US2578546A - Riveting and like machines with pressure limiting mechanism - Google Patents

Description

Dec. 11, 1951 A R HAVENER 2,578,546

RIVETING AND LIKE MACHINES WITH PRESSURE LIMITING MECHANISM Filed Dec. 28, 1948 2 SHEETS-Q-SHEET 1 A. R. HAVENER 2,578,546 RIVETING AND LIKE MACHINES WITH PRESSURE LIMITING MECHANISM Dec. 11, 1951 Filed Dec. 28, 1948 2 SHEETS-SHEET 2 Patented Dec. 11, 1951 RIV ETIN G AND LIKE MACHINES WITH PRESSURE LIMITING MECHANISM Arthur R. Havener, Wayland, Mass, assignor' to Judson L. Thomson Manufacturing Company, Waltham, Mass a corporation of Massachu setts Application December 28, 1948, Serial No. 67,705

2 Claims.

This invention relates to riveting and like machines with pressure limiting mechanism where the work piece is engaged between a pair of anvils which are pressed thereagainst during the operation of the-machine and are then separated for the release of the work piece.

While not limited thereto, this invention is particularly suitable foruse in' connection with work which may be of somewhat fragile nature, or which may vary somewhat in the thickness of the portion introduced between the anvils. When operating upon work of this character, the closing of the anvils upon the work may not be to the same extent in all cases due to variable thickness of the Work so that no fixed closed position of the anvil is possible, and it is also important that excessive pressure between the anvils be avoided. In order to meet these conditions the anvils are'brou-ght together under predetermined pressure conditions in accordance with this invention and when a desired maximum pressure has been reached, regardless of the spacing between the anvils at that time, the anvils are automatically moved apart for the removal of the completed work and the introduction of a new piece of work to be operated upon.

For a complete understanding of this invention, referencemay be had to the accompanying drawings in which Figure 1 is a side elevation and in section of a riveting the invention.

Figure 2 is a rear elevation of the upper portion of the same machine.

Figure 3 is a detail sectional view on line 3--3 of Figure 1.

Figure 4 is a detailed sectional view on line 4-4 of Figure 3.

Figure 5 is a fragmentary exploded perspective view of parts of the machine shown in section in Figures 3 and 4.

Referring first to Figures 1 and 2, the invention is shown as embodied in a riveting machine having a suitable frame I which may rest on a table or other suitable support. The frame I has a bracket 2 secured to its forward face beneath its upper end as shown best in Figure l, and in the outer end of this bracket is vertically adjustably positioned a normally fixed anvil 3. The frame 5 has an arm 4 which projects laterally over the bracket 2 and in this arm 4 there is mounted for vertical motion a movable anvil 5 which is in line with the fixed anvil 3. The frame l also supports at its upper end a hopper 6 of any suitable description for containing rivets partly broken away machine embodying from which hopper they are fed down automatically through the raceways l to a pair of rivetholding jaws 8 supported at the lower end ofthe vertically movable-bar 9 to the lower end of which is fixed the movable anvil 5. A suitable means, not shown herein, may be employed, as is well known in the art, for agitating the rivets in the hopper 6 and for presenting them to the raceway I from which they are taken off individually and presented between the jaws 8 beneath the movable anvil 5. The parts are arranged, as is well known in the art, so that at each down stroke of the bar 9, a rivet presented between the jaws 8 is brought down against the work and is driven into a suitable hole in the work and clinched therein by pressure exerted between the anvils.

The means for moving the movable anvil from and toward the fixed anvil, as shown, comprises a lever lil which is fulcrumed at l l on links i2 which, in turn, are fulcrumed at their lower ends to the frame arm 4 as on the fulcrum pin it. The forward end of the lever 1-0 is pivoted to the bar 9 as on the pivot pin 15, and the rear which is pivoted to the upper end of a piston rod H which extends down into a fluid pressure cylinder l 8 fulcrumed near its lower end on trunnions ['9 to the frame I.

The lower end of the cylinder I8 is provided with an integral transverse valve chamber 2!] within which is slidably mounted a spool valve 2!. This spool valve is adapted to be thrown to either one of two positions by the energization of a corresponding solenoid 22 or 23 carried in the lower portion of the cylinder block IB. Within this cylinder rides a piston 25 to which is connected the lower end of the piston rod l'i. It will be evident that by introducing fluid under pressure within the cylinder I8 beneath the piston 25, this piston will be raised and through its connection through the piston rod to the lever it], this lever It! will be rocked and the bar 9 depressed so as to bring the movable anvil toward the fixed anvil. By introducing fluid under pressure above the piston 25 it will be evident that the movable anvil will be raised from the fixed anvil to a position where completed work may be removed and new work inserted between these anvils.

