US3698310A

US3698310A - Strapping machine

Info

Publication number: US3698310A
Application number: US107269A
Authority: US
Inventors: Robert F Plattner; James A Kocian
Original assignee: Interlake Inc
Current assignee: Acme Steel Co; Interlake Cos Inc
Priority date: 1971-01-18
Filing date: 1971-01-18
Publication date: 1972-10-17
Anticipated expiration: 1989-10-17

Abstract

A strapping machine of the type including gripping means for holding the strap encircled in a loop about the object, seal feed mechanism, gathering jaws, tensioning means, sealing jaws, crimping die members and a shear blade, also comprises a single air-actuated piston adapted for reciprocating movement in directions substantially normal to the plane of the strap in the sealing region, the piston driving a crosshead having cam surfaces and abutment surfaces thereon respectively operative to produce substantially simultaneously a cammed movement of the sealing jaws to their sealing configuration, movement of the die members to their crimping position, movement of the shear blade to its shearing position and opening of the gathering jaws, all during a single stroke of the crosshead; novel linkage for coupling the piston to the crosshead is also disclosed.

Description

United States Patent Plattner et al.

[ STRAPPING MACHINE [72] lnventors: Robert F. Plattner, Chicago Heights;

James A. Kocian, Evergreen Park, both of I11.

[73] Assignee: Interlake, Inc., Chicago, Ill.

[22] Filed: Jan. 18, 1971 [21] Appl. No.: 107,269

[52] U.S. Cl ..100/4, 100/30 [51] Int. Cl. ..B65b 13/34 [581 Field of Search ..100/4, 26, 30; 140/934 [56] References Cited UNlTED STATES PATENTS 3,066,599 12/1962 Koehler ..100/26 X 3,104,606 9/1963 Kerrigan 100/30 X 3,139,813 7/1964 Hall et al. ..100/30X 3,120,171 2/1964 Hall et al. ..100/26 3,493,014 2/1970 Orban et al. ..100/30 X 3,232,217 2/1966 Harmon et al ..100/26 3,215,064 11/1965 Koehler ..100/30 X [451 Oct. 17,1972

Primary Examiner-Billy J. Wilhite Attorney-Prangley, Dithmar, Vogel, Sandler & Stotland [57] ABSTRACT A strapping machine of the type including gripping means for holding the strap encircled in a loop about the object, seal feed mechanism, gathering jaws, tensioning means, sealing jaws, crimping die members and a shear blade, also comprises; a single air-actuated piston adapted for reciprocating movement in directions substantially normal to the plane of the strap in the sealing region, the piston driving a crosshead having cam surfaces and abutment surfaces thereon respectively operative to produce substantially simultaneously a cammed movement of the sealing jaws to their sealing configuration, movement of the die members to their crimping position, movement of the shear blade to its shearing position and opening of the gathering jaws, all during a single stroke of the crosshead; novel linkage for coupling the piston to the crosshead is also disclosed.

PATENTEDnm 17 I972 SHEET 1 0F 9 INVENTOR$ ROBERT F: PLATTNER JAMES A. KOC/AN Jab Jmf PATENTEDHBI 17 I972 PPM SHEET 0F 9 MTENTEDnm 11 m2 SHEET 6 0F 9 N at STRAPPING MACHINE This invention relates to strapping machines, and in particular machines for automatically securing a length of flat strap around an object.

It is a general object of this invention to provide an improved strapping machine of simple construction and operation having a minimum of wearable moving parts.

It is an important object of this invention to provide a strapping machine for applying a length of flat strap around an object, said strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof and with one surface of the strap disposed in a predetermined plane, tensioning means for tensioning the loop of strap about the object by withdrawing the supply portion thereof relative to the leading end thereof, joint forming jaws movable between a retracted configuration accommodating tensioning of the strap loop by the tensioning means and a joint forming configuration for securing together the overlapped portions of the tensioned strap to provide a joint therebetween, a single fluid-actuated drive motor adapted for reciprocating movement in directions substantially normal to the predetermined plane of the overlapped portions of the strap, and drive linkage coupling the drive motor to said joint forming jaws for effecting movement thereof between the retracted configuration thereof and the joint forming configuration thereof.

It is another object of this invention to provide a strapping machine of the type set forth for applying a length of strap around an object, the strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof, tensionin g means for tensionin g the loop of strap about the object by withdrawing the supply portion thereof relative to the leading end thereof, a joint forming jaw assembly having cam follower surfaces thereon and being movable between a retracted configuration and a joint forming configuration, the joint forming jaw assembly in the retracted configuration thereof accommodating tensioning of the strap loop by the tensioning means, the joint forming jaw assembly in the joint forming configuration thereof securing together the adjacent overlapped portions of the tensioned strap to provide a joint therebetween, a crosshead having camming surfaces thereon respectively disposed in camming engagement with said cam follower surfaces on the joint forming jaw assembly, and drive mechanism coupled to the crosshead for effecting movement thereof in a predetermined direction to thereby effect a cammed movement of said joint forming jaw assembly from the retracted configuration thereof to the joint forming configuration thereof.

In connection with the foregoing object, it is another object of this invention to provide a strapping machine of the type set forth, wherein said strap is flat with one surface of the overlapped portion thereof being disposed in a predetermined plane, said drive mechanism including a single fluid-actuated drive motor adapted for reciprocating movement in directions substantially normal to the predetermined plane.

It is another object of this invention to provide a strapping machine of the type set forth, which further includes a shear blade movable between a retracted position out of engagement with the strap and a shearing position for severing the completed strap loop from the supply portion of the strap, said crosshead having an abutment surface thereon disposed for driving engagement with the shear blade to thereby effect movement thereof from the retracted position to the shearing position thereof in response to movement of the crosshead from the first position thereof to the second position thereof.

It is another object of this invention to provide a strapping machine of the type set forth, which further includes seal feed mechanism for feeding a seal from a supply thereof to a joint forming region adjacent to the overlapped portions of the strap, and a die member movable between a retracted position disposed out of the sealing region and a sealing position disposed in the sealing region for crimping the side edges of the seal and the side edges of the strap to facilitate the formation of the seal joint therebetween, the crosshead having an abutment surface thereon disposed for driving engagement with the die member to thereby effect movement thereof from the retracted position to the sealing position thereof in response to movement of the crosshead from the first position to the second position thereof.

It is another object of this invention to provide a strapping machine of the type set forth, including both a shear blade and a die member constructed and operated in the manner set forth.

It is another object of this invention to provide a strapping machine of the type set forth, which further includes strap gathering means movable between a closed condition engaging the strap for limiting the longitudinal movement of the leading end thereof along the supply portion thereof and an open condition out of engagement with the strap, said crosshead having an abutment surface thereon disposed for driving engagement with the strap gathering means to thereby effect movement thereof from the closed condition to the open condition thereof in response to movement of the crosshead from the first position to the second position thereof.

It is another object of this invention to provide a strapping machine of the type set forth, which includes a shear blade and a die member and strap gathering means, all constructed and operated in the manner set forth.

It is still another object of this invention to provide a strapping machine for applying a length of flat strap around an object, the strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof and with one surface of the strap disposed in a predetermined plane, tensioning means for tensioning the loop of strap about the object by withdrawing the supply portion thereof relative to the leading end thereof, joint forming jaws movable between a retracted configuration accommodating tensioning of the strap loop by the tensioning means and a joint forming configuration for securing together the overlapped portions of the tensioned strap to provide a joint therebetween, a single fluid-actuated drive motor assemblies;

having a fixed piston rod and a cylinder mounted for reciprocating movement relative thereto in directions substantially normal to the predetermined plane of the overlapped portions of the strap, a lever coupled to the cylinder and mounted for pivotal movement about a predetermined axis in response to the reciprocating movement of the cylinder, and drive linkage coupling the lever to the joint forming jaws for effecting movement thereof between the retracted configuration thereof and the joint forming configuration thereof in response to the pivotal movement of the lever.

In connection with the foregoing object, it is another object of this invention to provide a strapping machine of the type set forth, which includes a crosshead and a shear blade and a die member and strap gathering means of the type set forth all constructed and operated in the manner set forth.

Further features of the invention pertain to the particular arrangement of the parts of the strapping machine whereby the above-outlined and additional operating features thereof are attained.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood with reference to the following specification taken in connection with the accompanying drawings, in which:

FIG. 1 is a reduced fragmentary front elevational view of a strapping machine constructed in accordance with the present invention;

FIG. 2 is a front elevational view of the strapping head of the strapping machine of FIG. 1, embodying the features of and constructed in accordance with the present invention;

FIG. 3 is a top plan view of the strapping head of FIG. 2;

FIG. 4 is a reduced perspective view of an object after it has had strap bands secured therearound by the strapping machine of the present invention;

FIG. 5 is an enlarged perspective view of a completed seal joint produced in a strap by the strapping machine of the present invention;

FIG. 6 is a side elevational view of the strapping machine of FIG. 2, as viewed from the left-hand side thereof;

FIG. 7 is an enlarged fragmentary cross-sectional view of the eccentric shaft assembly, taken along the line 77 in FIG. 2;

FIG. 8 is a fragmentary top plan view of the track switch assembly of the strapping machine of the present invention, as viewed along the line 88 in FIG.

