US2224993A - Method of and apparatus for removing burrs from metallic fasteners - Google Patents

Description

1940- w. E. SWIFT ETAL 2,224,993

METHOD OF AND APPARATUS FOR REMOVING BURRS FROM METALLIC FASTENERS Filed May 25, 1938 2 Sheets-Sheet 1 in mm .322.

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METHOD OF AND APPARATUS FOR REMOVING BURRS FROM METALLIC FASTENERS Filed May 25, 1938 2 Sheets-Sheet 2 lllllllI-lllii IIIIIIIIII .zfcgrja 4e- 46 l "@25- 11. f j

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Patented Dec. 17, 1940 PATENT OFFICE T Q METHOD or AND APPARATUS Fort RE- MOVING BURKS FROM METALLIC FAS- TENEBS' Willard E. Swift and George A. Anderson, Worcester, Mass, assignors to United States Envelope Maine 7 Claims. The present invention relates to metallic fasteners of the type providing projecting tongues necessary to use the fingers and it has been found that the existence of burrsor rough edgeson the tongues is liable to cause finger injuries to persons handling large numbers of envelopes.

. The object of the present invention is to provide an improved method of and apparatus for removing burrs or rough edges from the bendable tongues of metallic fasteners, so that these tongues can always be bent by the fingers without any possibility of injury. In carrying out the invention, the bendable tongues of metallic fasteners are subjected to a compressing action which forms rounded corners where. there previously existed burrs, or edge roughness, resulting from initial punching of the tongues from sheet material. The invention further contemplates lateral deflection of the tongues, simultaneously with the burr removal, so that the tongues will be offset from the plane of theenvelope wall when :attached thereto, in order to facilitate initial bending of the tongue. The above and other advantageous features of the invention will hereinafter more fully appear from the following description considered in connection with the accompanying drawings in which:

.. Fig. 1 is a plan view of a metallic fastener.

Fig. 2 is an enlarged sectional view along the line 22.of Fig. 1. a

Fig. 3 is a plan view of a die for receiving the tongues of the fastener shown in Fig. 1.

- Fig. 4 is a sectional view of the die of Fig. 3

with a cooperating punch, shown in elevation.

Figs. 5 and 6 are sectional views, on an enlarged scale, illustrating the removal of burrs from the fastener tongues.

' Fig. 7 is an edge view of a completed fastener.

Fig.8 shows the fastener of Fig. '7 applied to an F s. 11 and 12 .are'diagrammatic, views il Company, Springfield, Mass, :a corporation of 2 Application May 25, 1938, Serial No. 209,900 I 29-13 1' i. I lustrating the removal of burrs from fastener tongues, as initially formedin strip material. 3

Fig. 13 is'afr'agmentary view, showing the burr-- removing mechanism of Fig. 10 on an enlarged scale.

' Like reference characters refer to like parts in the different figures.

Referring first to Fig. l, the invention is shown,- for purposes of illustration, as applied to a fastener of the type disclosed in Swift Patent No. 1,593,048, issued July 20, 1926, although, as will hereinafter appear, the invention can be practiced in connection with other forms of fasteners of thisisame general construction. Such a fastener comprises a base l provided at its four corners with bent-over attaching prongs 2 for piercing the back wall of an envelope preparatory to being clinched on the under side of the wall, in a manner well known in the art. A pair of flat bendable tongues 3 extend laterally from the central portion of the base I, and with the fastener attached to an envelope, upward bendingof the tongues 3 brings them into registry with a'holeprovided inthe seal flap of an envelope,- as indicated in dotted lines in Fig. 8. After such registration, the tongues 3 are bent back into horizontal position to retain the flap closed.

Heretofore fasteners of the type shown inFig. l-have-usually been'blanked out'from strip materialby means of a suitable punch and-die, with the prongs 2 lying fiat, as indicated in dotted lines. The edges of the punched tongues '3 on the punch side of a blank will often be so rough as to provide appreciable burrs, indicated at 3a in the'enlarged sectional showing of Fig. 2, due to'the molecular flowage of metal around the edges of the blanking punch. The presence of such roughness or burrs 3a. therefore results in cutting or scratching the fingers of a person; such asa mailing clerk, who may be called upon to bendthe tongues of a large number of envelopes, and there will next be described a method and apparatus for eliminating such burrs from thebendable tongues of metallic fasteners.

