Patent GB-1202361-A (GB)
Title: Improvements in or relating to a programme-controlled machine tool installation
IPC: B23Q41/00
Filed: 1966-05-12
Abstract: 1,202,361. Programmed control of machine tools. MOLINS MACHINE CO. Ltd. and D.T.N. WILLIAMSON. Aug.8, 1967, Nos.21223/66; 12196/67 and 21109/67. Heading G3N. [Also in Divisions B3 and B8] A machine tool installation for machining workpieces to produce a variety of components comprises aplurality of complementary numericallycontrolled machine tools which together are capable of performing the necessary machining operations to produce said variety of components, the workpieces being carried on pallets; a store for the palleted workpieces; transport means to transport the workpieces, the transport means being movable in both directions along a path past each of the machine tools and the pallet store, the workpieces being movable by the transport means into and out of the store and into and out of the machine tools away from said path so that the transport means has access to any position of the pallet store and to any machine tool and can carry a workpiece past other machine tools; programme control means to control the transport means to transport the workpieces between the store and a predetermined selection of machine tools and to control the selection of tools for machining operations performed by the machine tools so that any workpiece can be taken from the pallet store and taken to any selection of machine tools in any desired order so that each machine tool in said selection performs on the workpiece predetermined selected machining operations appropriate to the component of said variety to be produced from that workpiece. The machine tools may include drilling, milling, turning or grinding machines and may comprise a double spindle machine tool for operating on workpieces on a pair of linked pallets or may comprise a six-axis single spindle machine tool as shown in Fig.17 in which the pallets are fed singly. General layout The installation is made up of a row of machine tools 101-106, Figs.2 and 3 which are fed with pairs of link pallets carrying workpieces, and with tool magazines, by means of a transporter 114 movable along one side of a storage facility comprising pallet storage racks 113 and tool magazine storage racks 115. On the other side of the storage facility is a row of work-fixing tables 118-133 at which human operators set workpieces on the pallets, or re-set them on pallets between machining operations. Between the work-fixing tables 118-133 and the storage facility a transporter 138 operates to place loaded pallets into the racks 113 and loaded tool magazines into the racks 115. The storage facility also includes two columns of racks 116, 117, as a transit section for receiving from one side tool magazines loaded therein by human operations for movement to allocated storage racks 115 by the transporter 114, and for receiving magazines from the transporter 114 for removal by the operators to replace or change the tooling therein. A bin preparation area 140 Fig.3 is used to load up bins with workpiece blanks, setting templates and/ or instructions, for movement on conveyer 139 to the work-fixing tables 118-133. Empty bins and finished workpieces are moved on the conveyer 139 to the preparation area 140. The bin preparation area 140 includes its own conveyers 203, 204, transporter 146 and transmit sections 143, 144 and 145. Automatic control All bins, pallets and tool magazines have identification means, e.g. a row of binary magnetic/non-magnetic plugs, so that particular bins, pallets and tool magazines can be allocated to a particular workpiece and the machining operations therefore. The positions of the bins, pallets and magazines are continuously monitored . by a main scheduling computer 174 Figs.4A, 4B. For each workpiece there is scheduled a machining sequence which governs the movement of pallets and magazines to the appropriate machine tool and, if necessary, to a re-setting table where a workpiece is re-positioned to enable further machining operations. Each machine tool 106 Figs.4A, 4B has an associated numerical control unit 147 which controls relative movement between a spindle and a workpiece, and a function control unit 148 which controls all other functions of the machine tool, such as the choice of cutter speeds, tool changing, tool datum procedure &c. The control units 147, 148 are programmed from a tape deck 149 (149-154 in Fig.3) which runs through cassetted tapes selected from a random access tape store 165 (165-170 in Fig.3). The main computer 174 controls and programmes an on-line computer 173 which controls the transporting operations of transporters 114, 138, and 146 and also the machining operations by controlling the function control unit 148 to cause it to select a predetermined tape from the tape store 165 for use on the tape deck 