FIG. 9 is an enlarged front elevational view of the central portion of the strapping machine illustrated in FIG. 2, showing the strap gripping, sealing and seal feed FIG. 10 is a fragmentary side elevational view of the seal feed assembly of FIG. 9, as viewed from the righthand side of FIG. 9;

FIG. 11 is a fragmentary view in vertical section of the strap gripping assembly taken along the line l1--11 in FIG. 9, with portions of the assembly broken away to show the strap gripping jaws;

FIG. 12 is a fragmentary view in vertical section of the sealer assembly, taken along the line 12-12 in FIG. 9;

FIG. 13 is a further enlarged fragmentary view of a portion of the sealer assembly illustrated in FIG. 12, showing the crosshead in midstroke with the sealing jaws in their sealing configuration and the shear blade about to engage the strap;

FIG. 14 is a view similar to FIG. 13, showing the crosshear at the end of its downward stroke with the shear blade having severed the supply portion of the strap;

FIG. 15 is a view in vertical section of the sealer assembly taken along the line 15-15 in FIG. 14;

FIG. 16 is a fragmentary view in vertical section taken along the line 16l6 in FIG. 15, and showing the sealing jaw assembly in its fully retracted configuratron;

FIG. 17 is a view similar to FIG. 16, and showing the sealing jaw assembly in its sealing configuration, with the crosshead at the bottom of its stroke and the die member in crimping engagement with the sealed joint;

FIG. 18 is a fragmentary view in vertical section of the gathering jaw assembly, taken along the line 18- 18 in FIG. 9;

FIG. 19 is a schematic diagram of the pneumatic control circuit for the strapping machine of the present invention;

FIG. 20 is a diagrammatic representation of the strapping head of the present invention, illustrating the configuration of the parts immediately after the feeding of the strap around the object;

FIG. 21 is a diagrammatic representation similar to FIG. 20, and illustrating the configuration of the parts after the tensioning operation, with the crosshead in midstroke immediately before its engagement with the shear blade and die members;

FIG. 22 is a diagrammatic representation similar to FIG. 20, and illustrating the configuration of the parts immediately after engagement of the crosshead with the shear blade and die members; and

FIG. 23 is a diagrammatic representation similar to FIG. 20 and illustrating the configuration of the parts at the completion of the shearing and crimping operations, with the crosshead at the bottom of its stroke.

Referring now to FIG. 1 of the drawings, there is shown a strapping machine, generally designated by the numeral 40, for use in securing a strap web 35 about an object 30. The strapping machine 40 may include a main support stanchion 42 and one or more support legs 44, and a plurality of horizontally disposed parallel rollers 45 supported between the stanchion 42 and the legs 44 and defining a conveyor bed for supporting the object 30 during the strapping operation. Slidably mounted on the stanchion 42 for vertical adjustment therealong is a mounting arm 46 supporting thereon a strapping head, generally designated by the numeral 50, constructed in accordance with and embodying the features of the present invention. The strapping head 50 is preferably disposed immediately above the rollers 45, its position being vertically adjustable to accommodate different size objects 30.

Referring more particularly to FIGS. 2 through 8 of the drawings, the strapping head 50 includes a generally rectangular support plate 51 on which the other components of the strapping head are mounted. Hereinafter, the side of the main support plate 51 as viewed in FIG. 2 will be referred to as the front side of the strapping head 50, with the opposite side thereof being referred to as the rear side of the strapping head 50. An air motor 55 is disposed through a complementary opening in the main support plate 51 and is secured thereto by means of a plurality of mounting bolts 56. The air motor 55 may be provided with a muffler 57 and rotatably drives an output shaft 58 which has secured to the front end thereof a rotary dog or feed wheel 60. The circumferential outer surface 61 of the rotary dog 60 is disposed for frictional engagement with the circumferential outer surface 62 of an idler wheel 65 which is mounted for rotation about a shaft 63. As is best illustrated in FIG. 7, the idler wheel 65 is mounted on the shaft 63 by means of ball bearings 64, the rear end of the shaft 63 being secured to an eccen tric plate 66. Also secured to the plate 66 and extending rearwardly therefrom substantially parallel to the shaft 63 but eccentric therewith is a shaft 67 mounted in a ball bearing assembly 68 which is secured to the main support plates 51 by means of mounting bolts 69. Secured to the shaft 67 adjacent to the rear end thereof is a manual feed lever 70 which extends radially upwardly from the shaft 67 and is provided with a handle 71 at the upper end thereof. Also secured to the rear end of the shaft 67 is a torsion spring 72 which urges the idler wheel 65 into engagement with the rotary dog 60. A cover plate 73 is secured to the rear end of the shaft 67 to protect the torsion spring 72 and the other parts of the assembly described above. Also connected to the shaft 67 is an actuator arm for a tension switch (not shown), the construction and operation of which are disclosed in the copending application, Ser. No. 63,479, entitled STRAPPING MACHINE, filed by Frank C. Weller on Aug. 13, 1970, and assigned to the assignee of the present invention, the disclosure of which application is incorporated herein by reference.

Secured to the front side of the main support plate 51, adjacent to the periphery of the idler wheel 65, is an arcuate guide shoe 75, secured in place by a locking screw 76 and serving to guide the leading end of the strap 35 from the rotary dog 60 in a counterclockwise direction around the idler wheel 65, as viewed in FIG. 2. Secured to the main support plate 51 along the bottom edge thereof are a pair of side plates 77, respectively provided with retaining flanges 78 extending in wardly toward each other for guiding the leading end of the strap web 35 from the guide shoe 75 toward a straightener assembly, as will be described more fully below. The side plates 77 are urged toward each other by means of tension springs 79, the springs 79 permitting separation of the side plates 77 to accommodate removal of the strap web 35 from therebetween during the tensioning operation, as will be described more fully hereinafter.

Referring now also to FIG. 9 of the drawings, a straightening cylinder 80 is supported by means of a mounting bracket 81 immediately above the right-hand end of the side plates 77. The straightening cylinder 80 is provided with a piston rod 82 extending downwardly from the bottom end thereof and engageable with the front end of a lever 83 which is mounted at the rear end thereof for pivotal movement about a substantially horizontal axis, as viewed in FIG. 9. Disposed immediately beneath the lever 83 intermediate the front and rear ends thereof is a plunger 84a carrying a straightening roll 84 at the bottom end thereof. A backing plate 85 extends from between the side plates 87 beneath the straightening roll 84 and to the right as viewed in FIG. 9, the backing plate 85 having an arcuate depression 86 therein immediately underlying the straightening roll 84.

In use, the leading end 36 of the strap web 35 is fed from between the guide plates 77 along the upper surface of the backing plate 85, to the right as viewed in FIG. 9. When air is admitted to the upper end of the cylinder 80, the piston rod 82 is depressed, thereby engaging the lever 83 and pivoting it downwardly for thereby depressing the plunger 84a and the guide roll 84 toward thearcuate depression 86 and the backing plate 85 for frictionally engaging the strap web 35 therebetween. A pair of side plates 87 are respectively disposed on opposite sides of the backing plate 85 adjacent to the arcuate depressions 86 therein, the side plates 87 being respectively provided with retaining flanges 88 extending inwardly toward each other for a purpose to be described below. The side plates 87 are urged toward each other by springs 89 in the same manner as was described above with respect to the side plate 187.

Disposed rearwardly of the side plates 87 is a track switch assembly, generally designated by the numeral 90, and best illustrated in FIG. 8 of the drawings. The track switch assembly 90 includes a generally Z-shaped lever 91 pivotally mounted as at 92. At the front end of the lever 91 is a strap-engaging finger 93 extending into the strap path between the side plates 87 and beneath the backing plate 85. The rear end of the lever 91 is secured to a switchactuating bolt 94 which is disposed in engagement with the plunger 96 of an electric switch 95. A tension spring 97 is connected between the lever 91 and an anchor bolt 98 on the housing of the switch for biasing the bolt 94 against the plunger 96 to hold the plunger 96 depressed for maintaining the switch 95 in a predetermined condition. In operation, when the leading end 36 of the strap web 35 passes beneath the backing plate 85 and between the: side plates 87 after having encircled the object 30, it engages the finger 93 for pivoting the lever 91 in :a counterclockwise direction, as viewed in FIG. 8, and thereby actuating the track switch 95 to its opposite condition.

