switch cam 31. The worm gear 27 carries pawls 32 (as best shown in FIG. 6) mounted for engagement with the teeth of the ratchet wheel 29, the pawls being biased into an engaging position by springs 33.

The pawls 32 are positioned for driving engagement with the ratchet wheel 29 when the worm gear 27 is driven in its forward direction, shown by arrow A. Since ratchet wheel 29 is integral with the main drive shaft 28, the rotation of the worm gear in the forward direction A causes the main drive shaft 28 to rotate in this forward direction. It will be noted hereinafter as a feature of the invention that in the reverse direction, shown by arrow B, the pawls 32 ride over the ratchet wheel 29 and are not effective to rotate the ratchet wheel.

The forward rotation of the main drive shaft 28 causes the operating cam 30, which is keyed thereto, to rotate in the direction indicated by arrow A which causes the cam to engage the rearward end 34 of operating lever 35 causing the lever to pivot about pin 36 in a rivetpulling (clockwise) direction. The operation lever 35 has its forward end 37 (pictured in FIG. 10) formed as a yoke for engagement about a collet mount 38, so that the clockwise rotation of the lever 32 moves the collet 39 in a rearward or rivet-pulling direction.

As the operating lever 35 is pivoted about the pin 36 the rearward end thereof 34 is depressed by cam 30 into a lowered position where it is caught by a spring-biased latch 40. The tail of the lever 35 is formed to include a finger 41, which, when lever 35 is depressed, rides over the hook 45 of the latch 40.

The latch 40 is pivoted on a pin 46 and is spring-biased, as indicated at 43, toward the operating lever 35, and is moved away from lever 35 by a latch release plate 44 which is operated to move latch 40 away from lever 35 when the trigger 14 is released.

The latch 40 is pictured in FIG. 11, where, it will be noted, the hook overlies a notch 42 on the forward end of the latch, the rear of the latch being formed with a tail 47 which is acted upon by the latch release plate 44.

Normally, the latch release plate 44 (pictured in FIG. 8) is in a forward position holding the latch 40 against the pressure of spring 43 out of the path of the finger 41 of the operating lever 35. When the trigger is depresed the latch release plate 44 is moved in a rearward direction (either directly by the depression of the trigger 14, or indirectly through a solenoid as shown in FIG. 2). In either event, the release plate 44 is moved away from the tail 47 of latch 40 (see also FIG. 7), so that the spring 43 can cause the latch to pivot about pin 46 to move the hook 45 toward the operating lever and thereby be ready to catch the finger 41 when lever 35 has descended fully.

In the first forward rotation of the operating cam 30, the operating lever 35 is moved to its fully depressed position which accomplishes two things. First, finger 41 of the operating lever 35 is engaged by the hook 45 of latch 40 so that the operating lever 35 is held in its depressed position so that the yoke 37 holds the collet 39 in its retracted position against the pressure imposed by springs 48 and 49 which tend to bias the collet 39 and the rivet pulling jaws 50 forwardly into a projected position. Secondly, and as shown in FIGS. 2 and 3, the rearward end 34 of operating lever 35 (near the bottom of its stroke) I bears against a projection 51 carried by a switch plate 52 causing the switch plate 52 to be moved downwardly. Projection 51 extends through an opening 51 in a central web in which plate 52 slides. Since plate 52 carries

certain switches

53 and 54, these switches are moved into the path of the switch cam 31. As is shown in FIG. 3, in which switch plate 52 is in its inoperative position, the plate 52 is moved to the left (note arrow C) to shift contact arms 53' and 54' into operative position. Plate 52 is slotted at 52' to accommodate the main shaft 28. The switch plate 52 is normally biased into an elevated position by spring 55, the

switches

53 and 54 being thereby held out of the path of the rotating switch cam 30 so that the first forward rotation thereof can be completed without interference.

