US2381171A - Duplex head nail machine - Google Patents

Description

Aug. 7, 1945. R. A. LITTLE ET AL Y DUPLEX HEAD NAIL MACHINE.

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lil/ f l m wmk www enlarged horizontal' section illusktrating chiefly the pinch dies and related mech- Patented Aog. 7,'- 1945 DUPLEX HEADNAIL M Acnnm Roberta. Littl; Bonora, ana Joseph anios,

Vernon, Pa., assignors. to The American Steel and Wire Company of New Jersey, a cor'- poration of New Jersey Appuoouoo' october 18.1943, sei-iol No. 506,742 o claims. (ci. 1li-4s) The present invention relates to improvements in that type of rnail machine `adapted to form a duplex head on apiece of nail vstock at a single blow. l

4'Although -it' is broadly old to provide means for' forming a duplex head on a piece of nail stock at a Isingle blow, inthe machines `of the prior art excessive weartakes place, causing frequent shut-downs lof the machinery for replacement and repairs. "A primary object of the present v inventionis to 'provide an 'improved construetion and arrangement of pinch die parts which will have 'a long life and withstand the shocks to whichl mechanism ofthis type is repeatedly subjected.

A further object is to provide improved feeding meansfor advancing the'nail stock to the pinch dies.

Another object is to provide va construction andarrangement for accurately coordinating the action of the head-forming pinch .dies with the feed carriage. y

vAnadditional object is to provide 'a construction.I and arrangement whereby the pinch dies v tand feeding means can be adjusted tosuit the requirements of nails of different sizes.'

Another object is to so combine and coordinate 4 the various instrumentalities hereinafter described in detail that they" singly and jointly perform the .functions set forth;

the secondary pinch die therein,`with freedom for movement relative thereto.

Figure 8 is a section on line VHI-VIII of Figure '7.

Figure 9 is an end view of Figure 8 with a-portion broken away and shown in section to better illustrate means for guiding the secondary pinch die and limiting the relative movement thereof in itsholder.

Figure 10 is -a detail section throughthe secondary pinch dies and holders therefor when they are in retracted positiom l Figure 11 is a view similar to Figure 10, but showing the secondary pinch`dies gripping the n'ail stock and a head-forming hammer in the act of upsetting portions of the nail stock.

Figure 12 is a view similar to Figure 11 but Vshowing the position of the secondary pinch dies Y upon completion of the head-forming operation.

Figure 13.

Figure 13 is a view similar to Figure 8, illustrating a modified mounting for v.the secondary pinch dies. y

Figure 14 is a section on line XIV-XIV of lFigure 15 is an end view of'Flgure 14. with parts' broken away in the interest of clarity of illustration.

. The above andl other' related features of the invention will be 4more fully apparent from con` siderauon of the. following detailed disclosure and I the appended claims when read with the accompanying drawings.

in connection Figure 1 is aplan view of a duplex head nail f machine embodying a preferred form of the present invention, withparts broken awayand shown in section in the interests of clarity.

Figure 2 is a side elevation of the nail machine of Figure 1, with parts shown in section.

Figure 2* is a detail ofthe feed cams. Figure 3 is a transverse vertical section on line IIIA-III .of Figure 2.-A 'r Figure,y 4 is a transverse f Figure 6" is section taken on line VI-.VI of Figure 5.

section on line IV-IV enlarged jvertical .longitudinal Figure 16 is an enlarged detail view showing a nail with a duplex head formed b y our improved machine.

General' The machine of the present invention, as here- -inafter more fully described Ain detail, includes means for straightening wireor rod-liker'nail stock and advancing' it to a head-forming station in predeterminedincrements. At the headforming station, primary and secondary pinch dies grip the leading end of the stock while a heading hammer comes in play to form a duplexhead, such asshown in Figure 16, at a" single blow.. Such single-blow head formation is broadly old, and the means for accomplishing this result is'therefore not broadly claimed herein.

f However, in prior art mechanisms excessive wear of parts takes place and the pinch'dies and feeding mechanisms :heretofore generally used were frequently rendered defective or inoperative due to the continual pounding of the hammer and the inadequate supporting and guiding meansV for the head-forming dies, and because of the lost motion Vso the feeding instmment'auues.