As best shown in Figs. 3 and 4, a die 4 is provided which is formed with depressions 5'each having an outline substantially conforming to the tongues 3 of a fastener. The outer portions 5a of the depressions 5 lie in a common'plane, offset from a common plane in which lie the inner portions 5b. The portions 5a and 5b are joined by an inclined portion 50, and the central portion of the die is cut away at 6. The die 4 is rigidly mounted on a block 1, and-a plunger 8 slidable in the block I provides a set of alining pins 9 freely movable through openings I extending through the die 4. The pins 9 and the openings I are so arranged that when a fastener of the type shown in Fig. 1 is placed over the die 4, movement of the pins 9 into the -corners between the prongs 2 and tongues 3 will serve to accurately register the tongues 3 with the die depressions 5.

With the tongues 3 of a fastener thus registered with the die depressions 5, it is evident from Fig. 5 that the rough edges or burrs 3a of a tongue will face towards the bottom of a depression. Furthermore, the sides 5d of a depression 5 are slightly inclined outwardly and join the bottom of the depression with a curvature that is substantially the same as the curvature of the smooth edges of a tongue 3 opposite the burrs 3a. It is also to be noted that the average width of a die depression 5 between the inclined sides 5d is substantially the same as the width of a fastener tongue 3, so that a. tongue may readily enter a die depression 5 where it is widest.

After the tongues 3 of a fastener have been positioned in registry with the die depressions 5, a punch II is brought to bear on the fastener and then moved to force the tongues 3 into the depressions 5. As this occurs, the burred edges of each tongue engage the inclined sides 5d of a die depression before the tongue is entirely forced into the depression, as indicated in dotted lines in Fig. 5. Consequently, as the punch II moves, to force the tongues completely into the die depressions,v there occurs a compression along the rough or burred edges of both tongues. The effect of this compression is shown in Fig. 6, from which it is evident that the burrs 3a have been entirely eliminated, and that the compressed tongues 3 possess smooth rounded edges on both sides.

The forcing of the fastener tongues 3 into the portions 5a and 5b of the depressions 5, as described above, also has the effect of laterally deforming the tongues, so that their extremities are in a common plane offset from the plane of the central base portion I of the fastener which does not undergo any compression by the punch H, due to the fact that the die is cut away-at 6. Consequently, the tongues 3 are entirely free to conform to the shape of the depressions 5, which results in removal of the burrs or edge roughness and in offsetting the extremities of the tongues with respect to the remainder of the fastener.

A fastener is shown in Fig. 7 as it appears after being operated upon by the cooperating punch I I and die 4, from which it is evident that the attaching prongs 2 project oppositely with respect to the offset ends of the tongues 3. Consequently, when the fastener is attached to the rear wall I2 of an envelope by clinching over the prongs 2, the extremities of the tongues 3 are appreciably displaced from the outer surface of the envelope wall !2. Therefore, the prongs 3 may be readily seized by the fingers in order to bend them upwardly into the dotted line position preparatory to inserting the bent prongs into an opening provided by the seal flap of the envelope. Obviously such bending of the tongues 3 can be accomplished, as desired, without possibility of injuring the fingers, due to the previous removal of all rough edges from the tongues as a result of the compressing operation.

Referring-now to Fig. 9, there is indicated diagrammatically the functioning of a punch and die for compressing the tongues of metallic fasteners while the fasteners are still in flat blank form. In this arrangement, a metal strip I3 is operated upon by a punch I4 which serves to punch fiat blanks from the strip I3, with the burred edges of the tongues 3 uppermost. The flat blanks are then moved by a. suitable conveyor I5 into registry with the depressions 5 of a die 4 mounted above the conveyor. The tongues 3 are then operated upon by the punch II and die 4 which serve to compress the tongues and remove all burrs or roughness from the edges thereof. The blanks are then delivered to a suitable container I5 in which they are stacked in flat form. The blanks in the container I6 can be handled as a unit and utilized by any suitable fastener attaching mechanism.

In Fig. 10 there. is shown an arrangement wherein a magazine I? is provided containing a stack of flat fastener blanks just as they are punched from strip material. These fastener blanks are adapted to be removed one by one from the magazine I l by a device which also. serves to bend the prongs 2 in advance of delivery of the blanks to a chute I 8. A suitable mechanism for removing the blanks from the magazine I1 and bending the prongs thereon is fully shown and described in Patent No. 1,993,059, dated March 5, 1935, and for the purposes of the present application only certain essential parts of this mechanism will be next described, in order to set forth its cooperation with apparatus for removing burrs from the fastener tongues 3 in advance of the application of a fastener to an envelope.