As will later more fully appear, the switch 53 is a stop switch which functions to disconnect motor 10 from the source of electrical power. Switch 54 is a reversing switch which functions to restore the cam 30 to its initial position. Additionally, switch cam 31 carries a lobe 56 which engages arm 53 of stop switch 53 to enable the inertial forces of the electrical motor to be dissipated. Switch cam 31 also carries a second lobe 56' which engages with the arm 54' of reversing switch 54. The detailed operation of these elements will be discussed later.

Referring again to FIG. 2, operation of trigger 14 completes an electrical circuit which energizes solenoid 57 which pulls a ferrous bar 58 secured at the rear of release plate 44 to pull the release plate away from the tail 47 of the latch 40, the operation of the solenoid 57 overcoming the tension of a spring 59.

At the same time, and as previously indicated, the pulling of trigger 14 actuates the motor 20 though it will be understood that the completion of this circuit can be made dependent upon the movement of the ferrous bar 58 if desired, as will be described hereinafter.

The detailed construction of the latch release plate 44 and its operation will be discussed hereinafter.

Continuing with FIG. 2, the collet 39 carries the rivet pulling jaws 50, these jaws being biased forwardly by a spring 60.

Referring to FIG. 4, it will be seen that the central actuating portion 11 of the hand tool is constituted by a casting which provides a central web 61, upper and

lower walls

62 and 63 and

outer walls

64 and 65. The outer wall 64 is apertured for easy access, the opening being closed by access plate 66.

As will be evident, the various operating parts are mounted in appropriate portions of the casting as shown in the drawings, e.g., the operating shaft 28 is journaled in the central web 61 and the outer wall 65, latch plate 44 is slidably mounted in a keyway formed in lower wall 63 and switch plate 52 is slidably mounted in a keyway formed in central web .61.

Returning to FIG. 2, this figure shows the structure in a cross-section which conforms generally to a section taken along. the lines 22 of FIG. 4 so that the parts shown are enclosed by the lower wall 63, the upper Wall 62, the outer wall 65 and forward and

rearward walls

67 and 68, respectively. The rearward wall 68 is part of a separate casting which is bolted on as indicated by bolt 69.

Since the bulk of the structure has already been described, the remaining description will be keyed to the operation of the tool, attempting to proceed sequentially along the steps followed by the tool. As previously indicated, when trigger 14 is pulled, an electrical circuit is completed to solenoid 57 which retracts latch release plate 44, and actuates the motor 20 which operates to drive cam 30 in a first forward rotation (arrow A) so that cam 30 depresses operating lever 35, the lever 35 being held inits depressed position by the engagement of hook 45 with finger 41. As will be evident, the movement of operating lever 35 elevates collet 3-9 to pull the jaws 50 upward so that these jaws grasp the mandrel of a rivet (which would be inserted inthe die 70) to pull the mandrel upwardly and thereby pull the rivet.

As will be evident to those familiar with the pulling of blind rivets, the force required increases progressively to a maximum which occurs at the moment that the weakened portion of the rivet mandrel snaps. Consistent with the need dictated by the task, the slope of the cam surface on the cam 30 decreases from the beginning of the cam surface to the end of the cam surface so that the maximum mechanical advantage is achieved at the end of the stroke after the motor 20 has had a full opportunity to come to speed. This is in contrast with conventional powered blind rivet devices and of considerable importance in preventing the tool from becoming jammed which is quite embarassing because, when this happens, the tool is stuck to the rivet and the rivet is stuck to the work and the release of the tool from the rivet is no simple task.

Toward the bottom of the power stroke of the operating lever, projection 51 is moved to depress switch plate 52 to thereby carry the contact arms of

switches

53 and 54 into the path of the

lobes

56 and 56 carried by the switch cam 31.

