CNC turning and milling parts What is the difference between three-axis, four-axis and five-axis machining centers?
Some people say to learn three-axis first, and then go to four-axis and five-axis machining centers. What is the difference between these types of machine tools? Then this article will introduce the difference between the three-axis, four-axis and five-axis machining centers, and hope to be helpful to you!
The function and advantages of three-axis machining center:
The most effective processing surface of the vertical machining center (three-axis) is only the top surface of the workpiece, and the horizontal machining center can only process the four sides of the workpiece with the help of the rotary table. At present, high-end machining centers are developing towards the direction of five-axis control, and the machining of pentahedron can be completed in one clamping of the workpiece. For example, if it is equipped with a high-end CNC system with five-axis linkage, it can also perform high-precision machining on complex spatial surfaces.
What is four-axis simultaneous machining?
The so-called four-axis simultaneous machining generally adds a rotating axis, usually called the fourth axis. General machine tools only have three axes, that is, the workpiece platform can move left and right (1 axis), front and rear (2 axes), and the spindle head (3 axes) for cutting workpieces. The fourth axis is to install a 360-degree Rotating electric dividing head! In this way, it can automatically index and drill inclined holes, mill beveled edges, etc., without losing precision in secondary clamping.
Four-axis linkage processing features:
(1). The three-axis linkage processing machine cannot be processed or needs to be clamped too long
(2). Improve the accuracy, quality and efficiency of free space surfaces
(3). The difference between four-axis and three-axis;
Its code representation:
Determination of the Z axis: the direction of the axis of the machine tool spindle or the vertical direction of the table where the workpiece is clamped is the Z axis Determination of the X axis: the horizontal plane parallel to the workpiece mounting surface or the direction perpendicular to the rotation axis of the workpiece in the horizontal plane is the X axis, The direction away from the spindle axis is the positive direction.
Five-axis machining centers are divided into vertical five-axis machining centers and horizontal five-axis machining centers. What are their characteristics?
Vertical five-axis machining center
There are two types of rotary axes for this type of machining center, one is the rotary axis of the worktable.
The worktable set on the bed can rotate around the X-axis, which is defined as the A-axis, and the general working range of the A-axis is +30° to -120°. There is also a turntable in the middle of the workbench, which rotates around the Z axis at the position shown in the figure, which is defined as the C axis, and the C axis rotates 360 degrees. In this way, through the combination of the A axis and the C axis, except for the bottom surface of the workpiece fixed on the worktable, the other five surfaces can be processed by the vertical spindle. The minimum division value of A-axis and C-axis is generally 0.001 degree, so that the workpiece can be subdivided into arbitrary angles, and inclined surfaces, inclined holes, etc. can be processed.
If the A-axis and C-axis are linked with the XYZ three-linear axis, complex spatial surfaces can be processed. Of course, this requires the support of high-end CNC systems, servo systems, and software. The advantage of this arrangement is that the structure of the main shaft is relatively simple, the rigidity of the main shaft is very good, and the manufacturing cost is relatively low.
However, the general workbench cannot be designed too large, and the load-bearing is also small, especially when the A-axis rotation is greater than or equal to 90 degrees, the workpiece will bring a large load-bearing moment to the workbench when it is cut.
The front end of the main shaft is a rotary head, which can rotate 360 degrees around the Z-axis to become the C-axis. The rotary head also has an A-axis that can rotate around the X-axis, generally up to ±90 degrees, to achieve the same function as above. The advantage of this setting method is that the machining of the main shaft is very flexible, and the workbench can also be designed to be very large. The huge fuselage of the passenger plane and the huge engine casing can be processed on this type of machining center.
Features of horizontal five-axis machining center
There are also two ways for the rotary axis of this type of machining center. One is that the horizontal spindle swings as a rotary axis, plus a rotary axis of the worktable to realize five-axis linkage processing. This setting method is simple and flexible. If the main shaft needs to be converted from vertical to horizontal, the workbench can be easily configured as a three-axis machining center with vertical and horizontal conversion only by indexing and positioning. The vertical and horizontal conversion of the main shaft and the indexing of the worktable can realize pentahedral processing of the workpiece, which reduces the manufacturing cost and is very practical. The CNC axis can also be set on the worktable, the minimum division value is 0.001 degrees, but without linkage, it becomes a four-axis machining center with vertical and horizontal conversion, which can adapt to different processing requirements, and the price is very competitive.
Partial display of five-axis machining center products
The other is the traditional rotary axis of the worktable. The A-axis of the worktable set on the bed generally has a working range of +20° to -100°. There is also a turntable B-axis in the middle of the table, and the B-axis can rotate 360 degrees in both directions. This horizontal five-axis machining center has better linkage characteristics than the first method, and is often used to process complex curved surfaces of large impellers. The rotary axis can also be equipped with circular grating scale feedback, and the indexing accuracy can reach several seconds. Of course, the structure of this rotary axis is more complicated and the price is also expensive.
Most of the machining centers can be designed as a double workbench exchange. When one workbench is running in the processing area, the other workbench replaces the workpiece outside the processing area to prepare for the processing of the next workpiece. The time of workbench exchange depends on the workbench. The size can be completed from a few seconds to tens of seconds.
