Bag Closing Machine With Fluidic Control System

Abstract

An automatic bag closing machine for bags moving along a path wherein tape is folded over and along the open ends of successively arriving bags and then stitched to the bags to close them and the tape clipped adjacent leading and trailing edges of each bag. A fluidic control system with fluidic bag detection apparatus, including sensors located at spaced intervals along the path of the bags, actuates a sewing head when a bag is detected and continues sewing head operation until the bag passes through the machine. The fluidic control system also actuates a tape clipper assembly including a moving knife, swinging the knife to clip the tape adjacent the leading and trailing edges of the bag, the tape clipper assembly further including a pair of alternating pistons operatively connected to the knife to swing it across the path and return, a first piston being actuated by the control system when the detection apparatus signals the control system that the bag is a predetermined distance upstream from the knife, and a second piston being actuated to again swing and return the knife when the bag is a predetermined distance downstream of the knife. The invention also includes a method of closing taped bags with a bag closing machine having a fluidic control system wherein bags passing through the machine are detected by a fluidic bag detection apparatus.

Description

The purpose of the foregoing abstract is to enable the Patent Office and the public generally, and especially the scientists, engineers, or practitioners in the art who are not familiar with patent or legal terms of phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The abstract is neither intended to define the invention of the application, which is measured by claims, nor is it intended to be limiting as to the scope of the invention in any way.

BACKGROUND OF THE INVENTION

The present invention relates to the field of industrial bag closing machines and provides a bag closing apparatus utilizing a fluidic control system and fluidic bag detection apparatus thereby providing an extremely reliable, long lasting, trouble free machine with a greatly reduced number of moving parts in the control system.

Many industries require reliable, high speed bagging of their products as they pass along power conveyors to the final shipping point, and often thousands of bags per hour may pass through such a bag closing machine. To insure a continued flow of bags from the production line to the shipping point, it is essential that such a bag closing machine function smoothly and efficiently with a minimum of downtime and maintenance. When a machine fails, the plant output is immediately affected, the product flow rapidly slowing down and soon coming to a halt. Such stoppage is felt at all points along the production line. It is an object of the present invention to provide an automatic bag closing machine requiring a minimum of supervision and repair and a maximum of smooth, trouble-free operation.

Many bag closing machines close an open top bag by stitching the top of the bag to prevent the contents escaping. A problem often arises with this closure technique if the contents of the bag are powdery since such material can escape between the stitches or even through the holes in the bag made by the sewing head needle. To meet this problem, bags containing such material have a length of tape folded over the open top of the bag, the tape being supplied from a tape reel attached to the sewing machine and the tape unreeling continuously as bags flow through the machine and have the tape folded over each successive bag. Even if the contents of the bag are not powdery it is popular with many manufacturers to stitch a tape over bags that are to contain consumer products since a taped closure presents a more marketable appearance.

Another object of the invention is to provide an automatic apparatus to clip the tape at predetermined distances from the leading and trailing edges of the bag. Many manufacturers prefer an "ear" of tape to extend from each side of the bag closure to reduce the likelihood of the stitching unraveling and to improve the appearance of the bag, the ear length varying to suit the preference of individual manufacturers. Consequently the bag closing machine must be capable of producing a range of required ear lengths.

Taped closures over bag tops are known to the art and such bag closing machines are well established. All such known machines, however, have elaborate electrical, mechanical, or electro-mechanical control systems for actuating the machine. These control systems usually have quite elaborate electrical or mechanical systems and numerous moving parts which wear rapidly and require frequent repair when subjected to the heavy bag volume of most industries. The high volume places a severe strain on these elaborate control systems, and the numerous moving parts and component systems associated with the prior art bag closing control systems have substantially reduced the reliability of such control systems, resulting in substantial downtime and maintenance expense, and even more important, production line stoppage when bag flow comes to a halt due to control system failure.

SUMMARY OF THE INVENTION

The invention comprises an automatic bag closing and taping machine provided with a fluidic control system and fluidic bag detection apparatus for actuating a sewing head and a tape clipper assembly with a swinging knife.

The control system used with the invention is a fluidic system having a plurality of logic networks therein and actuated by a supply of pressurized air. Because the fluidic control system has no moving parts and is actuated by the signals from the fluidic bag detection apparatus which is also without moving parts, the likelihood of control system failure is minimized, resulting in greatly decreased downtime and repair expense and greatly increased reliability, performance, and efficiency.

The bag detection apparatus includes fluidic sensors mounted along the path followed by the bags and located at first and second predetermined distances upstream of the knife of the tape clipper assembly and a predetermined distance downstream of the knife.

When a bag is detected by the detection apparatus, a signal is produced thereby to which the control system is responsive, the control system then causing a clutch to engage to actuate the sewing head to begin stitching the bag as the bag passes through the machine, the sewing head continuing operation until a bag is no longer detected by the bag detection apparatus. As the bag reaches a point a predetermined distance upstream of the knife, a sensor detects it and signals the control system to actuate the tape clipping assembly with its knife which swings across the path of the bag and returns to its starting position to sever the tape extending downstream from the leading edge of the bag. This permits the length of the tape ear at the leading edge of the bag to be closely controlled. As the bag leaves the sewing head and is no longer detected by the detection apparatus a signal is produced and the control system actuates the tape clipper a second time thereby clipping the tape a predetermined distance from the trailing edge of the bag to determine the length of that tape ear. By proper spacing of the sensors of the bag detection apparatus relative to the tape clipper, the lengths of the tape ears extending from front and trailing edge of the bag can be closely controlled to meet the requirements of any industry.