As will now be appreciated,

lobes

56 and 56 on switch cam 31 are not engaged until after the forward rotation of cam 30 has moved the high point 71 of the cam past its point of engagement with the rearward end 34- of operating lever 35 at which moment motor 20 is operating under maximum load. It is desired to permit motor 20 to continue to rotate without external load with the current off so that the inertia of the motor can be partially dissipated. Thus, lobe 56 contacts arm 53' of stop switch 53 after high point 71 has passed lever 35 to shut oflf the current to motor 20 and shaft 28 continues to rotate further rotating cam 30 and switch cam 31 until lobe 56 contacts arm 54' of reversing switch 54 to cause a surge of electrical current to go to the motor 20 to power the motor 20 for an instant in the reverse direction (direction B in FIG. 2). This reverse surge of current causes the cam 30 and main shaft 28 to be rotated in a reverse direction disengaging the second lobe 56' on the switch cam 31 from the reversing switch. In order to maintain the forwardly directed current disconnected while the reverse rotation is taking place, the first lobe 56 on the switch cam 31 is sufiiciently long as to maintain the current off while the forward rotation is completed and also while the reverse rotation is completed.

The reverse inertial rotation of the operating cam 30 effected as described above causes the operating cam to rotate in a reverse direction until the step 72 thereof contacts a spring stop (pictured in FIG. 9). Since a direct drive would create inertial forces which would be difficult to stop, the invention relies upon a friction drive for the reverse movement.

As previously pointed out, the main shaft 28 is powered by the pawls 32 carried by the worm gear 27, the pawls rotating ratchet wheel 29 and shaft 28 secured thereto during the forward rotary movement. However, when the motor 20 is reversed, the pawls 32 merely ride over the teeth on the ratchet wheel 29 so that shaft 28 is not directly driven. Instead, Worm gear 27 is spring biased by means of compression spring 73 shown in FIG. 4, toward an inner face on the operating cam 30 to cause a friction drive thereof in the reverse direction. To foster this friction drive, the face of the worm gear 27 adjacent the operating cam 30 is surfaced with a leather clutch facing 74. When the reverse rotation B of operating cam 30 causes the step 72 thereof to engage the stop 75 of leaf spring 76, the spring 76 is moved toward the operating lever 35 to hold the operating cam 30 in an appropriate initial position against the friction drive until the reverse movement is spent. It is of interest to note that the spring 76 is a leaf spring which simply flexes out of the way during the forward rotation A of cam 30.

With particular reference to FIG. 3, when the switch cam 31 is rotated in the forward direction A, spring finger 77 pivots out of the way of an underlying lobe 78 mounted on a flat spring 79 so as to have no effect thereon. A small spring 80 causes the spring finger 77 to return to its initial position when the lobe 78 has been passed. On the reverse rotation B of the switch cam 31, the spring finger 77 is jammed against wall 81 and the lobe 78 is depressed. Accordingly, and while the operating cam 30 is returned to its initial position, the lobe 78 has been depressed to thereby flex the flat spring 79 which laterally moves a trigger catch 82, shown in FIG. 7, to release the release plate 44 by moving pin 83 carried by catch 82 out of notch 84 in release plate 44 (action best seen in FIG. 8). When plate 44 is released, spring 59 biases the plat-e downwardly against tail 47 to pivot the latch 40 and release the operating lever 35, whereupon the springs 48 and 49 (which bias the collet 39 and jaws 50 forwardly) take over to return the jaws to their projected position and to pivot the operating lever 35 so that its rearward end 34 is moved back into contact with the operating cam 30 adjacent the step 72, a position pictured in FIG. 2.

To facilitate cam action, the end 34 of lever 35 may be formed to include a roller 92 journaled in bearings 93.

