Patent GB-675310-A (GB)
Title: Automatic strapping machine
IPC: B65B13/06
Filed: 1949-09-07
Abstract: 675,310. Bundling machines. SIGNODE STEEL STRAPPING CO. Sept. 7, 1949 [Sept. 9, 1948], No. 23220/49. Class 94(i) [Also in Groups I and XV] An automatic strapping machine for encircling a package or bundle with a strap and for securing together overlapping portions of the strap, comprises a rotatable reel 41 for storing a long coiled length of strap, a strap feeding and retracting mechanism 290, 46 connected to the reel and adapted to feed and retract strap when operated in one direction or, the otherrespectively, track means 48 for directing the strap fed from the reel in a closed circuit to-bring a free end of the strap into overlapping relation to another portion thereof to form a loop about a bundle, strap gripping means 170 operating in conjunction with the reel for tensioning the strap :around the bundle by pulling the free end in one direction while the reel is actuated by the mechanism 48 to exert a pull in the opposite direction on the other portion of the strap and sealing means 37 forming a joint in the overlapped portions of the strap. General features.-A wheeled carriage, Fig. 2, which may be moved into binding position adjacent a bundle conveyer 35 or away from the conveyer supports the strap feeding and retracting and tensioning mechanism 41, 46, 290, the assembly 48 for training the strap around the bundle and the mechanism 37 for feeding seals into position, clamping them around overlapping parts of the strap, distorting the strap to make a joint and cutting the strap from the supply reel. The binding cycle and the movement of the carriage are controlled by an automatic system. The carriage is moved to binding position by a piston and cylinder 25 operated by compressed air and retracted by a spring 29 when the air pressure on both sides of the piston is equalized. The cylinder is connected between the carriage and its running rails. Strap feeding mechanism. A reel 41 having a detachable side plate 292 is driven by a reversible electric motor 290 to feed the strap to the training means 48. When the strap end overlaps the standing part of the strap in the sealing assembly and the end of the strap is gripped the motor is reversed to retract the excess amount of strap to pull 'the strap round the bundle. An idler wheel 42 bears on the strapping on the reel 41 to prevent the coils slipping in the feeding process. The idler wheel is mounted on a pivoted arm 298 and is pressed against the coils by a compressedair-actuated piston in a cylinder 302. Pressure on the piston may be reversed to retract the wheel to allow reloading the reel. Strap from the reel enters a guide 44 which directs the strap through the sealing mechanism to the training mechanism. The forward feeding of the strap is limited by the engagement of the strap end with a - spring-loaded arm 240, Fig. 9, in the sealing assembly which is adjustably pivoted for movement both longitudinally and transversely of the strap and which when moved upwardly by the strap, operates a switch 230 to reverse the motor 290. In the event of the strap end missing the arm 240 a pin 286 on the seal ejecting lever 120 raises the arm slightly later in the cycle to stop the motor 290. Strap training mechanism. This comprises a trough 372 of arcuate shape in longitudinal section which is secured to the carriage. Pivoted to the trough at 420 is a shoot 370, the other end of which fits into a receptacle 422 on the sealing assembly housing. A series of ball-bearing assemblies 416 form the base of the shoot. The shoot may be moved about its pivot so that it can pass through the centre of an annular shaped bundle, e.g. a coil of strip steel, by means of a manually operable pneumatic cylinder 426 which is connected to the shoot by links. Strap keepers 386, Fig. 4, project across notches in the trough 372 to guide the strap end into the sealing assembly. These keepers are pivotally mounted so that the strap may be pulled from them when it is tensioned. Sealing and cutting mechanism. The seals 114 are contained in a magazine 110, Figs. 3, 4, and are of the type described in Specification 675,304, [Group XV]. They are kept in contact with an ejector 132 by a spring-loaded follower 116. The ejector. 