When a signal from the detection apparatus is received by the fluidic control system, the control system actuates one or more interface valves which permit pressurized air to flow to clutch, brake, or tape clipper assembly. If no bag is detected by the bag detection apparatus, the control system opens an interface valve to actuate the brake, causing the brake to engage and the sewing head to stop operation. When a bag is detected, the control system ceases to actuate the valve associated with the brake and instead actuates a second interface valve causing the clutch to engage to start the sewing head.

The tape clipper assembly has a pair of alternating pistons coupled to a pivoting crank which actuates a knife, causing the knife to swing across the path of the bags, the forward movement of a single piston being adequate to swing the knife across the path and return and simultaneously causing the remaining piston to be cocked such that as it moves forwardly from the cocked position it also swings the knife across the path and back. Both pistons are pneumatically actuated and each piston is supplied with pressurized air from interface valves controlled by the fluidic control system. The control system actuates a first piston when a bag is detected a predetermined distance upstream of the clipper in order to clip the leading edge of the tape and actuates the second piston when the bag detection apparatus no longer detects a bag thereby assuring that the tape is clipped a predetermined distance from the trailing edge of the bag as it leaves the machine and that successive bags are separated from one other.

The invention also includes a method of closing taped bags with a bag closing machine having a fluidic control system wherein bags passing through the machine are detected by a fluidic bag detection apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective of a bag closing machine embodying the invention.

FIG. 2 is a schematic circuit diagram showing the fluidic control system and its relationship to the bag closing machine.

FIG. 3 is a side elevational view of the sewing head of the bag closing machine showing the external structure of the tape clipper assembly.

FIG. 4 is a bottom view of the bag closing machine taken in the direction of arrows 4--4 of FIG. 1 showing the location of sensors along the path of the bags.

FIG. 5 is a sectional perspective showing the internal structure of the tape clipper assembly.

FIG. 6 is an enlarged view of a switching subnetwork of FIG. 2.

DESCRIPTION AND OPERATION OF THE INVENTION

Referring now to FIG. 1, the automatic bag closing invention 10 is shown positioned beside conveyor 11 by which bags are moved in a downstream direction 32 along a path 12 through the bag closing machine for closure. A sewing head 13 located adjacent path 12 and disclosed in U.S. Pat. No. 3,478,709 is powered by a motor 14, the sewing head and motor being coupled by a clutch 15 and a brake 16 being provided to stop the sewing head, both clutch and brake being commercially available pneumatically actuated units.

A reel 17 supporting a supply of tape is attached to the machine and tape 18 is fed through the sewing head 13, passing about stationary tape guide 19 and folding apparatus 20 which folds the tape over the open top of each bag passing through the closing machine 10 to produce the result shown on bag 21 where the tape 18 has been stitched to the bag by the sewing head 13. The details of the guide 19 and folding apparatus 20 are known to the art and will not be further discussed. As the bag passes through the sewing head the bag top 22, which is already folded as shown and covered with tape as it enters the sewing head has the tape stitched to the bag, providing positive and reliable closure. A tape clipper assembly 23 is located along the path 12 of the bags adjacent the sewing head, the internal structure and operation of the tape clipper assembly to be described hereafter.

A control box 24 houses the fluidic control system which actuates the bag closing machine 10. Pressurized air is supplied to the control box 24 from factory air supply 25 through supply hose 26 and system air filter 27, assuring a supply of relatively clean air.

Referring now to FIG. 2, which shows a fluidic control system 28 within the dotted outline and useable with the invention. A factory supply 25 of pressurized air is connected by hose 26 to system air filter 27, from which the air flows through a valve 29, providing a means by which pressurized air to the machine 10 can be easily turned off. Valve 29 is connected by hose 30 to a system manifold 31 to which air lines 33, 34, 35, 36, 37 and 38 are connected.

Air line 34 supplies air at factory pressure to a filter 39, which further purifies the air before passing it to the fluidic logic circuit 40. A pressure regulator 41 establishes an optimum pressure level for the logic circuit, to be described hereafter.

Air line 33 extends to a pressure regulator 42 and thence to hose 47, emitter manifold 43, and emitter nozzles 44, 45 and 46 which are mounted on guide 48 along the bag path 12 and form a portion of a bag detection apparatus which will be described further hereafter. Each of these nozzles emits a jet of air across the path 12 followed by bags as they pass through the machine 10.

From system manifold 31 air line 35 extends to clutch interface valve 49 from which another air line 50 extends to clutch 15, the clutch being selected among commerically available units such that the clutch engages to transmit energy from motor 14 to the sewing head 13 when a command signal such as a supply of pressurized air reaches the clutch through interface valve 49. The interface valve 49 is also selected from commerically available valves, the valve passing pressurized air from hose 35 to hose 50 when the valve is opened by pressurized air from hose 51 supplied by the logic circuit 40 as will be discussed hereafter. Unless the valve 49 is opened by pressurized air from the logic circuit the valve 49 does not permit air flow to the clutch. All of the interface valves described in this disclosure function in identical fashion and serve merely as a kind of pneumatic relay by which a low pressure air flow from the logic circuit 40 can produce a higher pressure air flow to apparatus such as brake, clutch and tape clipper assembly to actuate them.

The system manifold 31 is also connected by hose 36 to brake interface valve 52 throughwhich pressurized air is supplied to hose 53 which extends to brake 16, air passing through valve 52 only when the valve is opened by a command signal such as pressurized air supplied along hose 54 from the logic circuit 40.

The brake 16 is selected from commerically available brakes and is constructed to engage and prevent operation of the sewing head 13 when a supply of pressurized air is supplied to it through interface valve 52 and hose 53. When no pressurized air flows to the brake, it disengages and does not retard sewing head operation.