Referring now also to FIG. 11 of the drawings, the sealing and gripping assembly, generally designated by the numeral 100, will be described. Disposed against the front surface of the main support plate 51 is a mounting bracket 101, including a stem 102 and carrying a pair of spaced-apart and rearwardly extending arms 103 at the upper end thereof. The mounting bracket 101 is disposed with the stem 102 thereof flat against the front surface of the main support plate 51, with the arms 103 overlying the upper edge of the main support plate 51. Set screws 104 are respectively received through complementary openings in the arms 103 and bear against the upper edge of the main support plate 51 for supporting the mounting bracket 11. The stem 102 may be secured to the main support plate 51 by suitable mounting bolts (not shown). Respectively secured to the opposite side edges of the mounting bracket stem 102 by means of mounting bolts 107, and extending forwardly therefrom are two spaced apart

parallel side plates

105 and 106. Also secured to the right-hand side of the side plate 106 by means of the bolts 107 is a side plate 106a, which extends upwardly above the upper edge of the side plate 106 and is provided with an irregularly shaped opening 106b at the lower end thereof. Disposed between the

side plates

105 and 106 and secured thereto by means of bolts 109, are a plurality of spacers 108.

Disposed along the outer surface of the side plate 105 are a pair of spaced-apart vertically extending support posts 111, the posts 111 being interconnected by a generally rectangular cover plate 113 disposed substantially parallel to the side plate 105, the posts 111 and cover plate 113 all being secured to the sideplate 105 by mounting bolts 112. Spanning the upper ends of the support posts 111 and secured thereto by mounting screws 116 is a generally rectangular horizontally disposed support plate 114. A vertically extending drive cylinder 115 is secured to the mounting plate 114 by means of a mounting nut 117, the cylinder 115 having a piston rod 118 extending vertically downwardly therefrom through a complementary opening in the mounting plate 114 and between the side plate 105 and cover plate 113. Secured to the piston 118 at the lower end thereof is a coupling member 1 19.

A pair of spaced-apart gripping jaws 120 are respectively mounted for pivotal movement about a pair of spaced-apart parallel pivot pins 121 which extend through complementary openings in the

side plates

105, 106 and 106a substantially normal thereto. The upper ends of the gripping jaws 120 are respectively coupled to the adjacent ends of a pair of coupling links 122 by means of coupling pins 123, the opposite ends of the links 122 being coupled to the lower end of the coupling member 119 by a connecting pin 124. Disposed between the gripping jaws 120 is a bridge member 125 having a generally rectangular recess 127 in the lower end thereof shaped complementary to the strap web 35. The lower end of the bridge 125 is disposed against the upper surface of the backing plate 85, the notch 127 cooperating with the upper surface of the backing plate 85 to provide a channel to accommodate passage of the strap web 35 therethrough. The lower surface of the backing plate 85, directly beneath the bridge 125, has a ribbed gripping surface thereon for cooperation with a plurality of gripping teeth 126 on the lower ends of the gripping jaws 120 to secure the leading end 36 of the strap web 35 therebetween, as will be described more fully hereinafter.

In operation, when air is admitted to the upper end of the cylinder 115, the piston rod 118 is extended downwardly for thereby separating the upper ends of the gripping jaws 120 and pivoting the gripping teeth 126 thereof inwardly and upwardly toward the gripping surface on the backing plate 85, for thereby securely holding the leading end 36 of the strap web 35 against the backing plate 85. The piston rod 118 is provided with a return spring, so that when the supply of air to the upper end of the cylinder 115 is shut off, the piston rod will be retracted upwardly into the cylinder 115 for thereby reopening the gripping jaws 120.

Referring now also to FIGS. 12 through 18 of the drawings, there is shown the details of a sealer assembly, generally designated by the numeral 130. A mounting bracket, generally designated by the numeral 131, is attached to the main support plate 51 for supporting the sealer assembly 130. More particularly, the mounting bracket 131 includes an upstanding attachment post 132 lying against the rear surface of the main support plate 51 and secured thereto by suitable means. The upper end of the attachment post 132 is provided with a clevis-shaped neck 134 extending forwardly over the upper edge of the main support plate 51 between the arms 103 of the mounting bracket 101. An arm 135 extends rearwardly from the bottom end of the attachment post 132 and is provided with an elongated slot 136 therein for accommodating passage of air conduits therethrough.

Disposed rearwardly of the main support plate 51 is a sealer drive cylinder 140, having a head plate 141 and a base plate 142 interconnected by a plurality of connecting rods or bolts 143. Extending vertically downwardly from the lower end of the cylinder is a piston rod 145 coupled at the lower end thereof to a clevis connector 146, which is in turn pivotally secured to the rear end of the arm 135 by means of a pivot pin 147 extending through complementary openings in the arm 135 and the clevis connector 146 and held in place with a cotter pin 148. Extending outwardly from the right and left sides of the base plate 142 of the cylinder 140, as viewed in FIG. 3, are a pair of trunnions 149, which are respectively mounted in a pair of bearings 151 of a trunnion yoke, generally designated by the numeral 150. The trunnion yoke is generally U- shaped and wraps around the front side of the cylinder 140 interconnecting the trunnion bearings 151. Extending forwardly and downwardly from the yoke 150, midway between the ends thereof, is an arm 152 the lower end of which is disposed between the arms of the clevis neck 134 on the mounting bracket 131 and is pivotally secured thereto by means of a pivot pin 153. The lower end of the arm 152 is also connected forwardly of the pivot pin 153 by means of a coupling pin 154 to the clevis-shaped upper end 156 of a coupling link 155. The coupling link extends vertically downwardly from the coupling pin 154 and terminates in a lower tongue end 157 which is coupled by means of a coupling pin 158 to the clevis-shaped upper end 161 of a crosshead, generally designated by the numeral 160.

The clevis is an elongated member which extends vertically downwardly from the connecting pin 158 and is provided with a stop tab 162 extending laterally therefrom intermediate the ends thereof and having a shoulder or bearing surface 162 along the upper edge thereof disposed for engagement with a stop member 163 which is mounted between the

side plates

105 and 106 and is channeled in a complementary groove 164 in the side plate 106. Extending laterally from the opposite side of the crosshead 160 intermediate the ends thereof, is an actuator arm 165 for a purpose to be described more fully hereinafter. Extending downwardly from the lower end of the crosshead 160 is a pair of feet 166 which cooperate to define a clevis. The lower end of each of the feet 166 is generally triangular in shape, having a pair of cam surfaces 169 converging downwardly to the flat bottom end of the foot, which defines a short horizontally extending abutment surface 168. Each of the feet 166 is also provided with a recess in the outer surface thereof which defines another horizontally extending abutment surface 167 parallel to the abutment surface 168 and disposed a slight distance thereabove.

Three pairs of sealing jaws 170 are respectively pivotally mounted on the pivot pins 121 between the

side plates

105 and 106. Each of the sealing jaws 170 is generally crescent shaped, with the jaws 170 of each pair of jaws being laterally spaced apart, as viewed in FIG. 12. The pairs of jaws 170 are separated from each other by means of two pairs of cam roll spacers 172, which are disposed adjacent to the upper ends of the jaws 170 and are secured thereto by a pair of coupling pins 173 extending through complementary openings in the spacers 172 and the jaws 170. Also respectively pivotally connected to the coupling pins 173 are the lower ends of two retracting links 174, the upper ends of which are disposed between the feet 166 of the crosshead 160 and are secured thereto by means of a pivot pin 177. The lower end of each of the sealing jaws 170 is shaped to form a sealing tooth or projection 175 adapted for sealing engagement with a suitable seal, as will be described more fully below. The pairs of sealing jaws 170 are also interconnected, intermediate the upper and lower ends thereof, by a pair of support pins 176 which are disposed substantially parallel to the pivot pins 121 and extend through complementary openings in the pairs of sealing jaws 170.

Respectively disposed between the adjacent pairs of sealing jaws 170 are two die members 180, each of which spans the adjacent pair of sealingjaws 170, being provided with a pair of vertically elongated slots 181 therein for respectively accommodating the pivot pins 121 therethrough. Extending laterally outwardly from the opposite side edges of each of the die members 180 adjacent to the upper edge thereof, are two stop tabs 182 which are respectively disposed immediately above the two support pins 176. Formed in the upper edge of each die member 180 and intermediate the opposite sides thereof is a bearing notch 183 shaped complementary to the lower end of the feed 166 on the crosshead 160. The bottom edge of each of the die members 180 is provided with a crimping notch 184 therein for a purpose to be described more fully below.

Disposed to the left-hand side of and spanning the left-hand pair of the sealing jaws 170, as viewed in FIG. 15, is a shear blade 185, provided with a pair of vertically elongated slots 186 therein for respectively accommodating the pivot pins 121 therethrough. The shear blade 185 is shaped similarly to the die members 180 and is provided with a pair of stop tabs 187 respectively extending laterally outwardly from the opposite side edges of the shear blade 185 and respectively immediately overlying the support pins 176. The upper edge of the shear blade 185, between the stop tabs 187, defines a bearing surface 188, and the lower edge of the shear blade 185 has a notch formed therein to define a cutting edge 189.

