High-speed machining center is a representative of the high speed machine tool products, high-speed features such as motorized spindle, high speed screw, and the development and application of linear motor greatly improves the cutting efficiency. To cooperate the efficiency of machine tool, as one of the important parts of processing center automatic tool change device (ATC) of high speed also become an important technology of the high speed machining center content accordingly.

Constant with the increase of cutting speed, cutting time shortened, exchange knife time requirements are also gradually increase, the speed of the tool change has become a high level of an important indicator of machining center.

As a result of processing center automatic tool changer require reliable and accurate, and structure is relatively complex, improve the transfer speed technology is difficult. Current foreign advanced machine tool production in order to adapt to the high speed machining of high speed machining center, are equipped with automatic tool change device quickly, many adopted new technologies, new methods. This article introduces some methods to improve the transfer speed technology and foreign advanced automatic tool change quickly, the high-speed machining center hope of some help to the development of the high speed machining center in China.

A fast automatic tool change technology

Fast automatic tool change technology is main purpose is to reduce auxiliary processing time, takes into account the factors of the machine tool, cutter has been accomplished in the shortest possible time to exchange the technical method. The technology includes knife library set, tool change, tool change, actuators and adapt to the structure characteristics of the high speed machine tools and so on.

(1) change speed indicator

Measuring tool change speed method mainly has three types: (1) to the knife tool change time: (2) to the cutting tool change time: (3) chip to chip in time. Due to the time of chip to chip in knife cutting the length of time between the two is basically a machining center, reflects the processing center in knife occupied by the auxiliary time, so the chip to chip tool change time should be is the most direct indicators to measure efficiency of machining center. And knife to knife tool change time is mainly reflect good or bad, the performance of automatic tool change device itself as a better performance of the machine tool automatic tool change device. The two methods are usually used to evaluate tool change speed. As for the tool change time how much is the high speed machine tool automatic tool change device does not determine indicators, in the case of technical conditions may, should improve the tool change speed as much as possible.

(2) the basic principles of raising the speed of the tool change

Processing center automatic tool change the basic starting point is in a variety of cutting tool in machining process, through the automatic tool change, reduce auxiliary processing time. On the high speed machining center, due to the increased cutting speed, automatic tool change device and tool storage configuration to consider as far as possible, shorten change knife time, thus coordinates and high-speed cutting machine tools.

Machining center tool change device is usually composed of knife library and tool exchange mechanism, the commonly used with and without mechanical manipulator type type, etc. Knife library form and put the position is different also. To fit the need of high speed, high speed machining center on the structure and the traditional processing center, is given priority to with tool motion feeding, reduce the quality of the moving parts has become the mainstream of the high-speed machining center design. When designing tool change device, therefore, to fully consider the new structure characteristics of high speed machine tools.

In setting up the tool change device on the high speed machining center, the time is not the only factor. First of all, should be in action on the basis of accurate and reliable tool changer raising the speed of the tool change. Especially the ATC is processing center part of the functional unit failure rate is relatively high, this is especially important: second, according to the application object and price performance ratio matching ATC. In the tool change time to affect the production process of applications, to improve the tool change speed as much as possible. For example, in auto production line, such as tool change time and the number of tool change to included in the parts production rhythm. In other places, such as mold cavity machining, tool change speed choice can ease some.

(3) improve the transfer speed of main technical methods

Suitable for high speed machining center of fast automatic tool changer technology basically has the following several aspects:

On the basis of the traditional automatic tool change device increase movement speed, or use action faster and drive components. For example, the structure of the mechanical CAM switch knife speed significantly higher than that of hydraulic and pneumatic structures. Japan SODIC MC450 vertical machining center produced by our company mechanical CAM structure of fast tool change device, knife to knife tool change time is 0.6 s.

According to the structural characteristics of high speed machine tool the new design knife library and tool change device of form and position. For example, the traditional library and in vertical machining center knife device installed at the side of the post, while the high speed machining center for pillar mobile feed way, to reduce moving parts mass, libraries and change knife device should not be installed on the pillar.

A new method to exchange tool quickly. No knife library and the way of manipulator, and use other ways to change. Don't have to change, for example, use the method of change the spindle.

