Automated Manufacturing System

Automated manufacturing system refers to the processing of raw materials into parts or the assembly of parts into products with less direct or indirect human intervention, and the automation of the management process and process in the processing. The management process includes the optimal design of the product; the preparation of the program and the generation of the process; the organization and coordination of the equipment; the planning and distribution of materials; and the monitoring of the environment. The process includes loading and unloading, storage and transportation of workpieces; assembly, adjustment, transportation and replacement of tools; cutting and processing, chip removal, cleaning and measurement of workpieces; transportation of chips, purification and treatment of cutting fluids, and so on.

Automated manufacturing system includes rigid manufacturing and flexible manufacturing, "rigid" means that the production line can only produce a certain type or production process similar to a certain type of product, manifested in the production of a single product. Rigid manufacturing including combined machine tools, special machine tools, rigid automated production lines. "Flexibility" refers to the form of production organization and production of products and processes of diversity and variability, which can be specifically expressed as the flexibility of the machine tool, the flexibility of the product, the flexibility of the processing, the flexibility of the batch, etc.. Flexible manufacturing including flexible manufacturing cell (FMC), flexible manufacturing system (FMS), flexible manufacturing line (FML), flexible assembly line (FAL), computer-integrated manufacturing system (CIMS) and so on. The following is a categorization of automated manufacturing systems based on their productivity and intelligence.

I. Rigid automated production

1. Rigid semi-automated stand-alone machine

In addition to loading and unloading, the machine tool can automatically complete a single process of machining cycle, such a machine tool is called rigid semi-automated machine tools. This kind of machine tool is generally mechanical or electro-hydraulic composite control type combination machine tool and special machine tool, can carry out multi-face, multi-axis, multi-tool simultaneous machining, processing equipment according to the workpiece machining process order in sequence; cutting tool by manual installation, adjustment, the implementation of the mandatory tool change at regular intervals, if there is a tool breakage, breakage, emergency tool change; for example: a single combination of machine tools, general-purpose multi-tool semiautomatic lathe, turret lathe and so on. In terms of complexity, rigid semiautomatic machines can be used to change tools. From the degree of complexity, rigid semi-automated single machine to achieve is the lowest level of processing automation, but less investment, quick results, applicable to the product variety of changes in the range and production batch are larger manufacturing system. The disadvantage is that the adjustment workload, processing quality is poorer, the labor intensity of workers is also large.
 

2. Rigid automated stand-alone machine

It is an automatic machine tool formed by adding automatic loading and unloading auxiliary devices on the basis of rigid semi-automatic single machine. Auxiliary devices include automatic workpiece conveying, loading, unloading, automatic fixtures, lifting devices and indexing devices, etc.; chip processing is generally completed by the scraper and screw conveyor. This type of machine also realizes the entire machining cycle of a single process. This machine tool often need to be customized or modified, commonly used in varieties of small changes, but the production batch is particularly large occasions. The main feature is that the investment is small, quick results, but poor versatility, is the most common processing equipment for mass production.
 

3、Rigid automated production line

Rigid automated production line is a multi-station production process, with the workpiece conveying system will be a variety of automated processing equipment and auxiliary equipment connected in a certain order, in the control system to complete the role of a single part processing complex large system. In the rigid automated line, the processed parts to a certain production beat, the sequence through the various work positions, automatically complete the parts scheduled for all the machining process and part of the inspection process. Therefore, compared with the rigid automated single machine, it is a complex structure, the task of completing the process more, so the production efficiency is also very high, is less varieties, a large number of production essential processing equipment. In addition, the rigid automatic production line also has the advantages that it can effectively shorten the production cycle, eliminate the intermediate inventory of semi-finished products, shorten the material flow, reduce the production area, improve the labor conditions and facilitate the management. Its main disadvantages are large investment, long system adjustment period, and inconvenient replacement of products. In order to eliminate these shortcomings, people have developed a combination of machine tool automated line, can significantly shorten the cycle of building lines, replacement of products only need to replace some parts of the machine tool can be (for example, can be replaced by the spindle box), greatly reducing the adjustment time of the system to reduce production costs, and can receive a better use of the results and economic results. Combined machine tool automated line is mainly used for box parts and other types of non-rotary body drilling, expanding, reaming, boring, tapping threads and milling and other processes. Rigid automated production line is now being developed in the direction of rigid-flexible combination.