It is of interest to note that when collet 39 is in its forward position pictured in FIG. 2 (biased into this position by springs 48 and 49) with its forward movement limited by the position of lever 35, the spring pressure forces the jaws 50 forwardly against a conical jaw separator "85 carried at the rear of a die 70. The conical jaw separator 85 bears against jaws 50, forcing the jaws to open to receive the mandrel of a rivet to be set. FIG. 1 show-s a blind rivet R in place. The conical separator 85 is positioned by the die 70 which, in turn, is carried by the nose piece 86. The nose piece, in turn, is threadedly secured tothe main body of the hand tool casting at 87 so that rotation of the nose piece 86 serves to move the conical jaw separator- 85 forwardand back. Since the forward projection ofvthe collet 39 is limited by the operating'cam, the 'position of the nose piece 86 in the threads 88 determines whether the conical jaw separator 85 will be able to adequately open the operating jaws or not at the end of each stroke. Thus, and for the first time in a rivet setting device, we have the opportunity of obtaining or maintaining a slight pressure on the rivet before or after the rivet setting operation by merely rotating the nose piece 86.

Accordingly, and by manipulation of the lever 19 to rotate the nose piece 86, we can grasp the rivet mandrel prior to pulling (the grasp being maintained after the rivet is pulled) and this is quite helpful when the tool is to be used in a downwardly pointing attitude, or we can go through the rivet pulling operation with the rivet mandrel being free of the jaws 50 both before and after the rivet pulling operation so that the spent rivet mandrels are automatically discharged from the tool when the tool is used in an upwardly pointing position.

Additionally, when the collet 39 is in its forward position with the operating jaws 50 bearing against the conical jaw separator 85, the die 70 at the forward end of the nose piece is jammed by the jaws. However, different dies are used, depending upon the diameter of the rivet to be set, and it is not convenient to change the die while pressure is maintained on the jaw separator 85. The invention permits the rivet pulling cycle to be stopped with the collet in a retracted position (when trigger 14 is not released or held by hold button 17), and we then have the die 70 freed of the jaws 50 so that one die can be easily removed and another inserted.

Further, the structure most subject to wear is the jaws themselves. Inaccordance with the invention, the jaws 50- can be replaced by merely removing the nose piece 86 and unscrewing the collet 39 from the collet mount 38 (note threads 89) whereby the jaws 50 can be removed and replaced. In this connection, the operating jaws are freely seated within the collet with the rear face of the jaws bearing against a forward end of a wedge element 90 which serves to spread the rear of the jaws apart when these jaws are. thrust rearwardly by contact with the previously described conical separator 85. One of the jaws 50 is picturedv in FIG. 12.

It is to be noted that as soon as the latch release plate 44 is retracted to release latch.40, catch 82 moves the pin 83 into the notch 84 on the plate 44 as a result of the pressure of compression spring 91. Accordingly, if the plate 44 is physically retracted by the action of trigger 14, the trigger 14 need not be maintained in a depressed position. Similarly, and when the solenoid 57 is relied upon, the electric powering of this solenoid need only be momentary. On the other hand, if the trigger 14 is maintained in its depressed position either by the continuation of finger pressure or by the use .of the hold button 17, then the plate 44 cannot be released and the latch 40 cannot be released so that the collet 39 remains retracted to facilitate the changing of die 70.

It is to be noted that during the reverse rotation of the cam 31, the spring finger 77 is moved and positioned directly over lobe78 of flat spring 79 holding the trigger catch 82 out of engagement with release plate 44, so that when the trigger 14 is held depressed to facilitate the change of .die 70, and then released, the plate 44 is free to be returned to its initial position by spring 59, thus releasing latch 40 and returning the operating jaws to their rivet accepting positions.

Also, andwith respect to the release of the latch 40, it is important that the lever 35 not become locked against the hook 45 in the event that a rivet mandrel fails to snap. To prevent any danger of locking, the hook 45 is positioned to become operable to engage the finger 41 a short distance before the lever 35 is fully depressed. A'clearance of40thousandths of an inch has been found to be appropriate.

Referring to FIG. 13, and when trigger 14 isdepressed, current flows from the terminals through

lines

101, 102 and 103 to energize solenoid 57. The solenoid then functions to move latch release plate 44 closing switch 98 so that the. current can flow from line 101 through

lines

104, 105 and 106 to operate motor 20, as explained below.

