US3017178A

US3017178A - Apparatus for stacking sheet articles

Info

Publication number: US3017178A
Application number: US814552A
Authority: US
Inventors: Donald J Brickle
Original assignee: National Destillers and Chemical Corp
Current assignee: Millennium Petrochemicals Inc
Priority date: 1959-05-20
Filing date: 1959-05-20
Publication date: 1962-01-16
Anticipated expiration: 1979-01-16
Also published as: GB929499A

Description

Jan. 16, 1962 i D. J. BRlCKLE 3,017,173

APPARATUS FOR STACKING SHEET ARTICLES Filed May 20, 1959 4 Sheets-Sheet l INVEN TOR.

Byzt/ W A TTVSA v Jan. 16, 1962 D. J. BRICKLE APPARATUS FOR smcxmc SHEET ARTICLES 4 Sheets-Sheet 2 Filed May 20, 1959 T0 MACH/NE CONTROLLER ALA/PM E W FF INVEN TOR Dona/d J Br/C/r/e Jan. 16, 1962 D. J. BRICKLE APPARATUS FOR STACKING SHEET ARTICLES 4 Sheets-Sheet 3 Filed May 20, 1959 wv ww/ I N V EN TOR. Dona/d JBr/bk/e Jan. 16, 1962 D. J. BRlCKLE APPARATUS FOR STACKING SHEET ARTICLES 4 Sheets-Sheet 4 Filed May 20, 1959 INVENTOR. Y fiZ/Dona/d JBr/ck/e B y, W, /7;{ A T175,

United States atent Patented Jan. 16, 1962 3,017,178 APPARATUS FOR STACKING SHEET ARTICLES Donald J. Brickle, Clifton Springs, N.Y., assignor to National Distillers and Chemical Corporation, a corporation of Virginia Filed May 20, 1959, Ser. No. 814,552 11 Claims. (Cl. 271-63) It is a general object of this invention to provide an apparatus for stacking sheet articles, more particularly sheet articles such as thin gauge, polyethylene garment bags as the latter are delivered directly from the machine for making the bags.

It is an important object of this invention to provide means for forming an even and symmetrical vertical stack of articles of this type by impaling the latter on horizontal pins which comprise a rack.

Another object is to provide an apparatus which permits a higher speed of stacking so as to accommodate the output of a high speed bag machine. A further object is to provide means for handling the bags as they are delivered so that they may be directly and positively transferred and impaled on the pins provided for receiving the bags without billowing and jamming despite air turbulence and its effect on the limp, thin bag material.

A further object is to provide a stacking apparatus which provides for storage of counted stacks in a vertical position affording a saving in plant space and facilitating the packaging of the stack of bags.

Another object is to provide a stacking apparatus which involves a relatively simple mechanical organization and yet provides high speed stacking of articles of the type described. A related object is to provide a machine having relatively simple components and controls, and yet which is less likely to jam or otherwise malfunction.

Other objects and advantages will become apparent as the following description proceeds, taken in connection with the accompanying drawings, in which:

FIGURE 1 is a perspective view showing schematically the stacking apparatus of this invention;

FIG. 2. is a schematic view illustrating both the stacking apparatus and associated bag machine;

FIG. 3 is a view of a typical garment bag which is stacked by means of the apparatus;

FIG. 4 is a view in elevation of the stacking head and support therefor, removed from the frame of the apparatus;

FIG. 5 is a sectional view taken in the plane of lines 5--5 of FIG. 4;

FIG. 5a is a fragmentary sectional view taken in the plane of lines Sa-Sa of FIG. 4;

FIG. 6 is a side elevational view of the vacuum bar and manifold subassembly shown separately from the stacking head;

FIG. 7 is a plan view of the subassembly shown in FIG. 6;

FIG. 8 is a front elevational view of the subassembly shown in FIG. 6;

FIG. 9 is an enlarged fragmentary view of the subassembly shown in FIG. 6;

FIG. 10 is a view illustrating the comb assembly actuating means; and

FIG. 11 is a diagram of the jam detecting circuit.