Figure 8-1 shows the general layout of a rigid automatic line for machining crankshaft parts. The automatic line produces 1,700 pieces of curved corner parts per year, and the blanks are ductile cast iron parts. Due to the irregular shape of the workpiece, there is no suitable conveying base surface, so the follower fixture is used for mounting and positioning to facilitate the conveying of the workpiece.

This automatic line for the machining of bends consists of 7 combined machines and 1 loading and unloading station. The whole line positioning and clamping mechanism is centrally supplied with oil by a pump station. The conveying of workpieces adopts pace conveyor belt, which is driven by wire rope traction drive. No automatic loading and unloading device is used because the blanks need to be manually corrected for positioning on the accompanying fixture. Compressed air blowing is used to eliminate chips in the machine tool machining station, and the compressed air is centrally supplied to the whole line. Chip transportation adopts chain plate chip conveyor, which transports chips from the middle of the machine under the base.

The layout of the automatic line is linear, with workpiece conveyor belts running through each station, and workpiece loading and unloading station 4 located at the end of the automatic line. The accompanying fixtures and workpiece blanks are lifted by elevator 5, and sent to the beginning of the automatic line from the top of the machine tool, and no chips are scattered to the machine tool, the conveyor belt and the ground in the conveying process. The direction of chip transportation is opposite to the direction of workpiece transportation, and the bucket chip elevator 1 is located at the beginning of the automatic line. The central console 6 is located at the end of the automatic line.

Rigid automatic line productivity is high, but less flexible, when the processing workpiece changes, you need to stop the machine, stop the line and the machine tool, fixture, tooling and other tooling equipment to adjust or replace (such as replacement of the spindle box, tooling, fixtures, etc.), usually adjust the workload, downtime is longer.

II. Flexible Manufacturing Cell FMC

Flexible Manufacturing Cell (Flexible Manufacturing Cell) is composed of a single CNC machine tool, machining center, automatic workpiece conveyor and replacement system. It is the realization of single-process processing variable processing unit, the cell of the machine tool in the process capacity is usually complementary to each other, can be mixed flow processing of different parts. The system has an external interface, and can be composed of flexible manufacturing system with other units.

1、FMC control system

The FMC control system is generally divided into two levels, the unit control level and the equipment control level.

(1) Equipment control level This is the stand-alone control for various equipment such as robots, machine tools, coordinate measuring machines, trolleys, conveyors, and so on. The control system at this level is connected to the unit control system with an interface upward and to the equipment downward. The function of the device controller is to convert workstation controller commands into operable, sequential and simple tasks and to monitor the execution of these tasks by means of various sensors. The equipment control level generally uses industrial controllers such as microcomputers, bus controllers or programmable controllers with strong control functions.

(2) unit control level This level of control system is to command and coordinate the activities of the equipment in the unit, handling parts pallets handed over by the material storage and transportation system, and through the control of the workpiece adjustment, parts clamping, cutting, chip removal, machining process inspection, unloading the workpiece as well as cleaning the workpiece, and other functions of the equipment level of the various sub-systems to carry out the scheduling. The unit control system generally uses a microcomputer or workstation with limited real-time processing capabilities. The unit control level communicates with the equipment control level through an RS232 interface, and can be used to form an FMS with other systems through this interface.

2、Basic control function of FMC

(1) Task management and scheduling of each processing equipment in a unit, including the development of a unit operation plan, management and scheduling of the plan, and logging and reporting of equipment and unit operation status.

(2) Management and scheduling of in-cell logistics equipment, including conveyor belts, tracked or trackless material carriers, robots, pallet systems, and workpiece loading and unloading stations.

(3) Tooling system management, including tool requests to shop floor controllers and tool presetters, and distribution of tools to machines that need them.

