US3147647A - Means and methods of clinching rivets - Google Patents

Description

p 8, 1964 D. G. DOWNES 3,147,647

MEANS AND METHODS OF CLINCHING RIVETS Filed June 22, 1961 2 Sheets-Sheet l INVENTOR. I 1 Dar/649 Eba ouA/ES ATTORNEYS 1 Sept. 8, 1964 D. G. DOWNES 3,147,647

\ MEANS AND METHODS OF CLINCHING RIVETS Filed June 22, 1961 4 2 Sheets-Sheet 2 FIG. 6

INVENTOR. DOUGLHS pow vgs FIGB [31W United States Patent 3,147,647 MEANS AND METHODS 63F CLINCHING RIVETS Douglas G. Downes, Natick, Mass, assignor to Judson L. Thomson Mfg. (10., Waltham, Mass, a corporation of Massachusetts Filed June 22, 1961, Ser. No. 118,946 7 Claims. (Cl. 78-46) The present invention relates to an improved method of clinching rivets and a rivet clinching machine related thereto.

It is often desirable to clinch rivets onto a workpiece without scratching or marring the rivet head and without gouging or 'deplating plated rivets by cold flowing the plating. It is also very often important to clinch rivets on a workpiece without scoring, the rivet or forming small lips or beads about the periphery of the rivet head. It is also desirable to provide a means and method of clinching rivets to very thin workpieces without distorting, bending, scoring or otherwise damaging the very thin and fragile workpiece. Such requirements are becoming increasingly important particularly in electrical and electronic fields where lower tolerances and greater accuracy are required in mass produced components.

The present invention provides a machine in which rivets may be secured to workpieces of various thicknesses without damaging or distorting either the rivet or the workpiece adjacent to the rivet.

The present invention also provides a method of clinching rivets to a workpiece in a manner which is faster and more certain of operation and which is adapted for automation.

In the present invention there is provided an anvil adapted to receive and support the bottom of the rivet while being clinched to a suitable workpiece, and a stem having a head adapted to engage the head of the rivet and drive it downwardly onto the anvil for clinching. In addition there is provided a pocket means which positions the rivet for subsequent insertion into the workpiece. The stem is interengaged with a probe that opens the pocket means and thereby releases the rivet after engagement of the rivet head with the head of the stem. The stem and probe are movable in a longitudinal direction toward the workpiece and the pocket means with both the stem and probe being actuated by some suitable means such as a cam drive. The stem is formed with an integral time delaymeans feature which assures the proper locating of the rivet prior to clinching but in a manner which does not reduce the operating capacity of the machine. This tirne delay feature includes means for imparting a non-linear rate of acceleration to the downward movement of the stem whereby the downward rate is minimum for a time interval after engagement of the rivet and stem and the rate is increased for a subsequent time interval.

These and other objects and advantages of the present invention will be more clearly understood when considered in connection with the accompanying drawings in which:

FIG. 1 is a fragmentary partially cross sectioned view of a rivet machine embodying novel features of my invention;

FIG. 2 is a cross sectional detail of the construction shown in FIG. 1 and taken substantially along the line 2-2 of FIG. 1; FIG. 3 is a detail taken along the line 33 of FIG. 1; FIG. 4 is 'a cross sectional detail of a portion -of the construction illustrated in FIG. 1 illustrating a portion of the machine in a sequentialstep of operation to that of FIG. 1; and I FIGS. Sand 6 show enlarged portions of the machine 3,147,647 Patented Sept. 8, 1964 illustrated in FIG. 4 but in successive positions of operation of the machine.

