US2185939A - Method of and apparatus for upsetting hollow rivets - Google Patents

Description

Jan. 2, 1940. 3, w DESI-ION r AL 2,185,939

METHOD OF AND APPARATUS FOR UPSETTING HOLLOW RIVETS v Filed May 3, 1939 3 Sheets-Sheet 1 Jan. 2, 1940.

s. w. DESHON El AL METHOD OF AND APPARATUS FOR UPSETTING HOLLOW RIVETS Filed May 3, 1939 5 Shee tsSheet 3 Patented Jan. 2, 1940 UNITED STATES METHOD OF AND PATENT OFFICE APPARATUS FOR UPSET? TING HOLLOW RIVETS George W. Deshon, Amann. Vitry,

Flemington, sey

Borough of N. J., a corporation of New Jer- Application May 8, 1939, Serial No. 271,556 In Great Britain May 2, 1938 17 Claims. (01. 218-19) This invention relates to riveting and is particularly concerned with the problem of upsetting hollow rivets in situations where access to one end of a rivet is possible only through the rivet itself, as in closed hollow structures such as a container fabricated from sheet metal or the fuselage of an airplane so designed that a workman could not operate inside the shell thereof. Riveting under these conditions has been accomplished heretofore with riveting mandrels of the break-head type which requires a new mandrel for each rivet so upset and clenched.

To avoid the waste and nuisance incidental to the use of break-head mandrels the present invention provides improvements in riveting methods and riveting apparatus, in consequence of which a riveting mandrel may be used to upset a large number of hollow rivets through or into which it may be inserted to place it in an operative position.

A feature of the invention is embodied in a riveting mandrel of novel construction which, by the exercise of the force of leverage, is capable of acting against both ends of a rivet simultaneously in addition to acting against the internal surface of the hollow shank thereof. We conceive it to be a new principle in this art so to utilize the force of leverage of a single instrumentality to upset both ends of a hollow rivet simultaneously and at the same time to expand, if conditions permit, the intermediate shank portion of the rivet.

Another novel feature of the invention is embodied in a riveting apparatus including such a mandrel and mechanism so organized as to utilize centrifugal force to supply the leverage above mentioned and a gradually increasing angle of displacement of the mandrel as the rivet responds to the forces acting upon it.

The features above mentioned and others are hereinafter described and claimed and are illustrated in the accompanying drawings, in which Fig. l is a sectionalview of a hollow rivet closed at one end and extending through two lapped metal plates about to be connected by upsetting the rivet with the mandrel located therein and accupying its initial position;

Fig. 2 is a similar view representing an intermediate stage of upsetting the rivet;

Fig. 3 represents the same rivet in its final stage, both ends thereof having been upset by the mandrel to secure the metal plates tightly one against the other;

Figs. 4 and 5 are sectional views of another type of rivet before and after being upset and of the neck of the type shown in riveting operations herein illustrated and de-,

scribed;

Figs. 12 isa cross-section of the machine partly in the plane of line and partly in a lower plane; and Fig. 13 is a sectional view of the structure intersected by line XIIIX[]I of Fig. 11.

Referring to the assembly of work represented in Figs. 1, 2 and 3, the problem is to secure together two plates l0 and II of sheet metal with hollow rivets of the type shown. Assuming that the elements Ill and II are lapped margins of plates to be fabricated to construct a shell accessible only from the outside, they are held in the desired relation while are bored through both at once. The rivet shown in Figs. 1, 2 and 3 is made of comparatively soft ductile metal such as aluminum, the end I! thereof being closed and the opposite end being open and having a radially projecting surface flange l3 to be seated against the outer plate 10. The shank portion ll of the rivet is cylindrical. The mandrel best suited to upset and clench a rivet of this type comprises a cylindrical shank I5, an annular upsetting shoulder l6. an upsetting head l'! and a tapered neck I8 connecting the shoulder and thehead, the smaller end adjoining the head and the larger end of the neck adjoining the shoulder. Preferably the largest portion of the neck is the middle zone IQ of a sphere (defined by broken lines in Fig. 1) the diameter of which is preferably commensurate with that of the head IT, to the end that this spherical zone will have a circular bearing on the internal surface of the rivet and provide a suitable fulcrum on which the mandrel may rock under the force of leverage to displace the head I! radially away from the axis of the rivet as the upsetting operation progresses.

