◎ Background
Henry Ford began to produce Model T cars. Based on the A-type design that he originally manufactured in 1903, the T-type car took five years to develop. Its birth initiated the mass production line as we know it today. This revolutionary idea is based on the concept of simply assembling interchangeable parts. Before that, carriages and baby carriages were made by professional craftsmen in small batches, and they rarely copied any specific parts. Ford's innovative design reduces the number of required parts and the number of skilled assemblers in the assembly operation, which gives Ford a great advantage in the competition.
For the first time, Ford set foot in the car assembly of Model A, and built the whole car on the assembly platform. Usually, an assembler assembled the whole car in one place. This man is doing the same thing over and over again on his fixed assembly platform. In order to improve efficiency, Ford shipped parts to each workstation as needed. In this way, each assembler needs about 8.5 hours to complete his assembly task. By the time the Model T was developed, Ford had decided to use multiple assembly platforms, and the assemblers moved from one assembly platform to another, and each person performed a specific function. This process reduces the assembly time of each assembler from 8.5 hours to only 2.5 minutes by familiarizing each worker with specific tasks.
Ford soon realized that it was a waste of time to walk from one booth to another, and when faster workers overtook slower workers, it would cause congestion in the production process. 19 13 In Detroit, he solved this problem by introducing the first mobile assembly line, which is a conveyor belt that moves vehicles through fixed assemblers. By eliminating the need for workers to move between workstations, Ford reduced the assembly task of each worker from 2.5 minutes to less than 2 minutes; The moving assembly conveyor belt can now track the fixed workers. The first conveyor line consists of metal bars, and the wheels are connected to the metal bars. The metal strip is tied to a belt, which rolls along the length of the factory, and then returns to the starting place under the floor. The reduction of manpower required to assemble a car has attracted the attention of car assemblers all over the world. Ford's mass production promoted the automobile industry for nearly 50 years, and was finally adopted by almost all other industrial manufacturers. Although technological progress has made many improvements in modern automobile assembly operations, the basic concept of fixed workers installing parts on vehicles when they pass through their workstations has not changed significantly for many years.
Raw materials
Although most cars are made of raw steel, petroleum products (plastics and ethylene) account for an increasing proportion of car parts. Lightweight materials extracted from petroleum have reduced the weight of some models by 30%. As the price of fossil fuels continues to rise, the preference for lighter and more fuel-efficient cars will become more obvious.
Design
It usually takes three to five years to launch a new model from start to assembly. The idea of developing new models is to respond to unsatisfied public needs and preferences. It is not easy to predict what kind of car the public wants to drive in five years, but the car company has successfully designed a car that meets the public's taste. With the help of computer-aided design equipment, designers develop basic concept maps to help them visualize the appearance of the proposed vehicle. Based on this simulation, they then build clay models, which can be studied by modeling experts who are familiar with what the public may accept. Aerodynamic engineers also review models, study airflow parameters, and conduct feasibility studies on crash tests. Only after all models have been reviewed and accepted, the tool designer is allowed to start manufacturing tools to manufacture parts of new models.
Manufacturing industry
process
ingredient
The automobile assembly plant is only the last stage in the automobile manufacturing process, because here, parts provided by more than 4,000 external suppliers (including all parts suppliers of the company) are assembled together, usually by trucks or railways. Those parts that will be used for the chassis are transported to one area, while those parts that will constitute the car body are unloaded in another area.
base
A typical car or truck is built from the ground. The frame is the foundation of the car body, and all subsequent assembly parts start from the frame. The frame is placed on the assembly line and clamped on the conveyor belt to prevent it from moving when it moves on the assembly line. From here, the car frame moves to the parts assembly area, where the complete front and rear suspension, oil tank, rear axle and drive shaft, gear box, steering box parts, wheel drum and braking system are installed in turn.
