US2837883A

US2837883A - Automatic packaging machine

Info

Publication number: US2837883A
Authority: US
Inventors: Fred J Bracey
Original assignee: Package Machinery Co
Current assignee: Package Machinery Co
Priority date: 1956-09-06
Filing date: 1956-09-06
Publication date: 1958-06-10
Anticipated expiration: 1975-06-10

Description

F. J. BRACEY 2,837,883

June 10, 1958' AUTOMATIC. PACKAGING MACHINE Y 4 Shets-Sheet 1 Filed Sept. 6. 1956 FIG. LL

INVENTOR. FRED J. BRACEY ATTQRN EYS June 10 1958 F. J. BRACEY AUTOMATIC PACKAGING MACHINE Filed Sept. 6, 1956 v 4 Sheets-Sheet 2 INVENTOR. FRED J. BRACEY BY I 4 U ATTORNEYS June 10, 1958 F. J. BRACEY AUTOMATIC PACKAGING MACHINE Filed Sept. 6, 1956 4 Sheets-Sheet 3 y WIN/A a A.

. g: a Q. I

INVENTOR. FRED J. BRACEIY ATTOR N EYS June 10, 1958 F. J. BRACEY AUTOMATIC PACKAGING MACHINE 4 Sheets-Sheet 4 Filed Sept. 6, 1956 F I G. 8-

INVENTOR. FRED .J. BRACEY flaw n Wm! ATTORN EYS t me? a i atenteel June 10, 1958 AUTOMATIC PACKAGRJG MACHINE Fred J. B'racey, Springfield, Mass, assignor to Package Machinery Company, East Longmeadow, Mesa, a corporation of Massachusetts Applicationseptemher 6, 1956, Serial No. 698,346

6 Claims. (Cl. 53-182) This invention relates generally to automatic packaging machine of the type designed to form, fill and complete tubular containers closed at opposite ends by transverse seals made by bringing the opposed surfaces of the tubular wrapper walls together by a draw-bar or clamp mechanism while simultaneously heat sealing the time required. to complete the tube drawing or feeding cycle of operation or the full stroke of. the draw-bar mechanism. As is well recognized. in the art, the length of stroke of the draw-bar on av particular machine determines the largest size package which the machine is designed to make. Packages of a smaller size (i. c. length) may be formed on a given machine by manual adjustments to shorten the draw-bar stroke, or, the drawbar clamps maybe caused to release the tube after drawing. and sealing: the same during, a portion only of the full stroke of the mechanism. Reference is made to the copending application of Walter R. Zwoyer entitled Automatic Packaging Machine, Serial- No. 404,242, filed January 15,1954, for a disclosure of the general: type of machine to which the present invention may be adapted and for a disclosure: of the mechanism by which the length of package may be controlled by causing a release of' the sealed tube prior to completion of the full :tube; drawing stroke of the clamp mechanism.

An object of this invention is to more precisely control the heat sealing cycle for making the tubular packages and to provide apparatus which will remove the heating elements from contact with the formed tube prior to the release of the tube by the clamping means at the end of the tube feeding or drawing operation. The tube feeding operation may or may not coincide with the termination of the full stroke of reciprocation of the draw-bar or clamp mechanism.

Another object is to provide heat seal release mec anism which will not only control the sealing cycle but Will in a second stage of operation control the tube feeding cycle. The heat sealing members thus will be operable. for a two-stage retraction stroke to terminate the sealing and feeding (drawing) cycles successively.

The above general objects and advantages of the invention, as well as more specific advantages and objects, will be best understood from the following disclosure in the drawings of which,

Fig. 1 is a front elevationalview of a packaging mashine with parts removed. and. other parts cut away to hi anism operable to separate the draw-bar clamps and to bring them together;

Fig. 3 is a detail view showing mechanism operable to raise and lower a draw-bar clamp assembly;

Fig. 4 is top plan of tl draw bar clamping and sealing mechanism associated n one of the package forming columns shown by 1',

Fig. 5 is a section on line of Fig. showing draw-bar clamps ad heat seal mechanism in advanced position for a d in and sealing operation;

Fig. 6 is a section line 6-6 of Fig. 4 showing the clamps still advanced for continued draw-bar operation, with heat sealer means withdrawn;

Fig. 7 is a section on line 7'7 of Fig. 4 showing the clamps partially retracted by further retraction of the heat sealing elements as at the end of a drawing operation; and

Fig. 8 is a schematic drawing of the hydraulic and electrical system for operation of the draw-bar clamps and sealing mechanism.