The fastener blank magazine. I1 comprises. spaced uprights I9, each providing a longitudinal slot for receiving the oppositely extending tongues 3 of the fastener blanks. The distance between the uprights I9 is such as to freely receive the flat prongs projecting from the body I of the blanks and so maintain the blanks in alinement with the magazine while permitting vertical movement of the blanks in the stack as they are removed one by one. The base of the magazine I! provides a horizontally movable anvil which is adapted toreceive a reciprocatory motion from a lever 26 operated by a cam 22 mounted on a shaft 23 to which is imparted an intermittent rotative movement.

The anvil 20 provides a seat substantially equal to the thickness of a blank in the magazine I'I, so that when the anvil is moved forwardly by the cam 22, a blank will be separated from the stack and carried into the prong bending position. With a blank positioned on the anvil. 20, the oppositely projecting pairs of flat prongs 2 extend beneath a pair of benders 2 slidably mounted to move parallel to the sides of the anvil 20. The benders 24- are adapted to be reciprocated in unison. by mechanism fully described in the aforesaid Patent No. 1,993,059, this mechanism being actuated from a cam 25 mounted on. the shaft 23. The relation between the cams 22 and 25 is such that, following movement of the anvil 2G to remove a fastener blank from the magazine H, the benders 24 will move downwardly in unison to engage the flat prongs on opposite sides of the tongues 3 and bend them downwardly, without disturbing the tongues 3.

Upon withdrawal of the anvil 20 following bending of the prongs 2, the fastener is stripped from the anvil and falls into the delivery chute I8 through which it passes to mechanism for removing the burrs from the prongs 3. In this mechanism "a die 4, ofthe character previously described; is mounted vertically on a block I and. a plunger 8 slidable in the block 1 provides horizontally disposed alining pins 9 freely movable through openings in the die 4, as best shown in Fig. 13. The plunger 8 is connected by 'a' yieldable link 25 to a fork 21 embracing a shaft 28 driven from the shaft 23. A roll 29 mounted on thefork 2! bears on a cam 30 turnable with the shaft 28, so as to impart a reciprocatory movement'to the link 26 and slide 8. A second yieldable link 35 is connected to the fork 21 and to a crank arm 32 connected to the punch ll through an eccentric 33.

The-cam 30 is so timed with respect to the anvil and bender-camsi22 and 25 .that when a fastener is released into the chute I8 it comes to rest in a vertical position when the pins 9 engage the body on opposite sides of a tongue 3. Continued rotation of the shaft 28 then causes the punch l I to force the tongues 3 into the die depressions 5 with the removal of all burrs, as previously described. This movement of the punch II with respect to the die 4 is permitted by the pins 9, due to the yielding link 28 between the slide 8 and the yoke 27. As the shaft 28 completes its rotation, the fingers 9 will be withdrawn, thereby permitting a fastener with smooth tongues 3 to fall into a lower chute portion l8a leading to a fastener attaching station. The pins 9 then return tothe position of Fig. 10 in readiness to intercept the next fastener that is stripped from the anvil 20 following the performance of a prong bending operation thereon.

A plunger 34 is provided at the fastener attaching station, the plunger 34 being carried by a reciprocatory head 35 driven from the shaft 23 through a crank 35. The crank 36 isso timed that the plunger 34 is in its raised position when the pins 9 deliver a fastener to the chute portion 18a, the curvature of which causes the fastener to be positioned in a horizontal plane below the raised plunger 34. Upon arrival of a fastener at the attaching station, it is yieldingly supported above a horn 3'! by devices which are fully described in the aforesaid Patent No. 1,993,059. The function of the horn 31 is to receive and support the rear wall l2 of an envelope when the latter is delivered by a suitable transfer mechanism from a stack 38 and cooperating feeding device 39. The envelope transfer mechanism is so timed that the rear wall of an envelope is positioned on the horn 31 coincidentally with the arrival of a fastener, after which the plunger 34 descends to force the downwardly extending prongs 2 of the fastener through the envelope wall and clinch them over against the wall of the envelope.

