US1718715A - Electric riveting machine - Google Patents

Description

3 Shots-Sheet 1 J. A. SPENCER ELECTRIC RIVETING IACHINB Original Filed lay 10, 1924 John 5 677667 6 June 25, 1929.

J. A. SPENCER ELECTRIC RIVETING MACHINE Original Filed May 10, 1924 2 Sheets-Sheet 2 I71 0611 $07 Jo 7171 a. 5706 71667 051: 1 a Zia 1 1163;

Patented. June 25, 1929.

UNITED srArps PATENT, OFFICE; 1

JOHN A. SPENCER, E REVERE, MASSACHUSETTS, ASSIGNOR T0 SPENCER THERMO- STAT COMPANY, OF CAMBRIDGE, CHUSETTS.

MASSACHUSETTS, A CORPORATION OF MASSA- ELECTBIC RTVETING MACHINE.

Application filed May 10, 1924, Serial This invention relates to metal working machines and more particularly to machines for upsetting rivets.

The principal object of the invention is to provide a rivet upsetting machine capable of performing the upsetting operation rapidly, accurately and under substantially uniform conditions of temperature andpressure. \Vith the above and minor objects in view the improved mechanism comprises inter alia a work supporting table or anvil which constitutes one terminal of an electrical heating circuit, a pressure applying element movable toward and from the work support or anvil and which constitutes the other termi-' nal of said circuit, an actuator, for example a treadle, for moving the pressure applying element toward the work support, a normally open circuit breaker for determining the flow of current insaid heating circuit, and connections for closing the circuit breaker substantially concomitantly with the movement of the pressure applying element into contact with work resting upon the work support.

The connections for actuating the circuit breaker are adapted to permit relative movement of the pressure applying element and circuit breaker during the actual upsetting operation so that while the circuit breaker is positioned to complete the circuit through the work the pressure applying element may com-' plete its movement toward the work support to upset the work. The pressure applying element per se is also resiliently mounted in its support or carrier so that pressure applied to the work is determined by the compression of a spring of known strength, while the period during which the circuit is closed is automatically determined by appropriate means.

In the exemplification of the invention herein chosen for illustration, the mechanism is designed primarily for upsetting rivets disposed in circumferentially spaced holes in a thin metal 'disk such as is employed as the controlling element in certain types of thermostatic regulator andfor this purpose the work supporting table or anvil is made circularto conform to the shape of the disk and is mounted to rotate whereby successively to No. 712',22o. Renewed June 11, 1928.

position the several rivets in the path of the pressure applying element.

One embodiment of the invention is shown by way of example in the drawings, in which Fig. 1 is a plan view of the mechanism, certain of the electrical connections being shown diagrammatically; I

Fig. 2 is a side elevation of the mechanism with its parts positioned as at the beginning of the upsetting operation, omitting certain elements of the heating circuit;

'Fig. 3 is a fragmentary vertical section showing the relative positions of the work supporting table and the pressure applying element substantially at the instant of contact of the pressure applying element with the work;

Fig. 4 is'a side elevation of the parts shown inFig. 3 but at the completion of the upsetting operation;

Fig. 5 is a fragmentary horizontal section substantially on the line 55 of Fig. 2,

Fig. 6 is a fragmentary vertical section substantially on the line 66 of Fig. 2;

Fig. 7 is a view similar to Fig. 6 but showing the parts positioned to close the circuit,

and i 1 Fig. 8 is another view similar to Fig.6 but showing the circuit as broken and the actuating pin for the circuit breaker returning 30 to normal position. I

Referring to the drawings for a more particular description of the invention the numeral 1 designates a base or frame adapted to rest upon a bench, or which may be provided with legs or other appropriate supports not shown. A block 2 is secured by means of bolts 3 to the upper surface of the base near the right hand end of the latter as viewed in Figs. 1 and 2. This block has a vertical bore for the reception of a stem 4, projecting downwardly from the center of a circular work supporting table 5 which rests upon the upper surface of the block 2. The outer edge of this table is preferably knurled. The lower part ofthe bore in the block 2 is enlarged to provide a chamber for a retaining head or disk 7 having a screw-threaded stem 8 1n the member 9. The

block and the table 5 in fixed position after adjustwhich engages a threaded axial opening in the lower end of the stem 4 of the table. The