It will be noted that the connection between the piston rod I1 and the lever I0 is not a plain pivot. Instead, as shown best in Figures 3, and 5, it comprises a pivot shaft 30 having two concentric bearing portions 3| and 32 on which the forked extremity 33 of the lever It is fulcrumed. Between the portions 3i and 32 is a third bearing portion 34 which is eccentric to the portions 3! and 32, and this portion 34 has journaled thereon a block 35 secured to or integral with the upper end of the piston rod H. The pivot shaft 30 carries fixed thereto an arm 36, which, as shown in Figure 1, normally extends along the lever Ill substantially parallel to its lower face. Spaced from the pivot 34 this lever 35 has bearing thereon a loading element comprising a spring pressed plug 31 backed up by an adjusting plug 38 against which bears a screw 39. It will be noted that the shaft 30 when in this angular position is so arranged that the maximum eccentricity of the portion 34 is substantially horizontal as shown in Figure 4. With this arrangement it is evident that when upward pressure is exerted on the piston rod l1, and which is exerted through the axis of the portion 34, this shaft 30 tends to be rotated into a position where the axes of the eccentric portions 34 and the journal portions 3| and 32 are in substantial alinement with the thrust, that is, substantially axially of the piston rod Thus the arm 36 tends'to be rotated upwardly against the pressure of the plug 31 thereon and should this pressure rise above that for which the spring has been set by adjustment of the screw 39, this will be accompanied by an upward motion of the forward end of the arm 36. The amount of pressure necessary to cause this turning of the shaft 3| with consequent angular motion upwardly of the arm 36 can be adjusted by adjusting the screw 39. Also bearing against the arm 35 is a switch-actuating element 40, this being carried by the lever l5. Thus when pressure has been built up beneath the piston 25 to a predetermined point sufficient to rock the arm 33, this actuating element 40 closes a switch 4|. As will later more fully appear, the closing of this switchconditions the valve 2| to effect separation of the anvils by upward motion of the movable anvil.

As shown, the piston rod an outwardly extending pin 42,

is provided with which, when the of the plug 31 until when a predetermined pressure has been reached, the switch element 40 is actuated to close the switch 4|. Closing of this switch 4|, the switch 44 now being open, due to the lifting of the pin 42 therefrom, establishes a circuit from the line 60 through the switch 4| and lead 15, solenoid 23, lead 16 back to the line 10. Energization of the solenoid 23 moves the valve 2| to the right into the position shown in Figure 1, allowing the fluid pressure to pass from the pipe 12 past the valve and into the passages 88 which communicate V with the upper end of the cylinder l8 above the piston 25 is in its lowest position, engages a switch actuating element 43 and causes closing of the normally open switch at 44. This switch 44 is in series with an operator-actuated switch 45. This switch 45 may be actuated by depression of a treadle 46, which is fulcrumed at 41 to a bracket 48 which may be positioned adjacent to the floor. The treadle 46 is normally held elevated, as by a spring 49, but when it is depressed so as to close the switch '45, switch 44 also being closed, a circuit is established from the line 6| through leads 6|, switch 45, lead 62, closed switch 44, 1ead'65, solenoid 22, lead =56, back to the line 10. The solenoid 22 now being energized, the valve 2| is moved to the left, opening a passage from the pressure supply pipe 72 through the valve casing 20 and through the casing passage 13 into the cylinder l8 beneath the piston 25 while opening the space above the piston 25 to discharge through passage 86 and through port '14. This causes the piston to be lifted, rocking the rear end of the lever l0 upwardly, causing its forward end to descend and pressing the movable anvil 5 toward the fixed anvil 3, thus to set a rivet in the work where the invention is applied to a riveting machine.

When the pressure exerted on the piston rod reaches a predetermined value, the shaft 3| is caused to turn by the pressure on the eccentric portion 34 as previously explained, lifting the forward end of the arm 36 against the pressure piston 25 while the space below the piston is open to discharge through passage '13, the valve casing and exhaust port 67. This piston 25 is thus driven downwardly, rocking the rear end of the lever l5 downwardly into the position shown in Figure 1.

Since the pressure exerted by the piston I1 is now in the reverse direction than on its up-stroke, the arm is moved away from the switch-actuating element by the spring pressed plug 31, opening the switch 4|. The parts are thus returned to their starting position with the switch 44 closed by the engagement thereon of the pin 42 in position for the cycle of operations to be repeated when the treadle 46 is depressed by the operator. It will be noted that the lifting of the piston rod ii at the start of a riveting operation releases the pressure of the pin 42 upon the switch actuating element 43, allowing the switch d4 to open. This conditions the parts for reversing the valve 2| as soon as the switch 4| is closed even though the treadle-operated switch should have been held closed, and the switch remains inoperative until after the switch 44 has been closed at the end of the rivet setting cycle.

It will thus be seen that the anvils are closed together under predetermined pressure, and as soon as this pressure has been reached, the anvils automatically separate for the removal of the work and there is no fixed position for the movable anvil to reach determining the end of the setting operation. Since there is no fixed position to which the movable anvil must reach before being retracted, allowance is thus automatically made for different thicknesses of material, by adjusting the maximum pressure between the anvils, enough may be had to insure proper setting of the rivets, but without permitting at any time an excess pressure which might break work of a somewhat fragile nature within which it is desired to set the rivets.

From the foregoing description of an embodiment of this invention it will be evident to those skilled in the art that Various changes and modifications might be made without departing from its spirit or scope.

I claim:

1. In a machine of the class described, parts comprising a movable member, and power means for moving said member, operative connections between said parts including a rockable element carried by one of said parts and means for applying pressure eccentrically to said element, yield ing means opposing turning of said element, and means responsive to said turning for reversing said power means.

2. In a machine of the class described, parts comprising a movable member, and power means for moving said member, operative connections between said parts including a rockable element carried by one of said parts and means for applying pressure eccentrically to said element, an arm fixed to said element, an adjustable loading element on which said arm bears, and means responsive to the position of said arm for reversing said power means on movement of said arm against said loading element to a predetermined angular position.

ARTHUR R. HAVENER.

REFERENCES CITED The following references are of record in the file of this patent:

6 UNITED STATES PATENTS Number Name Date Conklin Sept. 13, 1932 Norin Apr. 14, 1936 MacMillin et a1. Apr. 5, 1938 Conklin Sept. 20, 1938 Harrington Oct. 29, 1940 MacMillin Apr. 5, 1949

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