While the invention is susceptible of various modifications and alternative constructions, an illustrative embodiment has been shown in the drawings and will be described below in considerable detail. It should be understood, however, that there is no intention to limit the invention to the specific form disclosed, but on the contrary, the invention is to cover all modifications, al-

cally in FIG. 2.

ternative constructions and equivalents falling within the spirit and scope of the invention as expressed in the appended claims.

Turning now to the drawings, the stacking apparatus to which this invention is directed includes a frame structure 10 of angle iron members adapted for mounting on the production room floor adjacent a bag making machine 11, a portion of which is shown schematically in FIG. 2. The stacking apparatus is arranged to receive the output of the bag making machine directly, and provides means for stacking the finished bags 13 which are series delivered thereto, in a flat, substantially vertical position and suspended, momentarily halted (as shown in FIGURE 1) at the instant of delivery. The bags are severed from the continuous web 15 by cut-01f knives 16 provided in the bag machine 11, as shown schemati- In such an arrangement, with a bag made from polyethylene film, the lower, leading end 17 of the bag may have been heat sealed at the bag machine head 18 and the sides 19 of the bag creased if the bag is as the type shown made from a continuous tubular web.

Because of the limp, light character of the bag material, many difficulties have been encountered in stacking apparatus known heretofore in handling and transferring the bags. It has been the usual practice to take each bag when delivered and place the same on a horizontal stack. It is now proposed to overcome the difficulties heretofore experienced by stacking the bags while maintaining the same in the vertical delivered position and to accomplish the foregoing by transferring the bags while in the vertical position and impaling the same on horizontal pins which form racks.

For guiding purposes and to hold the bag in a vertical plane at the time of delivery, an air delivery arrangement is employed by means of which vertical streams of air 20 are directed downwardly on each side of the bag as it issues from the bag making machine and is fed directly into the stacking apparatus. These streams of air act to hold the bag in a substantially vertical, flat position and prevent the bag from swinging wildly around or billowing as it is fed downwardly into the stacking apparatus. In a typical installation, the bags may be delivered at the rate of 200 bags per minute or higher so that the material achieves an extremely high linear speed while being delivered. The lower end of the bag having been heat sealed, except for a small opening 21 in the neck of the bag, it is not liable to billow from air forced between the bag sides 19. However, the air delivery system assists the delivery of the bags into the stacking apparatus and maintains the same vertical so that they may be picked up and placed on the racks of the apparatus.

In accordance with this invention, upon the bags being delivered to the stacking apparatus in a flat, vertical condition, they are successively impaled upon spaced pins 22 which comprise a pin rack. For transferring the bags, the stacking apparatus includes a stacking head 23 comprising a vacuum bar 25 (FIGURE I) mounted on a horizontally reciprocable block 26 which shuttles back and forth carrying a bag on each stroke to one of two pin racks 27, 28 positioned on each side of the point of delivery. The pins 22 extend horizontally when positioned to receive the bags to pierce through the material of the bag when the latter has been moved so as to be received on the pins. Upon each stroke of the stacking head, in keeping with the invention, the latter picks up the successively delivered bags, holding the same by vacuum, and transfers the bags in one direction or the other to one of the pin racks. Thus the bags are stacked on both racks 27, 28 and each of the latter, when loaded with a predetermined number of bags, for example, 200 or 500 bags may be placed on each pin rack, are shifted to an offloading position. For example, the right-hand pin rack 28 is shown in FIGURE 1 in the process of moving to an off-loading position,

Stacking head construction and operation Referring now particularly to FIGURES 1, 4 and 5, for engaging and moving the bag laterally, the block 26 and vacuum bar 25 which together comprise the stacking head 23 are slidably mounted to shuttle back and forth on horizontal hardened shafts 30, and are driven by means of a chain 31 connected through a drive to the bag machine 11 so that the carriage movement is synchronized with the delivery of the bags. vFor mounting the shafts 38 on the frame, the shafts are threaded at both ends and fastened by means of nuts 32 tightened on the threaded ends to brackets 33 fixed to the stationary angle iron frame members.