When the flange l3 of the rivet is seated against the outer plate It, the closed end I! of the rivet projects a considerable distance beyond XII-m of Fig. 11

rivet-receiving holesthe inner surface of the inner plate I I, and when the mandrel-is correctly located in-the rivet, the

faces of the plate l and the flange l3. Moreover, the head l'l thenprojects beyond the inner face of the plate II and nearly but not quite to the closed end I! of the rivet. Now,' with the mandrel standing initially in coaxial relation to the rivet, the force of leverage applied to the outer end of the mandrel will tilt the latter about the center of the spherical zone l9, thereby displacing the head is one direction away from the axis of the rivet and displacing the upsetting shoulder It in the opposite direction. It is to be assumed, of course, that the hole bored in the plates Ill and II to receive the rivet will be only large enough for that purpose and that the rivet itself will not be tipped by the force of leverage applied to the mandrel.

The riveting operation utilizes not only the force of i leverage above mentioned but also utilizes movement of the mandrel about the axis 20 of the rivet with the result that the mandrel executes a gyratory motion which produces a spinning action .of the head I1 against the inner end of the rivet and a corresponding spinning action of the shoulder it against the outer end thereof. Thus, the head I! and the shoulder l6 simultaneously upset two diametrically opposite segments of the rivet, one at each end thereof. and these segments are extended circumferentially with a common direction of progression about the axis of the rivet in consequence of the gyratory motion of the mandrel. During the early stages of upsetting (see Fig. 2), the annular shoulder i8 is not effective to upset the open end of the rivet because it is slightly smaller than the latter but the head IT has no corresponding clearance and therefore takes effect immediately to impart a bulbous formation to the closed end of the rivet, thereby initiating the clenching effect of the rivet to maintain the flange I3 firmly against the outer plate Hi.

When the upsetting has progressed to the stage represented in Fig. 2, the annular shoulder l6 begins to upset or swage the open end of the rivet with outward displacement of the metal thereof. and the head I! of the mandrel cont nues to upset the closed end of the rivet until finally the tapering portion of the neck I8 is brought a ainst the still cylindrical portion I 4 of the rivet as shown in Fig. 3. When this stage is reached. the angular displacement of the mandrel from the axis of the rivet is arrested and the riveting operation is completed, but while the mandrel is gyrating in the angular relation shown in Fi 3. the neck l8 thereof will expand the still cylindrical portion l 4 of the rivet enough to make it quite tight against the wall of the hole in the plates l0 and I l In addition to its gyratory motion about the axis 20 of the rivet. the mandrel may rotate about its individual axis 2|, and in so doing it rolls on the rivet without excessive friction and does not become excessively heated or excessively worn. Moreover, during the latter stages of upsetting, the shoulder l6 and the head I! exert components of force toward the plates to tighten the flange i3 against the outer plate Ill and to tighten the clenched portion of the rivet against the opposite face of the inner plate II.

To remove the mandrel from a clenched rivet it is only necessary to return the mandrel to coaxial alinement with the rivet and thereupon withdraw the head II from the latter. This may be accomplished by arresting the rotation or gymtory action of the mandrel. 1

In some circumstances, as in aircraft construction, it may be preferable to use countersunk rivets such as that indicated at ll in Figs. 4 and 5 6 to avoid projection of the rivets from the outer surface of the shell thus fabricated. Accordingly, when the holes are bored for the reception of such rivets. they willbe countersunk to receive countersunk flanges such as that indicated at 22 in Fig. 4. 10 This procedure will permit the open ends of the rivets to lie vm substantially flush relation with the outer surface of the outer plate l0. For operating on rivets of thistype, a mandrel such as that shown in Fig. -5 will be used. This mandrel has the same general characteristic as that shown in Figs. 1, 2 and 3 but its form and proportions are modified according to the form and proportions of the rivet to be upset and clenched thereby. Nevertheless, this type of mandrel also comprises an annular upsetting shoulder it, a head H, a tapering neck l8 and a spherical zone'la. The shoulder I6 is preferably frusto-conical, and even though the internal surface of the open end of the rivet is not initially countersunk, it will finally derive a countersunk formation from the action of the shoulder l6 as represented in Fig. 5. In all other respects the results produced by this type of mandrel correspond to those produced by the mandrel shown in Figs. 1, 2 and 3.