Using the new development of machining center spindle assembly for 6 dof high speed movement this one characteristic, make main shaft directly involved in the transfer process, not only can make the knife library flexible configuration position, and can reduce the knife library movement of the degrees of freedom, significantly simplify the structure of library and change knife device.

Suitable for high speed machining center of the handle. HSK shank with light quality, inserted knife trip short pull, can increase the speed of automatic tool change device. Fast automatic tool change device adopts HSK hollow taper shank short dao is the trend of the development.

2 some structure methods of rapid change

In addition to the traditional tool change device on the basis of improve the action speed, also appeared some new methods and new structure change knife device.

Here are some of them for your reference.

More than (1) the spindle tool change

This machine does not have a traditional libraries and change knife device, but USES the multiple spindle fixed on the spindle side by side on the shelf, usually for 3 ~ 18. Each spindle directly by the respective motor drive, and each of the main shaft is installed on a different tool. Tool change when not on the spindle tool exchange, but installed on the clamp workpiece fast from a spindle machining position to move to another with a different tool spindle, realize the knife and immediately processing. The mobile time is tool change time, and very short. Completed by fixture rapid movement in knife, saves complex tool change mechanism. Austrian ANGERG the structure of machine tool production company, has realized the chip to chip tool change time of just 0.4 s. Is currently the world's chip to chip in shortest time machine. This structure of machine tools and machining center structure usually have changed. Not only can be used for fast tool change process, but also can multi-axis machining at the same time, suitable for use on the efficient production line.

(2) double spindle tool change

Processing center, there are two main shaft, but not used for machining at the same time. A main shaft for processing, and the other main shaft replaced during this period. But need to change the knife, the processing of the main shaft exit quickly, changing the tool spindle immediately into the processing. Because of the two processes can be done at the same time, in real time is already installed the knives, two main shaft displacement time, make the auxiliary time to a minimum, machine tool chip to chip in a knife at the shortest time. Because there are two main shaft, libraries, and in this kind of machine tool knife manipulator can be a set of, also can be two sets. Such as Germany Alfing - Kessler company production of machining center adopts double spindle system, using a set of libraries and change knife manipulator. While Germany Hornsberg - Lamb company produces the HSC - 500, the HSC - 630, HFC - 630 machining center have two main shaft and two swap knife system. Two spindle can use 1.0 ~ 1.5 s time moves to machining position and start acceleration to the maximum speed. Specific exchange time depends on the size of the machine tool.

(3) the knife library layout way around the spindle turret

This way, the knife library itself is equivalent to devise, library by knife inserted knife and pull in a sequential change knife, cutter machine chip to chip in time is shorter. This way if any change, will vary with the selected dao in libraries is different with the location of the length of time, the farthest dao may be chip to chip in for a long time. Therefore, this way as a high-speed automatic tool change device can only adopt the order selected knife.

(4) more robots

Similarly, knife library arrangement around the spindle, but adopt the way of each knife has a manipulator make tool change almost have no time to loss, and can adopt the way of arbitrary choice knife. Germany CHIRON company produce this kind of structure of the machine tool, cutter replacement time realized the chip to chip only 1.5 s, is currently the world's single spindle machine tool chip to chip in shortest processing center.

3 machining center equipped with automatic tool change device

Some technology at home and abroad advanced machine tool manufacturing company developed a variety of different technology is fast tool change device of high speed machining center, an important characteristic, the diversification of the tool change technology, its purpose is to shorten tool to exchange time. Listed in the table below is a chip to chip tool change time is less than 4 s high speed machining center.

4 conclusion

Metal cutting machine tool of high speed has become one of the important direction of machine tool, as a result, rapid tool change technology has become an important part of high speed machining center. New technology and new methods in constantly and improve, its purpose is only one, that is on the basis of accurate and reliable, shorten change knife time, improve the cutting efficiency of the high speed machining center. High speed machine tool manufacturing industry in China should learn in a timely manner and as soon as possible to grasp the method of advanced technology, constantly raise the level of domestic manufacturing of the high speed machining center. Double spindle machining center