What principles should be followed in the arrangement of CNC machining sequence?
The arrangement of processing sequence should be considered based on the structure of the parts and the condition of the blank, as well as the need for positioning and clamping, with the focus on ensuring that the rigidity of the workpiece is not damaged. The order should generally follow the following principles:
1. The CNC machining of the previous process should not affect the positioning and clamping of the next process, and if there are universal machine tool machining processes interspersed in the middle, comprehensive consideration should also be given.
2. First, proceed with the machining process of the inner shape and cavity, and then proceed with the contour machining process.
3. Connect with the same positioning, clamping method or CNC machining process with the same tool to reduce the number of repeated positioning, tool replacement, and moving of the pressure plate.
4. Multiple processes carried out in the same installation should first be arranged to minimize the rigid damage to the workpiece.
What aspects should be paid attention to when determining the clamping method of workpieces?
When determining the positioning reference and clamping scheme, the following three points should be noted:
1. Strive for consistency in design, craftsmanship, and programming calculations.
2. Try to reduce the number of clamping times and achieve CNC machining of all the surfaces to be machined after one positioning.
3. Avoid using manual adjustment schemes that occupy the machine.
4. The fixture should be unobstructed, and its positioning and clamping mechanism should not affect the cutting process in CNC machining (such as collision). When encountering such situations, it can be clamped using a vice or adding screws to the bottom plate.
How to determine the appropriate cutting point? What is the relationship between the workpiece coordinate system and the programming coordinate system?
1. The tool alignment point can be set on the machined part, but it should be noted that the tool alignment point must be a reference position or a precision machined part. Sometimes, after the D process, the tool alignment point is damaged by CNC machining, which can cause the second process and subsequent tool alignment points to be difficult to find. Therefore, when aligning the tool in the D process, it is important to establish a relative tool alignment position at a location that has a relatively fixed dimensional relationship with the positioning reference, This can retrieve the original tool alignment point based on their relative position relationship. This relative tool alignment position is usually located on the machine tool workbench or fixture. The selection principles are as follows:
1) Finding the right one is easy.
2) Easy programming.
3) Small tool setting error.
4) Convenient and traceable inspection during processing.
2. The origin position of the workpiece coordinate system is set by the operator themselves. After the workpiece is clamped, it is determined by tool alignment, which reflects the distance and position relationship between the workpiece and the zero point of the machine tool. Once the workpiece coordinate system is fixed, it generally remains unchanged. The workpiece coordinate system and programming coordinate system must be unified, that is, during machining, the workpiece coordinate system and programming coordinate system are consistent.