Off-line operation at this production stage matches the engine of the vehicle with the transmission. Workers use robotic arms to install these heavy parts into the engine compartment of the frame. After the engine and transmission are installed, one worker installs the radiator and another worker bolts it in place. Due to the nature of these heavy parts, the articulated robot performs all lifting and handling operations when the assembler uses a pneumatic wrench to fix the parts bolts in place. A careful economic study of each assembly task provides the safest and most effective tools for assembly workers.
body
Generally, the floor is the largest body part, and a large number of panels and brackets will be welded or bolted to it later. When it moves on the assembly line, it is fixed by the fixture, and the outer shell of the car is completed. First, the left and right quarter plates are automatically separated from the container prepared in advance, and placed on the bottom plate, which is fixed and welded by positioning fixture.
The front and rear doorposts, roof and side panels are assembled in the same way. The automobile shell assembled in this process is helpful to the use of robots, because the articulated arm can easily introduce various component brackets and panels into the bottom plate, and complete a large number of welding operations in a certain period of time, and its accuracy is beyond the reach of any manual worker. The robot can pick up and load 200 pounds (90.8 kilograms) of roof slabs and place them in the correct welding position accurately, and the tolerance variation is kept within 0.00 1 inch. In addition, the robot can tolerate smoke, welding flash and gas produced in the production process.
As the car body is removed from the isolated welding area of the assembly line, the car body components, including the fully assembled door, trunk lid, hood, fender, trunk lid and bumper reinforcement, are then installed. Although robots help workers to put these parts on the body shell, workers use pneumatic auxiliary tools to provide proper fit for most bolted functional parts.
pigment
Before painting, the car body must go through strict inspection procedures, and the car body should be operated in white. The outer shell of the vehicle passed through a bright white room, where the visual inspector wiped the outer shell completely with a cloth soaked with high gloss oil. Under the light, this oil can let the inspector see any defects on the sheet metal body panel. Skilled body mechanics can repair bumps, dents and any other defects on the production line. After the shell is thoroughly inspected and repaired, the conveyor belt is assembled to transport the shell to the cleaning station, where the shell is soaked and all remaining oil, dust and pollutants are removed.
When the shell leaves the cleaning station, it passes through a drying chamber and then undergoes a primer impregnation, which is an electrostatic primer (called E-coat) bath, covering every corner and gap inside and outside the body shell with primer. The coating is used as the surface of the substrate, and the topcoat of the color coating is adhered to it.
After the electrophoresis tank, the shell is dried in a small room again, and then the final painting operation is carried out. In most automobile assembly plants today, the car body is painted by robots, which are programmed to apply the exact amount of paint to the right area in the right time. A lot of research and programming have entered the dynamic process of robot painting to ensure the fine "wet" finish we expect. Since Ford's first Ts car came out, our robot painters have come a long way. These painters paint by hand with brushes.
Once the shell is completely covered with 1 V colored paint primer and transparent top coat, the conveyor belt transfers the body to the baking oven, and the paint is cured at a temperature exceeding 275 degrees Fahrenheit (135 degrees Celsius). After the shell leaves the paint area, it can be assembled internally.
Internal assembly
The painted shell passes through the internal assembly area, where workers assemble all instruments and wiring systems, instrument panels, interior lights, seats, doors and decorative panels, roof linings, radios, speakers, all glass except windshield, steering column and steering wheel, body sealing strips, vinyl tops, brakes and accelerator pedals, carpets and front and rear bumper panels.
Next, the robot equipped with suction cups takes the windshield out of the transport container, coats a layer of polyurethane sealant around the glass, and then puts it into the windshield frame of the car body. Robots will also select seats and decorative plates and transport them to vehicles to facilitate and improve the efficiency of assembly operators. After passing this section, the shell is subjected to water test to ensure the proper cooperation of the door panel, glass and weatherstrip. Now, it is ready to cooperate with the chassis.
mate
The chassis assembly conveyor belt and the body shell conveyor belt meet at this stage of production. When the chassis passes through the body conveyor, the shell is automatically lifted from the conveyor fixture and placed on the frame. Assembly workers, some on the ground, some in the working pit under the conveyor belt, bolt the car body to the frame. Once mating occurs, the car begins to receive the final decorative parts, batteries, tires, antifreeze and gasoline.
