Analyze the common functions of the following four machining centers:
(1) Vertical machining center
The spindle of the vertical machining center is in the vertical position. It can complete milling, boring, drilling, tapping and cutting threads and other processes. Vertical machining center is a three-axis two linkage, generally can achieve three-axis three linkage. Some can be five-axis, six-axis control, the process personnel can determine the processing range of the machining center according to the number of axes controlled at the same time.
Vertical machining center column height is limited, determine the Z axis range of motion to consider:
① Height of workpiece;
② Height of fixture;
The length of the tool;
The space occupied by the manipulator tool change.
After considering the above four cases, the vertical machining center has to reduce the processing range of box-type workpieces, which is the weakness of the vertical machining center. But the vertical machining center has the following advantages:
The workpiece is easy to clamp, can be used in general fixtures such as flat pliers, pressure plate, dividing head, rotary worktable clamping workpiece, workpiece clamping positioning convenience;
The tool motion trajectory is easy to observe, the debugging program is convenient to check and measure, and the problem can be found in time for shutdown processing or modification;
The cooling conditions are easy to establish, the coolant can directly reach the tool and the processing surface;
④ The coordinate system, that is, the three coordinate axes of X, Y and Z, is consistent with the Cartesian coordinate system, which feels intuitive and consistent with the perspective of the drawing;
The chip is easy to exclude and fall, to avoid the chip scratching the processed surface;
The structure of the general use of single column, it compared with the corresponding horizontal machining center, simple structure, small footprint, low price.
The vertical machining center is suitable for machining workpieces with relatively small dimensions in the Z axis direction. In general, except for the bottom surface, the remaining five surfaces can be processed with different tools for contour and surface processing.
(2) Horizontal machining center
The spindle of the horizontal machining center is set horizontally. The general horizontal machining center has three to five coordinate axes, often equipped with a rotary shaft (or rotary workpiece table), the spindle speed is within 10 ~ 10000r/min, the resolution is generally lμm, and the positioning accuracy is 10μm-20μm. The tool magazine capacity of horizontal machining center is generally large, and some tool magazines can store hundreds of tools. The structure of the horizontal machining center is more complex than the vertical machining center, the volume and the area is larger, and the price is higher. Horizontal machining center is more suitable for processing box parts. As long as a clamping on the rotary table, the box (in addition to the top and bottom surface) of the four surfaces for milling, boring, drilling, tapping and other processing. In particular, if there are position tolerance requirements for some holes and cavities on box parts (such as parallelism between hole systems, verticality between hole and end surface, verticality between end surface and bottom surface, etc.), and if there are strict dimensional accuracy requirements for holes and cavities and reference surface (bottom surface), it is easy to be guaranteed through one-time clamping processing on horizontal machining centers and is suitable for batch workpiece processing. When debugging the horizontal machining center program, it is not as intuitive and easy to observe as the vertical machining center, and it is inconvenient to check and measure the workpiece. Moreover, the debugging time for the machining program of complex parts is several times that of normal machining. Therefore, the more workpieces are processed, the less time each piece takes up on the machine tool. Therefore, it is economical to use the horizontal machining center for batch processing. However, it can achieve the accuracy and quality requirements that ordinary equipment is difficult to achieve, so some high precision requirements, other equipment can not meet the accuracy requirements of the workpiece, especially some space curved surface and complex shape of the workpiece, even if it is a single piece of production, can also be considered in the horizontal machining center processing. It can be seen that the machining center is an efficient and high-quality automated production equipment, and it is also a device to overcome technological problems.
The coordinate system of the horizontal machining center is spatially different from the coordinate system of the vertical machining center, that is, the three axes X, Y and Z. And horizontal machining center cooling conditions are not as good as vertical, especially for deep hole boring, milling, drilling, etc., the coolant is difficult to reach the cutting depth, therefore, must reduce the machine speed and feed, reduce the production efficiency. Compared with the vertical machining center, the horizontal machining center has many functions. The workpieces that cannot be processed on the vertical machining center can be processed in the horizontal machining center. In addition, some of the rotary worktables of the horizontal machining center are numerically controlled and some are indexed, and the workpiece can be machined in multiple stations at one time. Generally speaking, the horizontal machining center has its advantages and disadvantages. When using it, it is better to avoid its disadvantages.
(3) Multi-table machining center
A multi-table machining center is sometimes referred to as a flexible machining cell (FMC). It has more than two replaceable worktables. The finished workpiece can be moved out of the processing part together with the worktable (pallet) through the transportation track, and then the worktable (pallet) equipped with the workpiece to be processed can be sent to the processing part. Multiple exchangeable worktables can be set to realize multi-worktable processing. Its advantage is that online clamping can be realized, that is, at the same time of processing, the lower worktable is loaded and unloaded with workpieces to be processed. In addition, the workpieces to be processed can be loaded on other worktables. After the machine tool is started, the automatic processing of this batch of workpieces can be completed. The workpieces on the worktable can be the same or different. This can be handled by the program. Multi-workbench machining centers are vertical and horizontal. Whether vertical or horizontal, its structure is more complex, the tool library capacity is larger, the machine covers an area of large, more complete control system functions. The calculation speed is fast and the memory capacity is large. CNC systems are used, so the price is expensive.
(4) Compound machining center
Compound machining center is also called multi-surface machining center, which refers to the equipment that can complete the processing of multiple surfaces after the workpiece is clamped at one time. The existing five-sided machining center can complete the machining of five sides except the installation bottom surface after the workpiece is clamped at one time. This kind of machining center has the function of vertical and horizontal machining center, and can ensure the position tolerance of the workpiece in the process of machining. The common five-sided machining center has two forms, one is the spindle to do or the corresponding angle rotation, can become a vertical machining center or horizontal machining center. The other is that the worktable rotates with the workpiece, and the spindle does not change the direction to achieve five-sided machining. No matter what kind of five-sided machining center has the disadvantages of complex structure and high cost.
The function of the five-sided machining center is more than that of the multi-table machining center, the control system is advanced, and its price is about twice that of the multi-station machining center with the same table size.