The sealing jaws 170 are so constructed and arranged that the feet 166 of the crosshead 160 are respectively disposed in vertical alignment with the cam roll spacers 172, the abutment surfaces 168 being respectively disposed in vertical alignment with the bearing notches 183 of the die members 180 and the left-hand one of the abutment surfaces 167, as viewed in FIG. 15, being disposed in vertical alignment with the bearing surface 188 on the shear blade 185. Thus,

in operation, when the sealer assembly is arranged in the retracted configuration thereof illustrated in FIG. 12 and 16, the drive cylinder will be in its downward position, whereby the coupling link 155 and the crosshead 160 will be held in their upward or retracted positions, with the bearing shoulder of the stop tab 162 in engagement with the stop member 163, and with the sealing jaws 170, the crimping die members 180, and the shear blade 185 all being held in their open or retracted positions. It will be noted that in this configuration, the crosshead feet 166 are disposed between the upper ends of the sealing jaws 170, with the camming surfaces 169 of each of the crosshead feet 166 being respectively disposed for camming engagement with the adjacent pair of cam roll spacers 172.

When air is admitted to the upper end of the cylinder 140, the cylinder 140 will move upwardly with respect to the fixed piston rod 145, thereby pivoting the trunnion yoke in a clockwise direction as viewed in FIG. 6, about the pivot pin 153. This pivotal movement of the trunnion yoke 150 serves to move the coupling link and the crosshead downwardly. This downward movement of the crosshead 160 urges the feet 166 between the upper ends of the sealing jaws 170, the camming surfaces 169 being moved into camming engagement with the cam roll spacers 172 for pivoting the sealing jaws into the closed or sealing configuration thereof, illustrated in FIGS. 13 15 and 17 of the drawings, with the sealing projections 175 thereof disposed relatively close together and in sealing engagement with the associated seal. As the downward movement of the crosshead 160 continues, the abutment surfaces 168 thereof will respectively move into the bearing notches 183 of the die members for engagement therewith, and the left-hand one of the abutment surfaces 167, will move into engagement with the abutment surface 188 on the shear blade 185. The continued downward movement of the crosshead 160 will serve to drive the die members 1 80 into crimping engagement with the associated seal, as will be described more fully below, and also serves to drive the cutting edge 189 of the shear blade down through the supply portion of the strap web 35, to the left-hand side of the seal joint, as is best illustrated in FIGS. 14 and 15, for severing the completed and sealed strap loop 38 from the supply portion of the strap web 35.

When air is removed from the upper end of the drive cylinder 140 and admitted to the lower end thereof, the cylinder 140 will be moved downwardly along the fixed piston rod 145, for thereby pivoting the trunnion yoke 150 in a counterclockwise direction, as viewed in FIG. 6 about the pivot pin 153. This pivotal movement of the trunnion yoke 150 pulls the coupling member 155 and the crosshead 160 back upwardly to the retracted positions thereof, illustrated in FIG. 12 of the drawings. This retracting movement of the crosshead 160 serves to reopen the sealing jaws 170, by means of the link members 174, this retracting movement of the crosshead 160 being limited by the engagement of the stop tab 162 with the stop member 163. Preferably, a certain amount of lost motion is designed into the link members 174 to prevent loading thereof by the cylinder 140 in the retracted position thereof. As the sealing jaws 170 are pivoted back to their open configuration, the support pins 176 thereon engage the stop tabs 182 on the die members 180 and thestop tabs 187 on the shear blade 185 for carrying the die members 180 and the shear blade 185 back up to their retracting positions. This retracting movement of the die members 180 and the shear blades 185 will be limited by the engagement thereof with the pivot pins 121 at the bottoms of the

elongated slots

181 and 186, as is best illustrated in FIGS. 12 and 16 of the drawings.

It will be noted that, since the trunnion yoke 150 is a fixed length rigid member, pivoting at one end thereof about a fixed pivot pin 153, the cylinder 140 must undergo a slight sidewise movement as it reciprocates along the piston rod 145. This sidewise movement is accommodated by the pivotal mounting of the piston rod coupling member 146 to the mounting bracket arm 135. Thus, as the cylinder 140 reciprocates and pivots with respect to the axis of the trunnion bearings 151, the piston rod 145 will pivot slightly about the axis of the pivot pin 147.

Extending through the side plate 106, and secured thereto by a nut 191, is a hollow shaft 190. Secured to the shaft 190 for pivotal movement therewith, between the

side plates

105 and 106, is a latch plate 192 being generally triangular in shape and having an arcuate notch 193 formed adjacent to one corner thereof. The latch plate 192 is also provided with a mounting pin 194 to which is coupled one end of a tension spring 195, the other end of which is secured to a similar mounting pin 196 on the side plate 106 for urging the latch plate 192 toward pivotal movement in a clockwise direction about the axis of the shaft 190, as viewed in FIG. 12. A latch bolt 197 extends through the hollow shaft 190 and is provided at one end thereof with a hook 198 between the

plates

105 and 106, the free end of the hook 198 being disposed in the arcuate notch 193 on the latch plate 192, whereby the latch bolt 197 is pivotally movable with the latch plate 192. The free end of the hook 198 is also adapted for engagement in a complementary opening in the side plate 106, as will be described below. The other end 199 of the latch bolt 197 extends through and beyond the

side plates

106 and 106a, to the right as illustrated in FIG. 2. The latch plate 192 is also provided with an annular cam member 200 secured thereto by a coupling pin 201 and a nut 202, the pin 201 extending through an elongated slot 203 in the side plate 106.

Referring now also to FIG. 18 of the drawings, it will be seen that the other end of the pin 201 also extends through an elongated slot 204 in a generally triangular shaped link 205, the link 205 being coupled by means of a pin 206 extending into and being guided by an elongated vertically extending slot or channel 208 in the side plate 106. The other end of the link 207 is coupled by means ofa coupling pin 209 to the upper end of one of a pair of gathering jaws 210, the upper end of the other of the gathering jaws 210 being connected by means of a coupling pin 212 to the triangular link 205. The gathering jaws 210 are respectively pivotally mounted on the pivot pins 121 and are each provided at the lower end thereof with a strap retaining shoulder 214 and with an inclined strap abutment surface 215. Disposed between the lower ends of the gathering jaws 210, and cooperating therewith to hold the strap web in place, is a spring loaded vertically extending plunger 217. It will be noted that the irregular opening 106b in the side plate 106a is shaped to accommodate the gathering jaws and the above-described linkage therefor.

Referring now also to FIG. 10 of the drawings, a seal feed assembly, generally designated by the numeral 220, is disposed to the right-hand side of the side plate 106a, as. viewed in FIGS. 3 and 9. The seal feed assembly 220 includes a seal magazine 221 extending vertically upwardly along the side plate 106a and secured thereto by suitable means such as mounting bolts 222. A stack of seals 225 is loaded into the seal magazine 221 from the top end thereof and is held in place by a weighted follower member 223. Secured to the lower end of the magazine 221 is a retaining plate 224 which retains the bottom one of the seals 225 in the magazine 221 in place and prevents it from falling from the magazine 221. Each of the seals 225 is a generally channel-shaped member having a back 226 of a width slightly greater than that of the strap web 35, and a pair of side rails or legs 227 diverging outwardly therefrom, the seals being arranged in the magazine 221 with the legs 227 extending downwardly.

Mounted upon the magazine 221 is a seal feed lever 230 provided at the upper end thereof with a clevis 231 which is pivotally secured by means of a pivot pin 232 to a mounting stub 233 on the seal magazine 221. Pivotally secured to the lower end of the seal feed lever 230 by means of a mounting pin 236 is a seal feed bar 235 which projects outwardly beyond the end of the seal feed lever 230. The seal feed bar 235 is further secured to the mounting pin 236 by a torsion spring 237 which urges the seal feed bar 235 toward pivotal movement in a counterclockwise direction about the coupling pin 236, as viewed in FIG. 9. Pivotally secured to the seal feed lever 230, by means of a coupling pin 238 is a coupling block 239, which is in turn secured to the lower end of a piston rod 241 of a drive cylinder 240, which is secured to the front surface of the main support plate 51 by means of a suitable mounting bracket 242. Connected to the coupling pin 236 is one end of a tension spring 244, the other end of which is secured to the seal magazine 241, for a purpose to be described more fully hereinafter. Attached to the latch bolt 197, to the right of the side plate 106a, as viewed in FIG. 9, are two spaced-apart

spring retainers

246 and 247, retaining therebetween a compression spring 245 which is coiled about the latch bolt 197. It will be noted that the coupling pin 238 is so arranged that when the seal feed lever 230 is disposed in the seal feeding position thereof illustrated in FIG. 9, the pin 238 is in engagement with the end 199 of the latch bolt 197.

In operation, air may be admitted to the lower end of the drive cylinder 240 for moving the piston rod 241 up and thereby holding the seal feed lever 230 back in a retracted position (not shown), wherein the seal feed bar 235 is withdrawn from the lower end of the seal magazine 221 and the coupling pin 238 is disposed out of engagement with the latch bolt 197, and whereby the latch bolt 197 is fully extended to the right as viewed in FIG. 9 by the compression spring 249. In this configuration, the free end of the hook 198 of the latch bolt 197 is engaged in the complementary opening in the side plate 106 for preventing pivotal movement of the latch bolt 197 and the latch plate 192. When air is ad mitted to the upper end of the drive cylinder 240, the piston rod 241 is extended, thereby pivoting the seal feed lever 230 into the seal feeding position thereof, illustrated in FIG. 9, the seal feed bar 235 being extended into the lower end of the seal magazine 121 immediately above the retaining plate 224 for driving the bottommost seal 225 therein to the left, as viewed in FIG. 9, into a sealing region between the open sealing jaws 170, as is best illustrated in FIGS. 12 and 16. It will be noted that the action of the torsion spring 237 tends to urge the seal feed bar 235 outwardly against the retaining plate 224 to insure that only the bottommost seal 225 will be engaged by the seal feed bar 235.