Figure 8-2 Flexible Manufacturing Cell

1-CNC lathe 2-Machining center 3-Loading and unloading station 4-Gantry robot 5-Robot 6-Machining center controller

7-Lathe CNC controller 8-Gantry robot controller 9-Cart controller 10-Machining center controller 11-Robot controller

12-Unit controller 13, 14-Transportation trolley

Figure 8-2 shows a flexible manufacturing cell for machining mainly rotary body parts. It consists of a CNC lathe, a machining center, two transport trolleys for conveying between workpiece loading and unloading stations 3, the CNC lathe 1 and the machining center 2, a gantry manipulator 4 for loading and unloading workpieces for the CNC lathe and for changing tools, and a robot 5 for exchanging tools between the tool magazine of the machining center and an off-machine tool magazine 6. The control system consists of a numerical control unit 7 for the lathe, a gantry robot controller 8, a trolley controller 9, a machining center controller 10, a robot controller 11 and a cell controller 12. The cell controller is responsible for control, scheduling, information exchange and monitoring of the equipment comprising the cell.

Figure 8-3 Flexible Manufacturing Cell with Pallet Library

1-Tool magazine 2-Tool changer 3-Pallet magazine 4-Loading and unloading station 5-Pallet changing mechanism

Figure 8-3 shows a flexible manufacturing cell for machining prismatic parts. The main unit is a horizontal machining center, the tool magazine capacity of 70, the use of dual robotic tool changer, equipped with 8-station automatic exchange pallet library. The pallet magazine is a ring turntable, the pallet magazine table is supported on a cylindrical ring guideway, and is rotated by the inner ring chain drag, and the sprocket is driven by a motor. The selection and positioning of the pallet is controlled by a programmable controller, and the pallet bank has the functions of forward and reverse rotation, random selection and jump indexing. The exchange of pallets is realized by the hydraulic push-pull mechanism located in the center of the ring-shaped table. There is a workpiece loading and unloading station next to the pallet bank, and automatic chip removal devices are provided on both sides of the machine.

III. Flexible Manufacturing System FMS

Flexible Manufacturing System (Flexible Manufacturing System) is composed of two or more machining centers or CNC machine tools, and on the basis of processing automation to achieve the automation of the material flow and information flow, its basic components are: automated machining equipment, workpiece storage and transportation systems, tool storage and transportation systems, multi-layer computer control systems.

     
     1. Automated processing equipment

The automated machining equipment that make up the FMS are CNC machine tools, machining centers, turning centers, etc., or possibly flexible manufacturing cells. These processing equipment are computer-controlled, processing parts change generally only need to change the CNC program, and thus has a high degree of flexibility. Automated machining equipment is the most basic and important equipment of the automated manufacturing system.

2. Workpiece storage and transportation system

The FMS workpiece storage and transportation system consists of workpiece storage, workpiece transportation equipment and changing devices. Workpiece storage includes automated three-dimensional warehouses and buffer stations for pallets (workpieces). Workpiece transportation equipment includes all kinds of conveyor belts, transportation trolleys, robots or manipulators. Workpiece replacement devices include various robots or manipulators, pallet exchange devices and so on.

3. Tool storage and transportation system

The tool storage and transportation system of FMS consists of tool magazine, tool conveyor and exchange mechanism. Tool magazines are centralized tool magazines and machine tool magazines. Tool conveyors are different forms of transportation trolleys, robots or manipulators. Tool changing devices are usually tool changing mechanisms on the machine tool, such as tool changing robots.

4. Auxiliary equipment

FMS can be equipped with auxiliary equipment according to production needs. Auxiliary equipments generally include: ①automatic cleaning workstation; ②automatic deburring equipment; ③automatic measuring equipment; ④centralized chip transportation system; ⑤centralized cooling and lubrication system and so on.

5. Multi-layer computerized control system

The control system of the FMS uses three levels of control, which are the unit control level, the workstation control level, and the equipment control level. Figure 8-4 is an example of an FMS control system that includes an automatic guided vehicle (AGV), TH6350 horizontal machining center, XH714A vertical machining center, and storage equipment.

