US3376727A - Rivet setting device - Google Patents

Description

April 9, 1968 M. HINDEN 3,376,727

RIVET SETTING DEVICE Filed Oct. 8, 1965 2 Sheets-Sheet l United States Patent Office 3,376,727 RIVET SETTING DEVICE Milton Hinden, 15 Bay Link, Massapequa, NY. 11758 Filed Oct. 8, 1965, Ser. No. 494,055 Claims. (Cl. 72-391) ABSTRACT OF THE DISCLOSURE A tool for setting blind rivets and particularly blind rivets having smooth, cylindrical mandrel shanks, comprising moving and fixed handles, a chuck, including a cam surface, mounted on the movable handle, a tooth spaced from and directed toward said cam surface and a pair of side-by-side jaw members having follower surfaces engaging said cam surface, and a spring pressing said jaws against said cam surface, the latter camming the jaws toward said tooth, the device being characterized by said jaws being free to move laterally apart to a canted, spread relation when a gripping force is applied by said jaws against a mandrel.

This invention relates to a rivet setting device, and more particularly to an improved rivet setting tool of the type used to exert a drawing or pulling force on the mandrel portions of blind rivets to create an upsetting force on the shank of such rivets.

More particularly, this invention relates to an improved rivet setting device and chuck assembly therefor for pulling the frangible mandrels employed in setting such devices.

It is known to employ blind rivets as a means, for instance, for holding sheet metal pieces together, such rivets being most commonly used where access to one side only of metal sheets to be fastened is available. As is well known, such rivets include a tubular assembly, with a stop shoulder on one side. A frangible mandrel is inserted through the tubular member projecting outwardly beyond the shoulder portion. The reduced shank of the rivet is directed through the sheets to be fastened and a pulling force is exerted on the mandrel. The mandrel includes a large head which upsets the shank portion of the rivet, and when the desired end position is reached, the increased pulling force on the mandrel fractures the mandrel at a point adjacent the enlarged head.'

Numerous tools for effecting the pulling force on the mandrel have been'proposed. Industrially, several tools employing radially shiftable mandrel clam-ping jaws have enjoyed considerable commercial success. However, it has been diflicult to adapt these tools to the home market since they are too expensive to manufacture.

Less expensive tools specifically designed for home use have been devised but each such tool heretofore known has embodied drawbacks which detract from their utility. Typically, such tools employ as a chuck component, a movable member having a single jaw cammed to clamp the rivet mandrel when the handles of the setting tool are squeezed together. In all such devices there has been a high incidence of fracture of the mandrel at a point other than directly adjacent the head, as is desired. As a result, devices have been designed for use with mandrels provided with indentations, the setting tool being provided with complemental. indentations to augment the pulling force without necessitating great gripping pressures against the mandrel. While such devices have, in a measure, been successful, they are in many cases unsuitable for applications where high strength is required, and the cost of producing the indented mandrel members greatly exceeds the cost of producing smooth mandrels. Thus, while a relatively inexpensive tool is feasible for use with such 3,375,727 Patented Apr. 9, 1968 indented mandrels, the cost of the rivet members is high.

With the foregoing in mind, it is an object of this invention to provide an inexpensive rivet setting tool of the type described which may be used with smooth rivet setting mandrels.

A further object of the invention is to provide such a device wherein the likelihood of fracture of the mandrel at any point remote from the upsetting head is unlikely.

To attain these objects and such further objects as may appear herein or be hereinafter pointed out, I make reference to the accompanying drawings, forming a part hereof, in which:

FIGURE 1 is a perspective view of a blind rivet setting tool of the type described, and a rivet for use therewith;

FIGURE 2 is a perspective view of the rivet gripper jaws of the device;

FIGURE 3 is a magnified line 33 of FIGURE 1;

FIGURE 4 is a view similar to FIGURE 3, showing the position of the parts after the rivet has been finally set;

FIGURE 5 is a magnified line 5-5 of FIGURE 3;

FIGURE 6 is a magnified line 6-6 of FIGURE 4;

FIGURE 7 is a horizontal section taken on line 77 of FIGURE 4.

