Application of high speed machining center in the production of auto parts
Hub Assembly For HYUNDAI & KIA SHAOXING ZHENGHONG AUTO PARTS CO.LTD , https://www.kontinental-bearing.com
In order to solve this problem, a high-speed, high-efficiency new-generation machining center, a high-speed machining center, has emerged, which has solved the contradiction between processing flexibility and production, investment and renewal. It has satisfied many varieties of the automotive industry, large quantities, and less. The investment requirements also meet the requirements for the production of auto parts.
Characteristics of high -speed machining center The high-speed machining center refers to a type of machining center where the spindle speed exceeds 10000r/min, the feed speed exceeds 40m/min, and the feed acceleration is greater than 0.5G (5m/s2). In order to achieve stable processing at high speed and large cutting capacity, in general, high-speed machining centers have the following structural features:
1. The high speed spindle spindle speed is too low to meet the production efficiency requirements. If the speed is too high, it will bring various disadvantages in reliability. The spindle speed of the high-speed machining center is generally set between 46 and 16000 rpm. For this reason, the best structural solution is to install a direct-drive electric spindle. The electric spindle is not disassembled during use, no maintenance is required, and adjustment is not required. The spindle rotor is mounted on a composite ceramic ball bearing with a three-point support to ensure high dynamic rigidity and accuracy. There is a special water cooling system around the stator and rotor bearings to absorb heat.
2. Dynamic balance and thermal balance structure design Because of its high spindle speed, high feed rate and high feed acceleration, the high-speed machining center must require high static stiffness and dynamic rigidity. For this reason, some hydraulic devices are placed separately from the main shaft to reduce the influence of vibration on the accuracy of the main shaft.
The structure of the device is completely thermally symmetrical, which avoids the positional deviation of the spindle from the workpiece due to thermal deformation. In order to prevent thermal imbalance caused by chips as an important heat source, some are structurally designed so that the chips do not stay on the workpiece and on the pallet, and the chips are quickly discharged through the spiral chip conveyor on both sides of the Z-axis cover. The tank is cut to minimize the effects of heat caused by the chips.
To ensure the rigidity and stability of the motion, the design of high-speed machining centers usually follows the following principles:
(1) The force applied to each axis is always on the axis of each center of gravity to avoid the swing of the structural components of the device during acceleration and deceleration.
(2) The guiding means of the moving part is also on the plane of gravity to stabilize the structure of the device and to avoid the swing of the structural member during acceleration and deceleration.
(3) The component mosaic structure is adopted to improve the processing technology of the component to reduce the weight of the moving component.
(4) Each axis measurement is performed at the thrust center to obtain the most accurate measurement results and the maximum stability of position repeatability.
3. High rigidity three-point support bed
High-speed machining centers mostly use a three-point support bed with a coordinate boring machine. The finite element analysis method (FEM) is used for high-rigidity structural design to maintain high rigidity and stability, so that even at the maximum moving speed, even strong cutting and multiple times are required. In the processing of positioning movement, the optimal state of rigidity can be achieved.
4. Linear rolling guides combine rigidity and precision . The maximum feed speed and rapid traverse speed of each coordinate of the high-speed machining center are generally above 40m/min. These are precision friction-resistant linear motion ball screws. Implemented on the rail system. The ball screw uses a gap-free pre-stressed ball. The lubrication of the guide rail is quantitatively lubricated and is completed by a lubrication center. This system has excellent stability and dynamic rigidity and can respond quickly to computer commands. In some machines, the three coordinates of the machine adopt the new structure of the ball screw. In order to minimize the rolling inertia, the screw is fixed without rotation and the digital motor drives the ball screw nut through the toothed belt.
5. HSK Clamping Tool HSK Clamping Tool Clamping is a tool for high-speed machining centers. It has a very strong static and dynamic rigidity and can transmit torque safely and efficiently.
6. Tool change and exchange table quickly in a cutting cycle of the machining center, the tool change time and exchange table time often occupy a larger proportion. In the traditional non-high-speed machining center, the tool change time (chip to chip) is about 14~20s, while the exchange table time takes 3min or even longer. This is undoubtedly the processing of auto parts for high-volume, fast-paced production. It is not suitable. The high-speed machining center is designed to match the high spindle speed, high feed rate and feed acceleration in these two aspects. The tool change time (chip to chip) can reach 3.5s, and the exchange table time can be reduced to only For 6s. Each table has a precision mouse platen indexing mechanism to ensure accurate 360° division. If required by the user, 360,000 equal divisions can also be obtained, providing high flexibility in processing various surface parts and rigidity during operation.
