US2906010A - Panel assembly apparatus - Google Patents

Description

D. w. HANNABLE v 2,906,010

PANEL ASSEMBLY APPARATUS I Spt. 29, 1959. 0

Filed May 25 1955 A 7 Sheets-Sheet 1 Sept. 29, 1959 D. w. HANNABLE PANEL ASSEMBLY APPARATUS Filed May 25, 1955 7 Sheets-Sheet 2 A I a @Z V T? I E Z9914 1% fi [(95 Invenior flarziel WaZ/rerfiznnalv/e Sept. 29, 1959 D. w. HANNABLE PANEL ASSEMBLY APPARATUS 7 Sheets-Sheet 3 Filed May 25, 1955 I n ventor Dar/2e! Walker fifimzable By 52 3 Jttarney Sept. 29, 1959 D. w. HANNABLE PANEL ASSEMBLY APPARATUS Sept. 29, 1959 D. w. HANNABLE PANEL ASSEMBLY APPARATUS 7 Sheets-Sheet 5 Filed May 25, 1955 III..-

F 0 Tu n e U n I fiam'el Walker Ha nnable By his Attorney D. W. HANNABLE PANEL ASSEMBLY APPARATUS Sept. 29, 1959 '7 Sheets-Sheet 6 Filed May 25, 1955 I n we 12 to r pd/2i?! M a/kerfiannable By his Attorney Sept. 29, 1959 D. W. HANNABLE I PANEL ASSEMBLY- APPARATUS Filed May 25, 1955 7 Sheets-Sheet 7 United States Patent PANEL ASSEMBLY APPARATUS Daniel Walker Hannable, Beverly, Mass, assignor to United Shoe Machinery Corporation, Flemmgton, N.J., .a corporation of New Jersey Application May 25, 1955, Serial No. 510,963

3 Claims. (Cl. 29-203) This invention relates to machines for mounting Work pieces in predetermined relation on work supports, and more particularly to automatic means for accurately and detachably fastening onto successive pallets at a station on a conveyor assembly line a chassis in the form of a panel or printed wiring board. It will be appreciated that the invention is not limited to use in automatic assembly lines, nor to the mounting of work pieces for electric-al assemblages, various features of the invention being useful in widely different ways.

The invention is herein illustrated, by way of example, as embodied in apparatus for assembling electronic equipment, the mechanism being of the type disclosed in United States Letters Patent No. 2,772,416, granted December 4, 1956, in the names of Adolph S. Dorosz and Thomas W. Snow. As disclosed in the above-mentioned patent, there is provided a series of pallets each of which carries a chassis from one operating station to the next in a conveyorized assembly line, and positioning and clamping means are provided for acting on the pallets exactly to locate them upon arrival at successive stations. When the chassis, for example printed wiring boards, have thus been located and locked a signal calls for simultaneously operation of the machines or devices at the several stations followed by a releasing of the pallets for conveyance to their next stations. In this manner each chassis automatically receives a prescribed series of treatments, for instance component installations and tests. Production of electronic equipment norm-ally requires a high degree of precision, and this is especially true when operating a high output assembly line since printed conductor lines are finely delineated, the components themselves and their installation clearances are frequently quite small, and improper cross circuiting or electrical interferences must be avoided. As a consequence it is essential not only that each pallet be identically located at a station but that wiring boards all having the same particular circuit be precisely mounted each in the same way on its pallet.

As indicated in the patent mentioned above, the pallets are normally flat, open, metallic frames having means by which a wiring board is registered in fixed relation thereto, and further having means by which, when a board is so registered, it is detachably held. The registering means shown herein consists of a pair of spaced positioning pins uptanding from a pallet and a pair of preformed holes in each wiring board for respectively receiving said pins. The board holding means comprises spaced spring clips. In operating the apparatus set forth in the Dorosz et al. patent the preliminary matter of so mounting a number of Wiring boards that their locating holes receive the pallet positioned pins and their margins are retained by the spring clips is time consuming and burdensome if done manually.

In view of the foregoing it is a general object of this invention to provide, in a conveyorized production line employing a series of operating stations through which ICC work supporting pallets are to pass, improved mechanism ahead of said stations for detachably associating 1ndividual work'mounting pieces in predetermined relation with the successive pallets. To the end just stated, and in accordance with a feature of the invention, the illustrative apparatus herein shown includes in novel combination a conveyor for successively carrying work supporting pallets, a series of operating stations adjacent to the conveyor through which the pallets are to pass and which perform their work simultaneously, means adjacent to said conveyor and ahead of said stations for holding a plurality of work pieces in the form of wiring boards, means adjacent to said holding means for positioning successive pallets in juxtaposition to the conveyor, and transfer mechanism for cyclically moving a wiring board from said holding means and mounting it in predetermined relation with respect to the respective pallets thus positioned.