This movement of the seal feed lever 230 to its seal feeding position, also moves the coupling pin 238 into engagement with the end 199 of the latch bolt 197, thereby moving the latch bolt 197 to the left, as viewed in FIG. 9, against the urging of the compression spring 245 for disengaging the free end of the hook 198 from the complementary opening in the side plate 106. Thus released for pivotal movement about the hollow shaft 190, the latch plate 192 is urged by the tension spring 195 in a clockwise direction, as viewed in FIG. 12, into the position illustrated in FIG. 12, wherein the pin 201 is disposed at the upper end of the slot 203. This rotation of the latch plate 192 by the tension spring 195 causes a corresponding movement of the

links

205 and 207 into the configuration illustrated in FIG. 18, for moving the lower ends of the gathering jaws 210 toward each other and into the closed position thereof illustrated in FIG. 18. In this closed position, the gathering jaws 210 cooperate with the plunger 217 to restrain the strap web 35 from transverse movement while permitting longitudinal movement thereof.

When the crosshead 160 undergoes its downward sealing stroke, the actuator arm 165 engages cam member 200 for thereby pivoting the latch plate 192 and the latch bolt 197 in a counterclockwise direction, as viewed in FIG. 12, against the urging of the tension spring 195. This pivotal movement of the latch plate 192 in turn pivots the triangular link 205, thereby moving the coupling pin 206 vertically upwardly along the slot 208 and urging the upper ends of the gathering jaws 210 toward each other for reopening the gathering jaws 210.

When the seal feed lever 230 is returned to its retracted position by the piston 240, the coupling pin 238 will be disengaged from the latch bolt 197, thereby permitting return of the latch bolt 197 back to the right under the urging of the compression spring 245. Thus, the hook end 198 of the latch bolt 197 will be reengaged in the complementary opening in the side plate 106 to again secure the latch plate 192 against further pivotal movement under the urging of the spring 195. Accordingly, when the crosshead 160 is retracted, the latch plate 192 will remain in its latch position, thereby holding the gathering jaws in their open position.

It will be noted that the lower end of the tension spring 244 is coupled to the rear end of the pivot pin 236 and serves to exert a toggle type holding force on the seal feed lever 230. Thus, whether the seal feed lever 230 is in its retracted position or its seal feeding position, the toggle spring 244 will tend to hold it in that position. Accordingly, when the seal feedlever 230 is in its retracted position, and no air is admitted to the drive cylinder 240, the seal feed lever 230 will be prevented from falling from the retracted position thereof under the force of gravity. In like manner, when the seal feed lever 230 is in its seal feeding position, the toggle spring 244 will hold it in this position during the brief period between the shutting off of the air supply to the upper end of the drive cylinder 240 and the admittance of air to the lower end thereof, as will be described more fully below.

Attached to the bottom end of the main support plate 51 and disposed to the right of the seal feed assembly 220, as viewed in FIG. 2, is an output guide assembly, generally designated by the numeral 250. The guide assembly 250 includes a backing plate 251 secured to the main support plate 51 by means of mounting bolts 252 and a pair of side plates 253 urged toward each other by tension springs 254. The side plates 253 are generally of the same type as the side plates 77 and are respectively provided with retaining flanges (not shown) extending toward each other along the lower edges thereof. These retaining flanges extend to the left beyond the main body of the side plates 253 to form an entry tongue 255 disposed immediately below the bottom end of the seal magazine 221 for guiding the leading end 36 of the strap web 35 from the gathering jaws 210. Attached to the upper right-hand end of the main support plate 51 is an auxilliary mounting plate 256 supporting thereon a manifold valve assembly 257 for controlling the air actuated drive cylinders of the strapping head 50.

Referring now to FIG. 19 of the drawings, there is illustrated a schematic diagram of the pneumatic control circuit for the strapping head 50, of which the manifold valve assembly 257 forms a part. The control circuit 260 includes a source 261 of pressurized air and a plurality of control valves. More particularly, there is provided a seal feed valve 263, a strapping, feeding and straightening valve 264, a gripping and tensioning valve 265, a sealing valve 266 and a sealer retracting valve 267, the valves 263 266 all being of the solenoid-actuated type and being respectively controlled by

solenoids

263a, 264a, 265a and 266a, while the valve 267 is controlled by a pilot 267a. Preferably, the valves 264-266 are all mounted in a single unit in the manifold 257, but any suitable arrangement could be used. The valves 263 267 are all connected to the source 261 by a common input conduit 262, the valves 263 266 also being connected to a common exhaust conduit 268 while the sealer retracting valve 267 is exhausted through an outlet 269.

The seal feed valve 263 is connected to the upper end of the seal feed cylinder 240 and to the lower end of the straightener cylinder 80 by means of a conduit 271, while the strap feeding and straightening valve 264 is connected by a conduit 272 to one side of the air motor 55 and also to the the upper end of the straightening cylinder 80. A conduit 273 connects the gripping and tensioning valve 265 to the other side of the air motor 55 and also to the upper end of the gripping jaw drive cylinder 115. The sealing valve 266 is connected by a conduit 274 to the pilot 267a, to the upper end of the sealer drive cylinder and also to the lower or rod end of the seal feed cylinder 240. The other side of the pilot 267a is connected by a conduit 275 to the sealer retracting cylinder 267, which is in turn coupled to the lower end of the sealer drive cylinder 140 by means of a conduit 276.

Referring now also to FIGS. through 23 of the drawings, the mechanical operation of the strapping head will be described in detail. Initially, a length of strap web 35 is fed from a suitable supply thereof through the guide chute 49 and in the direction of the arrow in FIG. 2, for guiding the strap web 35 between the feed wheel and the idler wheel 65. For this purpose, the lever may be utilized to move the idler wheel 65 away from the feed wheel 60 a sufficient distance to permit the insertion of the strap web 35 therebetween. A package or object 30 will be placed upon the rollers 45 beneath the strapping head 50, preferably by means of a conveyor assembly. Then, the feed wheel 60 is rotated by the air motor 55 for frictionally feeding the strap web 36 in a counterclockwise direction around the idler wheel 65, as viewed in FIG. 2, along the guide shoe and the side plates 77 and thence along the upper surface of the backing plate and between the depression 86 therein and the straightening roll 84.

It will, of course, be recognized that a suitable electrical control circuit will be provided to control the operation of the pneumatic and mechanical parts of the strapping head 50. This control circuit may be of any design which will accomplish the sequence of operation to be described below, such a control circuit being illustrated and described in the aforementioned U. S. Application Ser. No. 63,479. The detailed structure of such a circuit will vary with the peculiar requirements of a particular users installation.

Initially, the valves 263 266 will all be closed, i.e., conditioned to connect the input conduit 262 to the exhaust conduit 268, whereby no air will be admitted to the

cylinders

80, and 240 or to the air motor 55 or to the upper end of the sealer drive cylinder 142 and the pilot 167a. Thus, the straightening cylinder roll 84 will be retracted, the gripping jaw drive cylinder piston 118 will be withdrawn into the cylinder 115, thereby holding the gripping jaws 120 open, and the seal feed piston rod 241 will be withdrawn into the cylinder 240 for thereby holding the seal feed lever 230 in its retracted position. The sealer retracting valve 267 will be open, i.e., air will be supplied from the input conduit 262 through the conduit 276 to the lower end of the sealer drive cylinder 140, for thereby holding the cylinder in its downward position on the piston rod 145, and holding the sealing jaws 170, the die members and the shear blade all in their retracted configurations, illustrated in FIGS. 12 and 16 of the drawings.

Upon energization of the solenoid 264a, the strap feeding and straightening valve 264 will be opened, thereby admitting air from the inlet conduit 262 through the conduit 272 to the air motor 55 for driving the air motor 55 in a strap feeding direction. It will be noticed that air is simultaneously supplied by the conduit 272 to the upper end of the straightening cylinder 280 for moving the piston rod 282 thereof downwardly and thereby moving the straightening roll 84 into engagement with the strap web 35 for clamping it between the straightening roll 84 and the depression 86 in the backing plate 85 to effect straightening of the strap web 35, the rod end of the cylinder 80 being exhausted through the conduit 271. After the leading end 36 of the strap web 35 has been fed between the open gripping jaws 120 and sealing jaws 170 and gathering jaws 215, the strap web 35 is guided by the tongue 255 between the side plates 253. By means of suitable timing apparatus in the electrical control circuit, after the leading end 36 of the strap web 35 has moved approximately 5 inches beyond the end of the output guide assembly 250, the solenoid 263a will be energized for thereby opening the seal feed valve 263 to admit air from the source 261 through the

conduits

262 and 271 to the upper end of the seal feed cylinder 240. Thus, the seal feed piston rod 241 will be moved downwardly for moving the seal feed lever 230 to its seal feeding position, illustrated in FIG. 9. Accordingly, in the manner described above, a seal 255 is fed from the seal magazine 221 into a sealing position between the open sealing jaws 170.