Application of high-speed machining center in auto parts processing industry 1. Application in auto parts processing industry At present, various large, medium and small, single-spindle or twin-spindle, from manual loading and unloading to single-tray type to flexible manufacturing unit Multi-tray high-speed machining centers have been widely used in the automotive parts industry. They are mainly used in the production of cylinder blocks, cylinder heads, differential cases, connecting rods, gearbox housings, steering knuckles and many other parts. The assembly line shows excellent overall performance.
According to the product output and the needs of users, the high-speed machining center production line can be arranged in series (process dispersion), parallel (process concentration) and hybrid. At present, the hybrid layout in the automotive industry production line is the most widely used, which can obtain the best production efficiency, maintain sufficient flexibility and reliability, and facilitate the production line layout in batches. The number of parallel machines in a hybrid arrangement should be between 1 and 4.
In the early 1990s, people often over-emphasized the need for high flexibility in processing and ignored the limitations of high-speed machining centers in some machining processes. After years of exploration, at present, people think that a reasonable automobile parts production line should be a special-soft combination scheme. For example, for the machining of automotive engine cylinder heads and cylinder blocks, the special-flexible combination scheme can be summarized as:
(1) Planar processing: aluminum parts - high speed machining center; cast iron parts, steel parts - CNC milling machines.
(2) Medium and small hole systems, screw holes - high speed machining centers; irregular and small plane milling - high speed machining centers.
(3) Important special surface machining (é•— cylinder hole, crankshaft hole, camshaft hole, long oil hole) - flexible special machine or combination machine tool.
The production line consisting of high-speed machining centers has the following characteristics:
(1) According to the production demand and the degree of investment, it is easy to realize the step-by-step implementation of the project and gradually expand the equipment.
(2) There is no need to adjust and update equipment on a large scale when changing production varieties. The production line built by one investment can not only meet the needs of the current market, but also meet the production demand for new products in the future market.
(3) The production efficiency is high due to its high cutting speed, high feed rate, and short tool change time.
Since most of the equipment on the production line consists of the same type of machine, it is easy to grasp, easy to repair and spare parts preparation, and maintain high equipment integrity.
2. Application examples
The production line of 220,000 gas cylinder heads produced by Shenlong Automobile Co., Ltd. on July 21, 2005 is a high-speed machining center, which is supplemented by special planes. The special machine on the production line is used to process parts. The part where the change occurs, and the high-speed machining center is mainly responsible for processing the parts that need to be changed on the part, so that both the production efficiency and the flexibility change can be considered.
The project is a key project for the development of the second phase of Shenlong Company, with an investment of more than 200 million yuan. The machining center adopts J4M high-speed machining center of Japan Makino Company. The whole line cutting process is completed by 31 J4M high-speed machining centers. These machining centers constitute 9 “processingâ€. "Island", each "processing island" consists of a two-arm gantry robot and three to five machining centers. A "processing island" is a process: the processing content between machining centers is exactly the same. Auxiliary equipment includes conduit/seat press, plug/steel ball press, leak detector, washing machine, marking machine, etc. It can meet the two-cylinder mixed-cylinder production of Shenlong TU and EW at the same time. It is the first to comprehensively apply a variety of technologies such as “processing islandâ€, accompanying pallets, robots, PROFIIBUS bus, etc., with high degree of automation and technical content. Leading.
The spindle speed of the high-speed machining center exceeds 16 000r/min, the feed speed exceeds 50m/min, and the product changeover time does not exceed 20min.
By the end of 2005, the production line has been able to produce four types of 16-valve aluminum alloy cylinder heads with a daily output of more than 700 units, meeting the needs of Shenlong's new products.
Conclusion
With the rapid development of China's automobile industry and the changing characteristics of the current automotive market, each automobile manufacturer can only take the initiative and favorable position in the automobile market by producing high-quality, low-cost and diversified automobile products. The emergence and development of processing technology and processing methods in high-speed machining centers provide an economically viable and efficient solution for the development of China's automobile industry, especially automotive parts.