A further feature of the invention resides in the provision in assembly apparatus of means for successively shifting work supporting pallets from one station to another, means for holding a supply of wiring boards each to be associated with a pallet when at said one station, said pallets and boards having coacting means for registering one with respect to the other, a carrier movably mounted adjacent to said station and having fingers constructed releasably to receive and support a wiring board, mechanism responsive to the arrival of a pallet at said station for transferring a wiring board from said holding means to said carrier fingers, and means responsive to opera-tion of said mechanism for causing the carrier to move the transferred wiring board into registered relation with the pallet at said station.

The above and other novel features of the invention, including, for example, pushers yieldably mounted on the carrier detachably to lock a positioned wiring board in holders on the pallet while elfecting release of said carrier fingers from the board, and means for automatically restoring the operating parts to their initial positions only when a Wiring board has been positioned on a pallet and the pallet has been released for travel to the next station, will now be more particularly described together with various novel details of construction and combinations of parts, in connection with illustrative panel loading apparatus and with reference to the accompanying drawings thereof, in which:

Fig. 1 is a view in side elevation of an exemplary machine in which the invention is embodied, the machine being shown in starting position and mounted at one of the stations of the conveyor system disclosed in said Dorosz et al. application, normally the first station arranged after the pallet loading mechanism therein disclosed;

Fig. 2 is a detail in elevation and largely in section of parts of control mechanism seen on a smaller scale in Fig. 1;

Fig. 3 is a plan view of a portion of the panel loading machine, the parts being in starting position;

Fig. 4 is a section taken on the broken line IV-IV of Fig. 3;

Fig. 5 is a plan view of mechanism seen in Fig. 3, the parts being enlarged and shown in the relative positions occupied during a later portion of their operating cycle;

Fig. 6 is a section taken on the line VI-Vl of Fig. 5

and showing construction details of the carrier and work parts at that stage in their cycle when a wiring board is.

being located by the carrier mechanism on a pallet;

Fig. 10 is a schematic wiring diagram of the apparatus, when its parts are in their normal starting positions, this view corresponding generally with Fig. 25 of the Dorosz et al. application; and

Fig. 11 is a perspective view of a wiring board to be mounted on a pallet.

In view of the complete disclosure in the above-mew tioned patent of the conveyor system herein employed by way of illustration, it will sufiice for present purposes briefly to describe hereinafter only so much of that system as seems necessary or desirable for attaining a clear understanding of the instant invention.

A plurality of work supporting pallets 20 (Figs. and ll) are successively conveyed by a pair of endless belts 22, 22 (Figs. 1, 5 and 9) to and through a series of operating stations wherein work pieces, in this case printed wiring boards 24, mounted on the respective pallets are tested, treated, or otherwise operated upon. One type of machine, for instance, that has been designed to insert lead bearing electronic components in wiring boards and that is intended to operate automatically, if desired, at one or more stations of the conveyor is disclosed in United States Letters Patent No. 2,791,772, granted May 14, 1957, in the names of Charles P. Cardani and Joseph Harrington, Jr. This machine may be presumed to be representative of the various devices and equipment which may be selected for mounting at the respective stations and is accordingly diagrammatically included in the wiring diagram of Fig. and there designated B. Preferably, prior to arriving at the operating stations and immediately after a pallet has commenced its travel on the belts 22, 22 each pallet will be provided with a wiring board 24, this being the function of the mechanism hereinafter to be explained.

Since fully explained and disclosed in the Dorosz et al. conveyor system, each station is provided with means not fully shown herein that is cooperative with successive pallets to dissociate them from the belts 22, 22 and to lock the pallets in predetermined operating position until, all the machines and devices of the several stations having operated, the pallets are restored for further travel on the belts. The illustrative machine to be described for locating wiring boards on the respective pallets may be assumed to be mounted at an initial but otherwise regular pallet positioning and clamping station of the conveyor system and is ahead of station B, the panel mounting machine accordingly being generally designated A in Figs. 1, 8 and 9.