Having completed the riveting with rivets of the type shown in Figs. 4 and 5, the cavities in the rivets may be filled as shown in Fig. 6 to leave no openings in the outer surface of the fabricated structure. The countersunk formation imparted to the rivet by the upsetting shoulder l6- provides a seat for a correspondingly shaped flange 23 formed on a metallic plug 24 which is preferably provided at its opposite end with a retaining Y flange 21 of a diameter that will enable it to pass through the clenched rivet. Before inserting the plug 24, the cavity in the rivet will be partially filled with some suitable plastic retaining material 28 that will harden and provide firm anchorage for the plug which, of course, will be immediately pressed home. The plastic material 28 may be a compound of Celluloid, acetone and aluminum paint.

In situations where greater strength is required than that afforded by aluminum rivets alone, the plates to be riveted may first be'secured to each other by lining rivets open at both ends, and when these have been upset and clenched to provide the required strength in the connection of the metal plates l0 and II, they may be reinforced and closed with' supplemental rivets ll (Fig. 9) open at one end and closed at the opposite end. This double riveting procedure is illustrated in Figs. '7, 8, 9 and 10 inwhich a relatively thin lining rivet 25 of stainless steel or 0 other comparatively hard metal is used first to connect the plates Ill and II and to provide greater strength than that afforded by rivets made of aluminum. The rivet 25 is initially provided with a flange 26 to be seated against the plate l0, and since a supplemental rivet is to be secured inside this" lining rivet, the latter is left open at both ends. The mandrel shown in Figs.

7 and 8 is designed to operate according to the same principles as that shown in Figs. 1, 2 and 3 but it differs therefrom in the form and proportions of its characteristic formations which include a frusto-conical upsetting shoulder IS, an upsetting head I'I a tapering neck It and a spherical zone I9 Moreover, the same prin- I spondingly curved tongue ciples of'operation heretofore described with reference to the mandrels shown in other figures are applicable to the mandrel shown in Fig. 'l to upset and clench the rivet 25 with the result shown in Fig. 8.

When a rivet of this type the opening therein may rivet M of softer metal 9) and operating on the latter with still another mandrel of corresponding size and proportions comprising a frusto-conical shoulder I6, a head |1, a tapering neck l8 and a spherical zone |9 at the larger end of the neck and adjoining the shoulder |6. A mandrel of this type will upset and clench the rivet H with the results pictured in Fig. 10.

It is, of course, possible to accomplish theseveral riveting operations hereinbefore described by operating the corresponding mandrels manually as by rolling them around the rivets with a gyratory motion while exerting a pressure laterally against their outer ends to apply the force of leverage by which the upsetting of the rivets. is'efiected. Nevertheless, speed of production calls for power-driven mechanism to operate the mandrels, and to this end the invention provides a portable mechanism adapted to be supported manually against the work to be riveted and adapted to utilize high speed of rotation of a power-driven member to operate ariveting mandrel and to apply the above-described force of leverage to the mandrel in consequence of centrifugal force developed by such rotation. A riv'eting apparatus constructed in accordance with these principles is shown in Figs. 11, 12 and 13.

This apparatus comprises a rigid frame including two parallel. bars 30, 30, a nose-piece 3| connecting them, and one or more cross-bars such as that indicated at 32. The bar's 30, are provided with gripsbr handles 33. The noseplece 3| is provided with a contact plate or disk 34 having a central hole 35 through which the mandrel projects, as shown in Figs. 1, 2 and 3, the outer face of this disk being counterbored to receive the flange of the rivet and to provide a shoulder by which the flange of the rivet may be pressed against the work to be riveted. The cavity thus formed in the disk 34 serves to centralize the nose-piece 3| and the rivet, and also serves to locate the center of the spherical zone ofthemandrel at th ends of therivet. r

A rotary operating member to be driven at high speed by. a power-shaft is journaled in a bearing 36-and comprises a'stem or a shaft portion 31, an arcuate head 38 formed thereon and two diametrically opposite lugs 39 formed on the head. The bearing 36 is mounted in the crossbar 32 to maintain the stem 31 midway between the bars 30, 30 and in coaxial relation to the rivet-receiving hole 35 in the contact plate 34. The stem 31 extends through an ax ally movable bearing member 40 located between the crossbar 32 and the head 38, this movable bearing member having grooves engaging the bars 30, 30 by which it is guided to and fro along the stem. The purpose of this to-and-fro movement of the bearing member is hereinafter explained.