In the present instance a comb assembly including a pair of pivotally mounted intermeshing

combs

34, 34 carried on the upper edge of the vacuum head, provides a means for maintaining the upper edge of each bag flat as it is impaled on the pins of the pin rack. The bag is shown being forced on the pins 22 in FIGURE 1. It will be observed from this figure that the pins 22 of the rack pierce through the bag between adjacent comb teeth. The combs 34, 34' serve when erect to support the filmy, light material, maintain it fiat, and give sufiiciently rigid support to the material so that it will be properly impaled on the pins.

The vacuum bar 25 is divided into

opposite side chambers

38, 39 which are alternatively supplied with vacuum from a manifold 40 mounted below the left side frame member as viewed in FIGURE 1, through a pair of

tubes

42, 43 which extend under the left horizontal frame member at the side of the machine. Each side of the vacuum bar is provided with rows of

ports

46, 47 to provide means for leading vacuum to the edges of the bar on which the bags are carried to hold the bags from falling as the stacking head operates. A valve 49 in the vacuum manifold 40 is operated automatically as the stacking head reaches the end of each stroke to release the vacuum leading to the chamber and ports on one side of the bar and to connect the vacuum to the opposite chamber and ports on the other side of the bar, so that on the reverse stroke of the vacuum bar a bag may be picked up and carried by vacuum across to the other pin rack.

To form the

opposite side chambers

38, 39, the hollow bar is internally partitioned by a vertical wall 61, the chambers being connected to the source of vacuum via the manifold 40. The connections to the chambers consist, in this case, of the

separate vacuum pipes

42, 43 which lead to the manifold assembly. A single vacuum supply pipe 63 leads from an external source of vacuum to the manifold. The vacuum control valve 4? in the manifold includes a valve plate 65 which is automatically moved between positions upon reciprocation of the stacking head. In the present instance, the manifold 40 is supported under the vacuum bar so as to move with the latter as the stacking head reciprocates to pick up and transfer the bags to the pin racks. The valve plate 65 protrudes from the manifold to engage a pin 66 fixed on the frame a short distance prior to the end of each stroke of the stacking head. This engagement is effective to shift the valve plate 65 horizontally to its opposite position whereupon it protrudes from the other side of the manifold 40 and is engaged by a similar pin 67 carried by the frame to be struck by the plate at a point near the end of the return stroke. As shown in FIGURE 1, the stacking head is moving to the right and the valve plate 65 protrudes from the leading face of the manifold. Both stop pins 66, 67 lie in the path to be traversed by the valve plate and are located to shift the plate so that it moves to the opposite position. As seen in FIGS. and 8, the valve plate 65 includes a rectangular opening 69 plate 88 mounted on the frame of the machine.

which connects the front chamber 70 of the manifold to one or the other of the

manifold connections

42, 43 leading to the vacuum bar, depending on the position of the plate. When the plate is in theright-hand position shown in FIGURES 1, 7 and 8, the opening 69 connects vacuum to the right side chamber 39 in the vacuum bar 25, so that the bar is effective to carry a bag picked up upon travel of the carriage toward the right. Similarly, when in the left position, the valve plate 65 directs vacuum to the left side chamber 38 so that the bar is effective when the carriage moves to the left. The valve plate 65 is held in one or the other of its operative positions by a resilient detent member 71 engaged in a notch in the lower edge of the plate, although some other means may be used to prevent accidental displacement of the plate.