With reference to Fig. i for an understanding of the general operation of machine on which the invention may be practiced, represents the machine frame of a duplex packaging machine a pair of conventional tube formers disposed in side by side columnar relation at the top of the frame with a reciprocable draw-bar mechanism spaced below the formers to clamp, draw out or feed, and transversely seal successive package lengths of tube from each of the formers Rollers l supply a web or sheet 5 of packaging material which is directed upwardly over a pair of former arms ti above the formers 2, then downwardly between concentric inner and outer forming

tubes

7 and 3 which bring the overlapping edges of the tubularly formed web together past standard side seam sealers as at 9 (which seal the overlapping edges of the web). Below the end of tube 8 the draw-bar assembly 3 grips the tubes for successive package feeding cycles.

The draw-bar 3 is reciprocated vertically between upper and lower positions as the dotted line and full line positions respectively. The length of the draw-bar stroke may be varied as will be seen. t the top of the stroke, opposed clamping frames are brought together to grip and seal the tube. A package length of tube is next drawn off tube former 8. At the bottom of the stroke the clamps are then separated for the return upward stroke and a passage upwardly past the sides of a formed and filled package length of tube. As will be understood in the art, the feeding of one package length of tube is accompanied by a transverse sealing of the tube to form the bottom seal of the package being drawn downwardly and a top seal for the previously formed package length. Simultaneously with the feeding stroke or on the return stroke of the draw-bar the contents for a single package may be dropped down through the inner tube b into the package being formed. On the next succeeding stroke the filled portion of the tube will be top sealed and the tubular container package completed. Also either simultaneously with the feeding and sealing operation, or subsequently, adjacent sealed package lengths may be severed. Such packages are commonly called pillow type packages.

The mechanism for reciprocating the draw-bar is motor driven. A motor lil, through reduction gearing indicated at lit, drives a main shaft 12. A cam at 13 is fixed to the shaft and an adjustable rocking lever apparatus is reciprocated by this cam. As in Fig. 3 a lever 14 is pivoted at 15 to frame it and carries a follower roll 16 at its outer end riding on the edge of cam 13. A connecting rod 17 is adjustably fixed in a slot 1?; of lever 34 at one end and is linked at itsother end to a rocker arm Illpivoted at 29 to frame 1 3 Thus cam 13 may rock the arm 19 to reciprocate the outer free end thereof. The stroke is adjustable by shifting the position of the end of rod 17 in slot 18. The working outer end at 21 of arm 19 is connected through a trunnion 22 to a slide bushing 23 slidable on a vertical post 24 fixed in the lower part of frame 1. On the bushing 23 is fixed a lug 25 having a horizontal slot in which the trunnion 22 is disposed. Up and down motion of the arm 19 is thus transmitted to the bushing by the trunnion sliding in the lug.

Fixed to the bushing 23 (Fig. 1) is a cross head support bar 26 at the ends of which are carried the lower ends of vertical shafts 27. Shafts 27 are carried in spaced frame mounts 28 and 29 of frame 1 and are rotatable with respect both to the support bar 26 and the opposed frames of clamp 3. Draw-bar assembly 3 extends between shafts 27 and is held against axial movement on shafts 27 by two spaced plates 39 and 31. between which the ends of the assembly are positioned. Thus vertical movement of the shafts vertically reciprocates the draw-bar 3.

The lower ends of shafts 27 having pinion gears 32 fixed thereto are journaled in the bastion shaped ends 33 of the support bar 26. The pinions are in mesh with the teeth of a horizontal rack bar 34 which is slidable horizontally of the support 26. A reversible piston rod 35 of a hydraulic cylinder 36 (mounted on the support 26) is provided with a connecting block 37 fixed to the rack bar and thus moves the bar to rotate pinions 32 and thus the shafts 27.

Rotation of the shafts 27, as will be seen, occurs at the top and bottom of the vertical reciprocatory stroke of the shafts and draw-bar 3. The clamps are closed at the top of the upstroke and opened at the bottom of the downstroke. A commercial form of apparatus to spread and close the opposed clamps of the draw-bar 3 is shown by the previously mentioned co-pending Zwoyer application. The diagrammatic showing of Fig. 2 will suffice to illustrate this operation. Opposed clamping frames 40 and 41 are shown normally urged together by a spring and rod connection 42. When the wings at 43 of a camming member 44 fixed on shaft 27 are turned into full line position the frames are spread to retract clamping members from advanced web gripping position. When the cam 44 is turned to a dotted line position, the frames will be brought to tube gripping position by the spring of the connection 42.