The head 38 of the rotary member is provided with arcuate grooves 4|, 4| in opposite faces (Fig. 13) and these grooves are occupied by correportions '42, 42 formed on confronting. cheeks of a mandrel-carrier 43.

To balance the rotary assemblage so. that it has been clenched. be closed by inserting a such as aluminum (Fig.

' prising occupies its initial desired point between the I the counterweight toward may rotate at high speed without excessive vibration, the head 38 also carries a counterweight 44 which is. also provided with tongues similar to the tongues 42 and these tongues are also "arranged in the grooves 4|.

Referring to Fig. 3, the'mandrel-carrier 43 is red and threaded to receive a threaded bushing "which provides a bearing for the shank of a riveting mandrel. The rear end of the mandrehis provided with a head '46 and the bushing 45 is counterbored to provide a socket for this head and is also internally threaded to receive a screwplug 41 which serves as a thrust bearing for the mandrel and maintains the latter against endshake. When the parts are assembled,'the center of the spherical zone' IQ of the mandrel lies on the axis of the rotary operating member comthe stem 31 and the head 38. Moreover, the axis ofcurvature of the arcuate grooves 4| intersects the axis member in coincidence with the center of the spherical zone of the mandrel. Consequently, the axis of the mandrel may'coincide with the axis of the stem 31 when the'mandrel-carrier position (Fig. 1), but when the mandrel is tilted with respect to the stem 31, its axis intersects that of the stem at the point where the center of the spherical zone of the mandrel lies.

The mandrel-carrier 43 and thecounterweight the movable bearing member 40 is utilized. to equalize their movements, to the end that the rotary mass will remain in balance at all stages of operation. Accordingly, an endless circumferential groove is formed in the bearing member. 40 and is occupied by diametrically opposite antifriction rolls 5| each carried by a pair of bellcrank levers 52. These pairs of bell-crank levers flank the lugs 39 formed on the head 38 and are pressed tightly "on pivot-pins 53 that extend through the lugs and have bearings therein. The tips 54 of one pair engage notches 55 in the mandrel-carrier, and the tips of the other pair engage similar notches 56 in the counterweight 44.

When the parts are at rest tension springs 51 normally pull the bearing member 40 to the position represented in broken lines in Fig. 11, thereby alining the axis of the mandrel with that of the stem 31, but when the stem is rotated at high speed, as by the shaft 60 of an electric motor, centrifugal force shifts the mandrel-carrier and the ends of the grooves 4|. This force is superior to the opposing force of the springs 51, and the bearing member'40 is ultimately carried by it to the position represented in full lines in Fig. 11.

Since the grooves 4| are curved to produce angular movement of the mandrel the force, of leverage is developed to upset and clench the rivets. The several factors involved in the operation of this riveting apparatus are brought about as follows: Rotation of the stem 31 produces centrifugal force; this force, acting on the mandrelcarrier and on the counterweight, is converted into the force of leverage by the curvature of the grooves 4| and applied as such to the mandrel to upset the rivet; the same rotation that generates the centrifugal force to displace the rivet metal radially also produces circumferential progression of the upsetting action about the axis of the rivet; and while all these factors are taking eifect the mandrel rotates about its individual axis as it rolls on the rivet. When the driving force is discontinued the mandrel will automatically reof the rotary operating 20 44 are movable toward and from each other, and

same time imparting a turn to its initial position in coaxial relation to the stem 31 and may be readily withdrawn from a clenched rivet.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. That improvement in methods of upsetting and clenching hollow rivets of circular cross-section which consists in simultaneously upsetting two diametrically opposite segments of a rivet, one at each end thereof, and extending the circumferential range of such upsetting in bothof said segments simultaneously with a common direction of progression about the axis of the rivet.

2. The improved method defined in claiml supplemented by expanding the shank portionof the rivet while the ends of the rivet are being upset as specified.

3. The improved method defined in claim 1 supplemented 'by against the upset segments respectively in opposite directions to press them progressively against opposite faces of the work asthe upsetting of the segments progresses circumferentially.

