Automobile industry relative to aviation, aerospace, ships, machine tools and other mechanical processing industry, its outstanding characteristic is the production batch is big, machining time is short, in order to adapt to the mass production of the single artifacts, by plane or plane automatic line production is the most economical, and therefore one of the most common choice. However, the current car user of diversity and personality requirements of the car, forcing auto enterprise product HuanXing faster and faster, product varieties vary widely, with the mass production of the original single artifacts into a wide variety of artifacts of their respective small batch is learned.on mass production, therefore, in the automobile manufacturing industry for many years the dominant combination machine tools (plane) production line have been unable to meet the needs of the reality of auto industry quick update, although plane or plane automatic line of high efficiency, flexible but limits the processing, the machine for processing parts varieties changes adaptability is very poor.

In order to solve this problem, a new generation of high speed, high efficiency machining center, high-speed machining center arises at the historic moment, to solve the flexible processing and production, the contradiction between investment and update, meet the automobile industry at present many varieties, large quantity, the requirement of less investment, but also satisfied the requirements of automobile spare parts manufacturing.

The characteristics of high speed machining center

Refers to the high speed machining center spindle speed of more than 10000 r/min, feed speed more than 40 m/min, feed acceleration is greater than 0.5 G (5 m/s2) of machining center. In order to achieve the stability under high speed, large amount of cutting processing, general, high-speed machining center has the following structure:

1. High speed spindle

Spindle speed is too low can't meet the requirements of the production efficiency, high speed, bring a variety of adverse factors in terms of reliability. High speed machining center spindle speed is generally between 46-16000 revolutions per minute. To this end, the best structure scheme for direct drive of the motorized spindle is installed inside, motorized spindle sealed in use, do not need to maintain, does not need adjustment. Spindle rotor is installed on the composite ceramic ball bearings, using three bearing way to ensure that the dynamic rigidity and high precision. Around the stator and rotor bearing have special water-cooling system to absorb heat.

2. The structure of dynamic balance and heat balance design

High speed machining center due to its high spindle speed, feed with high speed and high feed acceleration, inevitable requirement to its structure design has high static stiffness and dynamic rigidity. To this end, some place the hydraulic device and spindle separation, to reduce the vibration impact on the accuracy of the spindle.

Equipment structure is totally hot symmetrical, so that you can avoid due to the thermal deformation of spindle and workpiece position deviation. To prevent scraps as an important heat source heat imbalance, some from the structure design makes the chip is not processed workpieces and tray, and through the Z axis cover on both sides of the spiral chip conveyor to chip into the cutting fluid box, so that caused by the chip to minimize the effect of heat.

In order to ensure the rigidity and stability, the design of high speed machining center usually follow the following principles:

(1) of the axis of the axis of the force is always in the centre of gravity, to avoid the acceleration and deceleration when the motion of the device structure.

(2) the moving parts of the guide is in the center of gravity in the plane, to stabilize the device structure and avoid the motion of the structure when the acceleration and deceleration.

(3) by part Mosaic structure, improving the processing technology of the component, in order to reduce the weight of the moving parts.

(4) the axis measurement is in the center of the thrust, in order to get the most accurate measurement results and the stability of the biggest repeat precision.

3. High rigid support bed at 3 o 'clock

Most used coordinate boring machine type of high speed machining center three support lathe bed, through the finite element method (FEM) for high rigidity structure design, maintain a high rigidity and stability, with the largest mobile speed even need to be strong in the processing of cutting and multiple positioning mobile, can achieve rigid optimal state.

4. Precision linear rolling guide is rigid and well integrated together

The coordinates of the high speed machining center biggest feed and fast moving speed is generally in more than 40 m/min, these are all in the precision of the linear motion ball screw friction resistance on the guide rail system. Prestressed ball bearing, ball screw with no clearance guide rail lubrication using quantitative lubrication, performed by a centre of lubrication. This system has good stability and dynamic rigidity, can make quick response to computer instructions. Some machine three coordinates using the structure of the new line of ball screw, in order to minimize the rolling inertia, don't make rotary screw fixation and tooth shape by digital motor through a belt drive the ball screw nut rotation.

5. By using HSK clamp type

HSK clamp type cutter holder assembled system is designed for high speed machining center tool, its static and dynamic rigidity are very strong and able to be both safe and efficient transmission torque.

6. Change and change table quickly

In machining center of a cutting cycle, tool change time and change table often occupies the most proportion. In the tradition of high speed machining center, tool change time (chip to chip) around 14 ~ 20 s, and need to change table 3 min or longer, is no doubt that for mass production requirements of the fast rhythm, it is not appropriate to the auto parts processing. And the high speed machining center are the two aspects of design and its high spindle speed, feed rate and feed acceleration matching, tool change time (chip to chip) can reach about 3.5 s, change table time can be reduced to only for 6 s. And each table has a precision pressure plate of the rat dividing mechanism to ensure accurate dividing 360 °, etc. If the user needs, can also be dividing, such as 360000, to provide processing various parts processing the surface of the flexible and rigid at work.

Application of high-speed machining center in auto parts industry

1. The application in automobile parts processing industry

At present, all kinds of large, medium-sized, small, single or double spindle, spindle from single hand up and down material tray to more flexible manufacturing unit tray type high speed machining center in the auto parts industry has been more widely used, they are mainly used in the cylinder block, cylinder head, differential shell, connecting rod, gearbox shell, steering knuckle, and other various parts of production lines, shows excellent comprehensive performance.

According to the product yield and the needs of users, high speed machining center production line can be decorated tandem (procedure), parallel (process), and hybrid. Currently in hybrid decorate the most widely used in automotive industry production line, can get the best production efficiency, maintain enough flexibility and reliability, and is advantageous to the stage on the batch production line layout. Hybrid arrangement of the number of parallel machine tool should be between 1 ~ 4 units.

In the early 1990 s, people tend to over-emphasize the requirement of processing high flexible and ignore the high speed machining center in some limitations in the machining process. Now, after years of groping, people think that the reasonable auto parts production line should be designed - soft combination scheme. For example, for processing of the automobile engine cylinder cover and cylinder body, specially - soft combination scheme can be summarized as:

(1) the plane processing: aluminum - the high speed machining center; Cast iron pieces, steel parts, CNC milling machine.

(2), hole, screw holes, high speed machining center; Irregular and the plane milling of small, high speed machining center.

(3) important special surface processing (the cylinder boring hole and shaft hole, CAM shaft hole, long oil hole) - flexible plane or combination machine tools.

Made of high speed machining center mainly production line has the following features:

(1) according to the requirements of production and investment in place, easy to implement project was implemented step by step, gradually expand the equipment.

(2) the change of products not large-scale adjustment and update your equipment. A production line, built with investment can not only meet the needs of the market now, also can meet the production requirements of the future market for new products.

(3) because of its high cutting speed, high feed rate and tool change of short auxiliary time, thus the production efficiency is high.

Since most of production line equipment consists of the same type, easy to master, easy to maintenance and spare parts, maintain a high equipment intact rate.

conclusion

With the rapid development of domestic automotive industry and the current automobile market and changeable characteristics, each car factory only produce high quality, low cost, a variety of automotive products, can be in the car market is in active and advantageous position. High-speed machining center of the appearance and development of processing technology and processing means, for our country automobile industry especially the development of the auto parts provides an economically feasible and efficient solution. Double spindle machining center