Figure-'Tis a detail plan view of a secondary y.

pinchdie holder showing means for supporting The present invention provides .detailed features Vof design.` structure, and arrangement which prolong the useful life of the head-forming dies and feeding mechanism.

Referring in detail to the embodiment ofthe invention illustrated, represents the bed of thel machine which carries suitable bearings I2 supporting a main drive shaft |4 carrying a flywheel I6 and pulley I8 driven from a suitable source of power. The drive shaft has integrally formed therewith crank arms A20 connected by crank pin 22 which operates a connecting rod 24 which is connected by wrist pin 26 secured to a crosshead 28 sliding in suitable guides 30. The crosshead carries a hammer 32 which upon each 'forward stroke of the crosshead 28, in cooperation with the primary and secondary pinch dies -hereinafter referred to, forms duplex head portions h1 andh on the nail, as shown in Figure 16.

Duplea,` head forming i A particular feature of the present invention relates to the detailed construction and arrangement of the pinch dies for gripping and forming the duplex head upon the striking of the hammer blow. An upright portion 34 of the bed I0 is formed with an undercut groove 36 to receive the dovetailed portion 38 of a die block 40 which constitutes a removable unit supporting the primary and secondary head-forming dies. The die block has a rearward extension 42 fo med thereon, which is threaded to receive an djusting screw 44 adapted to be manipulated so as to locate the die block and dies carried therein with great precision, the adjusting screw being locked by a jam nut 46.

Thedie block is apertured at 46 to receive a hardened steel bushing 50 having a tapered passageway 52 extending therethrough, and adapted to accurately guide the advancing length of nail arm 92 and has secured thereto a spring 99 bear- 95 whose upper end engages an opening 91 formedv in the arm 86 of the bell crank and whose lower end passes freely through a lug 90 formed on the ing on a nut l0|threaded on the lower extremity of the rod-like link 95. 'I'he lever 94 carries a -follower 98 which coacts with a cam |00 secured to a shaft |02 carrying a gear |04 which meshes with gear |06 secured t'o the outer end of the main drive shaft 14.- The cam |00 and lever 94 thus serve to force the primarypinch diev 56 into gripstock S which is fed therethrough in separate increments by the feed carriage and relatedmechanism to be later described.

An undercut guide shoulder 54 is machined in y the die block to provide a slidable guide for the lower surfaces of the primary pinch dies 56 and 58. The upper edges of these pinch dies-are inclined'to match the inclination of the lower edge A 60 of a pair of guide gibs 62 seated against the upper shoulder 64 machined -in the die block. The primary pinch die 58 can be moved length- Wise relatively to the guide gib 62 by manipulation of an adjusting screw 66 threaded into a tapped aperture in the die block, the screw 66 being prot vided with a jam nut 68 for locking it in adjusted position. A gib locking screw 10 passes through' a tapped aperture in the die block, bears against the upper edge of the gib 62, and is provided with a lock nut 12. By these means the primar-y pinch die 58 lcan be accurately adjusted so that the stock-engaging notch 14 formed in the end vthereof is accurately positioned in proper alignment with the guiding aperture 52 formed in the guide bushing 50.

