The machine tool used in five axis horizontal machining center is usually called five axis machine tool or five axis machining center. Five axis machining is commonly used in machining fields, such as body parts, turbine parts and impellers with free-form surfaces. When describing the motion of CNC machine tool, the right-hand rectangular coordinate system is adopted; The coordinate axis parallel to the spindle is defined as Z axis, and the rotation coordinates around x, y and Z axes are a, B and C respectively. Generally, five axis linkage refers to the linear interpolation movement of any five coordinates in X, y, Z, a, B and C.

五轴卧式加工中 心的回转轴结构有两种方式：

There are two kinds of rotary shaft structure in five axis horizontal machining center

一种是通过主轴头的回转实现五轴联动。主轴前端是一个回转头，能自行环绕Z轴360度，即C轴。回转头上还带可环绕X轴旋转的A轴，一般可达90度以上，实现上述同样的功能。

One is to realize five axis linkage through the rotation of main shaft head. The front end of the spindle is a rotary head, which can rotate 360 degrees around the Z axis, that is, the c axis. The rotary head is also equipped with a-axis which can rotate around the x-axis, generally up to more than 90 degrees, realizing the same function as above.

这种设置方式的优点是主轴加工非常灵活，工作台也可以设计的非常大、船舶等领域的大型零部件都适合在这类加工中 心上加工。

The advantage of this setting method is that the spindle processing is very flexible, and the worktable can be designed to be very large. Large parts in ship and other fields are suitable for processing in this kind of machining center.

这种结构的加工中 心在高精度模具曲面加工领域的应用非常多，这是工作台回转式五轴加工中 心难以做到的。

The machining center with this structure has many applications in the field of high-precision mold surface machining, which is difficult to be achieved by the five axis rotary machining center.

另一种是通过工作台回转实现五轴联动。机床床身上的工作台可以环绕X轴回转（A轴），A轴一般工作范围+30度-120度。工作台的中间还设有一个回转台，可以环绕Z轴回转（C轴），C轴都是360度回转。

The other is to realize five axis linkage through the table rotation. The worktable on the machine bed can rotate around the x-axis (a-axis). The general working range of a-axis is + 30 degrees to - 120 degrees. There is also a rotary table in the middle of the worktable, which can rotate around the z-axis (c-axis), and the c-axis rotates 360 degrees.

这样通过A轴与C轴的组合，固定在工作台上的工件除了底面之外，其余的五个面都可以由立式主轴进行加工。A轴和C轴如与XYZ三直线轴实现联动，就可加工出复杂的空间曲面。

In this way, through the combination of a-axis and c-axis, the other five surfaces of the workpiece fixed on the worktable can be processed by the vertical spindle except the bottom surface. If a axis and C axis are linked with XYZ three linear axis, complex space surface can be machined.

这种结构的加工中 心主轴的结构比较简单、主轴刚性非常好、制造成本比较低，但一般工作台不能太大、承重也较小。

This kind of structure of machining center spindle structure is relatively simple, spindle rigidity is very good, manufacturing cost is relatively low, but the general table can not be too large, bearing is also small.