Figure 8-4 Example of FMS control system

(1) Device control level This is stand-alone control for various devices such as robots, machine tools, CMMs, trolleys, conveyors, and storage/retrieval. The control system at this level interfaces upward with the workstation control system and downward with the equipment. The function of the device controller is to convert workstation controller commands into operable, sequential, simple tasks and to monitor the execution of these tasks by means of various sensors.

(2) Workstation control level FMS workstations are generally divided into processing workstations and logistics workstations. Processing workstations to complete the workstation processing process, tool replacement, inspection and other management; logistics workstations to complete the raw materials, finished products and semi-finished products, storage, transportation, change of workstations and other management. This level of control system is to command and coordinate the activities of a group of equipment in the unit, handling parts pallets handed over by the material storage and transportation system, and through the control of workpiece adjustment, parts clamping, cutting, chip removal, inspection during processing, unloading and cleaning of the workpiece, and other functions of the equipment level of the various sub-systems to carry out scheduling. Equipment control level and workstation control level and other control systems are generally used with strong control functions with real-time control function of the microcomputer, bus control machine or programmable controller and other industrial control machine.

(3) Unit control level The unit control level, as the highest level of control of the FMS, is the overall control system for all production activities, and at the same time, it is also the bridge that carries on the upper and lower levels and communicates with the higher level (shop floor) controllers for information linkage. Therefore, the unit controller is very important for realizing the effective integrated control of the bottom three levels and improving the economic efficiency of FMS, especially the production capacity. Unit control level is generally used with a strong real-time processing capabilities of small computers or workstations.

Figure 8-5 shows a more typical FMS with 4 machining centers arranged in a straight line, and a workpiece storage and transportation system consisting of a pallet station 2, a pallet transport trackless trolley 4, a workpiece loading and unloading station 3, and a pallet changer 12 arranged in front of the machining centers. The tool storage and transportation system consists of a central tool magazine 8, a tool inlet and outlet station 6, a tool conveyor robot mobile vehicle 7 and a tool presetter 5. The unit controller 9, the workstation controller (not shown in the figure) and the equipment controls comprise a three-level computerized control. The chip transport system does not use centralized transport, and each machining center is equipped with a chip transport device.

Figure 8-6 Flexible Manufacturing System with Assembly Functions

1-Control cabinet 2-Manual station 3-Fastening robot 4-Assembly robot 5-Dual arm robot 6-Washing station 7-Warehouse

8-Turning Machining Center 9-Multi-coordinate Measuring Machine 10-Boring & Milling Machining Center 11-Tool Presetting Station 12-Assembly Robot 13-Small Piece Assembly Station 14-Clamping Station 15-AGV (Automatic Guided Vehicle) 16-Control Area

Figure 8-6 shows a flexible manufacturing system with flexible assembly capabilities. The right portion of the figure shows a machining system with a boring mill 10 and a turning center 8. 9 is a multi-coordinate measuring machine, 7 is a three-dimensional warehouse, and 14 is a fixturing area. The left part of the figure shows a flexible assembly system with a loading robot 12, three fixturing robots 3, 4, 13; a two-armed robot 5, a manual station 2 and conveyor belts. The two systems of flexible machining and flexible assembly are connected by an automated guided trolley as a transportation system 15. Measuring equipment is also integrated within the scope of the general control system.

The main features of the flexible manufacturing system are: ① high flexibility, adapt to multi-species small and medium-sized batch production; ② the system of machine tool process capacity is complementary and mutual substitution; ③ can be mixed-flow processing of different parts; ④ the system of local adjustments or repairs without interrupting the operation of the entire system; ⑤ multi-layer computer control, can be networked with the upper computer; ⑥ can be unmanned intervention in the production of three shifts.

IV. Flexible Manufacturing Line FML

Manufacturing Flexible Line consists of automated processing equipment, workpiece conveyor system and control system. Flexible manufacturing line FML and flexible manufacturing system between the boundaries are also very blurred, the important difference between the two is that the former like a rigid automatic line, with a certain production beat, the work along a certain direction of the sequential transmission, the latter does not have a certain production beat, the direction of transmission of the workpiece is also a random nature of the nature of the transmission. Flexible manufacturing line is mainly suitable for varieties of small changes in the batch and mass production, the machine tool on the line is mainly multi-axis spindle box box and turret type machining centers.