In Figs. 4-7 a draw-bar clamping mechanism for one of the tube forming columns of Fig. l is shown in detail. Supported on the opposed frame plates at opposite sides of the path of the tubular web are spaced facing

clamp mounting plates

45 and 46. Extending from the rear plate 46 is clamp assembly 47 and from the front plate 45 an assembly 48 for registration with assembly 47. Each assembly has a pair of mating vertically spaced clamping jaws with mating heat sealing elements between the jaws. The mechanism is adapted at the top of the tube feeding downstroke to bring the clamps and sealers together; on a partial downstroke to retract the sealers while the clamps are still engaged; on completion of a downstroke for a desired tube feed length to retract the clamps; and on completion of the full draw-bar downstroke to spread the frames apart and return the draw-bar unit to the top of its next stroke.

The rear assembly 47 is carried on plate 46 by sets of mounting pins 56 fixed to the plate by stud collar mountings at 51 (Figs. 4 and 6). At their outer ends pins support a jaw plate 52 having a longitudinally recessed face at 53 in which is mounted'heat sealer anvil block 54.

At the top and bottom of the jaw plates are carried upper'and lower anvil bars 55 and 56. The bars are spring mounted by springs pocketed between them as at 57 (Fig. l) and carried by pins 58 threaded in the bars and slidable in the jaw plate 52 (see Figs. 5 and 7). Nuts 59 may be turned to adjust the forward extension of the bars 55 and 56. The face of the bars is notched longitudinally as by a V groove 60 which carries a rubber tube encased rod 61 turned at the ends and anchored on ears 62 of the bars 55 and 56.

The heater anvil block 54 is also spring mounted between the anvil jaws as indicated at 65 in Fig. 5. The block as best shown by Fig. 6 is carried by pins 66 threaded in the block and slidable in jaw plate 52, a spring mounting at 67 balancing against the springs at 65 for a cushioned floating action. In the face of the block are upper and lower sealing anvils 68 and 69 for a package bottom seal and top seal respectively. Between these anvils is a hot wire anvil 70 with a grooved face in which a hot cut-off wire 71 is positioned.

The front assembly 48 is supported for slidable movement with respect to the frame plate 45 by sets of mounting pins 75. At their forward tip ends (Fig. 6) pins 75 are anchored to the upper and

lower sections

76 and 77 of the clamping jaw member 78 to support the latter in retracted or advanced position relative to plate 45. The opposite ends are slidable in collared sleeves 79 fixed in plate 45 (see Fig. 6). Stop nuts 80 are threaded on the end of each pin 79 which is enlarged at said end and formed with a shouldered abutment 81 extending forwardly of the collar 79 when in advanced position as in Fig. 6. The jaw member 78 is extended to the advanced position shown by sets of spring pins 82 best seen in Figs. 4 and 5. Pins 82 are anchored to plate 45 and provided with collars 83 against which springs 84 are seated. The springs encase free end portions of the pins and extend beyond to be seated in recesses 85 of the upper and lower jaw sections. As will be seen from Fig. 7 the jaws may be retracted against springs 84 in withdrawing the same toward plate 45.

Between the jaw sections in the face of member 78 three longitudinal slots (Fig. 7) are formed at 86, 87, and 88. Into

slots

86 and 87 the upper and lower heater faces 89 and 90 of movable heater block 91 may be projected. Slot 88 is adapted to receive a heater cut-ofi knife 92.

Block 91 is movable at the end of a piston rod 93 of a cylinder 94 mounted centrally on the plate 45. The end of rod 93 is fixed (Figs. 4 and 5) at its free end to a mounting plate 95 fixed to the heat seal block 91 by screws at 96. Block 91 also carries at its rear side a pair of jaw retraction plates 97 fixed thereto by screws at 98 and extending above and below the block 91 to slidably receive in suitable openings the mounting pins 75 (see Fig. 6).

On the jaw member 78 inwardly of the upper and

lower jaw sections

76 and 77 are air blast conduits as the flattened tubes extending longitudinally of these sections. The tubes are fed through inlets at 101 (Fig. 5) and adapted to chill the transverse seals formed against the anvils upon retraction of the heater block 91.