A pallet 20 is guided between stations and accurately located thereat by means of a pair of pins 26, 28 (Fig. 11) upstanding from a margin of the pallet and extending into a straight and continuous series of inverted U- shaped guideway channel members 30 (Fig. '1) secured to the top front of alined conveyor frame sections 32, only an upper portion of one being shown herein. These sections support the operating stations and the pallet control means referred to above as well as horizontal guide bars 34, 34 respectively, underlying the continuously operative belts 22, 22. As indicated in Fig. 9, an advancing pallet is positioned and clampedat the station A by being forced rearward by a lever 36 so that the trailing pin 26 abuts a stop 38 (Fig. 5) projecting in the channel member 30, and the advance pin 28 engages a plate 29 indicated in Fig. 6 and secured to the inner side of the member 30. Simultaneously with this pallet locating action a pallet is disassociated from the belts 22, 22 by riding up on a beveled back rail 40 affixed to the rear bar 34 and by riding up on a fiat topped cam insert 42 (Fig. 9) fast on a control bracket 44 adjacent to the front bar 34. The rearward margin of the pallet engages and displaces a pivotally mounted and spring backed dampening detent 46 supported by a bracket which is screwed to the rear bar 34.

While pallets may difier in shape and other details suitably to accommodate different types of work to b Operated upon, it is preferable for a particular run of wiring boards that the pallets used be all alike. In order that boards of different sizes and configurations may be mounted on a given group of similar pallets, the latter may have one or more corresponding internal projecting portions 48 (Fig. 11). The usually rather fragile wiring boards to be mounted may bear printed circuitry on at least one side thereof and are provided with spaced preformed holes 50, 52 for receiving round-ended indexing pins 54, 56, respectively, doweled in the portions 48 of the pallets. These pins are relied upon to register the wiring boards mounted thereon in appropriate corresponding relation to the respective pallets and hence to the operating tools of the respective stations. It is recognized that other registering means might be used in lieu of the pins 54, 56, snap fasteners, for instance, serving detachably to hold the work registered. A means for insuring that a mounted board is detachably held on the pins 54, 56 is provided in the form of spring clips 58 (Fig. 11) having upturned latching ends 60 which are arranged to be engaged by different marginal portions of the board. Each spring clip 58 is yieldably secured to a board by a pin-and-slot connection, a split tail portion of the clip cooperating with a pin 62 in the pallet to permit yielding of the clip bodily.

The panel mounting machine (Fig. 1) includes means mounted in front of and above the conveyor belts 22, 22 for storing and successively transferring wiring boards to be assembled with the respective pallets, and a carrier generally designated 64 now to be described which coopcrates with the transferring means just mentioned and is reciprocably mounted above the conveyor to deposit and detachably fasten each wiring board after it is received from said transferring means. The carrier comprises a rectangular clip plate 66 (Figs. 1, 6, 9 and 11) that is removably mounted on a threaded stem 68 of a cylinder 70 (Fig. 6), the plate being secured against the cylinder 70 and the bottom of an externally splined sleeve 72 in which the cylinder is pinned, by a washer and a nut 74. Adjustably depending vertically from each end and the rear side of the plate 66 is a pair of spaced studs 76, 76 to which receiving clips in the form of spring fingers 78 are respectively secured. These fingers are provided near their lower ends with portions bent to provide board-receiving notches 80 lying substantially in a plane and adapted yieldingly to engage different points along three edges of a wiring board, as indicated in Fig. 11. Preferably the end fingers 76 have theii notches 80 inclined to enable them yieldingly to receive a wiring board as it.is moved rearwardly in its own plane, by mechanism later described, between the cooperating fingers. A pair of stop pins 82, 82 depending from the plate 66 limits the rearward movement of a board being transferred to the carrier 64. For a purpose hereinafter explained, a vertical pusher 84 (Fig. 9) is yieldingly mounted for heightwise movement in each of two diagonally disposed portions of the plate 66. Thus, each pusher extends through a bore in a cylindrical member 86 which is clamped to the clip plate by means of a washer and a bolt 88, the latter being threaded onto a reduced upper end of the member. A compression spring 90 abutting the lower end of the member endwise, acts to urge the pusher downwardly to the extent adjustably permitted by a bolt 92 threaded on its upper end and engaging the top of the member 86. The lower ends of the pushers are respectively formed with a recess for accommodating the upper end of one of the indexing pins 54, 56.