'ofi'set portion 9 having a horizontal bore opening into the bore in the block 2 substantially in the horizontal plane of the disk 7. A ratchet block 10 slides in the bore in the offset 9 and this ratchet block is provided with a round end adapted to engage any of-a series of circumferentially spliced recesses 11 in the edge of the disk 7. The ratchet block 10 is provided with a tail 12 which is encircled by a coiled spring 13 one end of which bears against the block 10 and the other against a block 14 closing the bore spring pressed ratchet 10 is thus adapted to retain the disk 7 ment while permitting the table to be turned to a new position at will.

In the specific embodiment of the invention herein shown the upper surface'of the table is furnished with spaced depressions, corresponding in number to the recesses 11' in the disk, for the reception of the heads 15 of rivets 16 which project upwardly through suitable openings ina disk 17 which may be positioned upon the upper surface of the table by means of a pin 17*. Insulating washsired at either side of the plate 17 and the.

. wardly from the base member e'rs a and b may be placed on the rivet if deupper end of the rivet is headed over onto a metallic washerc in the manner hereinafter described. The disk 17 with its rivets and washers thus constitutes the work to be oper ated upon.

Spaced brackets 18 and 19 project upsite end of the latter from the brackets support a pivot pin 20 providing a fulcrum for one end of a lever arm 21 which overhangs the base-1 and whose free extremity is disposed substantially above the table 5. At a point intermediate its length the arm 21 is furnished with an opening 22 for the reception of the upper end of a rigid link comprising the' upper member 23 pivotally connected to the arm by apin 24, and provided at its lower end with an axial extension 23.

This extension telescopes'in an axial bore in the lower member 23 .of the link, the latter member in turn being pivotally connected at 24 to the intermediate part of a treadle lever 25 which is pivotally connected at 26 to a bracket 27 secured to the floor or a suitable point on the machine frame. The forward end of the treadle lever 25 is furnished with a foot engaging element 28. A coil spring encircles theadjacent ends of the link members 23 and 233, having its opposite ends se- ""cured to the respective members.

1 at the oppoblock 2. These fl within the sleeve 37.

A spring 29 is secured at one of its ends to the treadle lever'and at its opposite end to a bracket 30 mounted on the underside of the base 1. The strength'of the spring 29 is such as normally to sustain the. treadle link and lever arm 21in the inoperative position indicated in Fig. 2. v

To prevent unnecessary lift of the lever arm 21 a link 31 is'pivotally secured thereto atthe point 32 and projects down through an opening 33 in the base 1: The lower part of the opening 33 is enlarged to provide a chamber 34 carried by the link, such head being of a diameter larger than that of the link 31. Thishead is adapted to engage the upper wall of the chamber 34 thus preventing the lever 21 from rising excessively under the action of the spring 29 but permitting the arm 21 to within which is arranged a head 35- be depressed toward the table by the treadle.

provided with an attaching flange-38 for cngageinent by bolts 39 passing upwardly through suitable openings in-the end of the arm 21. Electrical insulating material 40 is interposed between the lower end of the sleeve 37 and the upper surface of the arm 21 and the bolts 39 are likewise insulated from the arm by suitable insulating sleeves surrounding them. i

The lower .end of the sleeve has an internal ange 37 constituting a stop shoulder. A plunger 41 is arranged to slide vertically This plunger is provided with a downwardly projecting head 42 of reduced diameter which protrudes from the lower end ofsleeve 37, the flange 37-li1niting downward movement of the plunger and diilicultly fusible electrically conducting metal.

The upper end of the sleeve 37 screw-threaded for the reception ed adjusting cap 44. A spring'45 is interis externally posed between the upper end of the plunger 41 and the inner surface of the cap. This spring tends to hold the plunger 41 downwardly against the stop shoulder 37 in the position may be adjusted by rotating the cap.