To describe the sequence of operation of the clamping and sealing mechanism, it will be seen that when the piston rod 93 is extended outwardly (Fig. 5) the heater block 91 will be advanced to the face of the jaw mem ber 78, the springs 84 having advanced the member 78 outwardly of plate 45. This is the condition of the parts when the

plates

45 and 46 are advanced toward each other at the top of a tube feeding downstroke. The opposing walls of a tubular package are thus pressed to gether between the

clamp assemblies

47 and 48. The notched jaws of

sections

76 and 77 are clamped against the rubber covered rods 61 of the anvil jaws; the

heaters

89 and 90 are seated on the anvils 68 and 69; and the knife 92 is in contact with the hot wire 71. When thus in clamped position the downstroke commences. It will be realized that the knife by engaging the hot wire cutofi will almost immediately sever the walls of a tube assasss transversely between the upper bottom seal area and the lower top seal area of a package. Thus any tension between thepackage lengths will be relieved at these areas for a smooth bonded seal. The relative positioning of the parts at this stage, as previously noted, is shown by Fig. 5.

Since, with certain specialty wrapper materials as with polyethylene sheet material the application of heat is critical, the apparatus is designed to retract the heaters while the clamping jaws remain engaged. Also to insure a slippery non-sticky engagement of the heaters with the material the surfaces may be suitably coated as by Teflon, the trade name for a polytetrafluoroethylene material. If the heaters were to be engaged beyond a limited time period the material would be destroyed and no sealed closure area would result. Accordingly, at the end of a suitable interval during the downstroke the heaters alone are retracted. The position of the parts is shown by Fig. 6. In this position the heater block 91 is withdrawn from the slots in the face of the jaw member 78 and the jaw retraction plates 97 are carried to a position adjacent the abutments 81 of the jaw mounting pins 75. This is accomplished by partial retraction of the piston rod 93 as will be explained.

In the position of Fig. 6 the upper and lower. clamps are advanced during the remainder of the drawing out or tube feeding stroke. It will be noted also that as soon as the heaters are withdrawn the air. blasts which are continuously operated from conduits tilt? at the inner side of the

sections

76 and 77 are directed against the sealed areas to chill the same and set the transversely bonded package end closures. Thus, while the tube lengths of the packages are still clamped tr e bottom and top heat seals are allowed a recovery period during which no stretching forces are exerted against the seal. When the clamps are finally released the seals are of suiiicient strength to be self-sustaining against any pressure of the contents in apackage.

At the conclusion of the tube feeding downstroke, which is governed by an electric eye scanner mechanism, the piston rod 93 is further retracted to withdraw the heater block 91 and thus the jaw retraction plates 97 against the shoulders 81 of pins 75. Thus the pins 75 are slidably carried against the pressure of springs 34 through the plate 45 until the plates 97 abut the ends of collars 79. This position of the parts is shown by Fig. 7. The clamping jaws are parted to free the end closure seals, a filled and sealed package at the bottom dropping away from the clamp assemblies and the sealed bottom of the upper package length hanging in position to receive its contents from the tube 8 of Fig. .1.

'If the tube feeding downstroke at this juncture coincides with the full mechanical downstroke of the drawbar mechanism the opposed clamping assemblies are spread apart for a return or upstroke. downstroke is to continue the clamps remain parted as in the position of Fig. 7 until the end of the stroke is reached, whereupon the

plates

45 and 46 are retracted to commence the upstroke.

The electric eye actuation of cylinder 94 to retract piston rod 93 in the sequence of operations just described is in response to the position of suitably spaced marks M (Fig. 1)- on the web of material. The eyes not shown) may be placed so as to scan the marks as the formed tubes leave the formers 3. The tube feeding movement is thus accurately interrupted to provide successive packages of the desired equal length from each column.

All the operations as detailed are accompiished in a manner best shown by the diagrammatic illustration of the hydraulic and electrical mechanism in 3. It will be realized that the valves and cylinders not before referred to may be mounted at suitable locations on the frame 1 of the machine of Fig. 1.

If the draw bar An hydraulic pump 105, driven by main drive shaft 12 through a pulley 1% (Fig. l) supplies pressure for operation of the cylinder 3r: which as has been said is to turn shafts 2-7 and advance andretract' the draw-bar clamp assemblies. It also supplies pressurefor each of the two cylinders as at 94 and 94 in Fig; 8. The mechanical operation of cylinder 94 has been described in connection with Figs. 47.- Cylinder 94' operates in the same way in connection with the second column of a duplex machine.