, Heightwise operating movement of the carrier 64 is effected by means next to be described, the splined sleeve 72 being slidable vertically in a bearing 94 that is adjustably supported in selected positions about its vertical axis by an overhanging split clamp portion of a hollow C-frame 96 (Fig. 1). The latter is arranged to be clamped to a Conveyor frame section 32 in difierent positions, the clamping means including, as set forth in :said copending applications, a crossbar 98, an operating handle 100, and a clamping bolt 102 extending through the crossbar and threaded into a housing 104 (Fig. 9). The latter is fixedly mounted for a purpose later to be described, a pair of cross rods 106, 106 extending through said housing and into opposite sides of the C-frame. As shown in Fig. 6, the splined sleeve 72, together with a piece 108 screwed thereto, affords a spherical socket for a ball-ended link 110 that is connected to driving mechanism similar to that disclosed in the mentioned patents.

The carrier driving mechanism is cyclically actuted by compressed air that is admitted from a source (not shown but common to the several machines and devices along the conveyor) via an inlet pipe 112 (Fig. 1) and controlled by a solenoid-operated three-way valve 114 (Figs. 1, This valve at the start of its cycle of carrier movement admits air under pressure via a pipe 116 to an air cylinder or motor 118 in the C-frame, air delivery from the inlet being subsequently cut off by the valve after a power stroke of the carrier 64 when an exhaust port (not shown) is opened. A piston rod 120 of the motor is threadedly connected to the lower end of a link 122 which is thereby raised against the resistance of a return spring 123 (Fig. 1) and hence actuates linkage including levers 124, 126 and a link 128 connected to the ball-ended link 110.

In order to provide suitable means for adjustably mounting the wiring board storage and transfer mechanism next to be explained, a bracket 130 (Figs. 1, 3 and 6) having parallel, horizontal slots 132 formed in opposite sides thereof is secured to the sides of the base of the C-frame 96, clamping bolts 134, respectively, extending through the slots 132 and threadedly engaging clamping bars 136 disposed within the C-frame. Bolted to the bracket 130 is a base plate 138 (Figs. 1 and 6) to which, with the aid of oppositely disposed braces 140, upright U-shaped frame pieces 142, 142 are secured. Ahorizontal plate 144 (Figs. 3 to 7 inclusive) is bolted onto and spans the upper ends of the frame pieces 142, the rearward portion of this plate overhanging the front conveyor belt 22. A pair of parallel rabbeted guide bars 146, .146 secured to the plate 144 define a passageway transversely of the direction of conveyor feed for a slide 148 (Figs. 3 to 7 inclusive) by means of which successive bottommost wiring boards of a vertically stacked supply are fed and delivered to the carrier 64 when the latter is in its normally raised position. The slide .148 is provided with a plurality of rearwardly extending fiat fingers 150 which are of sufiioient length when the slide has been shifted rearwardly, to extend above the rearward conveyor belt. Precaution is taken in the spacing of these fingers to avoid interference with any parts of the carrier 64, and vice versa. In order that the slide may act on the front edge faces of successive bottommost wiring boards a bar 152 (Figs. 3, 6 and 7) is screwed to the underside of the slide 148 to bridge the fingers 150, thus enabling resilient pull strips 154 to be affixed to the bar 152 and extend in the space between certain of the fingers. Preferably a screw-andslot connection between the bar and the respective strips is provided to permit a latch 156 on each of the latter to be adjusted to accord with the particular contour of the board edge to be engaged thereby.

In order to provide for uniform stacking of like wiring boards for a particular run, and for similar stacking of other wiring boards having different shapes but corresponding in size and configuration in other runs, arrangement is made for adjustable positioning on opposite sides of the slide 148 of four vertical right-angled standards 158 (Figs. 1, 3 and 7). For this purpose a pair of pins 160, 160 are press-fitted into the foot of each standard and project downwardly into parallel front-rear extending slots 162 in L-shaped plates 164,

164 (Figs. 3 and 6), respectively, that are disposed one on each side of the slide 148 and .for adjusting movement toward and from said slide. To hold each standard upright in adjusted position its foot is releasably anchored to one of the L-shaped plates 164 by a frontrear extending angular clamp 166 (Figs. 5, 6) that threadedly receives bolts 168 which are respectively threaded into said one of the plates 164. Releasably. to hold the respective L-shaped plates 164 in adjusted position in a path normal to the movement of the slide 148, bolts 170 (Figs. 3, 4 and 6) threaded through the plates 164, respectively, extend through a spacer 174 secured on the plate 144 and are respectively threaded into an insert 176 (Figs. 4 and 5)'slidable in a slot formed in the plate 144.