The invention illustrates an improvement in a conventional riveting machine which has a conventional feed 1 suitably supported on a conventional frame 2 for feeding rivets successively down the chute 3 to the lower end 4 of the feed mechanism. The rivets may be supplied from a conventional hopper not illustrated. The rivets are successively deposited into the pocket means 5 supported for vertical reciprocal movement in the pocket guide 6. The pocket guide 6 is a vertically oriented elongated channel which is secured at its upper end 7 to the frame 2 of the riveting machine. This pocket guide 6 as illustrated in FIG. 3 is formed with side wall members 9 and 10 having inner beveled surfaces 12 and an interconnecting bight 13. The pocket means 5 with is secured within the guide for vertical slidable movement over a limited distance is formed of two segments 15 and 16 spring tensioned together-by means of spring 17 secured by pins 18 on the outer sides of the segments. The pocket means 5 is positioned between and in sliding engagement with the pocket guide 6 and the lower end 4 of the feed 1 so that it may move only in a vertical direction. The pocket means 5 is tensioned upwardly by means of a helical spring 29 secured at its lower end to the pin 21, extending transversely through segments 15 and 16, and at its upper end to the pin 22, the pin 22 in turn secured to the pocket guide 6. Upward movement of the pocket means 5 is limited by lip 25'which may engage the lower end 4 of the feed 1. The downward movement of the pocket means 5 is limited by flange 28 integral with the lower end of the pocket guide 6 and in turn supporting a downwardly extending fixed locating pin 27. The locating pin 27 functions to locate the workpiece in a manner hereafter more clearly described.

Mounted in the frame 2 for longitudinal or vertical movement is the plunger 30 which may be moved vertically by suitable means as for example by the schematically illustrated cam 31. Probe 33 having an upper end positioned within recess 32 of the plunger 30 is secured to it by set screws 34. The lower end of the probe 33 is positioned to engage recess 40 of pocket means 5 on downwardly movement of the plunger 30 to thereby spread apart two sections 15 and 16 and in turn widen hole or slot 45 into which rivets are successively fed from the hopper chute 3.

Also secured to the plunger 36 is stem 50. This stem 50 is formed with a head 51 at its lower end having a concave surface conforming to the head of the rivets with which the particular machine is used The upper end of the stem is slidably positioned within a recess 53 in the plunger. Vertical movement of the stem is limited by a set screw 54 which is threaded through the frame 2 into the transverse slot 56 in the stem. The upper end of the stem terminates in a recessed cap 56. Helical spring 57 has its lower end engaged in the recessed cap 56 and its upper end engaged in a narrow recess 58 continuous with recess 53. The upper edge 59 of the cap 56 is spaced from the bottom of the recess 60 within which the stem is positioned. The normal distance between the upper surface 59 of the stem and the lower surface 60 of the recess'is slightly less than the distance between the uppermost edge of the set screw 54 and upper edge of the slot 56 so that the screw 54 is not normally engaged by the edge of slot 56 when the device is in actual use.

The spring 57 functions as a time delay mechanism. When a rivet is fed down the chute 3 into the pocket means 5 and cam 31 actuates a downward movement of the plunger 30, the head 51 is positioned in vertical spaced relation to the end of proble 33, such that head 51 first engages the head of the rivet in slot 45. Shortly thereafter the probe 33 engages recess 40 and connects to spread the two segments 15, 16 of the pocket means so as to release the rivet. Because the upper edge of the stem 50 is spaced from the plunger by means of spring 57, probe 33 has not released the rivet from pocket means 5, upon engagement of the rivet head in slot 45 with the head 51, the downward movement of the stem 50 is temporarily stopped until the plunger, continuing to move downwardly, compresses spring 57 and causes surface 60 to engage surface 59 (FIG. 1). This effectually creates a time delay in the downward movement of stem 50 during which the plunger 33 which continues to move downwardly engages and spreads the two segments 15 and 16 of the pocket sufliciently to release a rivet after the head 51 of the stem has firmly engaged the head of the rivet, and after the pocket means 5 has moved downwardly to its lowermost level to a point in engagement with the flange 28. The time delay sequence is important since it assures a proper interengagement of the rivet head with the head 51 which in turn minimizes the likelihood of damaging the rivet head when the rivet is actually clinched to the workpiece.