In Fig. Spump supplies pressure through line 107 to a conventional solenoid valve 8-1 which is connected to alternately supply pressure and to exhaust opposite ends of cylinder 36 through

lines

108 and 109. The pump also supplies pressure to a conventional solenoid valve S-3' which in turn is connected to supply the head ends'of cylinders 94 through a line as will be described, and to supply conventional solenoid valves S-2 and S to supply pressure to the rod ends of cylinder 94. A common return line 110 is connected to each of the solenoid valves.

A cycle illustrating the sequence of operations of the cylinders will be described beginning at the top of a downstroke. It will be realized the heater block piston rods 93 are extended and that the position of rod 35 has advanced the-draw-bar frame assemblies to gripping position. Line 109is under pressure from valve S-1 and line 108 is open to exhaust.

Valve 8-3 is here set to deliver pressure to line 110 and via branched conduits 111 and 112 to the head end of cylinder 94. Through branch conduit 113 the head end of cylinder 94 is under pressure from line 110. Thus the rods 93' and 93 of these cylinders are advanced. In the branch 111' and line 110 shut-off valves 114 are provided. These valves are normally open for passage of fluid. As will be later explained the valves 114 may be closed it a double retraction stroke is not desired in the cycle of operation as when the machine is being used with sheet material not requiring critical heat seal control. While the apparatus shown is specifically designed for operation in connection with special sheet material, it may also be used with standard types of heat scalable materials without the sequence being described. As will also be explained in this connection, the head ends of the cylinders 94 and 94' are connected via lines 115 and 116 to solenoid valves S-4 and 8-2. In these lines shut-oif valves 117 are provided. When the shut-oft valves 114 are opened, valves 1-17 are closed for operation of the double retraction stroke of cylinders 94 and 94 (and vice versa) for eliminating the double stroke.

Valve S3 is also connected through outlet 118' and branch 119 to solenoid valve 8-2; via branch 120 to solenoid valve 8-4; and by branch 121 to a pair of control cylinders generally indicated by 122 and 122. The latter are, as shown, each connected by

lines

123 and 124 to the rod ends of cylinders 94 and 94', respectively. Lines 123 and 124' are each provided with a pair of check valved passages.

Passages

125 and 126 of line 123 connect with solenoid valve S-2 via line 127.

Passages

128 and 129 connect with solenoid valve S-4 via line 130.

The check valve operations will be later described. At this stage the check valves are closing oil passage to or from valves S-2 and- 8-4 since at the top of the stroke the lines between solenoid valve 8-3 and valve S2, valve 5-4, and the

control cylinders

122 and 122 are open to exhaust. It will also be noted in. this condition of the system rods 131 of the control cylinders'are retractedinwardly. The volume of fluid in these cylinders and deliverable to the rod ends of cylinders 94 and 94', respectively, is of a metered amount and suflicient to cause the desired partial retraction of the rods 94 and 94' at the next stage of operation. It will also be noted that the outward extension of each control cylinder rod 131 may be against an adjustable stop provided by the members 132 threaded in the fixed overhanging supports 133 of each assembly.

As previously'set forth the draw-bar assembly descends from its uppermost position for a selected time interval during which the heat sealers are engaged and when the required heat application is made the piston rod 93 is partially retracted (see Fig. -6) to separate the sealing elements.

This is accomplished by an electric circuit (designated by single lines) in which a micro switch 135 is actuated as by an adjustable cam 134 mounted on the main drive shaft 12. Switch 135 is connected to an electric distributor 136 to open and

close circuits

137, 138, and 139 to valves 8-3, 8-2, and 8-4.

In the hydraulic system valve S-1 remains unchanged. Valve S-3, now actuated, opens to exhaust the line leading to the head ends of

cylinders

94 and 94 and supplies pressure to valves S-2 and 8-4 and to the control cylinders. Valves S-2 and 5-4, however, change only in that they are set to deliver pressure to lines 116 and respectively. Since shut-oil. valves 117 are normally closed in the system being described this operation of valves S-2 and 8-4 does not affect

cylinders

94 and 94 in any manner. Lines 127 and to the check valve ports to

lines

123 and 124 remain open to exhaust.