The slide 148 is operated by an air motor 178 (Figs. 3, 5 and 6) controlled by a solenoid actuated valve 180 (Figs. 1 and 10). The motor is supported by a bracket 182 afiixed to the plate 144 and is actuated in time relation to the pallet positioning-clamping mechanism .referred to above, the solenoid actuated valve being connected into an electrically-controlled system, as will subsequently be described. A slide operating bell crank lever 184 having one arm pivotally connected to a piston rod 186 of the motor is fulcrumed on a pin 188 (Figs. 3, 4 and 5) fixed in confronting ends of brackets 190, 192 which are secured to the plate 144. The other arm of the lever 184 is provided with a slot 194 for slidably receiving a bearing block 196 that is pivotally carried by a bracket 198 secured to the slide 148. The limit of rearward transfer movement imparted to the slide against the resistance of a motor return spring 199 (Figs. 3, 5) is adjustably determined by a stop stud 200 (Fig. 5) threaded into the plate 144 and arranged to abut the rod 186 endwise. As will later be explained in connection with Fig. 10, provision is made for a normally closed limit control switch 202 and a normally open safety switch 204 to be actuated by a pin 206 (Figs. 5 and 6) depending from the lever 184. The switches are mounted on a shelf 208 secured to the bracket 182. The arrangement is such that when the slide 148 is fully retracted, by the motor return spring, to its starting position the switch 204 is closed by the pin 206 yieldingly depressing a switch button 210. A pallet having been locked in board-receiving position, the valve 180 is energized to operate the motor 178 and swing the lever 184 clockwise as viewed in Figs. 5 and 10, the switch 204 thus being opened. As a consequence the slide 148 is moved rearwardly, the latches 156 pulling a bottommost wiring board rearwardly to seat it in the finger notches 80 of the carrier 64 (as shown in Fig. 11) until the switch 202 is opened by reason of the pin 206 yieldingly displacing a switch button 212 (Fig. 5). The opening of the switch 202 deenergizes the solenoid of the valve 180 to stop panel feed and the loaded motor return spring acts to return the lever 184 counterclockwise as seen in Fig. 5, thereby reclosing the switch 204 and energizing the solenoid valve 114 (Figs. 1 and 10) to effect the downward board inserting stroke of the carrier 64. It is to be noted (Fig. 7) that each latch 156 when retracted yieldably extends above the upper surface of the slide 148 upon which the wiring boards are stacked, but not more than the thickness of one board. Accordingiy, rearward movement of the latches transfers only the bottommost wiring board from beneath the stacked pile, the next-to-the-bottommost board being retained in vertical formation by a pair of stop studs 214 (Fig. 7) extending downwardly from the foot of each rearward standard 158. Upon subsequent forward movement of the slide 148, the next wiring board to be transferred will have fallen onto a front portion of the slide and the latches are depressibly cammed by their next board, as indicated in Fig. 7 until they can assume their normal position for engaging its front edge face.

Downward movement of the carrier 64 with its wiring board abutting the stop pins 82, 82 continues until, as shown in Fig. 9, the pushers 84 yieldingly thrust the board onto theindexing pins 54, 56 to register it on the pallet 20. In this process marginal portions of the board engage the latching ends 60 of the spring clips 58 to displace the latter until said ends can snap inwardly over the board edges detachably to hold the wiring board flat on the pallet. This is to say that the resistance afforded by the springs 90, 90 and the fingers 78 to heightwise movement of the board being positioned is enough to urge the clips 58 endwise laterally until they can return inwardly to retaining positions over the margin of the mounted board. The upward yielding of the pushers 84, especially in the event that one or both of the pins 54, 56 are not received in the holes 50, 52 during mounting movement of the board 24, serves to guard against the possibility of damaging parts due to overtravel of the carrier. Moreover, the independent action of the pushers is effective safely to mount nouuniformly bowed or warped boards which, because of their frangible character, are otherwise easily broken by transverse stresses. The holding influence exerted on a positioned board by a pair of the spring clips 58 is suflicient to elfect release of the mounted wiring board from the notches 80 when the carrier fingers 76 are thereafter elevated to their starting position. It will accordingly be appreciated that the board-holding power of the clips 58 (i.e. their resistance in this case to vertical separation of a mounted board from its pallet) exceeds the strength of the board-clasp by the spring fingers 78, the latter being laterally yieldable and adapted by themselves merely lightly to clasp the board with sufficient force to support it against gravity.

