Patent GB-708423-A (GB)
Title: Improvements in or relating to conveyors
Inventor: KEEN HAROLD HALL
IPC: H02P5/46
Filed: 1950-06-22
Abstract: 708,423. Conveyers. BRITISH TABULATING MACHINE CO., Ltd. June 21, 1951 [June 22, 1950; March 22, 1951], Nos. 15633/50 and 6908/51. Class 78 (1) An item conveying system in which a plurality of delivery means feed items to a common conveyer is controlled' by record cards bearing control data which are fed intermittently under control of the common conveyer past record card sensing means which causes the sensed data to selectively operate said plurality of delivery means. As shown, a motor vehicle assembly plant comprises storage sections 1, 2, 3, 5, 7 for the various sub-assemblies and small parts, and corresponding conveyers 8-12 leading from each storage section to an assembly point 6 at which the vehicles are assembled. In order to ensure that a complete set of sub-assemblies and small parts is delivered at the required times for assembling various types of vehicles the various type of sub-assemblies required are each stored in separate bays in the corresponding storage sections and a plurality of card feeds in tabulating machines located at a control point 4 is used to select the various sub-assemblies at the storage sections 1, 2, 3, and 7 and to feed them on to the various conveyers 8, 9, 10 and 12, and to cause the feeding of a card at the stores section 5 indicating what small parts are to be collected by the stores operative and placed in a bar on the conveyer, each of these selections, feeding of the sub-assemblies on to the conveyer, and feeding of a card at the stores section being arranged to occur at such times that all the parts arrive simultaneously at the assembly point 6. A tabulating machine is provided for each storage section and a set of record cards is prepared for each, for a day's work. At the beginning of the day the sets of cards are placed in the respective feed hoppers of the tabulating machines, and the axle, chassis, engine and body tabulators are started in turn at times calculated from the lengths and speeds of the conveyers 8, 9, 10 and 12, the first card in each set actuating relays to put the corresponding tabulators in a state whereby the respective conveyers control subsequent feeding of the cards. The tabulator for the stores, however, is controlled not by its own conveyer but by the body conveyer 12 and is started some time before the body control tabulator so that the feeding of a card at the stores occurs before a body is fed to conveyer 12, giving the stores operator time to collect the small parts together. Accordingly, each conveyer preferably consists of an endless chain provided with dogs for engaging trollies running on tracks, each trolley having a projection arranged to operate corresponding tabulator control contacts 27, Fig. 2A, at the side of the conveyer in advance of a series of loading points for the various loading bays, and in the case of body conveyer 12, further contacts 57, Fig, 4, for controlling the stores tabulator and which are arranged on the return run of the conveyer so as to be closed a pre-determined time before the body control' tabulator contacts 27. Detailed operation. Each tabulator has first and second sensing stations, closure of the corresponding tabulator contacts 27 or 57 initiating a card feed cycle causing a card to be passed through the second sensing station where a single figure control member is sensed for controlling the type of sub-assembly. A simplification of the second sensing station of the axle and chassis tabulators can be made in the example described wherein the axle and chassis are of only one type, the remaining tabulators being similar. Considering the body tabulator, START KEY, Fig, 2A, is first depressed which causes the energizing of a motor M to give a single revolution of a cam shaft and cause feeding of a single card to the first sensing station, Upon arrival at the first sensing station the card causes closure of card lever contact CL1. Upon subsequent closure of tabulator control contacts 27 motor M is again energized to cause a second feed cycle to feed the card on to the second sensing station. As the card is thus being fed the card is searched by the usual moving contacts. The purpose of this first sensing is to detect special inserted cards having "O" punched in all fields which are used to space the control cards as desired, the conveyer trollies corresponding to these cards thus not having a sub-assembly fed to them. As a result of detection, however, it is possible to cause a double card feed for up to four of these cards, each time they occur, in order to speed up delivery when desired by closing a switch SW1, 2, 3 or 4 and the switch marked CANCEL. A card lever contact CL2 is closed upon arrival of the card at the second sensing station which causes a further card feed cycle and a second sensing of the card so as to complete a circuit through the hole in the card via one of the relays CR1 ...... CR8, plug socket 21, a connection, one of the sockets 23, roll 25, contact R3c and intermittent cam switch CB. Each relay CR1 ......CR8 causes operation of a magnet 36, 38 or 40, Fig. 2B, or others not shown, through connections between the relay contacts CR1a ... CR8a and connections 46, 47, 48 and others not shown. The corresponding magnet 36, 38 or 40 attracts an armature in a drum 1, 2 or 3 respectively which is arranged to be stepped in synchronism with the conveyer. A catch member is arranged around the drum at an angular distance from the magnet corresponding to the spacing of the particular storage bay with which it is associated from the contacts 27. Thus any desired spacing of the storage bays, not necessarily corresponding to the spacing of the dogs along the endless chain may be used. The catch member resets the armature when the latter reaches it and completes a circuit through a timing contact C1 synchronized with the drum to a bay release magnet R34, 33 or 32 which causes a trolley carrying a sub-assembly to be delivered to the pre-selected conveyer dog. For details of the drum and catch member arrangements reference is made to Specification 555,995, [Group VIII]. To check that the sub-assembly is loaded on to the conveyer, contacts 43, 44, 45 are provided. Considering the second bay, a relay R28 was energized when magnet R33 was energized, this closing latched contacts R28a. Cam switch C2, however, remains open for a time sufficient to deliver the sub-assembly on to the conveyer, and, when correctly located on the trolley, contacts 44 are closed which energizes resetting coil R28A of relay R28 and so restores the circuit to normal. Incorrect delivery results in relay R29 being energized when contacts C2 close which operates a warning lamp 50. When the fault has been remedied an ERROR CANCEL switch via relay R25 restores the circuit to normal. Stores card feed devices. A plurality of these are provided each being selectively operated by the stores tabulator to feed a characteristic card on to conveyer 11 for viewing by the stores operative whenever contacts 57, Fig. 4, close. Each device is of the tvpe incorporated in a record card punch described more fully in Specification 571.492, [Group VIII]. When START contacts are closed the first card is fed from a magazine to a carriage. Initially two uniselectors 61, 62 having coupled contacts are on corresponding positions, a circuit being completed through the uniselectors and a resistance 63. A relay R43 placed across the uniselectors is thus not energized. Contact 57 cannot complete a circuit until relay R43 is energized. This is effected upon receipt of a single from the stores tabulator which is received at a socket 58 and energizes stepping magnet R44 of uniselector 61. Relay R43 is now energized and causes a second card feed cycle. During the cycle, which delivers the card on to conveyer 11, the stepping magnet R36 of uniselector 62 is energized so that the uniselectors 61, 62 are now again on corresponding contacts and de-energize relay R43 so as to prevent feeding of a further card to conveyer 11. If it is desired to build up a head of sub-assemblies at the assembly point to prevent wasted time in the event of a breakdown or to make up for time lost thereby, the body conveyer 12 may thus be speeded up for a short time whilst stores conveyer 11 is still run at the same speed or at a speed depending on the speed of assembly at the assembly point. This causes the stores tabulator to supplv impulses to the card feed device at a greater rate than that at which contacts 57 are closed As a result uniselector 61 may become several positions ahead of uniselector 62 so that successive card feed cycles continue to occur until such time as the head of bodies at the assembly point is removed. Specifications 422,135, [Group XIX],. 428,860 and 587,017 also are referred to.