In accordance with the invention, there is provided a rivet setting tool 10 including a stationary handle 11 and a movable handle 12. The stationary handle 11 includes a rearwardly extending, hollowed out portion or slideway 13 into which the chuck assembly, which is carried by the movable handle 12, is shiftably mounted.

At the forward end 14 of the stationary handle portion, there is disposed a rivet guide 15 having a central axial aperture 16. The movable handle 12 is pivotally mounted to the fixed handle 11 by a pivot pin 17, the jaws being normally maintained in spread condition by the spreader spring 18 interposed between the jaws.

A chuck mounting pin 19 is fixed to the movable handle 12 adjacent the upper end thereof, a hollow chuck housing 20- being pivotally mounted on said pin by passage of the pin through an aperture 21 formed adjacent the rear end of the housing.

The hollow housing 20 includes an upper wall portion 22 having a downwardly directed retainer tooth portion vertical section taken on the vertical section taken on the vertical section taken on the 23, the lower part of said hollow housing being provided with an inclined cam surface 24. The forward end 25 of the chuck housing is provided with a cylindrical aperture 26 through which the rearwardly directed cylindrical portion 27 of the mandrel guide 15 may slidably pass.

The chuck assembly includes a pair of mandrel gripper jaws 28, 28', see FIGURE 2, each of which is provided with a lower surface 29 defining a follower portion engaged with the cam surface 24. of the jaws 28, 28 is provided with gripper portions 30, 30', having serrations or toothed projections directed toward the tooth 23 in the housing 20.

The tooth portions on the surfaces 30, 30 include forwardly inclined edges and rearward, upwardly directed portions, the surfaces meeting in a sharpened apex, the portions 30, 30 being thereby permitted, on the forward or regripping stroke of the housing, to be cleared from the mandrel, the abrupt rear surface of the teeth assuring that there will be no slippage when a pulling force is exerted against the shank of a mandrel.

The rearmost faces 31, 31' of the jaws 28, 28 respectively, include rearwardly directed studs 32, 32, the said studs, in the side-by-side position of the jaw, preferably defining a single cylindrical member, the studs thus The upper surface of each d being essentially half cylinders with their fiat sides in side-by-side abutting position.

The housing 20, at a rearward portion, is provided with a downwardly directed spring seat 33 in the form of a post. A coil spring 34 has a rearward end looped over the post 33, the forward end of convolution 35 of the spring surrounding the rearwardly directed studs 32, 32' of the jaws 28, 28.

It will be observed that by the arrangement aforesaid, the spring 34 locates the jaws in side-by-side orientation but, nonetheless, permits a range of transverse relative movement between the jaws. Additionally, the spring 34 presses the jaws 28, 28' forwardly so that in the spread condition of the handles, as shown in FIGURE 3, the nose portions 36, 36 of the jaws engage against the rearmost portion of the mandrel guide extension 27.

As will be seen in FIGURE 3, the engagement aforesaid limits the forward movement of the jaws over the cam surface 24 and, thus, limits the transverse approach of the jaws toward the tooth 23. In this position, it will be seen that the shank 49 of the mandrel 41 can pass through the aperture 16 in the mandrel guide and into the interior of the chuck housing witout interference from the jaws 28, 28'.

In the use of the device, the mandrel 41, mounted inside the rivet device 42 in the usual manner, is inserted into the interior .of the chuck, the shank 40 of the mandrel being directed as far rearwardly as possible so that the stop portion 43 of the rivet abuts the nose of the mandrel guide 15. The head portion 44 of the mandrel is thus positioned against the forward end of the rivet shank, in the usual manner.

