What is the RTCP function on the five axis machining center?

There are five axis CNC machining center cannot simply called the five-axis CNC machining center, in the same way, a set of five axis CNC system controllability, nor to suggest for five axis CNC system, determine a five axis machine tool, CNC machine tool is a real five axis CNC system is system, must first to see if it has the function of RTCP, RTCP is the abbreviation of “rotating tool center point”. In the industry, it is often slightly escaped as “rotating around the tool center”, and some people translate it directly as “rotating tool center programming”. In order to make the tool holder rotate around the target track point (i.e. tool center point) when executing the RTCP function, the offset of linear coordinates of the tool center point caused by the rotation of the tool holder must be compensated in real time, so that the tool center point and the actual contact point between the tool and the workpiece surface can be kept unchanged, Changing the included angle between the tool handle and the normal at the actual contact point between the tool and the workpiece surface can give play to the best cutting efficiency of the ball head tool and effectively avoid interference. Therefore, RTCP seems to stand more on the tool center point (i.e. the target trajectory point of CNC code) to deal with the change of rotation coordinates.

Five axis machine tools and CNC systems without RTCP must rely on CAM programming and post-processing, and the tool path must be planned in advance. For the same part, if the machine tool is changed or the tool is changed, CAM programming and post-processing must be carried out again, so they can only be called false five axis.

What are the two working modes of the rotary spindle of the CNC machining center?

Depending on the rotation of the vertical spindle head：The front end of the main spindle is a rotary head, which can rotate 360 degrees around the Z axis to become the C axis. The rotary head is also equipped with the A axis that can rotate around the X axis, which can generally reach more than ± 90 degrees to achieve the same functions as above. The advantage of this setting method is that the spindle processing is very flexible, and the workbench can also be designed to be very large. The huge fuselage and huge engine shell of the aircraft can be processed on this kind of vertical processing center.

This design also has a great advantage: when the spherical milling cutter is used to process the curved surface, when the tool center line is perpendicular to the machining surface, the surface quality of the workpiece cut by the vertex will be very poor because the vertex linear speed of the spherical milling cutter is zero. The spindle rotation design is adopted to make the spindle turn an angle relative to the workpiece, so that the spherical milling cutter can avoid vertex cutting and ensure a certain linear speed, It can improve the surface processing quality.

This structure is very popular for high-precision surface machining of molds, which is difficult for the rotary vertical machining center of worktable. In order to achieve the high precision of rotation, the high-grade rotation shaft is also equipped with circular grating ruler feedback, and the indexing accuracy is within a few seconds. Of course, the rotation structure of this kind of spindle is complex and the manufacturing cost is high.

The second type is the rotary of the workbench: The table set on the bed can rotate around the X axis, defined as axis A, axis A generally working range of +30 degrees to -120 degrees.  There is also a rotary table in the middle of the table, which rotates around the Z axis as shown in the position, defined as the C axis, which rotates 360 degrees.  In this way, through the combination of axis A and axis C, the workpiece fixed on the workbench of the vertical machining center in addition to the bottom, the other five surfaces can be processed by the vertical spindle.

A axis and C axis minimum indexing value is generally 0.001 degrees, so that the workpiece can be subdivided into any Angle, processing inclined plane, inclined hole, etc..  If axis A and axis C are linked with XYZ three-axis axis, complex spatial surfaces can be processed, of course, this needs the support of high-grade CNC system, servo system and software.  The advantage of this setting is that the spindle structure is relatively simple, the spindle rigidity is very good, and the manufacturing cost is relatively low.

Three axis CNC machining center how to increase the fourth axis?

Three-axis CNC machining center and four-axis machining center we are very familiar with, three-axis CNC machining center refers to XYZ three axes, also known as the three-axis linkage machining center. Four-axis CNC machining center is in the three-axis CNC machining center on the basis of A fourth axis – CNC dividing head, we generally call it the A axis. We must make the CNC machining center to achieve four-axis linkage, if the CNC dividing head is directly installed on the three-axis CNC machining center can not be used.  We had to add a drive to the original three-axis CNC machining center and add the corresponding CNC system interface. Because the CNC system of the machining center is affected by the version and brand, some with the fourth axis interface. And some do not have a fourth axis interface. If there is no four-axis interface, it will be more troublesome, so we need to contact the system manufacturer to open it. If it is mitsubishi, Fanuc, Siemens and other imported systems, add a fourth axis interface to make the price higher. If you want to buy CNC machining center with the fourth axis we will recommend the appropriate CNC system brand and version.

All three axis CNC machining centers can increase the fourth axis, so how do we choose the fourth axis? Different types of CNC machining centers use the fourth axis model will be slightly different. We usually differentiate by the height of the center of the fourth axis.

CNC machining center to increase the fourth axis must first understand the following matters:

1. The fourth axis is different for the different materials of the workpiece.  If the workpiece is made of copper and aluminum, the pneumatic locking fourth axis is used. If the workpiece is made of cast iron and steel, the hydraulic locking fourth axis is used.
2. The shape and size of the workpiece are different, and the fourth axis selected is different. If the workpiece is round bar type, the fourth axis with three jaw chuck and thimble tailstock must be selected. When selecting the chuck, the outer diameter of the chuck shall not be greater than the diameter of the disk surface. If it is a special-shaped workpiece and more than 2 workpieces are processed at a time, it is necessary to purchase additional disc tailstock.
3. Check for interference in the Y direction.  The pre-selected fourth axis should be able to be placed in the available space of the machining center table.

4.First confirm the bearing load of the workpiece that the dividing head can bear, and then confirm the total load that the CNC machining         center can bear, and then the pre-selected dividing head, tail seat, bridge plate, workpiece and fixture weight together, such as the rotating diameter of the activity is too large, it is necessary to choose the large four-axis indexing plate.  The customer should select the appropriate fourth axis according to the weight and size of the workpiece being processed.  Avoid CNC machining center overload work to bring damage to the fourth axis.