The anvil 70 is formed with a narrow upper section 71 having a cup-like upper surface adapted to receive the lower end of the rivet to shape it. The anvil 70 also has a lower cylindrical member 72 positioned for vertical adjustment in a sleeve 73. The anvil plate 74 comprises a casing having an opening formed therein within which the anvil and sleeve 73 are positioned. A threaded adjusting screw 75 is threaded upwardly through an opening in the anvil plate 74- and engages the cylindrical member 72 of the anvil 70 which projects through a hole in the sleeve 73. A screw 75 may be adjusted vertically and in turn thereby adjusts the vertical position of the anvil 70. A set screw 76 projecting through the sleeve 73 secures the anvil 70 in position. A set screw 78 secures the screw 75 in position with the set screw 78 projecting through the anvil plate 74. Also located in the opening 79 are bellows 80 coaxial with the anvil 70. The bellows 80 comprise a cylindrical body having a plurality of surface convolutions with the lower edge 81 suitably sealed at the bottom of the opening 79 and the top edge suitably sealed to locating plate 83. The locating plate 83 comprises a flat plate having an opening to which depending collar 84 is secured. The anvil 70 projects through the collar 84 with the collar 84 and the narrowed upper section 71 of the anvil 70 forming a relatively close fitting seal so as to minimize the passage of air therethrough. The upper surface of the locating plate may be shaped to receive the particular workpiece being clinched with rivets. For this purpose a depressed section such as illustrated at 87 may be formed in the upper surface of the locating plate 83 so as to properly locate the workpiece over the anvil. The locating pin 27 engages an aperture in the locating plate 83 as illustrated in FIGS. 4 to 6 and thereby prevents the bellows 80 from rotating axially.

In the operation of this riveting machine a rivet fed down the chute 3 of feed 1 is deposited in the slot 45 of the pocket means 5 thereby aligning this rivet vertically with the head of the anvil 70 and stem 50. Immediately thereafter the plunger 30 actuated by suitable means such as the cam 31 moves downwardly at a first rate of acceleration toward the rivet positioned in the pocket. This plunger carries with it the stem 50 maintained in spaced relation as illustrated in FIG. 1 by the spring 57. Also carried with the plunger in rigid relation is the probe 33. The head 51 of the stem 50 first engages the head of the rivet in the pocket and forces the rivet downwardly carrying the pocket means 5 with it. The pocket means 5 reaches its lowest position when it engages the locking plate 28 and stops.

ever, continues to move downwardly. The resistance of The plunger, how

anvil (FIGS. 4 and 5).

the rivet against the head 51 stops the downward movement of the stem relative to the pocket means 5 and closes the gap formerly maintained by the spring 57 decreasing the ratio of acceleration of the stem to zero. The probe 33, however, continues to move downwardly. By the time the bottom of the probe 33 engages the slot 40 of the pocket means 5 there has been a time delay during which the stem 50 has remained relatively motionless with respect to the pocket means 5 thereby permitting a firm interengagement of the head 51 with the head of the rivet. The probe 33 then continues to move downwardly to separate the two halves 15 and 16 of the pocket. At the same time the stem 50, which is now under the compressive force of spring 57 as well as the force of gravity and the downward pressure of the plunger 30, forces the rivet downwardly through the workpiece 101 which by this time has been properly located on the Because of the several forces acting upon the stem after the pocket is opened the stem is moving dovmwardly at a rate faster than its initial downward rate.