System manifold 31 is connected by air line 38 to interface valve 55 throughwhich pressurized air is supplied to hose 56 and thence to piston No. 1 of the tape clipper assembly 23, air flowing through the valve 55 only when the valve is opened by pressurized air flow along hose 57 from the logic circuit 40.

Interface valve 58 is connected to system manifold 31 through air line 37 and is arranged to pass air therethrough to hose 59 and thence to piston No. 2 of the tape clipper assembly 23 only when the valve 58 is opened by air flow along hose 60 from the logic circuit 40.

An air line 34 extends from the system manifold 31 to a final filter 39 to purify the shop air to a level compatible with the narrow air passages of the fluidic logic network 40. The air from filter 39 is delivered to a pressure regulator 41 from which pressurized air at a lowered, but optimum pressure, enters the fluidic logic network, which will now be described in detail.

Pressurized air flows directly from the regulator to inlet channels 61, 62, 63, 64 and 65 of logic subnetworks 66, 67, 68, 69 and 70, respectively. Subnetworks 66, 67 and 68, all substantially identical to one another, are pressure sensitive switches of a type well known to those skilled in the fluidic logic art. Since these switches are substantially identical, detailed structure will be explained only for subnetwork 66.

Referring now to FIG. 6, air from regulator 41 enters inlet channel 61 of subnetwork switch 66, most of the air flow passing straight through and out primary outlet channel 71. A small amount of fluid, however, follows channel 72a and flows out the subnetwork along control channel 72 in direction 73, the hose 74 and nozzle 75 forming part of sensor 76 to detect a bag obstructing the nozzle. The nozzle 75 emits air therefrom and is positioned along the path 12 followed by the bags (FIG. 2), being positioned in confronting relationship with air nozzle 44, already described. These two emitting nozzles and hose 74 form a sensor well known to the fluidic art and consequently not described further in this disclosure. A secondary outlet channel 77 diverging at an angle from the inlet channel 61 (FIG. 6) provides an alternative flow path for air leaving inlet channel 61.

If a bag passes between nozzles 44 and 75 (FIG. 2) the pressure within nozzle 75 and hose 74 (FIG. 6) increases due to the obstructing effect of the bag, causing generation of a back pressure and a flow reversal in control channel 72 such that air within control channel 72 flows toward the juncture of primary outlet channel 71 and secondary outlet channel 77, the resulting flow along control channel 72 diverting the principal flow of air from primary outlet channel 71 to secondary outlet channel 77 where it exhausts to the atmosphere. When no bag is detected by the sensor 76 the flow along control channel 72 toward the juncture diminishes and air is instead emitted at the nozzle 75, causing the principal flow of air to switch back from secondary outlet channel 77 to primary outlet channel 71. Due to the described behavior of subnetwork 66, when a bag is detected at nozzle 75 the network switches its output flow to secondary outlet 77, the buildup of back pressure in hose 74 and resulting flow reversal providing a signal to which subnetwork 66 responds by switching the air flow to channel 77.

Correspondingly, the control channel 78 for subnetwork 67 is operatively connected through hose 79 to nozzle 80 which along with nozzle 45 collectively form a second sensor 81 substantially identical to the sensor 76 already described. Similarly, control channel 82 of switching subnetwork 68 is connected to hose 83 and nozzle 84, which along with nozzle 46 comprise a third sensor 85, all the sensors being located at predetermined locations along the path of the bag as will be described hereafter. These three sensors collectively comprise a bag detection apparatus and provide input signals to the control system thereby enabling the control system to actuate bag closing machine components at appropriate intervals as described hereafter. It should be understood that the shown fluidic bag detection apparatus is but one type of usable fluidic detection apparatus and that other compatible apparatuses and other arrangements and numbers of sensors may be used, all such alternatives being within the purview of the invention.

Referring now to FIG. 2 the primary outlet channel 71 of switching subnetwork 66 is connected directly to control channel 86 of subnetwork 87 known as an "or" circuit. Network 87 has its inlet channel 88 connected to the primary outlet channel 89 of switching network 68. The primary outlet channel 90 of subnetwork 87 exhausts to the atmosphere, and the secondary outlet channel 91 is connected to the control channel 92 of a second "or" circuit 93.

The "or" circuit 93 has its primary outlet channel 94 connected to interface valve 49 to actuate valve 49, such that when low pressure air is supplied from channel 94 to the interface valve 49, the valve opens, supplying air at shop air pressure to the clutch 15 which then engages to permit motor 14 to drive the sewing head, resulting in a bag being stitched closed and moved through the bag closing machine 10.

The secondary outlet channel 95 of "or" circuit 93 is connected to interface valve 52, the interface valve opening to pass air from hose 36 to hose 53 thereby causing brake 16 to engage to prevent operation of the sewing head when air is supplied to interface valve 52 instead of valve 49. Since air flow will occur through either channel 94 or 95 of circuit 93, but never both, there is no chance of clutch and brake operating simultaneously.

Switching subnetwork 67 has its primary outlet channel 96 connected to control channel 97 of "or" circuit 98, whose inlet channel 99 is supplied from the primary outlet channel 89 of switching subnetwork 68. The primary outlet channel 100 of "or" network 98 is permitted to exhaust to the atmosphere, and the secondary outlet channel 101 as connected to the control channel 102 of "or" circuit 103 whose primary outlet channel 104 is connected to interface valve 58, the secondary outlet channel 105 being connected to interface valve 55. Consequently when pressurized air leaves primary outlet channel 104 it opens interface valve 58 causing high pressure air to flow from hose 37 to hose 59 actuating piston No. 2 and causing it to swing knife 106 across the path of the bag to cut the tape extending from the leading edge of the bag as will be further described hereafter. When fluid instead flows out secondary outlet channel 105 of subnetwork 103 the air flow is delivered to interface valve 55 and opens valve 55 to transmit high pressure air to actuate piston No. 1 resulting in the knife 106 swinging across the path of the bags to cut the tape adjacent the trailing edge of the bag to separate the bag from the successively stitched bag.