The delivery of pressure to control cylinders 122 and 122' causes the delivery of fluid via

lines

123 and 124 to the rod ends of cylinders 94 and 94' and causes partial retraction of the

rods

93 and 93. The extent of retraction (which is governed by the extension of rods 131 against adjustable stop members 132 of the control cylinders) may be indicated as by the line at between the cylinders 94 and 94', metered flow from the control cylinders and the adjustable check valves 141 which permit flow at a later stage to lines 127 and 130 of valves S-2 and 5-4 are not overcome by the pressure delivered at this stage to the cyling stroke is reached (Fig. 7).

In the hydraulic system valve S-3 continues to keep line 110 and the head ends of cylinders 94 and 94' open to exhaust, and to deliver pressure to valves S-2, valve 8-4, and control cylinders 122 and 122'. Valves S-2 and &4 are now, however, changed to open sealed lines 116 and 115 to exhaust and to deliver pressure to lines 127 and 130 which lead to the check valved branches of

lines

123 and 124. As will be seen the lower check valves 141 seal against flow through

branches

126 and 128. Fluid under pressure does, however, flow through check valves 145 to

lines

123 and 124. Pressure is thus delivered to the rod ends of cylinders 94 and 94' and the pistons are thus fully retracted (the head ends being open to exhaust). Pressure is also exerted to the rodends of the

control cylinders

122 and 122. exerted at the head end thereof from valve 8-3 the rods Ietain their extended position. Thus the clamping jaws are retracted by the full retraction of

rods

94 and 94 At the bottom of the full draw-bar stroke a earn trips a micro switch 151 governing solenoid valve S-1 via circuit 152 and reversing the conditions in lines 108 and 108'. Pressurevia line 108 is delivered to spread the draw-bar units apart for the return upstroke. Valves 8-3, 8-2, and 5-4 remain unchanged and 36, 94 and 94 are in fully retracted condition.

It may also be noted here that in the event an electric eye fails to find an indicator mark on the package being formed so as to end the feeding downstroke and thus the grippers failto release the package as desired, the switch 151 operating to actuate valve 8-1 for retracting the rod The flow to the rod ends is a Since an equivalent pressure is 8 37, also operates to trigger the electric eye mechanism and thus hydraulically retract rods 93 or 93' fully. As will be understood, the rods are also mechanically being retracted with the draw-bar frames.

On the upstroke a further sequence of operations is effected. Represented by a cam 153 and switch 154 the circuits are actuated as follows. The electric eyes are reset for the next scanning operation. Solenoid valves S-d are actuated to open both outlet lines 127 (Check valves 145 thus return to seats against subsequent flow from

control cylinline

123 and 124 and adjustable valves 141 remain yieldably seated against flow from these lines except an: r pr sures of a predetermined value.)

salve 3-3 is also actuated to open to exhaust l to valves 8-?- and 8-4 and to control

cylinders

122 and 122'. in order to advance the clamping jaws and heaters again, line 1113 to the head end of cylinders 94 and 9'4 is again supplied with pressure. The full amount of fluid at the rod end of

cylinders

94 and 94 as will be understood. is greater than the capacity of the control cylinders 122 and 12.2 (since the latter are for partial retraction only). Thus, when pressure is exerted at the head end of cylinders 94 and 94' the amount of flow to the controls cylinders via lines 123 and is far greater than that necessary to recharge the cylinders. The check valves 141 (which, as shown, may be adjustably set) relieve

conduits

123 and 124 of all excess fluid by opening .he

passages

126 and 128 to exhaust through lines and 139 to valves 8-2 and 5-4.

Thus as the draw-bar assembly reaches the top of its stroke, the gripper and heater elements (actuated by the extension of the rods of cylinders 94 and 94) are advanced into position to clamp against opposite sides of the tubular package web.

At the top of the stroke a final cam 155 trips a switch 156 actuating solenoid valve 5-1 to reverse the condition in the outlets therefrom. Line 109 is placed under pressure and line 1% opened to exhaust. The draw-bar assembly is advanced and the cycle is completed to grip and form the bottom and top seals of successive package lengths and to repeat the sequence of operations as described.

As previously mentioned the step by step retraction of rods 93 and 93' may be eliminated by closing off valves 119 (shutting off flow from valve S-3) and opening valves 117 to supply pressure to the rod ends of

cylinders

94 and 94 directly from valves S-2 and 8-4 through lines 116 and 115, respectively. Thus when valve 5-3 is actuated and 5-2 and S-4 also, line 110 can be opened to exhaust and pressure supplied through 8-2 and 8-4 to lines 116 and 115, check valves 145, and the

rod end lines

123 and 124. The full retraction then of rods 93 and 93' separates the heaters and clamping means at one time. The electric eye circuits may be set to control the actuation of the solenoid valve circuits which as previously mentioned were responsive to cam 134 and switch 135.