The primary pinch die 56 is slldable along the.

undercut guide shoulder 54 formed in the dieV block. This movabley pinch die 56 is pushed toward the nail stock by va push rod 16, one end of which engages a notch 18 formed in the die and the other end of which engages an adjusting screw 80 carried by a bell crank 82 pivoted at 84,K this bell crank having an arm 86 adapted to be rocked in one direction by a rod 86 the lower end of which engages a socket 93 formed in the. upper face of an arm 92 of a lever 94 pivoted at 96. The

bell'crank is moved in a direction to retract the pinch die holder 56 by means of a rod-like link -pensate for wear. i

of the gibs |40 and |42 is effectedby manipulaping engagement with the nail stock. For retracting or releasing the grip of the primary pinch die 56, there is a rod 8| with an angular extremity 83 engaging an aperture formed in the pinch die. The opposite end of this rod 8| passes through an opening 81 formed on an extension 89 of the bell crank 82, and an adjustable nut 9| screwed to the extremity of the rod provides means for adjusting the relative position of the movable primary pinch die 56 with relation to its operating bell crank 62. -Slidably mounted in the die blockl 40 in faceto-face contact with the primary pinch dies 56 and 58 is a pair of coacting secondary holders |08 and H0.' These die holders are notched at' their outer ends for engagementl with push rods ||2 and ||4 which coact With'threaded bolts ||6 and IIB formed respectively in levers |20 and |22 pivoted on fixed trunnion studs |24 and |26. "I'he' parts thus arrangedg it is apparent that the secondary pinch dies |08 and I I0 can be moved into and out of gripping engagement with the -nail stock.

For guiding the secondary pinch die'holders |08 and ||'0 we provide pairs of gibs |40 and |42 which are secured by bolts 44 and |46 whose heads are accommodated in counterbores formed in the die block 40, the shank of bolt |44 passing freely through both the gib 62 and the die block,

and the shank of bolt |46 passing freely through the die block below the die 56, as shown in Figure -6. The upper and lower edges .of the secondary die-holders |08 and ||0 are tapered, and the inner faces of the gibs |40 and |42 are machined to a corresponding taper. Thus said gibs jointly define an undercut guide groove for the secondary pinch die holders. The fastening 'bolts |44 and |46 for the gibs |40 and |42 have sufcient clearance in the die block 40 and in the gib 62 to permit of -movement relative thereto. This makes it possible to adjust the gibs |40 and |42 toward or from the holders |08 and ||0, so as to initially accurately position the parts and also'to com- Such in-and-out adjustment tion of adjusting screws '|48 and |50 which are provided with lock nuts |52 and |54. i

The holders |08 and ||0 at their inner ex'- tremities are formed with guide recesses |56 and |58, to accommodate the secondary pinch dies l|60, and ||2 .4 lFigures '7, 8, and 9 show the preferred construction fory mounting the secondaryv pinch dies in their respective holders, with freedom for movement relative thereto in a direction axialof the nail stock to be acted upon.

Since both pinch vdiesand the. Iguiding means therefor are of identical construction, a description of one will sulice for both.

Each recess |56 and |58 is formed with oppossite? grooves |64, for coaction with guide pins |66 seated in ,notches |68 formed in opposite faces ofthe secondary pinch dies. As thus arranged, it is apparent thatthe secondarypinch dies can partake of a sliding movement within the guide recesses |56 and |58. Coacting with each secondary pinch die is a finger pivoted on a pin |12 lmounted'in the respective pinch die holder. This nger has a depending arm |14 engaged by one endl |16 of a tension spring |18 whose opposite end is secured to suitable anchorage pin |80 carried by thev respective pinch die holder. Thus the springs |18, acting through the fingers, tend to press the secondary pinch dies |60 and |62 outwardly from the primary pinch dies 56 and 58 to the position shown in Figure 10.