When switch 98 closes, cur-rentfiows through the closed switch and then, via line 106, switch 53, line 107, coils 108 and 109 and then to the brush 114via line 110, switch 54b,

andlines

112 and 113. The current exits from motor 20 through brush 115, line 116, switch 54a and

lines

117 and 103 to complete the circuit back to terminals 100.

Accordingly, motor 20-is now operative to drive the operating cam 30 to retract the operating jaws. At the same time, lobe 56 on switch cam 31 is rotated into engagement with switch arm 53' on the shifted switch plate 52. In this way switch 53 is opened to break the circuit described above which turns oif the power to motor 20.

The continued rotation of switch cam 31 then causes switches 54a, 54b and 540 (comprising switch 54 described hereinbefore) to be shifted into their reverse positions, shown in dotted lines in FIG. 13, to close the circuit to the motor 20 causing it to operate in the reverse direction.

When the switches 54 are shifted, current flows through

lines

101 and 104, switch 54c,

lines

118 and 107, coils 108 and 109 and then to brush 115 via line 110, switch 54b, and line 116. The current exits from motor 20 through brush 114,

lines

113 and 112, switch 54a,

lines

117 and 103 to complete the circuit back to terminals 100.

Accordingly, the motor 20 drives cam 30 and switch cam 31' in their reverse direction -so that the switches 54 return to their initial position to discontinue the current flow. As switch cam 31 is rotated in the reverse direction by the inertia of motor 20, lobe 56 remains in engagement with switch arm 53', so that, when the rotation of operating cam 30 and switch cam 31 is stopped by engagement of stop 72 with stop 75 on leaf spring 76, the circuit supplying current for the forward rotation of motor 20 remains open. This, of course, assumes that trigger 14 remains depressed.

When trigger 14 is re1eased, switch 98 is opened and all the circuits are open. At the same time, latch release plate 44 is released to pivot latch 40 and free lever 35 to free switch plate 52 which is moved to the right in FIG. 3. by spring 55 so that switch arm 53' is moved out of the path of lobe 56-and, therefore, switch 53 is no longer held in a circuit opening position.

It will be observed in FIG. 3, that switch arm 53' is constituted by a plate formed with slots 99 through which project pins 99' carried by plate 52 so that switch arm 53 can move back and forth with respect to plate 52. Movement of arm 53' to the right in FIG. 3 by lobe 56 moves feeler arm 53 to the right to open switch 53. Feeler arm 53' is spring biased to the left in FIG. 3 by a springnot shown which is part of the switch 53. Thus, and when lobe 56 does not hold feeler arm 53" to the right, spring pressure closes switch 53 moving switch arm 53' to the left utilizing slots 99.

When one attempts to vary the specific details of operation, it is possible to operate under circumstances in whichthe gun can become stopped with switch arm 53' riding on lobe 56. For such a situation, a release button may be providedon the cover plate 66, the button functioning to move leaf spring 79 to release the latch release plate 44" to release plate 52 so that operation of trigger 14' willcontinue the forward rotation of the motor 20.

To briefly summarize operation, trigger 14 initiates operation by releasing the latch 40 whereupon a forward rotation (direction A) of cam 30 pivots lever 35 to retract the operating jaws and thereby pull or set the blind rivet. At the bottom of its stroke, lever 35 shifts a switch plate so that further forward rotation of cam 30 turns off the electrical current to permitinertial forces to dissipate and a surge of reverse power is frictionally transmitted to the cam 30 whereby this cam is returned to an initial position. During the return motion, the latch 40 is pivoted to release the lever 35 returning the jaws 50 to a forward position in which the spent rivet mandrel may be discharged and a new blind rivet received.

The discharge of the spent rivet mandrel is of particular interest in accordance with the invention in that a tubular passageway 94 is provided through the collet mount 38 into a mandrel receptacle 95 which is defined by a cover 96 held in place by securing element 97.