It should be understood that the shown fluidic control system 28 and its included logic network 40 are but illustrations of types of fluidic circuitry useful to actuate the components of the disclosed automatic bag closing machine and that those skilled in the art can vary and modify the shown fluidic control system to produce substantially equivalent results, all such variations and modifications being within the purview of the invention claimed herein.

Referring now to FIG. 5 wherein the internal structure of the tape clipper assembly 23 is shown, a housing 107 contains piston cylinders 108 and 109 in which pistons 1 and 2 respectively are mounted for sliding movement. A chamber 110 contains a crank 111 swingably mounted on crank shaft 112, the shaft being mounted in the housing 107. The crank 111 has connecting rods 113 and 114 pivotally mounted thereto and extending to the pistons 1 and 2 respectively, the connecting rods being arranged such that when either piston moves forwardly in the direction of arrow 115 in response to a burst of pressurized air entering a piston cylinder, the crank 111 pivots about the axis of shaft 112. The crank 111 has a pivotally mounted drive link 116 extending to a bifurcated cam on the knife drive lever 117 which is securely attached to a knife shaft 118, the link 116 also being pivotally mounted to the cam on the lever 117. The knife shaft 118 is journaled in the housing 107 for limited rotational movement so as to swing in the directions of arrow 119 to in turn swing knife 106 across the path of the bags to cooperate with anvil 120 to sever the tape.

The knife 106 has a bifurcated mounting 106a and is securely attached to knife shaft 118 by screws 118a; the knife has a replaceable knife edge 121. A spring 122, under compression, rests against washer 123 and housing 107 and urges knife shaft 118 in the direction 124 to insure positive contact between knife edge 121 and anvil 120. The crank 111, link 116 and drive lever 117 are arranged such that a single forward piston stroke of piston 1 causes the knife to swing across the path of the bags to alternate position 125 (FIG. 3) and then to return to starting position 126 simultaneously moving the other piston to a cocked position 127. The knife behaves in exactly the same fashion when piston 2 slides forwardly to an extended position. Pistons 1 and 2 are provided with conventional sealing apparatus to provide acceptable seals between pistons and cylinders.

A cylinder head 128 closes the cylinder 108 and is retained against washer 129 and shoulder 130 by snap ring 131, sealing between head and cylinder being handled by an O-ring 132. A bumper plate 133 absorbs piston impact as the piston moves toward the cylinder head. An elbow 134 is threaded into the cylinder head 128 and extends to hose 56 and interface valve 55 from which air under pressure is supplied to piston 1.

Piston 2 is substantially identical in construction to piston 1, and the two pistons are connected to crank 111 in the shown manner such that one piston is always extended and the other in a cocked position permitting each piston to actuate the knife 106 and the pistons to operate alternately. Cylinder 109 is supplied with bursts of pressurized air through elbow 135 which communicates with hose 59 extending from interface valve 58.

In operation, an operator first determines the proper placement of sensors 76, 81 and 85 (FIG. 4). Nozzles 44 and 75 of sensor 76 are moved to a position along guides 48 and 48a, respectively where they are near the sewing needle 136 and feed dog mechanism of the sewing head 13 since the sensor's purpose is to detect an approaching bag so that control system 28 can actuate the sewing head to close the bag. The sensor 76 is located a first predetermined distance upstream of the knife 106 and also upsteam of the needle 136. It should also be understood that all the sensor nozzles are placed on the machine 10 at a height below the level of the tape on each bag and thus only encounter the moving bags and do not detect the tape.

Because sensor 81 generates the signal to cause the knife 106 to sever the tape extending in a downstream direction 32 (FIG. 1) from the leading edge 137 of a bag 21 passing through the machine, the sensor 81 is positioned at a second predetermined distance upstream of the knife along guides 48 and 48a such that the desired ear length of tape will be extending forwardly from the leading edge of the bag up to the knife when the bag obstructs sensor 81, thereby assuring that the knife 106 will sever the tape at this desired distance from the bag. This results in the downstream ear 138 having a length substantially equal to the predetermined distance from knife to sensor 81. It should be understood that when distances along the bag path are referred to and measured from the knife, the measurement is made along the path 12 from the point at which the swinging knife crosses the path.

Sensor 85 is positioned at a first predetermined distance downstream of the knife 106 on guides 48 and 48a such that a desired length of tape will be extending upstream from the trailing edge 139 of the bag 21 when the bag passes sensor 85 and is no longer detected thereby. When the bag is not detected by sensor 85 the sewing head ceases to operate and the knife 106 swings across the path 12 to cut the tape this desired distance at the rear of the bag thereby creating an ear 140 having a length equal to the distance between sensor 85 and knife 106. The exact positioning of sensors 76, 81 and 85 can be easily adjusted by loosening screws 141 which (FIG. 4) retain the sensors in position on the guides.

After these sensors are positioned in desired locations at the said predetermined distances from the knife, the operator connects the system filter 27 to a factory supply of pressurized air at an acceptable pressure such as 90 p.s.i. and opens valve 29 permitting the air to be purified as it passes through the filter 27 and then flows into control box 24 through hose 30, entering system manifold 31.