To support the stacking head for sliding movement on the pair of hardened shafts 30, a solid block 73 (FIGS. 4, 5) is provided with

bearings

75, 76 journaled on the shafts. The block 73 supports one end of the vacuum bar 25 which, in the present instance is carried cantilever fashion so as to be free at the opposite end. The block 73 is bored horizontally to receive hardened bushings or the like which serve as the

bearings

75, 76 for slidably carrying the block on the shafts. The vacuum bar 25 is carried on the block 73 by means of vertical plate 77 adapted to be fixed thereto by a plurality of bolts 78. The vacuum bar extends normal to the plate and is held level by a web 79 which may have reinforcing triangular shaped ribs 86 appearing in elevation in FIG. 8, and there shown carried on each side of the web and extending perpendicular to the face of the supporting plate 77. The vacuum bar and manifold form a subassembly shown removed from the slidable block 73 in FIGS. 6 and 7. When bolted onthe slidable block 73, the vacuum bar and manifold subassembly are positioned so that the manifold and tubing clear the frame and drive mechanism so that the stacking head may shuttle back and forth without interference for transferring the bags from the delivery position within the stacking apparatus to the pin racks on either side of the point of receipt.

As set forth previously, the horizontal hollow vacuum bar 25 is divided into

side chambers

38, 39, each outer side wall of the bar having two rows of

horizontal ports

46, 47, as shown in FIG. 6. The pair of intermeshed combs 34, 34' are carried on the top of the casing, each being supported on a rotatably mounted

horizontal shaft

82, 83. The mounting is such that the outer face of each

comb

34, 34 lies in the vertical plane defined by the side ofthe vacuum bar 25, when the combs are in the raised position. For moving the combs between the raised and lowered positions, cranks 85, 86 are provided on the ends of the

shafts

82, 83, which cranks are slidable on a cam The combs are operated by the cam so as to be in the raised position for the portion of the stroke that a bag is carried by the vacuum bar and as the latter approaches the pin racks. Thus the combs support the upper edge of the bags in a vertical plane so that the bags may be impaled on the pins of the racks.

The comb teeth 89 are spaced to provide support for the bag during the impaling of the latter on the pins of the racks. In the present arrangement the vacuum supplied to the vacuum bar 25 provides means for holding the bags against slipping downwardly during the lateral transfer. The combs 34, 34' serve the purpose of providing the required additional support.

As hereinbefore generally noted, for raising and lowering the combs 34, 34' between the upright and the flat positions, the present machine provides a cam 88 carried on the machine frame which coacts with the cranks 85, 86 fixed on the ends of the

shafts

82, 83 pivotally supporting the combs. While this is a matter of timing which may be varied to accommodate different situations, it is usually preferred that the combs be raised for a short period nearing the end of the vacuum bar stroke and therefore the cranks 85, 86 or cam followers ride across the higher fiat portion 90 of the cam 88 until nearing the end of the stroke of the vacuum bar. At this time the operative crank 85, 86 rides down the sloping camming edge 92 to the lower horizontal cam edge 93. A spring or other means connected in this instance, for example, directly to the crank, may be used for maintaining the crank arm in contact with the earn edge and to positively raise the comb into operative position. The lower horizontal cam surface maintains the vertical position of the comb for a period sufiicient to impale the bag onto the pin rack. Upon the return stroke of the stacking head the previously elevated comb is moved to its horizontal position. Near the end of the stroke in the opposite direction the other comb is raised by the opposite working cam surface and crank follower.