Consistent with control mechanism disclosed in said Dorosz et a1. patent, means is herein disclosed whereby, until a wiring board has registered on the pallet pins 54, 56 in a cycle of operations of the machine, the unloaded pallet cannot be released for travel from station A, the carrier 64 cannot be automatically elevated to starting position, and no pallets at other stations can be released for further advance. To this end a depressible contact member 220 (Figs. 2, 3, 6, 9 and ll) is arranged to be engaged and yieldingly displaced downwardly by the Wiring board as the latter is thrust into register on the pallet 20. This member 220 and associated parts to be described are movable heightwise into' and out of work engaging positions by the motor 118 and interconnecting mechanism now to be described. The upper end of the housing 104 (Fig. 9) is formed as a hollow cylindrical portion 222 for vertically guiding a hollow cylinder 224 that is pivotally supported on the upper end of a link 226. The latter is connected at its lower end in toggle formation to a toggle link 228. For adjustably determining the limits in heightwise movement of the cylinder 224, and hence of the member 220 carried thereby as will subsequently be seen, the lower end of the link 228 is pivotally carried by a lever 230 extending through the front of the C-frame 96 and it is pivotally supported at one end by the front cross rod 106. A knurled adjusting screw 232 threaded vertically through the front end of the lever 230 abuts the frame endwise and thus may be turned to determine the desired range of heightwise movement of the member 220. For operating the cylinder 224 in appropriate time relation to the board applying strokes of the carrier 64, the knee of the toggle 226, 228 is connected to the corresponding ends of a pair of parallel bars 234, 234 (one shown in Figs. 1 and 9) that are each provided at their rearward end with a slot 236 (Fig. l) for receiving a pin 238. This pin is carried by a pair of parallel levers 240 (one shown) pivoted at 242 in the C-frame and urged counterclockwise as seen in Fig. l by a spring 244 connecting them with the frame. The levers 240 have a lost motion connection with the piston rod 120 of the motor 118 in the form of corresponding slots 246 '(one shown) which receive a pin 248 that is carried by the lower ends of depending parallel links 250, 250 (one shown). The upper ends of the links 250 are mounted on a pin 252 secured in the rod and extending through oppositely disposed frame slots 254. From the above it will be seen that actuation of the motor 118 lowers a wiring board into predetermined position on the upper surface of a pallet and that the toggle 226, 228 is simultaneously straightened as indicated in Fig. 9 to lift the member 220 yieldingly to an initial board contacting position, the member being mounted as will now be explained.

An annular bearing 260 (Figs. 2, 9) is secured to the top of the cylinder 224 by screws 262, 262 (one shown) respectively recessed in oppositely disposed slots in the bearing and respectively extending through a flat insert 264 and into the cylinder. A cylinder 266 that is vertically bored slidably to receive a stem of the contact member 220 has its lower end nested in the bearing 260 and is formed with a collar that rests on the bearing; For holding the cylinder 266 in selected position against turning about a vertical axis, a pair of screws 268, 268 (Fig. 2) extend through a clamping ring 270 which bears on the just mentioned collar and into the bearing 260. The member 220 is normally held in rest position relatively to the cylinder 266 by a switch operating U-shaped spring 272 (Figs. 2 and 9) that has its upper end afiixed to that cylinder. The lower end of this spring is arranged to engage and yieldably depress the actuating button of a microswitch 274 (Figs. 2, 9 and 10) alfixed to the cylinder 266 and thus close a normally open circuit shown schematically in Fig. 10 which is thereby rendered operative to effect upward retraction of the carrier 64 and the release of the loaded pallet for conveyance upon the belts 22, 22. The construction and adjustments are such that the contact member 220 when extending upwardly into the opening of a pallet 20 cannot be depressed to an extent to actuate the control circuit unless the wiring board being mounted is thrust downwardly thereon sufliciently to lie flat on the pallet with the pins 54, 56 fully extending into their respective holes 50, 52. For suitably limiting the range of relative heightwise movement of the member 220 it is provided with a kerf in its stem, an L-shaped tongue 276 secured to the cylinder 266 extending across the kerf.

By way of stabilizing against possible rocking movement a pallet which has been positioned and is to be loaded with a wiring board 20 (it being recognized that in some instances it may prove desirable to mount a wiring board considerably nearer one margin of a pallet than its other margins) a guideway 280 is secured by screws 282, 282 (Fig. 9) to the top of the cylinder 266 and slidably receives the stem of the member 220. On this block is a slide 284 having a central longitudinal slot 286 through which said stem of the member 220 freely extends. A pair of clamping screws 288, 288 (Figs. 2 and 3) extends through the slot 286 and they are threaded into the block 280 on opposite sides respectively of the member 220, the slide 284 thus being adjustably movable in the direction desired to position a pair of set screws 290, 290 for engagement with marginal under portions of a locked pallet. These screws are adjustable heightwise, being threaded through the slide and held in adjusted position by lock nuts 292, respectively.