From the manifold 31 pressurized air flows through pressure regulator 42 and to the emitter manifold 43 (FIGS. 2, 3 and 4) from which it is delivered to nozzles 44, 45 and 46 on guide 48 positioned opposite nozzles 75, 80 and 84, respectively. In addition factory air is delivered to the interface valves 49, 52, 58 and 55 through hoses 35, 36, 37 and 38, respectively, the factory air being prevented from flowing through any of these valves unless the valve is opened by means of a pressure impulse delivered from the fluidic logic network 40.

Pressurized air flows from the manifold 31 through filter 39 and pressure regulator 41 which establishes a desired optimum pressure level of air supplied to the fluidic logic network 40 through hose 142 which provides a common connection to inlet channels 61, 62, 63, 64 and 65 within the fluidic logic network.

When no bags are detected by the bag detection apparatus comprised of sensors 76, 81 and 85 air flows through the fluidic logic network and control system in the following fashion. Pressurized air flows down inlet channel 61 of subnetwork 66, leaving the network by primary outlet channel 71 since there is no obstructing of nozzle 75 of sensor 76 and consequently there is no back pressure in control channel 72 to cause air flow to divert to secondary outlet channel 77. Consequently air flows along channel 143 to control channel 86 of "or" circuit 87. Since switching subnetwork 68 also detects no bag, it behaves in identical fashion to subnetwork 66 and pressurized air flows along inlet channel 63 and out primary outlet channel 89 and along channel 144 entering inlet channels 88 and 99 of "or" networks 87 and 98. Air flowing along inlet channel 88 of circuit 87 is diverted into secondary outlet channel 91 by the flow from control channel 86. This fluid leaves secondary outlet channel 91 and enters control channel 92 of "or" circuit 93 causing the stream of pressurized air from inlet channel 64 to be diverted into secondary outlet channel 95 which is connected through hose 54 to interface valve 52 thus supplying a command signal to valve 52 to cause it to open.

Pressurized air reaching interface valve 52 is adequate to open the valve and permit factory pressure air to be transmitted directly along hose 53 to the brake 16 causing the brake to engage and prevent operation of the sewing head. It should be understood that the electric motor 14 of sewing head 13 is activated at the same time the factory air supply is turned on, the motor being run continuously and coupled to the sewing head by clutch 15 when stitching is desired.

While no bag is detected by the bag detection apparatus, fluidic switching subnetwork 67 behaves in identical fashion to switching subnetwork 66 and pressurized air flows directly in inlet channel 62 and out primary outlet channel 96 then flowing along channel 145 to control channel 97 of "or" circuit 98, causing the air stream originating at primary outlet channel 89 of switching subnetwork 68 to be diverted into secondary outlet channel 101 of the "or" circuit 98. Consequently the pressurized air flows to the control channel 102 of "or" circuit 103 causing the air flow to be diverted to secondary outlet channel 105 and thence along hose 57 to interface valve 55, opening the valve and permitting factory air to flow from manifold 31 through hose 38, valve 55, hose 56 and to piston No. 1. Such air enters piston cylinder 108 (FIGS. 2 and 5) through elbow 134. Since piston No. 1 is in an extended position, it cannot move forwardly and consequently there is no further movement of piston No. 1 or of the knife 106. It is thus seen that when no bag is detected by the bag detection apparatus neither sewing head nor tape clipper assembly operates.

As a bag moves along the path 12, the bag first encounters sensor 76 and obstructs the air being emitted from the nozzles 75 and 44, resulting in a pressure buildup in hose 74 which produces a flow reversal in the control channel 72 diverting the air stream from primary outlet channel 71 to secondary outlet channel 77 from which the air exhausts to atmosphere. This results in no air stream along connecting channel 143 and consequently the air stream entering input channel 88 of "or" circuit 87 is no longer diverted along secondary outlet channel 91 and switches to primary outlet channel 90, exhausting to the atmosphere. This in turn eliminates the supply of pressurized air reaching control channel 92 of "or" circuit 93, causing the air stream from inlet channel 64 to divert from secondary outlet channel 95 to primary outlet channel 94. Since interface valve 52 then no longer has a pressure impulse from hose 54 opening the valve, it closes, and the brake 16 is no longer supplied with factory air along hose 53, and consequently, it releases. Simultaneously, interface valve 49 is opened by an air flow command signal from primary outlet channel 94 and opens, causing the clutch 15 to be supplied with factory air through hose 50 resulting in the clutch engaging the sewing head with the already operating motor 14 and the sewing head beginning operation to stitch the tape 18 (FIG. 1) over the bag top and urge the bag through the sewing head. It should, of course, be understood that the bag has already been folded closed prior to entering the sewing head and has had tape folded over the open top as it entered the sewing head. The sewing head stitches the tape securely to the bag and at this time the bag has a length of tape extending forwardly from the leading edge of the bag.