Referring now to Figs. 11 and 12, there is shown an arrangement for removing burrs from tongues that are formed in a metal strip in advance of the punching of a complete fastener blank from the strip. In this mechanism, a strip 40 is operated upon at intervals by a punch 4| and die 42 which cause separated tongues 43 to be cut out of the strip. The strip 40 is then advanced for operation upon by a pair of rolls 44 and 45. The upper roll 44 provides die depressions 46, while the lower roll provides punch projections 41 raised above the periphery of the roll.

The rolls 44 and 45 are substantially cylindrical in form, except for the depressions 46 and projections 41, and the circumference of each roll is slightly greater than the distance between the extremities of an opposed pair of punched-out tongues 43; Since the die depressions 46 are similarin form to the die depressions 5, previously described with reference to Fig. 3, passage of the strip 4l]'betvveen the rolls 44 and 45, with proper registration of the tongues 43 with the die depressions 43, will result in compressing the tongues 43 so as to remove all burrs, or other roughness, therefrom. After passage of the strip lilibetween the rolls 44 and 45 the compressed tongues: 43-eXtend above the plane of the strip, asindicated in Fig. 11, and the strip may now be acted upon by the punch 48 which serves to sever a portion of the strip between the tongues 43,

so as to constitute' the'body portion of a fastener blank. The cut made in the strip 40 by the punch 48 is indicated at 49 in Fig. 12.

From the foregoing it is apparent that by the present invention there is provided an improved method of and apparatus for removing any burrs or rough places from the bendable tongues of metallic envelope fasteners, so that these tongues can be freely manipulated by the fingers without possibility of injury. In carrying out the invention, the operation upon the tongues to remove the burrs canv be performed either upon a completed fastener, upon fastener blanks, before or after the formation of the attaching prongs, or upon tongues formed in strip material in advance of the punching out of complete blanks.

We claim,

1. Apparatus for removing edge roughness from the tongues of metallic fasteners, comprising a die having depressions with rounded contours, means for positioning a fastener with the rough edges of its tongues facing toward said die depressions and a punch for forcing the tongues of a fastener into said depressions to form rounded edges on said tongues.

2. In apparatus of the class described, the combination with a supply of metallic fasteners providing bendable tongues, and means for removing fasteners from said supply for delivery to a fastener attaching station, of means interposed between said fastener supply and said attaching station for removing edge roughness from the tongues of said fasteners.

3. In apparatus of the class described, the combination with means for conveying envelopes one by one to a fastener attaching station, a supply of metallic fasteners providing bendable tongues, and means for removing fasteners from said supply for delivery to said fastener attaching station, of means interposed between said fastener supply and said attaching station, and operating in timed relation with said envelope delivery and fastener feeding means, for removing edge roughness from the tongues of said fasteners.

4. Apparatus for removing edge burrs from the tongues of punched metallic fasteners, comprising a die providing a depression having an outline substantially conforming to a fastener tongue with the longitudinal sides of the depression inclined outwardly, means for positioning a fastener with the edge burrs of a tongue facing toward the bottom of said die depression, and a punch for forcing said fastener tongue into said depression to convert said burrs into rounded edges.

5. Apparatus for removing edge burrs from the tongues of punched metallic fasteners,- comprising a die providing a depression having an outline substantially conforming to a fastener tongue with the longitudinal sides of the depression inclined outwardly, means for positioning a fastener with the edge burrs of a tongue facing to- Ward the bottom of said die depression, said fastener tongue being of such width as to be supported by said inclined sides above the bottom of the die depression, and a punch for forcing said tongue completely into said die depression to convert said burrs into rounded edges.

6'. Apparatus for operating. on metallic fasteners of the type having tongues and attaching means, comprising a die having depressions with rounded contours, means for positioning a metallic fastener with the rough edges of its tongues facing towards said die depressions, and a punch for forcing the tongues of a fastener into said depressions to form rounded edges on said tongues, and to offset the end portions of the tongues from the plane of that portion of the fastener carrying the attaching means.

'7. Apparatus for operating on punched metallic, fasteners of the type having tongues and body attaching means between said tongues, comprising a die providing a depression having an outline substantially conforming to a fastener tongue, with the longitudinal sides of the depression inclined outwardly, and with the bottom of the depression lying in different planes, means for positioning a fastener with the edge burrs of a tongue facing toward the bottom of said die depression, and. a punchfor forcing said fastener tongue into said depression to convert said burrs into rounded edges, and to offset the end portion of the tongue from the plane of that portion of the fastener carrying the attaching means.

WILLARD E. SWIFI. GEORGE A. ANDERSON.

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