Operation of the illustrative apparatus will now be briefly reviewed and explained with particular reference to the electrical control system as shown in Fig. 10. After making any necessary adjustments along the conveyor line, including substitution, if need be, of an appropriately shaped clip plate 66 having spring fingers 78 differently disposed to accord with the wiring boards to be mounted, an operator need ascertain only that sufficient pallets are supplied for consecutive travel on the 9.. belts 22, 22 and that sufiicient wiring boards are periodically supplied to the pile in the standards 158. He starts the apparatus by means of a switch 300 controlling a motor 302 driving the conveyor belts 22, 22 and making power available to the control circuit, a stop switch 304, a manual clamping switch 306, and a manual unclamping switch 308. A three-pole switch having contacts 310, 312 and 314 is provided to permit optional elimination of the operation of the pallet loading machine at station A without affecting operation of the other stations. A switch having contacts 316, 318, and 320 serves a similar function in connection with the machine at station B. As explained in the Dorosz et al. patent, a normally open switch 322 is used in initially arranging for a pallet 20to be locked at each station so that fully automatic cooperation may thereafter commence. Fig. schematically illustrates the positions of parts when no pallet is at a station and the carrier 64 and the slide 148 are in their retracted initial positions. Upon pallets arriving automatically at their stations, for example at A and B in Fig. 10, pivotal signal levers 324 actuated by the respective pallets operate station limit switches 326, 328 of the pallet positioning and clamping mechanism, temporarily closing series contacts 330A, 330A and 33013, 33013 and opening contacts 332A, 332A and 332B, 332B. As a consequence, when the final one of the pallets being positioned has arrived at its station, a conveyor control rod 334 (Fig. 1) running nearly the length of the conveyor is shifted endwise simultaneously to operate the above-mentioned pallet clamping levers 36 (one partially shown in Fig. 9). Thus the closed contacts 330A, 330A and 330B, 330B signal for pallet clamping by energizing a clamping control solenoid 336 (Fig. 10) governing a valve 338 which causes an air motor (not herein shown) to eifect the required endwise shifting of the rod 334 against the resistance of a return spring, the energized solenoid 336 closing contacts 340, 342, and 344. The solenoid 336 is maintained energized by a circuit through the switch 308, the contacts 340 and 310 and a contact 346 hereinafter referred to. With the several pallets held clamped and positioned, the signal levers 324 under influence of return springs of their respective station switches 326, 328, open the contacts 330A, 330A and 330B, 330B, and close the contacts 332A, 332A and 33213, 3323 to signal for operation of the stations as will be explained.

For initiating the cycle of the panel loading machine, the link 122 is driven upwardly to deposit the wiring board as previously described, the contact member 220 being simultaneously raised for engagement with the registered wiring board. This action follows as a result of completing a circuit through the contacts 344, 312, 332A, 332A, a later mentioned carrier return contact 352 and the switch 204 to actuate the solenoid valve 114 admitting air under pressure to the motor 118 to lower the carrier 64. As noted above, the consequent engagement of the wiring board being mounted by the carrier with the member 220 urges the spring 272 to close the microswitch 274. Since it is not ordinarily desired that this closure immediately eflt'ect an upward return stroke of the carrier 64, conventional time delay mechanism is provided as indicated in Fig. 10 and disclosed in said Dorosz et al. patent. An arm 354 secured to the link 122 rises faster than a piston rod 356 during the operating stroke of the carrier, a spring backed piston rising at an adjustable rate determined by a needle sponding contacts 368, 348, 370 and 372, all of which are shifted by a solenoid 374 associated with station B, the solenoid 374 (corresponding with the solenoid 362) having been energized on completion of a circuit through 332A, 332B, an anvil switch 376 which was closed upon insertion of a component, and a contact 378 (corresponding with contact 360) of time delay mech anism associated with station B. When the carrier return contact 352 is opened, the valve 114 is deenergized, provided the switch 204 has been closed by the lever 184 fully retracting the slide 148, to allow air to exhaust from the motor 118 and thereby permit the return upward stroke of the carrier 64 and lowering of the member 220 together with reopening of the contact 274 and lowering of the contact 360 to reclose a circuit. During this return stroke of the carrier, the solenoid 362 is maintained energized through the contacts 344, 312 and 366. Having registered a wiring board on a pallet at station A (and having simultaneously operated the other stations), the pallet at station A (and atv the other stations) is unclamped by deenergizing the solenoid 336. This is attained by energizing a solenoid 380 which is effected by completing a circuit through the lowered contact 378 which has then returned to its position shown in Fig. 10, through the now closed contacts 370, the lowered contact 360, 364 and a pallet unloading switch designated 381 that remains closed unless too many loaded pallets accumulate at an unloading point on the conveyor line. Energizing the solenoid 380 results in its contact 382 opening a holding circuit to de energize the solenoid 336 and hence unclamp the pallets, the detents 46 thereupon respectively restoring them to the belts 22, 22 for further conveyance. Energizing the solenoid 380 results in deenergization of the solenoids 362, 374 to return their respective contacts to positions shown, and lastly the energizing of the solenoid 380 results in the contact 382 closing a circuit through the normally closed switch 202 and actuating the valve whereupon air under pressure is admitted to operate the motor 178 and thus cause pivotal movement of the lever 184 to move the slide 148 and feed a wiring board into the raised carrier fingers 78. It will be understood that as this Wiring board is thus being fed, the pallet which is to receive it is being delivered by the belts 22, 22 for positioning at station A. When the switch 202 is opened by the pin 206 depressing the button 212, the return spring of the motor 178 is allowed to retract the empty slide 148 forwardly and the pin 206 now closes the switch 204. The valve 114 is thus actuated again to initiate the next cycle by a circuit including the switch 204, the contacts 352 (the latter having closed when the next pallet to be provided with a wiring board has been clamped at station A as above indicated), 332A, 332A, 312, and 344.