As the bag moves through the sewing head along the path 12 it next reaches sensor 81 and obstructs its nozzles 80 and 45 which generates sufficient pressure in hose 79 to cause the air to reverse its flow in control channel 78 and divert the air stream passing along inlet channel 62 from primary outlet channel 96 to secondary outlet channel 147, exhausting to the atmosphere. Since no flow now passes through connecting channel 145, pressurized air entering inlet channel 99 of "or" circuit 98 is no longer diverted to secondary outlet channel 101 and returns to primary outlet channel 100, exhausting to the atmosphere. Consequently the control stream 102 of "or" circuit 103 no longer passes significant air flow and air entering inlet channel 65 switches from secondary outlet channel 105 to primary outlet channel 104. Since interface valve 55 is no longer supplied with an air flow, the valve 55 closes and no more factory air reaches piston 1. Simultaneous with the closing of interface valve 55, pressurized air is supplied to interface valve 58, opening the valve 58 and sending pressurized air to piston 2 through hose 59 and elbow 135. This drives piston 2 forward to an extended position, the connecting rod 114 swinging crank 111 about crank shaft axis 112. As the crank swings, drive link 116 swings knife drive lever 117 resulting in partial rotation of knife shaft 118 in one direction and then the other. This partial rotation is ample to swing the knife 106 across the path of the bag to position 125 (FIG. 3) and back again to starting position 126. The knife edge 121 cooperates with anvil 120 (FIG. 5) to clip the tape 18 extending in a downstream direction 32 from the leading edge 137 (FIG. 1) of the bag. Naturally, the knife severs any cord or thread chain from the sewing head which may be extending between the bag and the sewing head. As the piston 2 reaches its extended position, piston 1 is restored to a cocked position by movement of crank 111 transmitted to the piston 1 through connecting rod 113. Continued transmission of factory air to piston cylinder 109 retains the piston 2 in an extended position.

As the bag continues to move through the sewing head it is detected at sensor 85 causing the air emitted from nozzles 84 and 46 to be partially obstructed causing a buildup of pressure in control channel 82 and a reversal of flow in subnetwork 68. This flow reversal diverts air flow from primary outlet channel 89 to secondary outlet channel 149, exhausting to the atmosphere. When this occurs no air flow is delivered to inlet channels 88 and 99 of "or" circuits 87 and 98 respectively, resulting in no fluid flow passing along channels 91 and 101 to control channels 92 and 102, respectively, of "or" circuits 93 and 103, respectively. Consequently air flows directly down inlet channel 64 of "or" circuit 93 and out primary outlet channel 94 to interface valve 49, thus assuring that the clutch 15 is supplied with factory air to maintain it in engagement and actuate the sewing head even if the bag is no longer detected at sensor 76. Consequently the sewing head continues operation until no bag is detected at either sensor 76 or sensor 85.

So long as a bag is detected at sensor 85, there is no air flow in control channel 102 of "or" circuit 103 resulting in the air flow from inlet channel 65 of circuit 103 passing straight through the circuit and leaving by primary outlet channel 104 causing interface valve 58 to open and piston 2 to receive factory air. Since piston 2 is already extended, no further clipping action occurs as yet.

At the instant that the bag passes sensor 85 and no longer obstructs air flow from the nozzles 84 and 46, pressurized air passing down inlet channel 63 of switching subnetwork 68, flows straight out primary outlet channel 89, dividing to enter inlet channels 88 and 99 of "or" circuits 87 and 98, respectively. Since neither sensor 76 nor 81 now senses any bag, air flow passes directly through subnetworks 66 and 67 leaving by primary outlet channels 71 and 96, respectively. Air flow from subnetwork 67 flows directly to control channel 97 of "or" circuit 98 diverting the air flow from primary outlet channel 100 to secondary outlet channel 101. Air flows from secondary outlet channel 101 into control channel 102 of "or" circuit 103 causing the air flow of circuit 103 to be diverted to secondary outlet channel 105 to open interface valve 55. Factory air flows through interface valve 55, entering piston cylinder 108 and driving piston 1 forward, resulting in the crank 111 swinging to in turn move link 116 and rotate knife shaft 118 about its axis and return it to starting position causing knife 106 to swing across the path 12 to sever the tape 18 a predetermined distance from the trailing edge 139 of the bag 21, (FIG. 1) the movement of piston 1 also resulting in piston 2 being retracted to a cocked position.

Simultaneous with the actuation of piston 1, air flows from primary outlet channel 89 of subnetwork 68 to inlet channel 88 of "or" circuit 87 and is diverted to secondary outlet channel 91 by flow along control channel 86 from switching subnetwork 66. This results in air flowing to control channel 92 of "or" circuit 93, diverting the air flow from primary outlet channel 94 to secondary outlet channel 95. Since flow then no longer can reach interface valve 49, the clutch 15 disengages. Pressurized air is instead supplied to interface valve 52 which opens to pass factory air to brake 16 which then engages and the sewing head 13 ceases operation until the next successive bag is detected by the bag detection apparatus.

The described bag closing machine thus detects an approaching bag with sensor 76, releases the brake 16, and engages the clutch 15 to start sewing head operation to attach the tape to the bag, sewing head operation continuing until no bag is detected at sensor 85. When the bag is detected by sensor 81, the tape extending downstream of the leading edge of the bag is clipped. When the bag is detected by sensor 85, the sewing head operation is continued even if sensor 76 is not obstructed. When sensor 85 ceases to detect a bag, the tape extending upstream from the trailing edge of the bag is clipped and the clutch disengaged and the brake engaged to stop sewing head operation.

It should also be understood that the tape clipper assembly, the fluidic control system, and the bag detection apparatus disclosed herein may form an accessory which may be attached to already manufactured tape bag closing machines. If it is not necessary that the sewing head be stopped and started by the accessory, one can further simplify the fluidic control system. Such simplification is well within the skill of the art and will not be described further herein, but it should be understood that such an accessory, whether or not with a simplified control system, is within the purview of the claimed invention.

While the preferred embodiments of the present invention have been described, it should be understood that various changes, adaptations and modifications may be made therein without departing from the spirit of the invention and the scope of the appended claims.