132 is connected to a push rod' 96, which actuates the sealing jaws, by pivoted levers 120 and moves a seal between, the sealing jaws when the push rod 96 is retracted after a sealing operation. The lower part of the ejector is a spring-loaded finger 140 which holds the seals while they are moved from the magazine to between sealing jaws. The sealing jaw assembly comprises three sets of jaws 166 for folding the seal about the overlapping parts of the strap, two notching members 168 positioned between the three folding jaws and which notch the strap portions through windows in the seal, a set of edge-gripping jaws 170 underneath the folding jaws which grip the end of the strap after it has been trained round the bundle and allow it to be retracted and tensioned, and underneath the jaws 170 a movable cutter 172 which co-operates with a fixed cutter 234. An anvil 169 is supported on the edge-gripping jaws 170 and extends between the folding jaws 166. The jaws 166, 170 are mounted on five pins 186, 192, 202; the pins 186 are guided by grooves 224 in the top and bottom of the jaw housing and the pins 192 are guided by blocks, arranged so that the jaws 166, 170 are first moved forward by the push rod 96 with the jaws open and the jaws are then closed on the seal and strap respectively. The holes connecting the edge-gripping jaws 170 with the rods 192 are oversize to prevent excessive pressure on the edges of the strap. The jaws 166 are connected to the rod 202 by spring links 184 to allow for variations in the seal and strapping size. The pins 186, 192, 202 pass through elongated holes in the notches 168 and cutter 172 so that these can move independently of the folding jaws. The notchers and cutter are moved forward by a bearing plate on a bracket 208 which supports the pin 202 at a time when the pin 202 has substantially reached a dead centre position between the pins 192 so that the jaws 166, 170 are not effected by movement of the pin 202 when the bracket 208 moves the notchers and cutter. The push rod 96 is moved by two compressed-air-operated pistons 58, 64. Movement of the piston 58 is adjustably limited by a stop bolt 68. The rod 60 of piston 58 butts against piston 64 and movement of piston 58 controls the initial movement of the following jaws 166 and edge-gripping jaws 170 up to the position in which the jaws 170 grip the strap end, the seal is bent by the jaws 166 but does not grip the strap. Movement of piston 64 then causes the folding jaws to finish bending the seal to grip the strap and move the notchers 168 and cutters 172 to notch and cut the strap. Movement of the piston 64 is adjustably limited by bolts 100. A cam on one of the pins 192 moves the feed-limiting arm 240 transversely of the strap during the sealing operation to facilitate removal of the bundle. The whole sealing assembly is attached to the carriage for pivotal movement about a pin 88 to aid in the tensioning of the strap. Strap tensioning means. The strap reel 41 has an annular flange 296 which is engaged by a sprag 332, Fig. 11, which is connected to a pneumatically operated piston in a cylinder 340. The sprag is biassed by a spring 342 so that when the piston moves downwardly the spring causes the sprag to engage the flange 296 and rotate the reel in a clockwise direction to tension the strap. When the piston is retracted the sprag slips on the flange, the pressure of the idler wheel 42 being sufficient to hold the reel stationary. When the piston is fully retracted a bolt 350 on the sprag butts against the bottom of the cylinder 340 and positions the sprag so that the reel can be rotated freely. To prevent the sprag swinging horizontally a bolt 353 engages a vertical plate 355. The cylinder 340 is pivotally attached to the sealing assembly and the reaction of the piston against the cylinder causes the sealing assembly to pivot about its mounting pin 88 so applying tension to the end of the strap in opposition to that applied to the standing part by the sprag. Automatic control means. The pneumatically operated cylinders 50, 52 and 340 which operate respectively the strap and grippers 170, the sealing jaws 166, notchers 168 and cutter 172 and the tensioning sprag 332 are connected to a compressed air line 460, Fig. 16, through solenoid operated vales 464, 468, 472, 482. When the solenoids are not operated, the cylinder 50 controlled by valve 464 is connected to the atmospnere. The rod side of the sealing piston 64 is connected to the air pressure line through valve 472 and, since the rod side of cylinder 25 is connected to the rod side of cylinder 52, the carriage is retracted from the conveyer line 35. The other side of piston 64 is connected to the atmosphere through valve 468. The tensioning cylinder 340 has pressure on the rod side of the piston and the other side is corinected to atmosphere through valve 482. Valve 482 is connected to the air supply through a manually regulated pressure valve 484. The electrical circuit shown in Fig. 17, is arranged so that when a starting switch 514 is operated the machine carries out a binding cycle and stops at: its completion; it comprises (a) a self-locking starting relay 510 which starts motor 290 and operates valve 472, (b) a stopping relay 582, (c) the switch 280 which is operated by the strap feed limit arm 240 and which reverses the feed motor 290 and operates the solenoid of the clamping cylinder valve 404, (d), a switch 406, which is mounted on the strap training trough 372 so that the operating arm 404 bears on the strap during training so that when the strap is pulled away from the arms during retracting by the motor 290, the switch is operated to energize a relay 542, (e) the relay 542 which has three contacts