Fmc Corporation

Amplas, Inc.

Robert J Wech

David K Stock

A draw tape bag is formed from a plastic web. An edge folding unit, a notching unit, a tape inserting unit, a heat sealing unit and a web folding unit form a compact continuous line in a rectangular path. The hem folder includes a L-shaped plate within the hem to receive a draw tape. The plate is pivotally mounted the tape within the hem. A wheel is rotatably and pivotally mounted for pulling the hem onto the plate. A single strap on a roll has a width equal to both tapes. The roll is driven and the strap passes over a knife to sever the strap from the tapes. A tension control roll is coupled to moving the strap and controls the strap feed to hold a constant tape tension. A folding board includes spaced edge channels in a V-shape for folding the flat web. An air layer is interposed between the web and the folding channels to provide a low friction movement. A bag making machine includes a presealer to form tape edge seals, a cooler for cooling the tape hems and an edge sealer and cutting unit to form the side edges of the bag.

Draw tape bag forming method and apparatus

A draw tape bag apparatus passes a web of plastic material having edge notched hems in the opposite edges to receive closing tapes. A hem sealer unit seals the folded layers of the web longitudinally of the folded edge to form the hem. The sealer unit includes a drum unit rotatably mounted on a shaft. The drum unit includes first and second drum parts having coaxial peripheral surfaces. A heat concentrating and release tape is secured to each drum part. The adjacent intermediate ends of the drum parts have telescoping and mating fingers and receses. Separate adjustment screws are coupled to the machine frame adjacent each drum part. Each screw is coupled to the outer race of a ball bearing secured to the adjacent outer end wall of the drum part. The setting of the screw accurately locates the heat concentrating tape axially of the drum. Hot air nozzles are mounted externally to the drum parts in alignment with the tapes and heat the web passing over the tapes to heat seal the web layers in the hem.

Multiple seam forming apparatus for continuously running webs

In a clutch-brake mechanism wherein an input member rotates first in one direction and then in the other, an axially shiftable output member, spline-connected to an output shaft, is clutched to the input member while it rotates in one direction and is declutched and braked while the input member rotates in the opposite direction. The output member has a driven clutch element facing in one axial direction for cooperation with a driving clutch element on the input member and has an oppositely facing braking element cooperating with a relatively stationary braking element which, however, is adjustingly rotatable. All said elements have axially projecting circumferentially spaced teeth for slipless torque transmission. A barrel cam rotating in synchronism with the input member control shifting of the output member through a lever that has a fulcrum, a connection with the output member spaced from the fulcrum, and a cam follower portion engaging the cam. The fulcrum is mounted for movement parallel to the output member axis, but pneumatic cylinders bias it in both directions towards a medial position from which it is displaced during full engagement of the braking elements and the clutching elements. A sensor responsive to fulcrum position can provide for automatic braking in response to excessive resistance to output member rotation.

Intermittent rotational drive

A short dwell indexing drive system for intermittently moving a web of thermosealing material through a bag machine includes a conjugate cam defined by a pair of disc cams on a continuously driven input or cam shaft which engage cooperating groups of cam followers on an intermittently driven output shaft that yields one web draw/dwell cycle for each revolution of the cam shaft. In the preferred embodiment the contour of the cams smoothly index the web by first accelerating the output shaft from zero velocity through a relatively low peak velocity and thereafter decelerating the web to zero velocity at a point in the cycle in excess of 180.degree. before the output shaft is held stationary to the end of the cycle during a dwell period. Belt drives and an adjustable jackshaft which allows the use of different pulley ratios are connected between the output shaft and a web engaging draw roll for amplifying or reducing motion of the output shaft and for providing articles such as bags of different sizes. If articles such as heat sealed thermoplastic pouches are to be made from webs of thermosealing material or laminate, the drive system may be modified by changing the cam configuration to provide a long dwell that requires in excess of 180.degree. of each cycle of operation with the remaining portion of the cycle being used to advance the web.

Indexing roll drive system

This application discloses an apparatus for preventing heat damage to thermoplastic web material being converted to produce bags. After a selected number of bags have been made, the web feeding rolls are automatically stopped for a short period, which may be for one or more machine cycles or stopped for an indeterminate period on command of the operator, to allow removal or transfer of a completed stack of bags. When web movement is stopped, the web feeding rolls that are driven by a belt, are rotated in a direction opposite to the feed direction to withdraw the leading edge of the web from the plane in which the heated seal bar reciprocates. Withdrawing of the web occurs by applying additional tension to that reach of the belt which will effect reverse rotation of the feeding rolls. Such additional tension is created by freely rotating pulleys mounted on a plate oscillated by an actuator.

Bag machine cycle interrupt

A multipurpose sealing and severing mechanism for a bag machine capable of providing one or more seals in thermosealing wrapping material, and severing or perforating the material adjacent the seal area. The mechanism may readily be adapted to produce side weld bags from longitudinally folded wrapping material; open end first bags from tubular wrapping material; closed end first bags from tubular material; or sheets from single or multiple webs. The mechanism includes a stationary sealing head and a reciprocating sealing head each of which includes a pair of spaced resistance wire heaters with an oscillating cutter or perforator movable therebetweento either completely sever or merely perforate the material. Resiliently loaded, segmented film clamps extend parallel to and immediately adjacent the cutter and apply a holding force on both sides of the cutter throughout the length of cut during the severing operation to thereby firmly clamp the web preventing undesirable stresses from being applied to the seal area during the severing operation.

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Green Bay, WI, United States of America

Robert J Wech