Claims

We claim:

1. An automatic bag closing machine for bags moving along a path wherein tape from a tape reel is folded over the open ends of successively arriving bags and then stitched to the bags to close the bags and the tape is clipped adjacent leading and trailing edges of each bag, the machine using a shop supply of pressurized air comprising:

a sewing head adjacent said path positioned to stitch the tape to each successively arriving bag as it moves along said path;

a motor for driving said sewing head;

a wholly fluidic control system including a fluidic logic network, a fluidic clutch interface valve and fluidic brake interface valve, each said interface valve constructed to transmit pressurized air through the valve when the valve is opened by a fluidic command signal delivered to said valve and to otherwise prevent fluid flow therethrough, each said interface valve being connected in fluid flow relationship with said fluidic logic network so as to be opened when a command signal is received by each said valve from said logic network;

a pneumatically actuated clutch linking said motor and said sewing head to transmit driving energy from said motor to said sewing head and connected in fluid flow relationship with said clutch interface valve to receive pressurized air from said clutch interface valve when said clutch interface valve is open;

a pneumatically actuated brake positioned to stop operation of said sewing head and connected in fluid flow relationship to said brake interface valve to receive pressurized air from said brake valve when said brake valve is open;

a pneumatically actuated, tape clipper assembly located along said path, including a knife to sever the tape joining successfively stitched bags, the tape clipper assembly being connected in fluid flow relationship with the said wholly fluidic control system;

a fluidic bag detection apparatus, said detection apparatus connected in fluid flow relationship to said fluidic logic circuit of said fluidic control system and having a first sensor positioned to detect a bag along said path at a first predetermined distance upstream of the knife, a second sensor positioned at a second predetermined distance upstream of the knife and a third sensor positioned at a first predetermined distance downstream of the knife, each said sensor providing a signal when a bag is detected at any of said predetermined distances; and

said fluidic logic network including a plurality of pressure sensitive fluidic switches and fluidic or circuits, said switches operatively connected to receive signals from said sensors and in response thereto fluidically actuate a plurality of said fluidic or circuits to fluidically open said clutch interface valve thereby engaging said clutch when a bag is detected by said first sensor at said first predetermined distance upstream and thereafter retaining said clutch interface valve in an open condition until the bag passes said third sensor at said first predetermined distance downstream, thereby maintaining the sewing head in operation while the bag is detected by said third sensor at said first predetermined distance downstream, a plurality of said fluidic or circuits fluidically actuating said tape clipper assembly in response to a said pressure sensitive switch receiving a signal from said second sensor when a bag is detected at said second predetermined distance upstream so as to sever the tape extending in a downstream direction from the leading edge of the bag to control tape length, a plurality of said fluidic or circuits fluidically actuating said tape clipper assembly in response to a said pressure sensitive switch receiving a signal from said detection apparatus when the bag is no longer detected by said third sensor at said first predetermined distance downstream from said knife, thereby severing the tape adjacent the trailing edge of the bag to separate the taped and stitched bag from a successive bag, and a plurality of said fluidic or circuits fluidically opening said brake interface valve to engage the brake in response to no bag being detected by said sensors.

2. The combination according to claim 1 wherein said fluidic control system includes a pressure regulator operatively connected to the source of pressurized air to provide air at reduced pressure for said fluidic logic network, and and each said plurality of pressure sensitive fluidic switch has a control channel connected in fluid flow relationship to said fluidic bag detection apparatus and an inlet channel connected in fluid flow relationship to said pressure regulator to receive air at reduced pressure therefrom.

3. The combination according to claim 1 wherein each said fluidic or circuit and said pressure-sensitive fluidic switch has a primary outlet channel and a secondary outlet channel, each said secondary outlet channel of said switches exhausting to the atmosphere and each said primary outlet channel of said switches being connected in fluid flow relationship to one of said fluidic or circuits.

4. The machine according to claim 1 wherein said tape clipper assembly further includes:

first and second fluidic interface valves, each said interface valve constructed to transmit pressurized air through the valve when the valve is opened by a fluidic command signal delivered to said valve and to otherwise prevent fluid flow therethrough, each said interface valve being connected in fluid flow relationship with said fluidic logic network so as to be opened when a command signal is received by each said valve from said logic network;

first and second pistons; a housing including first and second piston cylinders slideably mounting said first and second pistons, respectively, said first and second cylinders connected in fluid flow relationship to said first and second interface valves, respectively, to deliver pressurized air to said cylinders from said valves;

a crankshaft rotatably mounted in said housing for rotational movement about its longitudinal axis;

a crank fixedly mounted on said crankshaft for movement with said crankshaft;

first and second connecting rods pivotally mounted to said crank and to said first and second pistons, respectively, said rods transmitting longitudinal sliding piston movement along said cylinder to said crank to produce limited rotational movement of said crank and crankshaft about said crankshaft axis;

a knife shaft rotatably mounted in said housing for movement about its longitudinal axis, said knife shaft mechanically coupled to said crank for reciprocating swinging rotation about its longitudinal axis in response to rotation of said crank and crankshaft about said crankshaft axis; and

said knife being mounted adjacent an end of said knife shaft, exterior to said housing, and positioned to swing across said path as said knife shaft reciprocatingly rotates thereby severing the tape extending from a bag.

5. An automatic bag closing machine using a supply of pressurized air in which open top bags move along a path and have tape folded over their open tops and attached thereto for closure, the tape interconnecting successive bags and the continuous tape thereafter being severed to separate one bag from the next comprising:

means for attaching the tape to each bag wherein the tape is folded over the open top of each bag and attached to the bag;

a pneumatically actuated tape clipper assembly including a knife positioned to sever the otherwise continuous length of tape interconnecting successively closed bags;

a fluidic bag detection apparatus located along said path including a first sensor positioned to detect a bag at a predetermined distance from said knife, said apparatus producing a signal on detection;

a wholly fluidic control system connected in fluid flow relationship between said sensor and said clipper assembly to receive said signal, said fluidic control system including a fluidic logic network and a first interface valve constructed to permit flow of pressurized air therethrough when actuated by said fluidic logic network and otherwise to prevent air flow therethrough, said first interface valve connected in fluid flow relationship between the source of pressurized air and said tape clipper assembly and also connected to said fluidic logic network to permit flow of pressurized air through said first valve to said tape clipper assembly when said first valve is opened by said fluidic logic network, actuating said tape clipper assembly to sever the tape interconnecting successive bags, said fluidic logic network being responsive to a signal from said detection apparatus to open said first interface valve when a bag is detected at the predetermined distance from said knife by said first sensor.