It will be understood that in the foregoing description, the electrical hand tool under consideration has been described in what may be termed a downward position in which it might be used to pull rivets in a floor. On the other hand, it will be understood that the tool is useful when held in any position, despite the fact that certain features of the tool are of greater importance when the tool is to be used in a particular position, e.g., the capacity of the tool to hold the rivet independent of the rivet pulling action is of particular value when pulling rivets in a floor whereas the capacity of the tool to store spent rivet mandrels is used to best advantage when the tool is used in an upraised position, e.g., to pull rivets in a ceiling.

The invention is defined in the claims which follow:

I claim:

1. An electrically powered blind rivet setting tool, cornprising electric motor means powering a rotary cam which provides the rivet setting action for said tool, means for supplying electrical current to said motor, means to rotate said cam to thereby cause the rivet setting action to occur, means for disconnecting said electrical current after said rivet setting action is substantially completed, whereby the inertia developed may be dissipated by the continued movement of said motor and cam while no electricity is supplied to the motor, and a reversing mechanism actuated by the said continued movement of said cam to reverse the direction of rotation of said motor and cam.

2. An electrically powered tool as recited in claim 1 in which said reversing mechanism is a switch operated instantaneously to supply a momentary surge of electrical current in a reversing direction to cause said motor to reverse its direction for an instant.

3. An electrically powered tool as recited in claim 2 in which the reverse rotation of said motor is frictionally transmitted to said cam whereby said cam can be stopped where desired while the remaining energy of said motor is dissipated.

4. An electrically powered blind rivet setting tool, comprising electric motor means powering a rotary cam carried on an operating shaft to provide the rivet setting action for said tool, means for supplying electrical current to said motor, means to rotate said cam including a ratchet wheel secured to said shaft and spring-biased pawl means carried by a worm gear mounted on the same shaft to thereby cause the rivet setting action to occur, means for disconnecting said electrical current after said rivet setting action is substantially completed, whereby the inertia developed may be dissipated by the continued movement of said motor and cam while no electricity is supplied to the motor, and a reversing mechanism actuated by the said continued movement of said cam to reverse the direction of rotation of said motor and frictionally transmit this reverse rotation through said worm gear to said cam.

5. An electrically powered blind rivet setting tool, com prising electric motor means powering a rotary cam which provides the rivet setting action for said tool, means for supplying electrical current to said motor, means for transmitting the power of said motor to rotate said cam in a forward direction to cause the rivet setting action to occur, a switch plate carrying switch means for disconnecting said electrical current and switch means for reversing the rotation of said motor, said switch plate being held in an inoperative position while said rivet setting action takes place, means responsive to the substantial completion of said rivet setting action to shift said switch plate into an operative position, whereby said switch means cannot interfere with the forward rotation of said cam and become effective only after the rivet setting action is completed.

6. An electrically powered blind rivet setting tool comprising electric motor means, a rotary cam including a sloped cam surface and a step for powering the rivet-pulling action, said cam surface having a slope which decreases continuously from the bottom to the top of said step, gear means including a ratchet wheel and springbiased pawl means carried by a worm gear for directly transmitting the power of said electric motor to directly drive said rotary cam in a forward powering direction, means for momentarily reversing the direction of rotation of said electric motor and said worm gear after said rotary cam has completed its powering stroke and friction means for transmitting the reverse rotation of said worm gear to said rotary cam whereby said rotary cam can be returned to and held in an appropriate initial position for commencin g said rivet pulling action.

7. An electrically powered blind rivet setting tool as recited in claim 6 in which a leaf spring having a stop portion at its forward end is positioned to catch the step of said rotary cam when said cam is reversely rotated.

8. An electrically powered blind rivet setting tool as recited in claim 6 in which means are provided to disconnect the electrical current to said motor after the rivet pulling action has been completed and to maintain said electrical current disconnected until after the reverse rotation has been completed.