The bellows 30 has a very low mass and spring rate. Consequently a workpiece positioned on the locating plate 83 with an opening coaxial with the anvil is supported about the periphery of the anvil head without a strong restraining force. The rivet is moved downwardly by stem 50 and engages the head of the anvil. It is then compressed about the workpiece 101 with little or no restraining force immediately adjacent the rivet head because there is very little resistance due to the low inertia and spring rate of the bellows. No excessive force is applied to the workpiece at 102 which may comprise the lip of a contact blade or the like. But for the bellows arrangement having a low mass and a low spring rate, the workpiece could easily bend or be distorted. When the workpiece comprises a contact blade for use in electric relays and the like such distortion could have materially adverse eifects on the proper operation of the device. In the completely clinched position of the rivet as illustrated in FIG. 6 the rivet 100 is formed with perfectly accurate heads on either side with no lip or scoring and without distorting, bending or otherwise damaging the workpiece 101. As the stem returns, the little amount of stored energy in the bellows ejects the completed workpiece which then can be fed by suitable means into a chute or conveyor.

If desired the sequence of operation of the stem and plunger may be controlled by an electronic circuit including a sensor which detects the proper location of the workpiece and thereafter 'actuates the downward move ment of the plunger 30 through the cam 31 by any suitable means such as a motor drive gear operably engaging the cam 31.

Having now described my invention, I claim:

1. In a machine for clinching rivets on a workpiece, an anvil adapted to receive and reshape the bottom of a rivet under compressive force, pocket means for receiving and supporting said rivet in vertical alignment with said anvil, means for applying a compressive force to said rivet comprising impacting means for engaging the head of said rivet while supported in and in fixed relation to said pocket means and driving it downwardly onto said anvil, means independent of said rivet for releasing said rivet from said pocket means subsequent to engagement of said impacting means and rivet head, and means for delaying the downward movement of said rivet and said impacting means relative to said pocket means for a time interval after engagement of said impacting means and said rivet.

2. A device as set forth in claim 1 wherein said impacting means comprises a stem vertically oriented with respect to said anvil and having a head adapted to engage the head of said rivet, said pocket means having an expandable opening aligned with said impacting means, said IEHI S independent of said rivet for releasing said rivet including a probe adapted to engage and expand said pocket for releasing a rivet therefrom, a plunger positioned to engage said stem and force it downwardly said delaying means comprises means forming a vertical space between said stem and plunger, and a compressible spring positioned in said space and normally maintaining said space at a selected width, said width adapted to be compressed on application of selected compressive forces between said anvil and plunger.

3. In a machine for clinching a rivet on a workpiece, an anvil having a head adapted to receive and reshape the bottom of said rivet while being clinched to said workpiece, a pocket having an expandable opening aligned with said head for receiving and aligning said rivet with said head, feed means for feeding said rivets from a supply thereof to said opening, means for cyclically expanding said pocket to release said rivet and thereafter drive said rivet downwardly onto said head for clinching said rivet on said workpiece comprising a reciprocatable plunger positioned and supported for reciprocation with respect to said opening and head and operably engaging a stem and probe, said stem having a rivet head engageable portion aligned with said opening and head, and said probe positioned to engage and expand said pocket for releasing a rivet therefrom after engagement of said rivet head engageable portion and said rivet, means for securing said stem and probe in longitudinal relation with said plunger with said securing means including a compressible spring normally tensioning and spacing said plunger and stem apast except when the force of said spring is overcome by a force applied to said head of said stem when engaged with said rivet.

4. A method of clinching rivets on a workpiece comprising the successive steps of aligning the length of and securing a rivet in spaced relation with an opening in said work-piece and an anvil for said rivet, moving a driving means in a dirction aligned with the length of said rivet at a first constant rate of acceleration, decreasing the rate of acceleration to zero when said driving means engages said rivet for a time interval during which said rivet is released, moving said driving means in said direction at a rate of acceleration in excess of said first constant rate until at least said rivet engages said anvil.

5. In a rivet clinching machine having an anvil on which a rivet may be clinched and impacting means for clinching said rivet on said anvil, means for supporting a workpiece to which said rivet is to be clinched comprising a bellows at least partially surrounding said anvil and having an upper surface forming a workpiece receiving surface extending generally parallel to the upper surface of said anvil and adapted to normally support at least a portion of a workpiece above said upper surface of said anvil.