It will be observed that the seal 225 has a length substantially equal to the distance between the right and left-hand ends of the sealing jaw 170, as viewed in FIG. 9, the seal 225 being so positioned that the right and left-hand ends thereof are, respectively, substantially in alignment with the outer ends of the right and left-hand pairs of the sealing jaws 170. The seal feed lever 230 is coupled, by means not shown, to a control switch LS2 connected in the electrical control circuit, and operating in a manner similar to that described in the aforementioned copending US Application Ser. No. 63,479 for preparing the control circuit for later operations.

The opening of the seal feed valve 263 also admits air through the conduit 271 to the lower end of the straightening cylinder 80, thereby balancing the air pressure at the upper end of the cylinder 80. Accordingly, at this time, the piston rod 82 of the cylinder 80, which is of the spring return type, will be withdrawn upwardly into the cylinder 80 for disengaging the straightening roll 84 from the strap web 35.

It will be noted that the electrical control circuit may be so arranged that the strapping machine 40 may continuously recycle for strapping an uninterrupted series of objects or packages 30, or it may be arranged for undergoing a separate manually initiated cycle for each new object 30 after it is placed in strapping position. Similarily, the point at which the cycle begins and ends may be varied, but normally the circuit will be arranged to cycle the strapping machine 40 in the manner set forth in the aforementioned copending US. application, Ser. No. 63,479. Thus, the actuation of the control switch LS2 upon movement of the seal feed lever 230 to its seal feeding position will serve to reclose the feeding and straightening valve 264 for shutting off the supply of air to the air motor 55 and the straightening cylinder 80. Thus, the air motor 55 will be de-energized for interrupting the strap feeding operation. This point, with the leading end 36 of the strap web 35 extending a slight distance beyond the end of the output guide assembly 250, will mark the beginning and ending point of each strapping operation. Thus, at this point, an object 30 will be moved into strapping position beneath the strapping head 50, after which the strapping cycle may be initiated by manual actuation of a suitable cycle switch.

As described above, movement of the seal feed le'ver 230 to its seal feeding position causes the coupling pin 238 to move the latch bolt 197 to the left, as viewed in FIG. 9, for disengaging it from the complementary opening in the side plate 106, whereupon the gathering jaws 210 are moved to the closed position thereof under the urging of the tension spring 195. Thus closed, the retaining shoulders 214 on the gathering jaws 210 will respectively engage the opposite side edges of the strap web 35 for preventing lateral movement thereof, the gathering jaws 210 cooperating with the plunger 217 for limiting transverse movement of the strap web 35.

Upon initiation of the strapping cycle, as described above, the feeding and straightening valve 264 is again opened, and the leading end 36 of the strap web 35 is fed completely around the object 30, and is guided by suitable guide means (not shown) back between the side plates 87 along the underside of the backing plate 85. As the leading end 36 of the strap web 35 passes between the side plates 87, it engages the finger 93 of the track switch lever 91 for pivoting the lever 91 about the pivot pin 92 in a counterclockwise direction, as viewed in FIG. 8, thereby moving the actuator bolt 94 to the left against the urging of the tension spring 97 and opening the track switch LS4. The track switch LS4 is so connected in the electrical control circuit that, upon actuation thereof, the solenoid 264a is deenergized for thereby reclosing the sealing and straightening valve 264 and shutting off the supply of air to the air motor 55 and straightening cylinder 80. Thus, the straightener roll 84 is again retracted and the air motor 55 is de-energized, terminating the strap feed. However, the inertia of the air motor 55 and the feed wheel 60 and the idler wheel 65 continues to advance the leading end 36 of the strap web 35 a short distance sufficient to carry it again between the open gripping jaws 120 and sealing jaws 170 and into engagement with the inclined surfaces 215 on the now closed gathering jaws 210. Thus, these inclined surfaces 215 serve to terminate the longitudinal movement of the leading end 36 of the strap web 35, as illustrated in FIG. 20. At this point, the various parts of the strapping head 50 will be disposed in the configuration illustrated in FIG. 20.

The opening of the track switch 95 will also serve to energize the solenoid 265a for thereby opening the gripping and tensioning valve 265 and admitting air from the source 261 through the

conduits

262 and 273 to the other side of the air motor 55 and to the upper end of the gripping jaw drive cylinder 115. Thus, the piston rod 118 will be extended downwardly for thereby closing the gripping jaws 120 in the manner described above and securely clamping the strap web 35 between the gripping jaw teeth 126 and the underside of the backing plate 85. Simultaneously, the air motor 55 will be energized and driven in a strap tensioning direction, for withdrawing the supply portion of the strap web 35 to take up the slack therein and tension the loop of strap about the object 30. This tensioning operation will continue until a predetermined tension is reached, at which time the eccentric shaft 67 will be rotated to actuate the tension switch (not shown), in the manner described in the aforementioned copending Application Ser. No. 63,479. It will be noted that, as the strap loop is tensioned about the object 30, the strap web separates the pairs of

side plates

77, 87

18 and 253 and is pulled from therebetween and is wrapped snugly about the object 30.

The tension switch is so connected in the electrical control circuit that actuation thereof in the manner described above serves to energize the solenoid 266a for thereby opening the sealing valve 266 to admit air from the source 261 to the pilot 267a, the upper end of the sealer cylinder and the lower end of the seal feed cylinder 240 through the

conduits

262 and 274. Accordingly, the seal feed piston rod 241 is retracted, thereby returning the seal feed lever 230 to its retracted position. The air from the pilot 267a is ad mitted through the conduit 275 to the sealer retracting valve 267, for thereby closing the valve 267 to disconnect the input conduit 262 from. the conduit 276 and connected to the exhaust conduit 269. Thus, the supply of air to the lower end of the sealer cylinder 140 is cut off, whereby the air admitted to the upper end thereof through conduit 274 is operative to move the sealer cylinder 140 upwardly with respect to the piston rod to thereby drive the crosshead downwardly in the manner described above. This downward movement of the crosshead 160 will cause a cammed movement of the sealing jaws to their sealing configuration, illustrated in FIG. 13, in the manner described above. As the sealing jaws 170 move to this sealing configuration, they respectively engage the legs of the seal 225 and wrap them around the overlapped portions of the strap web 35, as is also apparent from FIGS. 12 and 13. At this point, the parts of the strapping head 50 are arranged in the configuration illustrated in FIG. 21.

As the crosshead 160 continues :its downward stroke, the abutment surfaces 160 thereon engage the die members and the left-hand one of the abutment surfaces 167 thereon engages the shear blade 185, all as described above. At this point, the parts of the strapping head 50 are arranged in the configuration illustrated in FIG. 22, immediately prior to completion of the formation of the seal joint and severing of the completed strap loop from the supply portion of the strap web 35.

As the crosshead 160 reaches the bottom of its downward stroke, it drives the die members 180 into crimping engagement with the seal 225 for forming crimps 229 in the opposite side edges of the seal 255 and the overlapped portions of the strap web 35, as illustrated in FIG. 5. Simultaneously, the cutting edge 198 of the shearing plate is driven through the supply portion of the strap web 35, cooperating with the adjacent end of the backing plate 85 for severing the supply portion of the strap web 35 from the completed seal joint. When the seal feed lever 230 is retracted in the manner described above, the coupling pin 238 is moved back out of engagement with the adjacent end 199 of the latch bolt 197, thereby freeing the latch bolt 197 for return to its latch position. Thus, when the crosshead 160 undergoes its downward sealing stroke, the actuator arm 165 pivots the latch plate 192 and the latch bolt 197 in a counterclockwise direction, as viewed in FIG. 12, in the manner described above. Accordingly, when the crosshead 160 has reached the bottom of its stroke, the gathering jaws 210 will be reopened arid the hook end 198 of the latch bolt 197 will snap back into the complementary opening in the side plate 106 under the urging of the compression spring 245, thereby latching the gathering jaws 210 in their open position. At this point, the parts of the strapping head 50 are arranged in the configuration ilspring-return type, will retract its piston 118, for

thereby reopening the gripping jaws 120, and the air motor 55 will be de-energized. The actuation of the switch LS2 by the retraction of the seal feed lever 230 will also, after a delay sufficient to permit the completion of the sealing operation, de-energize the solenoid 266a, for thereby reclosing the sealing valve 266 to shut off the supply of air to the pilot 267a and to the upper end of the sealer cylinder 140 and to the lower end of the seal feed cylinder 240. The removal of air from the pilot 267a serves to reopen the sealer retracting valve 267 to readmit air to the lower end of the sealer cylinder 140 through the conduit 176 for thereby moving the cylinder 140 back to its downward position with respect to the piston rod 145. This downward movement of the cylinder 140 serves to retract the crosshead 160 in the manner described above for thereby retracting the die members 180 and the shear blade 185 and reopening the sealing jaws 170. Thus, at this time, all of the valves 263 267 have been returned to their initial conditions and all of the

jaws

120, 170 and 210 are open to permit removal of the strapped object 30 from the strapping head 50 and placement of a new object 30 into the strapping position.