For reciprocating the stacking head 23 horizontally, a power drive is provided including an endless chain 31 trained around sprockets 95, 97 mounted on the left horizontal frame member and connected by means of a drive link 98 to the block 73. In the present instance, as shown schematically in FIGURE 1, the power for moving the block 73 and thus the vacuum bar 25, is supplied directly from the associated bag machine 11 by means of a chain 99 so that the timing of the shuttling movements of the stacking head may be automatically synchronized with the operation of the bag machine. The reciprocation of the stacking head 23 may be timed with the receipt of the bags so that a bag is picked up upon each horizontal pass of the vacuum bar and transferred in one direction or the other to one of the pin racks. Power may be obtained from the bag machine by means of a chain or belt drive including the chain 99 connected to drive an initial sprocket or pulley 101 fixed on one end of a drive shaft 103. The other end of the drive shaft 103 receives one of the sprockets 95 connected directly to the block 73. The endless chain 31 employed to reciprocate the block 73 and vacuum bar 25 carries a connector link 98 which serves to connect the chain to the stacking head and provides for reciprocation of the latter. For this purpose, as shown in FIG. 5, the connecting link 98 carries a horizontally extending pin 102 on the end of which is a roller 104. This roller 104 is received in a vertical slot 105 provided in a plate 106 carried spaced from the face of the block 73 by legs 108. Upon the travel of the drive or connecting link 98 in the top course of the chain (to the left in FIGURE 1), the block 73 is moved forward by virtue of the connection provided by the pin 102 in the slot 105. As the drive link 98 travels around the lefthand sprocket 95, the pin affixed thereon rides vertically downwardly within the slot 105 in the plate, the motion of the block being halted and then reversed as this occurs. The connecting link 98 travels to the right in the lower course of the chain 31 moving the block 73 to the extreme right limit of the stroke, where again the block and therefore the vacuum bar is brought to a halt and then reversed while the pin is raised to the upper edge of the slot as the connecting link 98 hearing the same travels around the sprocket 97.

In the present instance the sprockets 95, 97 carrying the endless chain 31 used to operate the stacking head are driven continuously, and, as mentioned hereinbefore, in synchronism with the bag machine 11, so that the stacking head 23 shuttles back and forth timed in accordance with the receipt of the bags so as to transfer the latter at the instant of receipt to one or the other of the stacking pin racks.

Pin racks and drive therefor In carrying out this invention, the pin racks are mounted on each side of the plane of delivery of the bags, and positioned so as to impale the bags as they are transferred by the stacking head. As shown particularly in FIGURE 1, each rack comprises a set of pins 22 spaced trans versely of the stacking apparatus and mounted on a horizontal support member 115. The pins 22 are carried at about the same level and extend, when the support member is in an operative position, in a horizontal direction pointing toward the bags. The level and location of the pins 22 is established so that the pins pass over the vacuum bar 25 between the comb teeth as the bags, held fiat and in a vertical plane by one of the combs 34, 34', are impaled. Any appropriate means may be employed for fastening the pin racks to the chains, belts, or any other equivalent conveyor means that may be used to support and carry the individual pin racks. As shown, the opposite ends of the support members are fastened to a link in each of the chains trained around the pin rack sprockets 117. In this manner the chains carry the pin racks when loaded, from the point of receipt of the bags to an off-loading station. As shown in FIGURE 1, each endless chain assembly may carry a pair of individual pin racks so that one rack may be positioned to receive bags from the stacking head while the other pin rack is positioned for off-loading. It will be evident that the stack of bags may be removed from the pin racks in the course of transferring each pin rack from the position at which it receives bags to the position above the sprocket. It also may be desired to include additional pin racks in each of the assemblies so as to increase the storage capacity of the apparatus. The removal of the stack of bags from the pin racks may be by automatic or manual means, as preferred.

For driving the sprockets and chains carrying the pin racks, as shown in FIGURE 1, each of the assemblies is connected by a series of sprocket-and-chain drives to the shafts providing power to the sprockets 95, 97 operating the block 73 and vacuum bar carried thereon. A single revolution clutch 118 is interposed in these drive trains, with a solenoid actuator 119, to operate the pin rack assemblies so that a pin rack carrying a stack of bags is shifted and an unfilled rack moved to receive the bags from the stacking head. The solenoid actuator is, in this case, operated by a control including a counting mechanism (not shown) operated by the drive for the stacking head, so that the pin racks are automatically shifted for off-loading when a predetermined number of bags are placed on each rack.