6. The bag closing machine according to claim 5 wherein said bag detection apparatus has a second sensor positioned to detect a bag at a second predetermined distance from said knife to produce a signal on detection of a bag at said second predetermined distance, and said fluidic control system includes a second interface valve constructed to permit fluid flow therethrough when fluidically actuated by said fluidic logic network and to otherwise prevent fluid flow therethrough, said second interface valve connected in fluid flow relationship between said tape clipper assembly and the source of pressurized air to said second interface valve to energize said second valve, and connected in fluid flow relationship to said fluidic logic network, said fluidic logic network fluidically opening said second interface valve, in response to said logic network receiving a signal from said detection apparatus that a bag is detected by said second sensor at said second predetermined distance, thereby energizing said tape clipper assembly with pressurized air and severing the tape.

7. The machine according to claim 6 wherein said tape clipper assembly includes first and second pneumatic pistons connected in fluid flow relationship to the downstream side of said first and second interface valves, respectively, to receive pressurized air from said valves and said knife is swingably mounted along said path of the bags to swing across said path from the starting position clear of said path and return to the starting position in response to a said piston being extended by pressurized air from a said interface valve when a said interface valve is opened by said fluidic logic network, said pistons being mechanically coupled to said knife such that a stroke by said first piston in a single direction swings said knife across said path of the bag and returns it to starting position, said second piston then assuming a cocked position from which it can, when actuated by pressurized air from said second interface valve, deliver a stroke to swing said knife across said path and return it to starting position, said first and second pistons operating alternately as said first and second interface valves, respectively, are opened by said fluidic control system, thereby severing the tape extending from the edges of each bag.

8. The bag closing machine according to claim 7 wherein said tape clipper assembly further includes:

a housing including first and second piston cylinders slideably mounting said first and second pistons, respectively, and connected in fluid flow relationship to said first and second interface valves, to respectively, receive pressurized air from said valves;

a crankshaft rotatably mounted in said housing for rotational movement about its longitudinal axis;

a crank fixed to said crankshaft for movement with said crankshaft;

first and second connecting rods pivotally mounted to said crank and to said first and second pistons, respectively, said rods transmitting longitudinal piston movement to said crank to produce limited rotational movement of said crank and crankshaft about said crankshaft axis;

a knife shaft rotatably mounted in said housing for movement about is longitudinal axis, said knife shaft mechanically coupled to said crank for reciprocating swinging rotation about said knife shaft longitudinal axis in response to rotation of said crank and crankshaft about said crankshaft axis, said knife being mounted adjacent an end of said knife shaft exterior to said housing and swinging across said path as said knife shafe reciprocatingly rotates thereby severing the tape extending from a bag.

9. The bag closing machine according to claim 8 and further including a knife drive lever fixed to said knife shaft and having a bifurcated cam extending outwardly therefrom and a drive link with an end pivotally mounted to said crank and the remaining end pivotally mounted to said bifurcated cam, said drive link transmitting movement from said crank to said knife drive lever to reciprocatingly rotate said knife shaft.

10. An automatic bag closing machine for bags moving along a path, the machine using a shop supply of pressurized air comprising:

a sewing head adjacent said path positioned to stitch closed each successively arriving bag as it moves along said path;

a motor for driving said sewing head;

a wholly fluidic control system including a fluidic logic network and a clutch interface valve and brake interface valve, each said interface valve constructed to transmit pressurized air through the valve when the valve is opened by a fluidic command signal delivered to said valve and to otherwise prevent fluid flow therethrough, each said interface valve being connected in fluid flow relationship with said fluidic logic network so as to be opened when a command signal is received by each said valve from said logic network;

a pneumatically actuated clutch linking said motor and said sewing head to transmit driving energy from said motor to said sewing head and connected in fluid flow relationship with said clutch interface valve to receive pressurized air from said clutch valve when said clutch valve is open;

a pneumatically actuated brake positioned to stop operation of said sewing head and connected in fluid flow relationship to said brake interface valve to receive pressurized air from said brake valve when said brake valve is open;

a fluidic bag detection apparatus, said detection apparatus connected in fluid flow relationship to said fluidic logic circuit of said fluidic control system and have a first sensor positioned to detect a bag along said path at a first predetermined distance upstream of said sewing head and a second sensor positioned at a first predetermined distance downstream of said sewing head, each said sensor providing a signal when a bag is detected at any of said predetermined distances; and

said fluidic logic network including a plurality of pressure sensitive fluidic switches and fluidic or circuits, said switches operatively connected to receive signals from said sensors and in response thereto fluidically actuate a plurality of said fluidic or circuits to fluidically open the clutch interface valve thereby engaging said clutch when a bag is detected by said first sensor at said first predetermined distance upstream and thereafter retaining said clutch interface valve in an open condition until the bag passes said second sensor at said first predetermined distance downstream, thereby maintaining the sewing head in operation while the bag is detected by said second sensor at said first predetermined distance downstream, a plurality of said fluidic or circuits fluidically opening said brake interface valve to engage said brake in response to no bag being detected by said first and second sensors.