From the foregoing, it will be apparent that the invention provides a highly useful organization for loading work pieces in predetermined relation upon conveyorized work supports.

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

1. Apparatus for mounting generally planar wiring boards in predetermined relation on pallets having board registering and retaining means comprising means for supporting work supporting pallets, means adjacent thereto for holding a supply of wiring boards each to be associated with a pallet on said supporting means, a carrier mounted for movement toward and from a pallet thereon and having fingers constructed releasably to receive and support a wiring board, mechanism for transferring a wiring board from the holding means to a predetermined position on said carrier fingers when the latter are retracted from the pallet, and means responsive to operation of said mechanism for causing the carrier to move the transferred board into registered relation with '11 the pallet, said carrier being provided with yieldable members respectively spaced and arranged to engage and bear on the board closely adjacent to the pallet registering means when said fingers approach the pallet whereby the board is urged into position to be retained in flattened condition by said retaining means.

2. Apparatus for mounting fragible work elements in predetermined relation on pallets having registering and retaining means, comprising means for supporting work supporting pallets, means adjacent thereto for holding a supply of the work elements each to be associated with a pallet on said supporting means, a carrier mounted for vertical movement toward and from a pallet thereon and having laterally yieldable fingers constructed and arranged releasably to receive and support a fragible work element, mechanism for transferring a fragible work element horizontally from the holding means to a predetermined position on said carrier fingers when the latter .are retracted from the pallet, and means responsive to operation of said mechanism for causing the carrier to move the transferred work element into registered relation with the pallet, said carrier being provided with pusher members independently yieldable heightwise and respectively spaced and arranged to engage and bear with increasing force on the work element closely adjacent to the pallet registering means when the latter is engaged by the work element whereby the latter is urged downwardly into position to be retained by said retaining means.

31 In a machine for mounting generally planar wiring boards in predetermined position on work supports, a carrier mounted for movement toward and from a work support along a path normal thereto, said carrier having spaced, depending fingers laterally yieldable and formed with board receiving recesses releasably to support each board by its edges for transfer, gage means on the carrier disposed to abut at least one edge-of the board for determining its position while supported by the fingers, and spaced depending pusher members yieldingly mounted on the carrier, said members being arranged and adapted to extend in inoperative positions at one side of the board during its reception by the fingers and subsequent transfer, and to bear on the board to urge spaced portions thereof against the work support at the end of the approach of the carrier with respect thereto.

References Cited in the file of this patent UNITED STATES PATENTS 1,726,220 George et al. Aug. 27, 1929 2,253,283 Minaker Aug. 19, 1942 2,294,274 Buxbaum Aug. 25, 1942 2,296,013 Bell Sept. 15, 1942 2,304,927 Kane Dec. 15, 1942 2,457,233 Henshaw Dec. 28, 1948 2,772,416 Dorosz Dec. 4, 1956 may

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