It will be noted that the electrical control circuit will preferably be so arranged that the actuation of the switch LS2 by the retraction of the seal feed lever 230 will, after a delay sufficient to permit the removal of the strapped object 30, re-energize the solenoid 264a for reopening the valve 264 to reinitiate the feeding operation. After the strap has been fed a few inches beyond the output guide assembly 250, and the seal feed cylinder 240 has been energized in the manner described above, the reactuation of the switch LS2 by the movement of the seal feed lever 230 to its seal feeding position will serve to then de-energize the solenoid 2640 for interrupting the strap feed. Thus, at this point of interruption of the strap feed, the strapping cycle is completed, and a new cycle may be started by actuation of a manual cycle switch after placement of another object 30 in strapping position. This type of cyclic operation is described in detail in the aforementioned copending U. S. Application Ser. No. 63,479.

From the foregoing, it will be seen that there has been provided an improved strapping machine of simple and economical construction and utilizing a minimum of wearable parts. More particularly, there has been provided a strapping machine which utilizes a single air-actuated piston for performing the sealing and shearing operations, which piston is adapted for reciprocating movement in directions substantially nor- .mal to the plane of the portion of the strap in the joint forming region.

There has also been provided a novel crosshead which has camming surfaces thereon disposed in camming engagement with cam follower surfaces on the sealer jaw assembly for producing a cammed movement of the sealer jaws from their retracted configuration to their sealing configuration.

There has also been provided a crosshead having a plurality of abutment surfaces thereon, respectively adapted for moving the die members to their crimping position and moving the shear blade to its shearing position and moving the gathering jaws to their open condition, all simultaneously with the movement of the sealing jaws to their sealing configuration.

Finally, there has been provided a novel drive linkage for the sealer assembly, including an air-actuated cylinder movable with respect to a fixed piston rod, and a trunnion yoke assembly for transmitting the reciprocating motion of the drive cylinder to the crosshead.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be appreciated that various modifications may be made therein and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A strapping machine for applying a length of strap around an object, said strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof, tensioning means for tensioning the loop of strap about the object by withdrawing the supply portion thereof relative to the leading end thereof, a joint-forming jaw assembly having cam follower surfaces thereon and being movable between a retracted configuration accommodating tensioning of the strap loop by said tensioning means and a joint-forming configuration for providing a joint between the overlapped portions of the tensioned strap, a shear blade movable between a retracted position out of engagement with the strap and a shearing position for severing the completed strap loop from the supply portion of the strap, a crosshead having camming surfaces and an abutment surface thereon and being movable between first and second positions, said camming surfaces being disposed in camming engagement with said cam follower surfaces thereby to effect a cammed movement of said joint-forming jaw assembly from the retracted configuration to the jointforming configuration thereof in response to movement of said crosshead from the first position to the second position thereof, said abutment surface being disposed for driving engagement with said shear blade thereby to effect movement thereof from the retracted position to the shearing position thereof independently of said joint-forming jaw assembly in response to movement of said crosshead from the first position to the second position thereof, and drive mechanism coupled to said crosshead for effecting movement thereof between the first and second positions thereof.

2. The strapping machine set forth in claim 1, wherein said shear blade and said crosshead are so constructed and arranged that said shear blade moves into the shearing position thereof after the movement of said joint forming jaw assembly into the joint forming configuration thereof.

Claims

1. A strapping machine for applying a length of strap around an object, said strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof, tensioning means for tensioning the loop of strap about the object by withdrawing the supply portion thereof relative to the leading end thereof, a joint-forming jaw assembly having cam follower surfaces thereon and being movable between a retracted configuration accommodating tensioning of the strap loop by said tensioning means and a joint-forming configuration for providing a joint between the overlapped portions of the tensioned strap, a shear blade movable between a retracted position out of engAgement with the strap and a shearing position for severing the completed strap loop from the supply portion of the strap, a crosshead having camming surfaces and an abutment surface thereon and being movable between first and second positions, said camming surfaces being disposed in camming engagement with said cam follower surfaces thereby to effect a cammed movement of said joint-forming jaw assembly from the retracted configuration to the joint-forming configuration thereof in response to movement of said crosshead from the first position to the second position thereof, said abutment surface being disposed for driving engagement with said shear blade thereby to effect movement thereof from the retracted position to the shearing position thereof independently of said joint-forming jaw assembly in response to movement of said crosshead from the first position to the second position thereof, and drive mechanism coupled to said crosshead for effecting movement thereof between the first and second positions thereof.

3. The strapping machine set forth in claim 1, wherein said abutment surface is disposed adjacent to one end of said crosshead for engagement with said shear blade when said crosshead is intermediate the first and second positions thereof.

4. The strapping machine set forth in claim 1, wherein said shear blade includes a pair of support projections, said joint forming jaw assembly including a pair of pins respectively disposed for engagement with said support projections when said joint forming jaw assembly moves from the joint forming configuration to the retracted configuration thereof for thereby carrying said shear blade from the shearing position to the retracted position thereof.

5. A strapping machine for applying a length of strap around an object, said strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof, tensioning means for tensioning the loop of strap about the object by withdrawing the supply portion thereof relative to the leading end thereof, seal feed mechanism for feeding a seal from a supply thereof to a joint-forming region adjacent to the overlapped portions of the strap, a joint-forming jaw assembly having cam follower surfaces thereon and being movable between a retracted configuration accommodating tensioning of the strap loop by said tensioning means and a joint-forming configuration for providing a seal joint between the overlapped portions of the tensioned strap, a die member movable between a retracted position disposed out of said sealing region and a sealing position disposed in said sealing region for crimping the side edges of the seal and the adjacent portions of the strap to facilitate the formation of the seal joint therebetween, a crosshead having camming surfaces and an abutment surface thereon and being movable between first and second positions, said camming surfaces being disposed in camming engagement with said cam follower surfaces thereby to effect a cammed movement of said joint-forming jaw assembly from the retracted configuration to the joint-forming configuration thereof in response to movement of said crosshead from the first position to the second position thereof, said abutment surface being disposed for driving engagement with said die member effect movement from the retracted position to the sealing position thereof independently of said joint-forming jaw assembly in response to movement of said crosshead from the first position to the second position thereof, and drive mechanism coupled to said crosshead for effecting movement thereof between the first and second positions thereof.

6. The strappIng machine set forth in claim 5, wherein said abutment surface is disposed at one end of said crosshead for engagement with said die member when said crosshead is intermediate the first and second positions thereof.

7. The strapping machine set forth in claim 5, wherein said joint forming jaw assembly includes three ganged pairs of joint forming jaws aligned longitudinally of the overlapped portions of the strap, and further including two die members respectively disposed between adjacent pairs of said joint forming jaws.

8. The strapping machine set forth in claim 5, wherein said joint forming jaw assembly includes three ganged pairs of joint forming jaws aligned longitudinally of the overlapped portions of the strap, and further including two die members respectively disposed between adjacent pairs of said joint forming jaws, said crosshead having a pair of projections at one end thereof respectively disposed for engagement with said two die members.

9. A strapping machine for applying a length of strap around an object, said strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof, tensioning means for tensioning the loop of strap about the object by withdrawing the supply portion thereof relative to the leading end thereof, seal feed mechanism for feeding a seal from a supply thereof to a joint-forming region adjacent to the overlapped portions of the strap, a joint-forming jaw assembly having cam follower surfaces thereon and being movable between a retracted configuration accommodating tensioning of the strap loop by said tensioning means and a joint-forming configuration for providing a seal joint between the overlapped portions of the tensioned strap, a shear blade movable between a retracted position out of engagement with the strap and a shearing position for severing the completed strap loop from the supply portion of the strap after formation of the seal joint, a die member movable between a retracted position out of said sealing region and a sealing position disposed in said sealing region for crimping the side edges of the seal and the adjacent portions of the strap to facilitate the formation of the seal joint therebetween, a crosshead having camming surfaces and first and second abutment surfaces thereon and being movable between first and second positions, said camming surfaces being disposed in camming engagement with said cam follower surfaces thereby to effect a cammed movement of said joint-forming jaw assembly from the retracted configuration to the joint-forming configuration thereof in response to movement of said crosshead from the first position to the second position thereof, said first abutment surface being disposed for driving engagement with said shear blate thereby to effect movement thereof from the retracted position to the shearing position thereof independently of said joint-forming jaw assembly in response to movement of said crosshead from the first position to the second position thereof, said second abutment surface being disposed for driving engagement with said die member thereby to effect movement thereof from the retracted position to the sealing position thereof independently of said joint-forming jaw assembly in response to movement of said crosshead from the first position to the second position thereof, and drive mechanism coupled to said crosshead for effecting movement thereof between the first and second positions thereof.