9. An electrically powered blind rivet setting tool comprising electric motor means, a rotary cam including a sloped cam surface and a step for powering the rivetpulling action, gear means for directly transmitting the power of said electric motor to directly drive said rotary cam in a forward powering direction, means for reversing the direction of rotation of said electric motor after said rotary cam has completed its powering stroke, and friction means for transmitting the reverse rotation of said motor to said rotary cam whereby said rotary cam can be returned to and held in an appropriate initial position for commencing said rivet pulling action.

10. An electrically powered blind rivet setting tool, comprising electric motor means, a main operating shaft, means including a worm gear freely mounted on said shaft, a ratchet wheel secured to said shaft and pawl means on said worm gear for rotating said ratchet for transmitting a forward rotation of said motor to said shaft, a rotary cam including a sloped cam surface and a step mounted on said shaft for powering the rivet-pulling action, means including a collet mount and a lever extending between said cam and said mount to enable said cam to move said mount in a rivet-pulling motion, a switch plate carrying switch means for disconnecting said electrical current and switch means for reversing the rotation of said motor, said switch plate being held in an inoperative position while said cam, lever and mount are moved through said rivet-pulling action, means responsive to the substantial completion of said rivet-pulling action to shift said switch plate into an operative position in which the switches carried by said switch plate are moved into the path of a switch cam carried by said shaft, friction means for transmitting the reverse rotation of said worm gear to said rotary cam, and a leaf spring adapted to flex out of the path of said cam on a forward rotation thereof and to engage with the step of said cam on a reverse rotation thereof.

11. An electrically powered blind rivet setting tool as recited in claim 10 in which latch means are provided for holding said lever when said cam depresses the same, said latch means being biased into lever-holding position, and trigger-operated release means for disengaging said latch from said lever.

12. An electrically powered blind rivet setting tool as recited in claim 11 in which said release means is springbiased toward said latch and means are provided for holding said release means in its disengaged position, and means are further provided to free said release means during the reverse rotation of said cam.

13. A powered blind rivet setting tool, comprising a rotary cam including a sloped cam surface and a step, a collet mount carrying a collet which houses the rivetpulling jaws and an operating lever, said lever having one end thereof interconnected with said collet mount and the opposite end thereof biased toward engagement with said cam surface, whereby said cam can depress the end of said lever biased toward said cam surface to pivot said lever and thereby move said jaws to pull a rivet.

14. In a powered blind rivet setting tool, said tool including rivet setting jaws spring-biased into a projected position and means for powering said jaws into a retracted position, and in which said tool further includes a jaw separator carried at the rear of a rivet mandrelreceiving die andlmeans limiting the projected position of said jaws, the improvement comprising. a threadedly mounted nose piece carrying said die whereby the position of said die may be adjusted to regulate the spreading action of said jaw separator on said jaws.

References Cited UNITED STATES PATENTS CHARLES W. LANHAM, Primary Examiner. G. P. CROSBY, Assistant-Examiner.

Claims

1. AN ELECTRICALLY POWERED BLIND RIVET SETTING TOOL, COMPRISING ELECTRIC MOTOR MEANS POWERING A ROTARY CAM WHICH PROVIDES THE RIVET SETTING ACTION FOR SAID TOOL, MEANS FOR SUPPLYING ELECTRICAL CURRENT TO SAID MOTOR, MEANS TO ROTATE SAID CAM TO THEREBY CAUSE THE RIVET SETTING ACTION TO OCCUR, MEANS FOR DISCONNECTING SAID ELECTRICAL CURRENT AFTER SAID RIVET SETTING ACTION IS SUBSTANTIALLY COMPLETED, WHEREBY THE INERTIA DEVELOPED MAY BE DISSIPATED BY THE CONTINUED MOVEMENT OF SAID MOTOR AND CAM WHILE NO ELECTRICITY IS SUPPLIED TO THE MOTOR, AND A REVERSING MECHANISM ACTUATED BY THE SAID CONTINUED MOVEMENT OF SAID CAM TO REVERSE THE DIRECTION OF ROTATION OF SAID MOTOR AND CAM.