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CNC machine tool automatic tool changer, you know several?

2017/09/06 Hits:

CNC machine tools in order to be able to complete a multi-step workpiece in the multi-channel processing steps to shorten the auxiliary time to reduce the installation of the workpiece caused by the error, must be equipped with automatic tool changer. Automatic tool changer should meet the tooling time is short, the tool repeat positioning accuracy is high, the tool storage is enough, the knife area is small and safe and reliable basic requirements.
First, the form of automatic tool changer
1. Rotary toolholder change tool
Rotary turret is one of the most simple automatic tool changer, commonly used in CNC lathes. Can be designed into a square knife, hexagonal turret or disc-type axial tool holder and other forms. Rotary turret are installed on the four, six or more of the tool, and according to the instructions of the NC device tool change.
The rotary turret must have good strength and rigidity in the structure to withstand the cutting resistance during roughing. Since the machining accuracy depends to a large extent on the tool nose position, the tool position is not manually adjusted for the CNC lathe, so it is more necessary to select a reliable positioning scheme and a reasonable positioning structure to ensure that the rotary knife The frame has the highest possible repeatability (typically 0.001 to 0.005 mm) after each transposition.
Under normal circumstances, the rotary turret tool change, including the knife lift, turret position and turret pressure and so on.
2. Replace the spindle head tool change (tool rotation is the main movement)
Replacement of the spindle tool is a rotary tool with a rotating tool for a relatively simple tool change. This spindle head is actually a turret magazine, as shown in Figure 7-15.
The spindle head has both horizontal and vertical, usually with the turret of the turret to replace the spindle head to achieve automatic tool change. In the main shaft of the turret, the rotary tool required for each process is preliminarily installed. When the tool change command is issued, the main shaft heads are sequentially turned to the machining position and the main movement is switched on, so that the corresponding main shaft drives the tool rotation. While the other spindle in the non-processing position is disengaged from the main movement.
This replacement of the spindle tool change device, eliminating the need for automatic loose, clip, unloading knife, tooling and tool handling and a series of complex operations, thus reducing the tool change time and improve the reliability of the tool change. However, due to the spatial position of the constraints, so that the spindle component structure size can not be too large, thus affecting the rigidity of the spindle system. In order to ensure the rigidity of the spindle, you must limit the number of the spindle, otherwise it will increase the size of the structure. Therefore, the turret spindle head is usually only applicable to less process, the accuracy requirements are not too high machine tools, such as CNC drilling, milling and so on.
3. Automatic tool changer with magazine
As the rotary turret, the turret head tool changer to accommodate the number of tools can not be too much, can not meet the complex parts of the processing needs, therefore, automatic tooling CNC machine tools with more automatic tool changer tool. The automatic tool changer with magazine is made up of magazine and tool changer, and the tool change process is complicated. First of all, the processing of all the tools used in the installation of the standard handle, the size of the machine outside the pre-adjusted, according to a certain way into the magazine. When the tool change, the first knife in the knife, and then by the tool changer from the magazine or spindle to remove the tool, the exchange, the new knife into the spindle, the old knife back to the magazine. The magazine has a large capacity, either on the side or above the spindle box. As a result of the automatic tool changer with a tool changer, there is only one spindle in the spindle box of the CNC machine, and the stiffness of the spindle part is high to meet the precision machining requirements.
In addition, the number of tools within the magazine, which can be complex parts of the multi-process processing, greatly improving the adaptability of the machine and processing efficiency. The automatic tool changer system with tool magazine is suitable for CNC drilling center and machining center.
Second, the knife and the choice of tools
1. magazine type
The role of the magazine is to reserve a certain number of tools, through the robot to achieve the tool with the spindle swap. The types of the magazine are disc magazine, chain magazine and other forms, the form and capacity of the magazine according to the scope of the machine to determine the process. Figure 7-16 shows the disc magazine, the direction of the tool with the spindle in the same direction, the toolbox when the spindle box rose to a certain position, so that the tool on the spindle just at the bottom of the magazine that position, the tool was folder The spindle is moved under the control of the CNC, the tool holder is released, the disc magazine moves forward, pulls out the tool on the spindle, and then the magazine rotates the tool used in the next operation to the position aligned with the spindle, Retract the new tool into the spindle hole, the spindle clamping handle, the spindle box down to the working position, complete the tool change task, the next process processing. The advantages of this tool changer are simple structure, low cost, better tool change reliability; shortcomings is a long tool change, suitable for small tooling capacity of the processing center.
For the magazine capacity needs a larger processing center can be used chain knife library (Figure 7-17), chain knife library structure is compact, large capacity of the magazine, the chain shape can be made according to the layout of the machine Shape, but also can change the tool hole in order to facilitate the tool change. When you need to increase the number of tools, just increase the length of the chain can be to the magazine design and manufacturing has brought convenience.
2. Tool selection method
The general knife library storage of more than the tool, each time before the knife to be selected for the election knife, the commonly used method of selecting the knife and the order of any election knife, the order of the knife is in the processing before processing parts will be required The tool is inserted into the magazine of the magazine in turn according to the process requirements. The machining is in the order of the knife, and the tool sequence in the magazine must be re-adjusted when machining different workpieces. The advantage is that the drive and control are relatively simple. Therefore, this approach is suitable for processing large batch, a small number of parts of the small and medium-sized CNC machine tools for automatic tool change.
With the development of numerical control system, most of the current CNC system are used in any way of the election knife, which is divided into knife sets of coding, tool coding and memory and other three.
3. Tool coding method
Tool code or cutter code need to be installed on the tool or knife cover for the identification of the code, are generally based on the principle of binary encoding code. The tool code selection method uses a special tool holder structure and encodes each tool. Each tool has its own code, so the tool can be repeated in different processes repeated use, replaced the tool do not have to return to the original knife seat, the capacity of the magazine can also be reduced accordingly. But each tool with a dedicated coding ring, the length of the tool longer, manufacturing difficulties, the structure of the magazine and the robot becomes more complex. Knife sets of code is a tool only corresponds to a knife cover, removed from a knife set of tools must be put back into the same knife sets, take the tool is very troublesome, tool change time is long. Currently in the processing center on the use of a large number of memory-based way. This method can be the tool number and the knife set in the corresponding position of the tool to remember the PLC in the CNC system, regardless of which tool set in the knife, the tool information is always stored in the PLC. The magazine is equipped with a position detection device to obtain the position information of each blade. So that the tool can be arbitrarily removed and sent back. There is also a mechanical origin on the magazine, so that each time the election knife near the selected.
Third, the tool exchange device
In the automatic tool changer of CNC machine tool, the device that realizes the transfer and loading and unloading of the tool between the magazine and the machine tool spindle is called the tool exchange device. There are two ways of exchanging the tool: the tool movement is switched from the relative movement of the magazine and the machine tool spindle, and the tool is exchanged with the robot. The tool for exchanging tool with the relative movement of the tool spindle and the tool spindle must first be used to return the used tool to the magazine and then remove the new tool from the magazine. The two movements can not be carried out at the same time. Longer. And the use of mechanical tool changer device in the tool change can simultaneously grasp and load the machine tool spindle and tool magazine tool, so tool change time is further shortened. The use of robots for tool exchange is the most widely used. This is because the robot tool change is flexible, fast action, and simple structure. The robot is able to complete a series of actions such as a knife - pull knife - turn - insert - return. In order to prevent the fall of the tool, the movable claws of the manipulator are provided with self-locking mechanism.

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