In the above described manner the bag machine 11 feeds bags directly to the stacking apparatus which is operated in synchronism with it. The vacuum supplied stacking head is effective to pick up a bag on each stroke of its operation. As previously indicated, vacuum is supplied from the manifold 40 to one of the

chambers

38, 39 in the vacuum bar 25 depending on the direction of movement of the bar. As the bar in its movement from one pin rack to the other passes through the plane of delivery of the bags the vacuum acting through the ports along the side of the bar is effective to draw the bag against the bar and hold it against falling while the bar completes its stroke. As will be evident, the absolute pressure in thechambers within the bar varies in the course of the operating cycle. The valve plate 65 is effective at the end of each stroke to shut off the vacuum to the chamber carrying the bag. In this way the bag is released so that it remains on the pins of the rack. Furthermore, simultaneously with the shutting off of the vacuum to one chamber (38, 39) in the bar, the other chamber is connected to the source of vacuum by the shifting of the valve plate 65 to its opposite position. In the initial period prior to the point of bag pick-up, due to the ports in the side of the bar being uncovered, the pressure in the chamber drops only a few pounds below atmospheric. However, when the vacuum bar is brought into contact with the bag, the latter covers the ports and effectively seals the chamber. The pressure in the chamber then drops substantially below the pressure then prevailing. It has been found that for the remaining portion of the stroke, until the bag is impaled on the pins of the rack, and the vacuum released, the pressure in the chamber remains substantially constant at the lower value.

In accordance with a further aspect of this invention, the lower pressure (or relatively high vacuum) within the vacuum bar which remains at a fixed value while the bag is carried by the bar, is used as a signal in a control which is effective to detect jams in the bag machine. To this end a pressure responsive switch 150 (FIGS. 5, 11), which in the present case is a standard Mercoid water differential type switch, is mounted on the wall of the manifold 40 so as to be actuated by the pressure prevailingin the chamber 70 which pressure is the same as that prevailing in the operative chamber in the bar. The switch 150 is connected in parallel with a pair of cam operated

microswitches

154, 156 in a circuit shown in FIG. 11, which also includes a holding relay 162. The circuit operates to sound a warning by means of the alarm 164 and to shut off the bag machine and auxiliary equipment when a jam is detected by the failure of the bag machine to feed a bag to the stacking apparatus. To this end the pressure switch 150 is set to close for the intervals in the normal operation of the stacking apparatus when a bag is carried by the stacking head. One of the normally closed

microswitches

154, 156 is momentarily opened by the associated

cam

158, 160 during each cycle of the bag machine at a time when the pressure switch should be closed due to the presence of a bag against the vacuum bar. In the event of a jam, indicated by a no bag condition of'the stacking head, the momentary opening of the circuit by one of the cams 158, 164) actuating the associated

microswitch

154, 156 causes the relay 162 to drop out and by suitable control means such as a circuit breaker, the bag machine to be shut off and the warning to sound. As shown in FIG. 4 the

cams

158, 160 operating the

microswitch

154, 156 are carried by the chain 31 so as to actuate the switch at the proper time.

I claim as my invention:

1. In a stacking apparatus for bags 'of flexible material delivered to a point within the stacking apparatus frame in a fiat condition and suspended in a substantially vertical plane, the combination comprising, a pair of pin racks one on each side of the plane of delivery of the bags and facing the latter, each of said pin racks having a pair of spaced sharpened pins facing the bags, means including a horizontally reciprocable stacking head movable through the plane of delivery of the bags between said pin racks, a vacuum bar on said head including means for support ing said bags by vacuum from the point of delivery until impaled on the pins of said pin racks, means for timing the reciprocation of said stacking head with the delivery of the bags so that said vacuum bar takes a bag on the forward stroke and impales the latter on one of said pin racks and takes a succeeding bag on the return stroke and impales the latter on the other of said pin racks, and means for controlling the supply of vacuum to said vacuum bar so that the vacuum is applied while a bag is carried from the plane of delivery to one of said pin racks and is released substantially at the limit of horizontal movement of said vacuum bar to release the bag leaving the latter on said racks.