' A stem,46 projects upwardly from the of a thread 4 shown in Fig. 2 and the tension of the spring plunger 41 through a centralopening in the cap 44 and is provided with means for attaching thereto one end, of an electrical conductor 47 whose opposite end is grounded at 48 upon the base 1.

An intermediate portion of theconductor 47 constitutes the coarsely'wound secondary coil 49 of a stepdown transformer. The finely wound primary coil 50 of this'transformer is connected at one end to a conductor 51 leading from a suitable source ofelectrical energy. The other terminal of the primary coil is connected by aconductor 52 to one element of acircuit breaker.

A 53 while a second conductor 58, corresponding to conductor 51 leads from the arm 54 to the source of electrical energy.

Thefbar 57 is provided with an opening substantially. opposite to theposition of the contacts 55 and 56 and this opening constitutes a guid-eway for a slide 59. This slide is provided with a pin 60 (Fig; 6) which projects through a slot in the end of the bar 57- and which constitutes a stop to limit move ment of the slide andwhieh also prevents the slide from turning within its gu'ide opening. The slide projects from opposite ends of the bar 57, a coiled spring within a chamber in 'the bar 57 tending to move the slide away from the contact supporting arm 54.

The inner end of the slide is provided with a cam lever 61 pivotally secured to the slide at 62 and has a spring 62" which tends to swing the lever in a counterclockwise direction as viewed in Fig. 6. This lever thus normally occupies the position shown in Fig.

:6 with its free extremity bearing against the adjacent face of bar 57. Lover 61 is furnished with a forwardly projecting cam ledge or flange 61 for a purpose hereinafter described.

7 A rod 63 is arranged to slide vertically in an opening in the base 1. This rod is furnished with a keyway 64 which is'eugaged by zukcy member 65 attached to the base by a screw 66. The upper end of the rod 63 is provided with an outstanding pin 67 whose end overlies the cam ledge 61- of the cam lever 61.

- The lower end of the rod 63 is bent laterally and secured to the lower end of the piston rod of a dash-pot 68 secured at 69 to the base 1. This dash-pot is of .usual construction, pre fcrably of one-way type. opposing resistance only to downward movement of its piston. the latter being furnished with a spring. not shown, for restoring it to normal position. The lower end of the piston rod 70 spring is also connected to the upper end of a still spring 71 whose lower end is attached at 72 to the treadle lever 25.

In operating the device above described rivet heads are arranged in the several cavities in the upper surface of the work support and the apertured disk 17 is positioned upon the work support witlrthe rivets projecting up through its apertures, the washer a, b and 0 being applied, if desired. As above described. the parts are so positioned that when the ratchet slide 10 engages one of the recesses in the disk 7, one of the rivet retaining openings of the table is axially aligned with the plunger 41. 4 b

The operator now pluces his foot upon the t'readle member 28 thereb pulling the arm 21 downwardly to bring t ie pressure applying element 43 into contact with the rivet- 16. Downward movement of arm 21 may continue until flange 36 engages washer 0 thus placing spring 45 under compression. Furthcr movement of the treadle is now permitted by the resilient connection between link members 23 and 23 During the early part of thedownward movement of lever 21, the rod 63 also moves downwardly, its movement being delayed however by the action of dash-pot 68. This movement of rod 63 causes pin 67 to bear against the inclined cam ledge 61 of lever 61, thus swinging the lever about its upper end as a fulcrum and movin slide 59 to bring contacts and 56 into engagement. After contacts 55 and 56 are engaged. the pin 67 continues to move down along the now substantially vertical cam ledge 61 which in the position acts as a dwell to retain the contacts engaged until pin 67 escapes from the lower end of the cam ledge, whereupon the ront-acts immediately separate.