With the parts thus positioned, the mandrel head and the shank of the rivet may be passed through the aligned aperatures A, A defined in the sheet metal or other components S, S to be secured together. With the elements thus disposed, a squeezing force is exerted on the movable handle 12, causing it to shift against the tension of spring 18 from the spread to the parallel position of the handles, as shown in FIGURE 4.

It will be observed that in the initial closing movements of the handles, the chuck 20 is drawn rearwardly and, thus, the nose portions 36, 36 of the jaws are cleared from engagement with the rearward face of the mandrel extension 27. With the nose portions of the jaws thus cleared from the extension, the spring 34 is free to expand and slide the jaws forwardly, sliding the follower surfaces 29 of the jaws forwardly over the cam surface 24 of the chuck housing. This forward movement is accomplished by a transverse movement of the jaws toward the tooth 23, thus firmly clamping the mandrel shank between the gripper portions of the jaws and the tooth.

It will be understood that a further rearward movement .of the housing will be accompanied by an augmented camming action against the jaws, with the result that the gripper portions of the jaws become firmly and deeply embedded in the shank of the mandrel, to provide a firm grip.

It is an important feature of my invention that the jaws 28, 28' be independently laterally movable one with respect to the other, in the course of application of the tightening tension. This relationship is illustrated best in a comparison of FIGURES 5 and 6. In FIGURE 5, the jaws are shown in their opened condition wherein the insertion of a mandrel shank is permitted. In FIGURE 6, the jaws are shown in tightened condition against the mandrel shank. By reason of the relatively movable relationship of the jaws, and the rounded under-surface of the mandrel shank, the jaws are cammed open upon the application of pressure against the shank and thus, in practice, do not grip the shank at adjacent or abutting portions but, rather, the gripping force is exerted on spaced parts of the shank. Otherwise stated, although the jaws are initially in abutting position, there is a surface area of the mandrel shank interposed between the jaws when the latter are in gripping position which is free from engagement with said jaws.

I have discovered that under the stresses which inhere in setting a rivet of this type, the use of a single, solid jaw identical in all other respects to the two jaws 28, 28 will result in a large percentage of fractures .of the mandrel shank at portions remote from the junction of the head and shank of the mandrel, at which latter point such fracture is intended. I have discovered that the provision of separate jaws which may initially engage the mandrel shank in abutting position but which will be subsequently cammed apart, completely eliminates undesired or premature fracture at points other than the junction of the shank and head of the mandrel.

While I am unaware of the reasons why a two part jaw structure can effect the desired pulling force without fracture medially of the shank whereas a single part jaw cannot, repeated tests show the two part jaw structure to be comparable in effectiveness to industrial types of rivet setting devices employing expensive radially cammed chuck structures.

Without limitation thereto, it may be theorized that the tendency of the jaw members to spread apart and thus provide an interruption in the indentations defined by the individual jaw members does not detract from the structural strength of the mandrel at the jaw engaging portions thereof. A single jaw making an indentation may be said possibly to weaken the structural strength of the shank to a degree which is conducive to a premature rupture or fracture of the shank. I have found this to be true, notwithstanding that the total indentations .or depressions formed in the shank, i.e. the total amount of metal of the shank displaced by the gripping force exerted by the jaws, is the same as or even greater where a split jaw structure is employed.

A further factor in the improved performance of the split jaw device lies in the tendency, upon the application of gripping and regripping pressures of the split jaw device, to induce slight increments of rotation of the rivet shank. Specifically, in the tightening stroke, one of the two jaws may initially contact the mandrel slightly before the other, which contact causes a rotation of a few degrees of the mandrel. This rotation may well be a contributing factor in the improved performance of the split jaw device, which may be the result of the fact that regripping cannot occur in the indentations formed by a prior gripping stroke due to the partial rotation.

In the solid jaw device, no rotation of the mandrel shank occurs and, therefore, it is not unlikely that regrippin-g in the prior stressed indentations formed by an earlier pulling stroke may occur.

