| 摘要 |
916,788. Endless conveyers for stacking trays. BAKER PERKINS Ltd. Nov. 11, 1959, No. 38196/59. Class 78 (1). In apparatus for stacking trays of the type comprising a pair of endless conveyer chains 9 having retractable tray supports 6 engages each tray 2 in turn at a loading station 4, carries the trays over a pair of sprockets 8, and deposits the trays one on top of another to form a stack 11 on a roller platform 37, the chains are driven step-by-step through a one-revolution clutch which is tripped by the arrival of each tray at the loading point operating a switch 35 through a feeler 34. The one-revolution clutch comprises a gear-wheel 51 constantly driven through a worm 50 from an input shaft 19, a ring 65 bolted to the wheel 51 and having internal rack teeth, and a pawl 60 pivoted at 61 on a boss 57 which is secured to a driven shaft 55. A control arm 62 is secured to the pawl and normally engages a spring-loaded plunger 64 so that the pawl is disengaged from the ring 65. The plunger 64 is withdrawn, causing one revolution of the driven shaft 55 which drives the chains 9, by a solenoid 66 energized through operation of switch 35. The trays are counted as they pass from the loading station by a counter wheel 77 having rack teeth 78 engaged successively by a pawl 81 carried by an arm 80 which is oscillated through an operating arm 82 and linkage 83 from an eccentric 84 on the shaft 55, so that wheel 77 is moved one tooth pitch for each rotation of shaft 55, this being arranged to constitute one tray pitch. After every fortieth tray has operated the one-revolution clutch 60, 65 (there being forty teeth on wheel 77) a second one-revolution clutch comprising a gearwheel 52 driven by the worm 50 and having secured to it an internally-toothed ring 76, and a pawl 71 pivoted at 72 on a boss 70, of shaft 44, is actuated by contact of an arm 86 secured to the wheel 77 with a peg 88 carried by a spring- loaded lever 75 which normally maintains the pawl 71 disengaged from the ring 76 through contact with control arm 73. In consequence, the lever 75 releases the arm 73 and shaft 44 is driven one revolution to cause operation, through a crank 43 on shaft 44, link 40 and a lever 39 pivoted at 42, of a pusher 38 to push a completed stack of height 12 from the apparatus. In order to allow of correct initial phasing of the machine when starting a day's work, irrespective of whether the previous day's work ended with a complete or incomplete stack, and so prevent an oversize stack from being formed, an arm 89 is secured to wheel 77 and is adjusted angularly relative to the wheel such that it raises a plunger 91 to operate a switch 94 when the arm 86 is four teeth 78 away from the lever 75, this representing the number of trays in transit when a stack is completed. The switch 94, which has normally closed contacts, is out of circuit during normal running of the apparatus but on operation of a manual switch 95 is brought into circuit with the solenoid 66 to cause continuous running of the conveyer chains until opened by contact of arm 89 with plunger 91. The trays remaining in transit would normally be removed by inching of the conveyer before switch 95 is operated to rephase the apparatus. When the supply of trays to the loading point 4 is resumed the manual switch 95 is returned to normal running position so that after four trays have been lifted by the supports on the chains 9 the pusher 38 makes an idle stroke. The apparatus now has the usual four trays in transit as would normally occur after a stack has been delivered so that subsequent trays form stacks of correct size. |