In the formation of the duplex nail head, the

nail stock is gripped at a point spaced a considerable distance from the last cut end thereof. Thus the primary pinch dies firmly grip the nail stock and hold it positively against movement in an axial direction. This condition is illustrated in Figure 10, just prior to the time the secondary pinch dies come into play. As the heading hammer 32 advances toward the nail stock, its /forward extremity strikes the cut ende of the nail stock. Thereupon the secondary pinch die holders |08 and ||0 are moved from the position of Figure 10 to approximatelyl the position of Figure 1l, thus causing the secondary pinch dies |60 and |62 to grip the nail stock .adjacent the outer end thereof. As the hammery head 32 continues to move toward the nail stock it simultaneously upsets head h1 by reason of the fact that the anvil portionsllla and |62a exert an upsetting pressure against the laterally extended body portion of 'thenail stock. It will be-understood that while this action is taking placethe secondary pinch dies |60 and |62 slide relative -to the holders |08 and 'l |0,and during this slidingmovement they are guided by the pins |66 sliding in the grooves |64. The outer faces of the secondary pinch dies |60 and |62 are formed Awith recessesf|6v|lr and |62, which serve toV conne the plastic ow of the outer'end of the nail stock so that the combined action of the headinghammer 32 and the recessed secondary pinch dies is to shape the f outermost head h2 on the nail to a predetermined desired contour such as illustrated. l As this) action takes place, the secondary pinch dies areA moved approximately from the position of Figure l1 to the-limit of their head-forming movement illustrated in Figure l2, under force of vthe irnpact of the heading hammer 32. stroke of the hammer rocks'the fingers |10 in a direction yto put the springs |18 under tension, Thus upon retractionv `of the hammer 32 the springs I 18 will return the secondary pinch dies to the outer position such as illustrated in Figure 10, it being understood that as the' hammer isretracted the secondary pinch die holders move outwardly away from the nail stock to the position shown in Figure l0.

Immediately after the completion `of the heading operation and retraction of the primary and secondary pinch dies, the nail stock is advanced axially for a distance equal to the desired length of nail by a feeding mechanism to be later described. Thereupon cutters |82and |84 (see Figure 3) carried by-arms |86 and |88 pivoted at |90 and |92, come into play' to' sever the nail stock and form the point p, as vindicated inFigure 16.

The heading of the machine bed proper.

Cutting movement is imparted to the cutters |82 .and |84 through push bolts |94 and |96 threaded in the free extremity of levers |98 and 200 pivoted at 202 and 204, these levers carrying cam followers 206 and 208 coacting with cams 2|0 and 2|2 secured to and moving with the aforementioned crosshead 28. The cutters |82 and |84 are retracted by means of links 2`|4 and 2|6 connected by universal joints 2|8 and 220 with said arms |86 and |88, these links having a balland-socket Yconnectionlindicated at 222 and 224, with lugs 226 and 228 on the levers |98 and 200. With the cutter parts constructed and arranged as described, it is apparent that as the connecting rod 24 retracts the crosshead and heading hammer, the cams 2| 0 and 2|2 will rock the cutter ends of the levers |98 and 200 inwardly, thus shearing and pointing the end of the nail stock. At a succeeding part of the cycle, the cutters |82 and |84 will be retracted, suitable leaf-springs 230 and 232 being provided which are effective to rock the levers |98 and 200 in a direction opposite to that inA which theyA are rocked by cams 2|0 and 2|2.

Stock feed The nail stock S, such as rod or wire, is fed in predetermined increments through a series of conventional straightening rollers 234 carried by a sub-frame 236 secured by bolts 238 to the rear This sub-frame 236 is formedV with beveled guide tracks 240 which coact with guide portions 242 of a feed carriage indicated generally at 244. This feed carriage has members 246 secured thereto by bolts 248,