The completion of the electrical circuit through the primary winding 50 oi the transformer energizes the circuit comprising the wire 47 and 01" which the work supporting table and the pressure applying element 43 respectively constitute the terminals. The completion of this circuit takes place substantially simultaneously with the contact of: the pressure applying element 43 with the upstanding end of the rivet shank. As soon as this contact is accomplished, the circuit being completed, a heavy heating current flows through the circuit of which the rivet now becomes a part, thus heating the rivet to the desired temperature tor upsetting. As the 45 has'been placed under compression, the head 43 bears with a predetermined pressure upon the work and as soon as the rivet softensunder the heat applied, the head 43 advances and upsets it. The pressure upon the rivet thus depends upon the strength of spring 45 and upon the distance to which head 43 initially protrudes beyond the lower face of flange 36 and is unatlected by exceslonged depression of the treadle. When the sive depression of the treadle, While the length of time to which the rivet is subjected to heat is also unafi'ectedsby excessive or protreadle is released, arm 21 rises and pin 67 passes up between arm-57 and lever 61, swing ing the latter, as shownin Fig. 8 until the pin arrives at its initial position, whereupon spring 62 restores lever 61 to the position shown in F1g. 6. Q

The operator now turns the table 5 until- 1 the nextrivet is below the pressure applying element whereupon the operation is repeated. By this means the riveting or upsetting operation may be performed with great expedition, the rivets are heated to a substantially uniform temperature and subjected to a substantially uniform pressure, eventhougli the operator maintains his foot on the treadle for an unnecessarily long time, so that uniformity in product is secured and-waste and loss of material substantially eliminated.

While the mechanism has herein been illus-.

of which the pressure applying element and work support respectively constitute the terminals, means normally holding the pressure applying'element in spaced relation'to the work support,'and means for swinging the arm to move the pressure applyingelemcnt into contact with work resting on the work support.

. I I 2. A machine of the. class-described comprising a horizontal work support, an-arm oscillable in a vertical plane, a pressure applying element mounted upon the free end of the arm to move toward and from the work support,the pressure applying element being electrically insulated from the arm, the pressure applying element and work support constituting terminals of an electrical circuit, a treadle, and connections between the treadle and arm for swinging the latter to cause the pressure applying-element to approach the work support.

3. A machine of the'class describedcomprising a rotary work support, means for holding the: work support in selected positions of angular adjustment, anoscillatory pressure applying element movable toward and from the work support, a treadle, connections'behyeen the treadle and pressure applying element for moving the latter toward the work support, and means for heat- 'in'g workresting upon the work support while engaged by the pressure applying element. I

4. A machine of the class described comprising a, rotary work support, a spring pressed latch for retaining said support in selected position of angular adjustment, a

swinging arm, a pressure applying element mounted upon the arm and movable toward and from the: work support, a treadle, an extensible link connectingthe treadle to the:

c the treadle and tlle arm with its arrn,'and a spring engagin normally acting to hold 7,

pressure applying elementaway from the work support. p

' 5. A machine of the class described comprising a work support, a pressure applying element movable toward and-from the work Y support, anactuator for moving the pressure applying element toward the work support to apply pressure to work supported thereon, means for completing an electrical circuit to send current through the work support the work and the pressure applying element'- tor heating the work, lost motion connections between said latter means and the actuator, additional means for limiting the pressure. on the work irrespective of the velocity. of

motion of theactuator and a dash pot as-;

sociated witlr said connections to closing ancl opening of the'circuit. I

6. A machine of the class described comprising an upsetting. element, a work sup-' porting element, said elements constituting the terminals of an electncal heating c1rtime the cuit, a circuit breaker for determining the flow of current in said circuit comprising normally spaced contacts, and means for moving said upsetting element into engagement with the work comprising a treadle, tilescopically engaging 1nembers,"means connee-ting one of said members to the treadlc,

and a spring, connecting said members.