6. In a machine for clinching rivets on a workpiece, an anvil adapted to receive and reshape the bottom of a rivet under compressive force, pocket means for positioning said rivet in vertical alignment with said anvil, means for applying a compressive force to said rivet comprising impacting means for engaging the head of said rivet while in said pocket means and driving it downwardly onto said anvil, said impacting means comprising a stem vertically oriented with respect to said anvil and having a head adapted to engage the head of said rivet, a plunger positioned to engage said stem and force it downwardly, means supporting said pocket means in limited vertical movement when said rivet is engaged by said stem, means normally tensioning said pocket means toward said stem, means for releasing said rivet from said pocket means subsequent to engagement of said impacing means and said rivet head, means for delaying the downward movement of said rivet and said impacting means relative to said pocket means for a time interval after engagement of said impacting means and said rivet, said delaying means comprising means forming a vertical space between said stem and plunger and a compressible spring positioned in said space and normally maintaining said space at a selected with, said width adapted to be compressed on application of selected compressive forces between said anvil and plunger, a locating plate adjacent said anvil for supporting a workpiece to which said rivet is being clinched, a bellows providing support means having low inertia and a low spring rate for resiliently positioning said locating plate in a plane substantially parallel with the upper end of said anvil and thereafter ejecting said workpiece.

7. In a machine for clinching a rivet on a workpiece having a hole through which said rivet is to be clinched, anvil means for receiving and reshaping the bottom of a rivet under compressive downward force, means for supporting said workpiece for resilient vertical movement with said hole aligned with said anvil means, said supporting means comprising a bellows having an upper workpiece receiving surface normally coplanar with the upper portion of said anvil, said bellows coaxial with said anvil and substantially surrounding it, means for releasably positioning said rivet in vertical alignment with said anvil, impacting means for engaging said rivet while in said positioning means and thereafter applying a downward and compressive force to said rivet whereby said rivet will be driven downwardly from said positioning means through said hole and into engagement with said reshaping means whereby said rivet may be clinched about said workpiece, said impacting means including a rivet engaging member, means for moving said rivet engaging member downwardly and drive means for imparting a non-linear rate of acceleration to said moving means whereby said rate is minimum for a time interval after engagement of said rivet and rivet engaging member and said rate is increased for a subsequent time interval when said rivet is engaged by said reshaping means.

References Cited in the file of this patent UNITED STATES PATENTS 2,056,559 Berliner Oct. 6, 1936 2,244,878 Havener June 10, 1941 2,925,748 Ross Feb. 23, 1960 FOREIGN PATENTS 499,555 Germany June 7, 1930 540,348 Great Britain Oct. 14, 1941 1,123,028 France Sept. 17, 1956

Claims (1)

1. IN A MACHINE FOR CLINCHING RIVETS ON A WORKPIECE, AN ANVIL ADAPTED TO RECEIVE AND RESHAPE THE BOTTOM OF A RIVET UNDER COMPRESSIVE FORCE, POCKET MEANS FOR RECEIVING AND SUPPORTING SAID RIVET IN VERTICAL ALIGNMENT WITH SAID ANVIL, MEANS FOR APPLYING A COMPRESSIVE FORCE TO SAID RIVET COMPRISING IMPACTING MEANS FOR ENGAGING THE HEAD OF SAID RIVET WHILE SUPPORTED IN AND IN FIXED RELATION TO SAID POCKET MEANS AND DRIVING IT DOWNWARDLY ONTO SAID ANVIL, MEANS INDEPENDENT OF SAID RIVET FOR RELEASING SAID RIVET FROM SAID POCKET MEANS SUBSEQUENT TO ENGAGEMENT OF SAID IMPACTING MEANS AND RIVET HEAD, AND MEANS FOR DELAYING THE DOWNWARD MOVEMENT OF SAID RIVET AND SAID IMPACTING MEANS RELATIVE TO SAID POCKET MEANS FOR A TIME INTERVAL AFTER ENGAGEMENT OF SAID IMPACTING MEANS AND SAID RIVET.

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