which members carry rollers 250 journaled on pins 252 secured in yoke portions of said members 246, as shown. The rollers 250 coact with feed cams 254 secured to a shaft 256 journaled in bearings formed in the extremities of bracket 258'bolted at 260 to the rear of the nail machine bed I0. The carriage 244 has mounted thereon a wire' gripping tool 262 of conventional form mounted in a suitable holder 264 and adapted to A move the wire nail stock longitudinally whenever a forward stroke isimparted to the'feed carriage. Feeding movement is imparted to the shaft256 through agear 266 secured thereto which meshes with a gear sector 268 keyed to a rock shaft 210. Adjustably secured to the sector 268 is a connection plate 212 having an arcuate tongue 214 ltted in a, similarly shaped groove 216 formed in the sector, The connection plate 212 is provided with a pair of elongated slots 218 through which freely pass bolts 280 adapted to adjustably secure the connection plate to the sector'in a desired position. The connection plate carries a stud 282 which passes through the end of a link 284 the opposite end of which is connected to a crank pin 286 having a head 288 adjustable in a'T-slot 296 formed in the crank disc 292 carried by the aforesaid intermediate shaft |02. As thus arranged it is' apparent that by varying the position of the crank pin 286 within the T-slot 290, the desired length of stroke can be imparted to the feed carriage to suit the particular length of nail to be made. In the layout of the machine illustrated, the stroke of the crank pin 286 is sufficient to rock the shaft 210 toan angle of approximately The pitch radius of the sector 268 is approximately three times the pitch radius of the gear 266. Therefore the stroke in one of the crank pin 28B the cam shaft will be retracted for a half revolution. The designed contour of the cams 254 is such that a feeding movement is imparted to the stock by the active parts of the cams between the radial lines o-a and o-b in Figure 2a for approximately 100 rotary movement of shaft 256. This permits the heading operation to take place when the crank pin 285 is in one dead center position and the cutting operation to take place when the crank pin is in the opposite dead center position (hammer retracted).

The feed table actuating mechanism as described produces essentially a positive delayed action feed because the cam rollers 250 are at all times in firm contact with the cams 254. Thus the length of wire stock fed to the dies is always of a constant length and can be held to unusual close tolerances, thereby producing nails of exactly uniform predetermined lengths. Since the feeding movement of each cam 254 requires only 100, as indicated by the angle af-oL-b in Figure 2, of the total 180 movement imparted to the shaft 255 it is apparent that a sufficient concentric dwell portion, for example, 80, as indicated by the angle a-o--c in Figure 2', can be provided on the cam to permit the operation of the primary and secondary dies at the proper time intervals, and because of the adjustable connection between the sector 25B on the connection plate 212, the starting time of the feed stroke can be closely controlled by adjusting the plate 212 relative to the sector 268 and locking the parts by manipulation of the bolts 289. The feed table is retracted by a spring (not shown) acting in a direction opposite to that of the cams 254.

Figures 13, 14,`and illustrate a slight modification of the means for mounting the secondary pinch dies. In these gures the secondary pinch die is of dovetail form in plan so as to ride in the undercut recess 294 formed in the outer end of the holder, and a lip 236 is provided to limit the movement imparted to the pinch die by the spring-actuatedfinger |10. Suitable openings 298 will be formed in the lips 29B to permit the escape of chips or foreign matter.

From the drawings and the foregoing detailed disclosure, it is manifest that the improved machine will make a double-headed nail with a single blow, upon each revolution o-f the powerdriven drive shaft I4.

While we have described quite specifically the design and construction of machine which an actual reduction to practice has ,shown to be highly practical, it is not to .be -construed that we are limited thereto, since various modifications and substitutions of equivalents may be made by those skilled in the art without departure from the invention as dened in the appended claims.

We claim:

1, A nail machine comprising a feed carriage carrying a nail stock gripper, a guide for said carriage, means positively advancing said carriage in stock feeding direction for a predetermined time interval and holding said carriage and stock stationary for a predetermined time interval, means for retracting said carriage to starting position, coacting head-forming pinch dies for upsetting a duplex head on the nail stock during the interval it was held stationary, and

cutting means for severing the headed nail from v the stock advanced by said carriage.