The vehicle can start now. From here, it was driven to an off-line checkpoint, where its engine was checked, its lights and speakers were checked, its tires were balanced, and its charging system was checked. Any defects found at this stage need to be sent to the central maintenance area, usually near the end of the production line. At this stage, a group of skilled troubleshooting personnel analyze and repair all problems. When the vehicle passes the final audit, it will be labeled with a price tag and sent to a staging area, where it will be transported to its destination.
quality management
All the parts of the car are produced elsewhere. This means that thousands of parts that make up a car must be manufactured, tested, packaged and transported to an assembly plant, usually on the same day that they are used. This requires a lot of planning. In order to do this, most automobile manufacturers require external parts suppliers to carry out strict testing and inspection of their parts, similar to the methods used by assembly plants. In this way, the assembly plant can expect that the products arriving at its receiving terminal are approved by SPC and have no defects.
Once the automobile parts are assembled in the automobile factory, the production control experts can track the progress of each prototype automobile through the vehicle identification number (VIN) assigned at the beginning of the production line. In many more advanced assembly plants, a small radio frequency transponder is connected to the chassis and chassis. The sending unit carries VIN information and monitors its progress during the assembly process. Knowing what the vehicle has gone through, where it is going and when it should arrive at the next assembly station enables production managers to electronically control the manufacturing sequence. During the whole assembly process, the quality audit station tracks important information about the integrity of various functional parts of the vehicle.
This idea comes from the change of quality control thought over the years. Previously, quality control was regarded as the final inspection process, and only after automobile manufacturing was completed did we try to find defects. In contrast, today's quality is regarded as a process based on the design and assembly of automobiles. In this way, if the workers find defects, the assembly operator can stop the conveyor. You can then make corrections or check the supply to determine whether the whole batch of components is bad. Vehicle recall is expensive, and manufacturers will do everything possible to ensure the integrity of products before delivery to customers. After the vehicle is assembled, the verification process is carried out at the end of the assembly line to verify the quality audit of each inspection point in the whole assembly process. The final audit tested the correct installation of the panel; Dynamic; Squeak and creak; Electrical components in normal operation; And that position of the engine, the chassis and the wheels. In many assembly plants, vehicles are regularly pulled out of the audit line and subjected to comprehensive functional tests. Today, all efforts are made to ensure the quality and reliability of assembled products.
The future.
The development of electric vehicles will be attributed more to innovative solar energy and aviation engineering and advanced satellite and radar technology than to traditional automobile design and manufacturing. Electric vehicles have no engine, exhaust system, transmission, muffler, radiator or spark plug. It needs neither adjustment nor truly revolutionary gasoline. Instead, it will be powered by an alternating current (AC) motor, with a brushless design and a speed of up to 20,000 rpm. The batteries that power these motors will come from high-performance batteries that can generate more than 100 kilowatts of electricity. In addition, unlike the past and present lead-acid batteries, the future batteries will be environmentally safe and recyclable. The braking system of the vehicle will be integrated with a power inverter, which will convert direct current back to the battery system once the accelerator is released, thus acting as a generator of the battery system, even if the vehicle is driven for a long time in the future.
The increase of automobile usage and the increase of road construction resistance make our highway system crowded and outdated. However, the new electronic ic automobile technology may soon become possible, which can make cars drive on crowded roads and even drive automatically. Giving the operation of our car to the computer means that the computer will collect information about congestion from the road and find the fastest route to the designated destination, so as to make better use of the limited road space. The arrival of electric vehicles is due to the rare combination of environment and capability. G. Growing intolerance of pollution and extraordinary technological progress will change the global transportation mode and bring us into the 2 1 century.