From the foregoing, it will be readily understood that the device operates, in general, in the same manner as known devices of this type, namely, repeated opening and closing stroke of the handle cause a progressive overturning of the shank portion of the rivet 42 from the cylindrical shape shown in FIGURE 3 to the upset condition shown in FIGURE 4. When the head of the mandrel reaches substantially the position of the rearmost metal sheet S, forward movement of the mandrel head is stopped and a tensioning force sufiiciently great to fracture the mandrel at the weakened area between the head and the shank is developed.

From the foregoing it will be apparent that the device of the present invention is a highly improved, inexpensive blind rivet tool. Great forces may be exerted by the tool against the mandrel shank without fear .of premature rupture of the said shank. Large savings are, therefore, etfected in economy of time and materials, and proper setting is assured.

Having thus described the invention and illustrated its use, what is claimed as new and desired to be secured by Letters Patent is:

1. A tool for setting fasteners of the blind rivet type by exerting a pulling force on the smooth mandrel shank of said rivet, comprising a movable handle and a stationary handle pivotally mounted thereto, a slideway formed in said stationary handle, a mandrel guide carried by said stationary handle and extending into said slideway, a chuck member pivotally mounted on said movable handle and movable toward and away from said guide responsive to opening and closing movements, respectively, of said handles, said chuck including a cam surface, a tooth portion spaced from and directed toward said cam surface, and a pair of side-by-side jaw members having follower surfaces engaging said cam surface, spring means biased against said jaw members to urge said members forwardly toward said guide and, under the camming influence of said surface, transversely toward said tooth, said jaws being free to move laterally apart to a canted relation one to the other whereby, when a gripping force is exerted by said jaws against a mandrel, the gripping portions of said jaws shift from an initial side-by-side relation to a spaced-apart relation.

2. A tool for setting fasteners of the blind rivet type employing a smooth, cylindrical setting mandrel, comprising a fixed handle having a recess for receiving the free end of a mandrel, a transversely directed tooth extending into said recess, a cam surface in said recess inclined toward said tooth, a pair of side-by-side disposed gripper jaws in said recess, said jaws each including a follower surface engaging said cam surfaces, a stop nose portion, and a gripper surface, spring means biased against said jaws and urging said jaws forwardly, thereby to shift said jaws transversely toward said tooth by the coaction of the cam and follower surfaces, said jaws being angularly movable one with respect to the other whereby, when a cylindrical mandrel is interposed between said tooth and said gripper surface and a pulling pressure is applied by said handle, said gripper surfaces are spread from an initial abutting position to a spaced apart condition.

3. A device in accordance with claim 2 wherein said jaws include rearwardly directed stud portions and said spring means comprise a coil spring, the forward convolutes of said spring being sleeved over said stud portions.

4. A tool for setting blind rivets of the smooth mandrel type, comprising a stationary handle having a slideway, a mandrel guide on the forward face of said handle and extending into said slideway, a movable handle pivotally mounted to said stationary handle and having a chuck assembly extending into said slideway, said assembly including a pair of side-by-side disposed jaws having gripper surfaces, spring means urging said jaws forwardly to gripping position of a mandrel inserted into said slideway through said guide, said jaws being independently transversely movable to spread condition upon exertion of a pulling force on a mandrel shank, thereby to shift from initial side-by-side engaging position to a spaced apart spread condition of said gripper surfaces upon application of said pulling force.

5. A device in accordance with claim 4 wherein said jaws include rearwardly directed stud portions and said spring means comprise a coil spring, the forward convolutes of said spring being sleeved over said stud portions, the spring including rearward convolutions biased against said chuck.

References Cited UNITED STATES PATENTS 3,003,657 10/1961 Siebol 72-391 3,048,296 8/1962 Heidenwolf a- 72391 3,280,615 10/1966 Molitor 72391 CHARLES W. LANHAM, Primary Examiner. C. P. CROSBY, Assistant Examiner.

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