The main advantages of flexible manufacturing line is: with rigid automatic line of the majority of the advantages, when the batch is not very large, the production cost is much lower than the rigid automatic line, when the variety of changes, the system requires much less time than the adjustment of the rigid automatic line, but the total cost of the establishment of the system is much higher than the rigid automatic line. Sometimes in order to save investment and improve the operational efficiency of the system, flexible manufacturing line often use a combination of rigid and flexible form, that is, a part of the production line equipment using rigid special equipment (mainly combined machine tools), the other part of the use of change box or change the knife type of flexible processing machine tools.

1、Automated Machining Equipment The automated machining equipment that makes up FML includes CNC machine tools and interchangeable spindle box machines. Interchangeable spindle box machine is an intermediate model between machining centers and combination machines. Interchangeable spindle box machines are surrounded by a spindle box magazine, and the spindle box can be changed according to the needs of the machined workpiece. The spindle box is usually multi-axis, and the interchangeable spindle box machine is a highly efficient machine for simultaneous multi-face, multi-axis, and multi-tool machining of workpieces.

2. Workpiece Conveyor System The workpiece conveyor system of FML is similar to the rigid automatic line, using various conveyor belts to convey the workpieces, and the flow of the workpieces is consistent with the machining sequence, and passes through each machining station in turn.

3, tool Convertible spindle box is equipped with a number of tools, the spindle box itself plays the role of the tool library, tool installation, adjustment is generally carried out manually, the use of timed forced tool change.

Figure 8-7 Diagram of Flexible Manufacturing Line

Figure 8-7 shows the schematic diagram of a flexible automatic line for machining box parts, which consists of two CNC milling machines arranged opposite to each other, four turret-type box-changing machines arranged two by two opposite to each other, and one cycle-type box-changing machine. A roller conveyor is used to transport the workpieces. This automated line does not look different from a rigid automated line, but it has a certain degree of flexibility.FML has some of the characteristics of both a rigid automated line and an FMS. It is close to FMS in terms of flexibility and close to rigid automated line in terms of productivity.

V. Flexible Assembly Line FAL

A Flexible Assembly Line usually consists of an assembly station, a material handling device and a control system.

1. Assembly station

Assembly stations in FAL can be programmable assembly robots, non-programmable automated assembly devices and manual assembly stations.

2、Material conveying device

In FAL, the material conveyor provides various assembly parts for the assembly line according to the assembly process flow, so that different parts and assembled semi-finished products can flow reasonably between assembly points, and at the same time, it also has to transport the finished parts (or products) away from the site. Conveying device consists of conveyor belt and reversing mechanism and so on.

3. Control system

FAL's control system schedules and monitors the entire line, primarily controlling the flow of materials, automated assembly stations and assembly robots.

Figure 8-8 Schematic of Flexible Assembly

1-Unmanned conveyor 2-Conveyor belt 3-Dual arm assembly robot 4-Assembly robot

5-Threading robot 6-Automatic assembly station 7-Manual assembly station 8-Feeding station

Figure 8-8 shows a schematic diagram of the FAL with a line consisting of an unmanned conveyor 1, a conveyor belt 2, a dual-arm assembly robot 3, an assembly robot 4, a thread-screwing robot 5, an automated assembly station 6, a manual assembly station 7, and a feeding workstation 8. The feeding workstation has a magazine and a pickup robot. The magazine has multiple layers of overlapping boxes that can be pulled out, also called drawers, in which the parts to be assembled are stored. The picker robot has various grippers that automatically remove the parts from the boxes and place them on a pallet. The tray with the parts is automatically delivered by a conveyor belt to the assembly robot or assembly station.