7. Anlachine of the class described comprising a work support, a pressure applying element movable toward and from the work support, an actuator for moving said element into contact with work resting upon the support, gconnectionsbetween the actuator and said element by which the vpressure exerggd on thework is limited, an electrical lieati g circuit for heating work-upon the support, a normally open circuit breaker for controlling the flow o1" cnrrent in said circuit, means for transmitting movement from the actuator to the circuit breaker comprising-resilient eX- tensible connections and a dash pot associated with said connections to time the closingan'd opening of the circuit. 1

8. A machine of the class described comprising a work support, a pressure applying element movable toward and from the work support, an actuator for moving the pressure applying element'tov apply only a limited pressure to Work on the work support, con

, electrical circuit having the pressure applying element and work support as its terminals, a normally open circuit breaker for de-' termining the flow of currentin said circuit, a treadle for actuating the pressure applying element, and means for transmitting movement from the treadle to said element comprising an elongate member pivotally connected to the treadle, a second elongate ,member telescopically engaging the first,

resilient means opposing separation of said members, and means connecting-the second of said members to the supporting means for the pressure applying element. M

10. A machine of the'class describedcomprising cooperating upsetting elements eon-' stituting terminals of an electrical heating circuit, a circuit breaker for determining the flow ofcurrent in said circuit comprising normally spaced contact members, resilient means supporting one of said members, a

slide for pushing said latter member toward the first member, a cam element carried by the slide, a movable pin, engageable with the cam element for moving the slide,and means operating in timed relation to the operative actuation of the upsetting elements for moving the pin relatively to the cam element.

11 A machine of the class described comprising cooperating upsetting elements constituting terminals of an electrical circuit. a circuit breaker for determining the flow of current in said circuit comprising normally spaced contacts, resilient supports for the respective contacts, a slide movable into engagement with one of said supports to move it toward the other, a normally inclined cam element carried by the slide, a spring normally retaining the slide in inoperative position, a bar reciprocating in a path transverse to the path of movement of the slide, said bar having a pin engageable with the cam element of the slide to move the latter, and means operating in timed relation to the operative actuation of the upsetting elements and comprising a resiliently extensible connection for moving the reciprocating bar to cause its pin to actuate the slide.

12; A machine of the class described comprising cooperating upsetting elements constituting terminals of an electrical heating circuit, a circuit breaks. for determining the flow of current in said circuit comprising normally spaced relatively movable contacts, a slide member for moving one of said contacts into engagement with the other, a cam element upon said slide member, a part movable into engagement with said cam element for actuating the slide ,meniber, and common means for moving said part and for operatively'actua'tingthe upsetting elements. v

13. A machine of the class described comprising a work support, a member movable toward andlfrom the support, stop means for positivelylimiting movement ofasaid memher, an e ctrically insulated guide sleeve carried by said member, a plunger sliding within the guide sleeve and having a head engageable with work on the work support, a spring normally projecting one end of the plunger from the sleeve toward the work support, theplu'nger and work support con-' stituting terminals of an electrical circuit,

and means for moving the movable member with its guide sleeve toward the Work suport.

14. A machine of the class described comprising a relatively fixed work support, a swinging arm, a treadle for moving the arm toward and from the work support, and a spring pressed electrically insulatedplunger constituting one terminal of'an electrical circuit mounted upon the arm in a position to contact with work on the work support as the arm is swung toward the latter, the work resting upon the work support being electrically connected'to the other terminal of the circuit.

15. A machine of the class described comprising a work support, an oscillatory arm having an aperture near its free extremity, a guide sleeve secured to the arm coaxially with the aperture in the arm, electrical insulation between the sleeve and arm, a plunger sliding in the sleeve having a head projecting through the aperture in the arm, a cap having threaded engagement with the free end of the guide sleeve, a spring interposed between the cap and plunger, and means for moving the arm toward and from the Work support, said support and the plungerrespectively constituting terminals of an electrical circuit.

16. A machine of the class described comprising an electrical circuit, a circuit controller, and means for actuating the controllercomprising a slide, a lever pivotally connected to the slide, an abutment surface perpenpath and operatively'engageable with the cam lever when moving in one direction to actuate the slide and passing the cam lever Without operati'vely afi'ecting'the slide when moving in the opposite direction.

18. A machine of the class described comprising a work support, a pressure applying element movable toward and from the Work support, a movable carrier for tlle pressure applying element, a spring interposed between the carrier and saidelement, the carrier having a stop to limit its movement, control- JOHN A. SPENCER.-

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