4. That improvement in methods of securing rivets in sheet material which consists in executing the method defined in claim 1 first with a rivet open at both ends and thereafter with a ,rivet closed at one end and extending through the rivet first secured.

5. That improvement in methods of riveting sheet material which consists in executing the method defined in claim 1 first with a rivet of relatively hard and thin metal open at both ends, and thereafter with a rivet of relatively soft and thick metal closed at one end and extending through the rivet first secured.

6. That improvement in methods and clenching hollow rivets of circular crosssection which consists in inserting a mandrel of circular cross-section into a rivet far enough to place its tip beyond the plane of the work to be riveted, tilting the mandrel against diametrically opposite segments of the rivet and at the gyratory motion to the mandrel with movement about the axis of the rivet.

'7. A riveting mandrel having an annular upsetting shoulder, an upsetting head and a tapered I neck connecting them, the smaller end of'said neck adjoining said head and the largest diameter of said neck being as large as said head.

8. A riveting mandrel as'defined in claim '7 in which the portion of largest diameter of said.

neck is-a spherical zone adjoining said shoulder.

9. A riveting mandrel as defined in claim '7 in which said upsetting shoulder is tapered and flares outwardly from the larger end of said neck.

10. A riveting machine comprising a frame structure, a rotary memberjoumaled therein, power-driven means by which said member may be rotated at high speed, a mandrel-carrier, and a. riveting mandrel journaled in said carrier to turn about its individual axis, said mandrel-carrier being carried by said rotary member with which it iscoupled by arcuate tongue-and-groove connections that constrain the mandrel and its carrier to tilt about a point on the axis of said rotary member and on the individual axis of said mandrel in the rivet-engaging portion of the latter.

11. A riveting machine as defined in claim 10 in which said tongue-and-groove connections are arranged ,to permit said mandrel to take one applying components of force of upsetting position in which its individual axis coincides with that of said rotary member.

12. A riveting machineas defined in claim 10 in which said mandrel-carrier is so weighted as to tilt the axis of said mandrel away from alinement with the axis of said rotary member under rotary member also having tongue-and-groova connections, and means by which said mandrel- .carrier and said counterweight are constrained to move toward and from each other with equal increments of travel to maintain centrifugal balance of the load they impose upon said rotary member.

\ 14. A riveting machine as defined in claim 10 comprising'alsoa work-engaging plate afiixed to said frame and having ahole through and beyond which the-rivet-engaging portion of said mandrel projects.

15. A riveting machine as defined in claim 10 comprising also a workengaging plate affixed to said frame and having a hole in concentric relation to the axis of said rotary member, the wall of said hole being formed to surround and engage the fiange of a rivet to maintain centered relation of the riveting machine and thework.

16. A riveting machine comprising a frame structure, a rotary member journaled therein, power-driven means by which said member may be rotated at high speed, a mandrel-carrierand a counterweight both carried by said rotary member, a. riveting mandrel journaled in said mandrel-carrier to turn about its individual axis, said mandrel-carrier and said counterweight having arcuate tongue-and-groove connections with said rotary member that. constrain them to angular movement about a point at once on the axis of said rotarymember and on the individual axis of said mandrel in the rivet-engaging portion thereof, means by which said rivet-carrier and said counterweight are constrained to move toward and from each other with equal increments of travel to maintain centrifugal balance of the load they impose upon said rotary member, and resilient means arranged toplace said mandrel in coaxial relation to said rotary member in the absence of centrifugal force in opposition thereto. 1'7. A riveting machine comprising a frame structure, a rotary shaft journaled therein, a bearing member engaging said shaft, movable lengthwise thereof and, guided by said frame structure, power-driven means by which said shaft may be rotated at high speed, a mandrelcarrier and a counterweight both carried by said shaft and arranged to maintain balance of centrifugal force due to rotation of said shaft, said shaft having arcuate tongue-and-groove connections with said mandrel-carrier and said counterweight by which both of the latter are constrained to move about a transverse axis intersecting the axis of said shaft, means including said movable bearing member by which the movements of saidmandrel-carrier and said counterweight about said transverse axis are equalized, and a riveting mandrel held by said mandrel-carrier and intersected by both of said axes.

GEORGE W. DESI-ION. PAUL EMILE MARIE AMANN.

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