2. In a stacking apparatus for bags of flexible material, said apparatus having a frame, the combination comprising, means for delivering said bags to a point within the stacking apparatus frame in a flat condition and suspended in a'substantially vertical plane, a pair of pin racks one on each side of the plane of delivery of the bags and facing the latter, each of'said pin racks having a pair of spaced sharpened pins facing the bags, means including a horizontally reciprocable stacking head movable through the plane of delivery of the bags between said pin racks, a vacuum bar on said stacking head for supporting said bags from the point of delivery until impaled on the pins of said pin racks, manifold means connecting said vacuum bar to a source of vacuum, said manifold means including valve means for controlling the supply of vacuum to said vacuum bar, means for operating said valve means to release said bags by shutting off the supply of vacuum to said vacuum bar substantially at the limits of horizontal movement of said stacking head, and means for timing the reciprocation of said stacking head with the delivery of the bags so that said vacuum bar takes each of said bags in the vertical position upon delivery and moves it to one of said pin racks.

3. In a stacking apparatus for bags of flexible material, said apparatus having a frame, the combination comprising, means for delivering said bags to a point within the stacking apparatus frame in a fiat condition and suspended in a substantially vertical plane, a pair of pin racks one on each side of the plane of delivery of the bags and facing the latter, each of said pin racks having a pair of spaced sharpened pins facing the bags, means including a horizontally reciprocable stacking head movable through the plane of delivery of the bags between said pin racks and supporting said bags from the point of delivery until impaled on the pins of said pin racks, and means for timing the reciprocation of said stacking head with the delivery of the bags so that said stacking head takes each of said bags in the vertical position upon delivery and impales it on one of said pin racks.

4, An apparatus for transferring sheets of flexible material from a point of delivery laterally to a stacking station, said apparatus comprising in combination, a horizontal hollow bar having a flat side edge, means for moving said bar toward said stacking station with said flat side edge moving through said point of delivery from a position opposite thereto, means defining ahorizontal row of ports in said flat side edge, meanssupplying vacuum via the interior of said hollow bar to said ports so as to hold a sheet against said side edge of the bar while the latter moves horizontally to transfer said sheet to the stacking station, a comb pivotally mounted on the upper edge of said bar on an axis lying in the plane of said side edge of the bar, and means for moving said comb to an upright position in the plane of said edge so that the teeth of said comb maintain the sheet flat during transfer to the stacking station.

5. An apparatus for stacking sheets of flexible mateterial as the sheets are series delivered moving downwardly in a vertical plane to the apparatus, said stacking apparatus comprising in combination, a frame including fixed horizontal members adjacent one side edge of the sheets at the time of delivery and extending perpendicular thereto, a pair of pin racks carried on said frame one on each side of the vertical plane of delivery of said sheets, each said pin rack having pins facing the sheets, a stacking head reciprocable horizontally on said fixed horizontal members between said pin racks through said plane of delivery of the sheets, and a bar mounted on said stacking head extending perpendicular to said members parallel to said sheets and operable on the forward stroke of the head to pick up an interposed sheet and impale the latter on one of said pin racks, and on the return stroke to pick up a succeeding interposed sheet and impale the latter on the other of said pin racks.

6. An apparatus for stacking sheets of flexible material as the sheets are series delivered moving downwardly in a vertical plane to the apparatus, said stacking apparatus comprising in combination, a frame including fixed horizontal members adjacent one side edge of the sheets at the time of delivery and extending perpendicular thereto, a pin rack carried on said frame on each side facing the sheets at the time of delivery, each said pin rack having pins facing the sheets, a stacking head reciprocable horizontally on said fixed horizontal members between said pin racks through said plane of delivery of the sheets, a bar mounted on said stacking head extending perpendicular to said members parallel to said sheets and adapted on each stroke of the head to pick up an interposed sheet for transfer to the pin racks, and vacuum means mounted on each face of said bar for holding the sheets against the respective faces while the bar moves 9 horizontally to transfer the sheets and impaling the sheets on the pins of said pin racks.