六、CIMS

Computer Intergrated Manufacturing System is a set of market analysis, product design, processing and manufacturing, business management, after-sales service and integration, with the help of computer control and information processing functions, so that the enterprise operation of the information flow, material flow, value flow and human resources organic fusion, to realize the rapid updating of the product, productivity, quality stability, effective use of funds, reduce losses, rational allocation of personnel, rapid market feedback and good service of the new enterprise production model./span>

1. Functional composition of CIMS

The functional components of CIMS include the following, as shown in Figure 8-9.

(1) Management Functions CIMS is capable of rational allocation and effective coordination of production planning, material procurement, warehousing and transportation, capital and finance, and human resources.

(2) Design function CIMS can use CAD, CAE, CAPP (computer-aided process preparation), NCP (numerical control programming) and other technical means to realize product design, process design and so on.

(3) Manufacturing function CIMS can automatically organize and coordinate production equipment (CNC, FMC, FMS, FAL, robots, etc.), storage and transportation equipment and auxiliary equipment (feeding, chip removal, cleaning and other equipment) to complete the manufacturing process in accordance with process requirements.

Figure 8-9 Components of CIMS

(4) Quality control function CIMS uses CAQ (computer-aided quality management) to complete the quality management and quality assurance of the production process, which not only forms a quality management system in software, but also participates in the testing and monitoring of the production process in hardware.

(5) Integrated control and network function CIMS adopts multi-layer computer management mode, such as factory control level, workshop control level, unit control level, workstation control level, equipment control level, etc., with clear division of labor and resource sharing among all levels, and relying on the network to realize the transmission of information.CIMS is also able to set up a network communication channel with the customers to realize the automatic ordering, service feedback, outsourcing and cooperation.

From the above introduction, it can be seen that CIMS is currently the highest level of automated manufacturing system, but this does not mean that CIMS is a fully automated manufacturing system. In fact, the current sense of the CIMS degree of automation is even lower than the flexible manufacturing system, CIMS emphasizes the main information integration, rather than the automation of the logistics of the manufacturing process.CIMS is mainly characterized by a very large system, including a lot of content, to be fully realized in an enterprise is very difficult. However, partial integration can be taken to gradually realize the integration of information and functions of the whole enterprise.

2. Key technologies of CIMS

CIMS is a product of the comprehensive application of traditional manufacturing technology, automation technology, information technology, management science, network technology and system engineering technology, which is a complex and large-scale system engineering.The main features of CIMS are computerization, informationization, intelligence and high integration. At present, each country is in the stage of local integration and lower level of application, CIMS needs to solve the key technologies are mainly information integration, process integration and enterprise integration and other issues.

(1) Information Integration For the different units of design, management and processing and manufacturing, realizing the correct and efficient sharing and exchange of information is the first problem that must be solved in order to improve the technology and management level of the enterprise. The first issue of information integration is to establish the enterprise system model. Using the system model of the enterprise to scientifically analyze and synthesize the functional relationship, information relationship and dynamic relationship of each part of the enterprise, and to solve the relationship between the material flow, information flow, value flow and decision-making flow of the enterprise, which is the foundation of enterprise information integration. Secondly, since the system contains different operating systems, control systems, databases and application software, and different communication protocols may be used between the systems, information integration should also deal with the interface problems between the information.

(2) Process Integration In order to improve T (efficiency), Q (quality), C (cost), S (service), E (environment) and other objectives, in addition to the means of information integration, it is also necessary to deal with the optimization and coordination of processes. Process integration requires that the serial processes in product development, process design, manufacturing, supply and sales be transformed into parallel processes as far as possible, such as in product design to take into account the downstream work of manufacturability, assemblability, maintainability, etc., and to foresee the quality of the product, the content of after-sales service, etc.. Process integration also includes rapid response and dynamic adjustment, i.e., when unforeseen deviations occur in a certain process, the relevant process adjusts its planning and program in a timely manner.

(3) Enterprise Integration Making full use of global material resources, information resources, technology resources, manufacturing resources, human resources and user resources to meet the human-centered intelligence and user-centered product flexibility is the goal of CIMS globalization, enterprise integration is to solve the resource sharing, resource optimization, information services, virtual manufacturing, parallel engineering, network platforms and other aspects of the key technologies.