2. A nail machine comprising a feed carriage carrying a nail stockgripper, a guide for saidcarriage, means positively advancing said carriage in stock feeding direction for a predetermined time interval and holding said carriage and stock stationary for a predetermined time interval, means for retracting said carriage to starting position, vhead-forming means for upsetting a duplex head on the nail stock during the interval it was held stationary, cutting means for severing the headed nail from the stock, said head-forming means including coacting primary pinch dies for gripping said nail stock at a distance from the severed end thereof, holders carrying secondary pinch dies `for gripping the stock adjacent the severed end thereof, means for supporting the secondary pinch -dies with freedom for limited movement relative to said holders in a direction axially ofv said stock, a hammer effective` to strike the severed end of said stock and impart movement to said secondary pinch dies axially of said stock whereby at a single blow of said hammer one nail head is upset between said primary and secondary pinch dies and another nail head is upset between said hammer and said secondary pinch dies, means retracting said holders, and means for retracting said secondary pinch dies axially of the stock after said nail heads have been upset.

3. A nail machine comprising means for advancing wire nail stock axially in predetermined increments, stock-severing means, duplex heading mechanism including primary pinch dies, means'eifective to cause the latter to grip the nail stock at a distance from the end thereof, holders movable transversely of the nail stock, secondary pinch dies slidable in said holders axiallyv of said nail stock, means limiting the extent of slidable movement of said secondary dies in said holders, and a hammer effective to upset two heads on said nail stock by coaction with said primary and secondary pinch dies.

4. A nail machine comprising means for advancing wire nail stock axially in predetermined increments, stock-severing means, duplex heading mechanism including primary pinch dies, means effective to cause the latter to grip the nail stock at a distance from the end thereof, holders movable transversely of the nail stock, secondary pinch dies slidable in said holders axially of said nail stock, means limiting the extent of slidable movement of said secondary dies in said holders, a hammer effective to upset two heads on said nail stock by coaction with said primary and secondary pinch dies by causing said secondary dies to slide in said holders toward said primary dies, means for retracting -.said holders, and means for shifting said secondary pinch dies relatively t0 said holders to starting positions controlled by said limiting means.

5.- A nail machine of the character described, comprising a die block, respective fixed and movable primary pinch dies mounted therein, secondary pinch die-holders having recessed portions, said holders being slidably supported in the die block adjacent said primary pinch dies, secondary pinch dies, and means for slidably guiding the latter in the recessed portions of the holder and limiting the slidable movement thereof.

6. A nail machine of the character described, comprising a die block, respective fixed and movable primary pinch dies mounted therein, secondary pinch die-holders having recessed portions, said holders being slidably supported in the die block adjacent said primary pinch dies, secondary pinch dies, means for slidably guiding the latter inthe recessed portions of the holder and limiting the slidable movement thereof, and spring actuated means for shifting saidv secondary dies to predetermined starting positions in the recessed portions of said holders.

7. A nail machine of the character described,

comprising a die block, respective fixed and movyable primary' pinch 'dies mounted therein, secondary pinch die-holders having recessed por-A able primary pinch dies mounted therein, secondary pinch die holders having recessed portions, said holders |being slidably supported in the die block adjacentysaid primary pinch dies, secondary pinch dies movable in said recessed portions, said secondary dies having notches formed in edge portions thereof, saidr holders having grooves facing said notches, and guide pins seated in' said notches and adapted to slide along said grooves to guide said secondary dies and` limit the extent of travel thereof within the recessed portions of the holders.

9. The combination with a nail machine having coacting pinchv dies, a cutter and a reciprocating hammer effective to form a duplex head on nail stock fed thereto, of a delayed action stock feeding means comprising a power-driven member whose movements are synchronized With those of said hammer, a drive plate pivotally connected to said member, a sectoradjustably secured to said drive plate and arranged to be oscillated through a predetermined angle by said member, a shaft carrying a gear actuated by said sector, a cam on said shaft, and av nail stock feed carriage actuated by said cam and carrying a nail stock' gripper, said cam having an active I feed portion effective to advance nail stock to position. to be gripped by the aforesaid pinch `.dies and a passive dwell portion to provide a delay interval of sufficient duration to allow for the-actuation of the aforesaid cutter, pinch dies and hammer While said power-driven member is in motion. n

' ROBERT A. LITTLE.

JOSEPH A. RICE.

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