7. An apparatus for stacking sheets of flexible material as the sheets are series delivered moving downwardly in a vertical delivery plane to the apparatus, said stacking apparatus comprising in combination, a frame including fixed horizontal members adjacent one side edge of the sheets when the latter are delivered and extending perpendicular to the delivery plane, a pin rack carried on said frame on each side facing the delivery plane, each said pin rack having pins facing the sheets, a stacking head reciprocable horizontally on said fixed horizontal members between said pin racks through said plane of delivery of the sheets, a bar mounted on said stacking head extending perpendicular to said members parallel to said delivery plane and adapted on each stroke of the head to pick up an interposed sheet for transfer to the pin racks, comb members pivotally mounted on each face of said bar, cam means mounted on the frame, and cam follower means mounted on said bar and cooperating with said cam means, said cam means and cooperating cam follower means being arranged to raise the comb members to an upright position during the final portion of the transfer stroke of the bar so that the teeth of said comb members maintain the sheets flat to facilitate impaling the flattened sheets on the pins of said pin racks.

8. In a stacking apparatus for articles of flexible sheet material, said articles being serially delivered to the stacking apparatus in a flat condition moving downwardly in a substantially vertical plane, the combination comprising, means for applying air under pressure in converging streams directed downwardly along both sides of the material for guiding said material and supporting the material so that it remains substantially vertical, stack forming means including a plurality of pins mounted facing the articles at the point of delivery and laterally adjacent thereto, a stacking head mounted for movement toward said pins so as to engage the articles and impale the latter on said pins, and means for operating said stacking head in time with the receipt of the articles.

9. In an apparatus including a bag machine serially feeding bags to a stacker having a movable vacuum supplied stacking head mounted to pick up and carry a bag upon delivery and means connecting a source of vacuum to said stacking head; ja-m detecting means comprising in combination, vacuum responsive means associated with said stacking head and connected to be subject to the vacuum prevailing therein, said head having a port against which the article is carried during the transfer operation,

the article having the eifect of reducing leakage through said port when so carried to maintain a higher vacuum in the head, and control means connected to said pressure responsive means and actuated by a drop in vacuum due to leakage when a bag is" normally carried by said head to stop the bag machine.

10. In a stacking apparatus for articles of flexible sheet material, said articles being serially delivered to the stacking apparatus in a flat condition and suspended in a substantially vertical plane, the combination comprising, a pair of pin racks one on each side of the plane of delivery of the bags and facing the latter, each of said pin racks having a pair of spaced sharpened pins facing the bags, means including a horizontally reciprocable stacking head movable through the plane of delivery of the bags between said pin racks and supporting said bags from the point of delivery until impaled on the pins of said pin racks, and means for timing the reciprocation of said stacking head with the delivery of the bags so that said stacking head takes one of said bags on the forward stroke and impa-les the latter on one of said racks and takes a succeeding bag on the return stroke and impales the latter on the other rack.

ll. In a stacking apparatus for articles of flexible sheet material, the combination comprising, means for serially delivering said articles to the stacking apparatus in a flat condition and suspending said articles in a substantially vertical delivery plane, stack forming means including a plurality of pins and a stacking head, means mounting the pins laterally adjacent said delivery plane with the ends of the pins facing the articles, said stacking head being mounted for movement toward said pins to engage the articles and impale the latter on said pins, said stacking head including vacuum operated holding means releasably retaining the articles on said stacking head for transferring said articles from said stacking head to said pins, means for movably supporting said stacking head including horizontal members disposed adjacent one side edge of the articles when the latter are delivered to said delivery plane, saidhorizontal members extending perpendicular to said delivery plane, means for moving the stacking head in timed relation with respect to receipt of the articles at the delivery plane, and means for releasing the vacuum supplied to said holding means substantially at the limit of movement of said stacking head toward said pins to release the articles from said stacking head after said articles are impaled upon said pins.

References Cited in the file of this patent UNITED STATES PATENTS 181,387 Yost Aug. 22, 1876 278,607 Schmidt et al. May 29, 1883 2,362,134 Honig Nov. 7, 1944