10. The strapping machine set forth in claim 9, wherein said die member and said shear blade and said crosshead are so constructed and arranged that said die member moves to the sealing position thereof and said shear blade moves to the shearing position thereof after the movement of said joint forming jaw assembly to the joint forming configuration thereof.

11. A strapping machine for applying a length of strap around an object, said strapping machine comprising a strap gRipper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof, strap gathering means movable between a closed condition engaging the strap for limiting the longitudinal movement of the leading end thereof along the supply portion thereof and an open condition out of engagement with the strap, tensioning means for tensioning the loop of strap about the object by withdrawing the supply portion thereof relative to the leading end thereof, a joint forming jaw assembly having cam follower surfaces thereon and being movable between a retracted configuration accommodating tensioning of the strap loop by said tensioning means and a joint forming configuration for providing a joint between the overlapped portions of the tensioned strap, a crosshead having camming surfaces and an abutment surface thereon and being movable between first and second positions, said camming surfaces being disposed in camming engagement with said cam follower surfaces to thereby effect a cammed movement of said joint forming jaw assembly from the retracted configuration to the joint forming configuration thereof in response to movement of said crosshead from the first position to the second position thereof, said abutment surface being disposed for driving engagement with said strap gathering means to thereby effect movement thereof from the closed condition to the open condition thereof in response to movement of said crosshead from the first position to the second position thereof, and drive mechanism coupled to said crosshead for effecting movement thereof between the first and second positions thereof.

12. The strapping machine set forth in claim 11, wherein said strap gathering means includes a pair of gathering jaws movable between said closed and open conditions and drive linkage coupled thereto, said abutment surface being disposed for driving engagement with said drive linkage when said crosshead moves from the first position to the second position thereof for effecting movement of said gathering jaws from the closed condition to the open condition thereof.

13. The strapping machine set forth in claim 11, and further including apparatus coupled to said strap gathering means for effecting movement thereof from the open condition thereof to the closed condition thereof.

14. A strapping machine for applying a length of strap around an object, said strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof, strap gathering means movable between a closed condition engaging the strap for limiting the longitudinal movement of the leading end thereof along the supply portion thereof and an open condition out of engagement with the strap, tensioning means for tensioning the loop of strap about the object by withdrawing the supply portion thereof relative to the leading end thereof, seal feed mechanism for feeding a seal from a supply thereof to a joint-forming region adjacent to the overlapped portions of the strap, a joint-forming jaw assembly having cam follower surfaces thereon and being movable between a retracted configuration accommodating tensioning of the strap loop by said tensioning means and a joint-forming configuration for providing a seal joint between the overlapped portions of the tensioned strap, a shear blade movable between a retracted position out of engagement with the strap and a shearing position for severing the completed strap loop from the supply portion of the strap after formation of the joint, a die member movable between a retracted position out of said sealing region and a sealing position disposed in said sealing region for crimping the side edges of the seal and the adjacent portions of the strap to facilitate the formation of the seal joint therebetween, a crosshead having camming surfaces and first and second and third abutment surfaces thereon and being movable between first anD second positions, said camming surfaces being disposed in camming engagement with said cam follower surfaces thereby to effect a cammed movement of said joint-forming jaw assembly from the retracted configuration to the joint-forming configuration thereof in response to movement of said crosshead from the first position to the second position thereof, said first abutment surface being disposed for driving engagement with said shear blade thereby to effect movement thereof from the retracted position to the shearing position thereof independently of said joint-forming jaw assembly in response to movement of said crosshead from the first position to the second position thereof, said second abutment surface being disposed for driving engagement with said die member thereby to effect movement thereof from the retracted position to the sealing position thereof independently of said joint-forming jaw assembly in response to movement of said crosshead from the first position to the second position thereof, and said third abutment surface being disposed for driving engagement with said strap gathering means thereby to effect movement thereof from the closed condition to the open condition thereof in response to movement of said crosshead from the first position to the second position thereof, and drive mechanism coupled to said crosshead for effecting movement thereof between the first and second positions thereof.

15. A strapping machine for applying a length of flat strap around an object, said strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof and with one surface of the strap disposed in a predetermined plane, tensioning means for tensioning the loop of strap about the object by withdrawing the supply portion thereof relative to the leading end thereof, joint forming jaws movable between a retracted configuration accommodating tensioning of the strap loop by said tensioning means and a joint forming configuration for securing together the overlapped portions of the tensioned strap to provide a joint therebetween, a single fluid-actuated drive motor having a fixed piston rod and a cylinder mounted for reciprocating movement relative thereto in directions substantially normal to the predetermined plane of the overlapped portions of the strap, a lever coupled to said cylinder and mounted for pivotal movement about a predetermined axis in response to the reciprocating movement of said cylinder, and drive linkage coupling said lever to said joint forming jaws for effecting movement thereof between the retracted configuration thereof and the joint forming configuration thereof in response to the pivotal movement of said lever.

16. The strapping machine set forth in claim 15, wherein said predetermined axis is fixed, said piston rod being mounted for pivotal movement about a second fixed axis to accommodate the reciprocating movement of said cylinder.

17. The strapping machine set forth in claim 15, wherein said cylinder is provided with a pair of trunnions extending outwardly therefrom, said lever comprising a generally Y-shaped yoke pivotally connected to said trunnions.

18. The strapping machine set forth in claim 15, wherein said lever is a first-class lever.

19. A strapping machine for applying a length of flat strap around an object, said strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof and with one surface of the strap disposed in a predetermined plane, strap gathering means movable between a closed condition engaging the strap for limiting the longitudinal movement of the leading end thereof along the supply portion thereof and an open condition out of engagement with the strap, tensioning means for tensioning the loop of strap about the object by withdrawing the supply portion thereof relative to the leading End thereof, seal feed mechanism for feeding a seal from a supply thereof to a joint forming region adjacent to the overlapped portions of the strap, a joint forming jaw assembly having cam follower surfaces thereon and being movable between a retracted configuration accommodating tensioning of the strap loop by said tensioning means and a joint forming configuration for providing a seal joint between the overlapped portions of the tensioned strap, a shear blade movable between a retracted position out of engagement with the strap and a shearing position for severing the completed strap loop from the supply portion of the strap after formation of the joint, a die member movable between a retracted position out of said sealing region and a sealing position disposed in said sealing region for crimping the side edges of the seal and the adjacent portions of the strap to facilitate the formation of the seal joint therebetween, a crosshead having camming surfaces and first and second and third abutment surfaces thereon and being movable between first and second positions, said camming surfaces being disposed in camming engagement with said cam follower surfaces to thereby effect a cammed movement of said joint forming jaw assembly from the retracted configuration to the joint forming configuration thereof in response to movement of said crosshead from the first position to the second position thereof, said first abutment surface being disposed for driving engagement with said shear blade to thereby effect movement thereof from the retracted position to the shearing position thereof in response to movement of said crosshead from the first position to the second position thereof, said second abutment surface being disposed for driving engagement with said die member to thereby effect movement thereof from the retracted position to the sealing position thereof in response to movement of said crosshead from the first position to the second position thereof, said third abutment surface being disposed for driving engagement with said strap gathering means to thereby effect movement thereof from the closed condition to the open condition thereof in response to movement of said crosshead from the first position to the second position thereof, a single fluid-actuated drive motor having a fixed piston rod and a cylinder mounted for reciprocating movement relative thereto in directions substantially normal to the predetermined plane of the overlapped portions of the strap, a lever coupled to said cylinder and mounted for pivotal movement about a predetermined axis in response to the reciprocating movement of said cylinder, and drive linkage coupling said lever to said crosshead for effecting movement thereof between the first and second positions thereof in response to the pivotal movement of said lever.

20. A strapping machine for applying a length of flat strap around an object, said strapping machine comprising a strap gripper for holding the strap encircled in a loop about the object with the leading end of the strap overlapping the supply portion thereof and with one surface of the strap disposed in a predetermined plane, tensioning means for tensioning the loop of strap about the object by withdrawing the supply portion thereof relative to the leading end thereof, a joint-forming jaw assembly having cam follower surfaces thereon and being movable only pivotally between a retracted configuration and a joint-forming configuration, said joint-forming jaw assembly in the retracted configuration thereof accommodating tensioning of the strap loop by said tensioning means, said joint-forming jaw assembly in the joint-forming configuration thereof securing together the overlapped portions of the tensioned strap to provide a joint therebetween, a single fluid-actuated drive motor adapted for reciprocating movement in directions substantially normal to the predetermined plane of the overlapped portions of the strap, a crosshead having camming surfaces thereon respectively disposed in camming engageMent with said cam follower surfaces and being movable between first and second positions, movement of said crosshead from the first position thereof to the second position thereof effecting a cammed movement of said joint-forming jaw assembly from the retracted configuration thereof to the joint-forming configuration thereof, link members coupling said crosshead to said joint-forming jaw assembly for effecting movement thereof from the joint-forming configuration thereof to the retracted configuration thereof in response to movement of said crosshead from the second position thereof to the first position thereof, and means coupling said crosshead to said drive motor for moving said crosshead between the first and second positions thereof in response to the reciprocating movements of said drive motor.