149. The on-line computer 173 exercises control via a multiplexer 175 through three communication channels 176, 177, 178 leading to AID (Address, Instruction, Data) points 179-188 which are connected to positions in the system which are to be interrogated or instructed by the computer. The fully automatic and computerlzed control enables the work-fixing tables 118-133 to be manned e.g. for an 8 hour shift, whilst the machining operates over a 24 hour shift. Machine tool loading unit Each machine 101-106 includes a loading unit 107-112 Figs.2 and 17 for receiving pallets and tool magazines from the transporter 114 and feeding them to the machine tool, and for removing them therefrom for return to the transporter 114. The loading unit Fig.9 comprises a lower set of paddles 404, 405, 406, 407 each are capable of receiving pallets 408 carrying a workpiece 409, and an upper set of paddles 442-446 each one capable of receiving a tool magazine 448. The paddles are rotated in steps to bring the required pallets and tool magazine to a vertical position where identifying means are read by a read head. The pallets and magazine are moved sideways into the machine tool by a driven beam 501. When a single spindle machine tool is used the pair of linked pallets are separated by a mechanism and the individual pallets are machined separately. Transporter The transporters 114, 138 and 146 are of similar construction and only the transporter 114 is described in detail. Referring to Fig.29 the transporter comprises a main frame movable along the racks 113, 115 on rails 641, 642 by a chain 251. The frame supports a vertically movable platform 643 having two sections 644, 645 for carrying linked pallets, one section for returning a pair of pallets to the racks and the other for receiving pallets from the racks. The platform 643 also has an upright 646 for tool magazines which are stored vertically in the racks 115. The platform 643 is positioned vertically by means of actuation of one or more of three hydraulic jacks that operate on fixed ended chains. The sections 644, 645 and the upright 646 include chain driven means for moving the plattens and magazines into and out of the racks and hydraulic pushers and pullers to bring the pallets and magazine into the range of operation of the chain driven means. The main frame is moved along the rails 641, 642 with a fast traverse which is automatically slowed down as it approaches its destination. Hydraulic plungers locate the main frame accurately at a selected destination. Work setting and re-setting An operator is positioned at a station which comprises an indicator light display 822 which tells an operator whether a pallet has to be set, re-set, or unloaded; a digital clock 823 which provides a count-down for each job by the operator; a work setting template guide 824; a loudspeaker/microphone intercommunication 825; a pneumatic screw-driver 826; and a holder 827 for change tools for use in the screw-driver. Received pallets are positioned on air bearings 821 on a plate 809. Bins carrying required material, e.g. workpiece blanks, setting template, instructions &c. are delivered from the bin preparation area along the upper run of conveyer 139. Under computer control a gate 801 deflects a bin down a chute 802 to a required workfixing table. Pallets are delivered by the transporter 138 to the required work fixing table and shuffled on to plate 809. An operator then, loads, unloads, set, or re-sets according to instruction. Bins carrying the used materials, and possibly a finished workpiece, are returned to the bin preparation area along a lower return run of conveyer 139. Bin preparation area This area 140, Figs. 3 and 4B comprises storage racks 141, 142 with a movable transporter 146, transit section 143, 144, 145, oppositely movable conveyers 203, 204 fed by the conveyer 139, and work benches 201, 202. The online computer keeps a "Bin Status File" which enables it to determine the location, contents and availability of all bins at any time. The scheduling computer 174 issues a print-out designating the jobs to be loaded into bins on each day, the print-out indicating to human operators the necessary tooling, templates, and work-fixing instructions, and to prepare, e.g. light alloy, workpiece blanks, for each job. Tool magazine preparation area A bench 220 is provided for loading and unloading tool magazines adjacent the magazine transit racks 116, 117. The on-line computer 173 keeps a "Tool Magazine Status File" which contains the information as to the tools contained in each magazine and to the location of each magazine. The scheduling computer 174 issues a daily print-out which informs the operators of tool changes, if necessary, required in particular magazines, and which lists the cassetted tape numbers required in the random access tape store of each machine tool so that they can be altered if necessary.