What is claimed is:

1. In a tubular package forming machine having a reciprocable clamp device including opposed gripping members and heat sealing members to grip, seal, and feed a package length of tube during a portion at least of one stroke of clamp reciprocation, in combination, means to close said clamp on the tube including yieldable means advancing one of said gripping members in oppositely extended relation to the other member and heat seal advancing means effective on the closing of said clamp to hold one of said sealing members in extended position for tube engagement with said latter sealing member being slidable relative to said yieldably urged gripping member and positioned at an outer limit of travel, means to then move said clamp to feed the tube, selectively adaaszsss from extended position and independently of said closed position of said gripping members for completing the cycle for sealing said tube, means responsive to the position of the tube to subsequently complete a full inward stroke of movement of said slidable member, said slidable member being engageable adjacent its inner limit of movement with said yieldable means of the said one gripping member and effecting withdrawal of the latter from tube engagement to complete the tube feeding movement of said clamp, and means effective on completion of said one stroke of clamp reciprocation to open said clamp closing means to permit return of said clamp to the opposite end of its reciprocating stroke and at said latter end to advance said slidable heat sealing member to its outer position of travel to repeat a gripping, sealing and feeding cycle on a succeeding portion of the tube.

2. In a tubular package forming machine having drawbar mechanism comprising a reciprocable clamp device with opposed gripper members and heat sealing members to grip, seal, and feed a package length of tube during a portion at least of one stroke of its reciprocation, in combination, means to close said clamp device, means to then move said device in tube feeding direction, one of said heat sealing members being associated with a gripper member and movable relative thereto and hydraulic power means for actuating said sealing member independently of said clamp closing means, said power means being effective to extend said one sealing member for tube engagement on closing said clamp device and having a two-stage retraction withdrawal stroke from said extended position, means operated in response to a selected position of tube feed towithdraw said sealing member for a first retraction stage to complete a sealing cycle, said associated gripper member being yieldably mounted to extend in tube engaging position relative to the other gripper member and having means interengageable with said movable sealing member during further withdrawal of the latter to oppose said yieldable mounting and retract said gripping member and means responsive to an actuator on the tube being fed for withdrawing said sealing member for a second retraction stage to part said gripping members and terminate the feed of said tube.

3. The structure of claim 2 in which said gripper members comprise opposed pairs of vertically spaced jaws and said sealing members comprise opposed pairs of vertically spaced heat sealing elements, and tube severing members are positioned between said spaced pairs of sealing elements, the severing member between said power operated scaling members being movable therewith.

4. The structure of claim 3 in which cooling means are mounted with said gripping members adjacent the 10 position of said heat sealing members for cooling the sealed areas of said tube on withdrawal of said powered operated sealing member and prior to the release of said tube.

5. Draw-bar mechanism for automatic packaging machines adapted to grip, feed, and transversely seal a tubular container package and comprising a pair of reciprocable frames having clamp members with oppositely disposed pairs of vertically spaced gripper jaws with means to advance and retract said clamp members to and from gripping relation, a pair of vertically spaced heat sealing elements with tube severing means between same mounted on the frames between the jaws of each clamp with one of said pair of sealing elements being independently movable on its frame to an advanced sealing position and having means for retracting the same therefrom in two stages, the pair of vertically spaced gripper jaws associated with said movable sealing elements having a spring urged mounting on the frames thereof for an extended gripping position and engageable by said movable elements for withdrawal from said gripping position to release the tube while the frame mounted clamp members are in advanced condition.

6. Draw-bar mechanism for automatic packaging machines adapted to grip, feed, and transversely seal a tubular container package and comprising a pair of reciprocable clamp members having oppositely disposed pairs of vertically spaced gripper jaws with means to advance and retract said members towards and away from opposed gripping relationship, opposed heat sealing members mounted between the jaws of each clamp member, one of said sealing members being movable relative to the jaws of the clamp member on which the same is mounted, and power means to advance and retract said movable sealing member independently of References Cited in the file of this patent UNITED STATES PATENTS Patterson Sept. 18, 1945 Andina May 19, 1953