Typical questions and answers of the hottest NC ma

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Typical question and answer of NC machining

I Q: how much confusion do you have about the quality of? How to divide the processing procedures

answer: the division of NC machining processes can generally be carried out according to the following methods:

(1) tool centralized sequencing method is to divide processes according to the tools used, and use the same tool to process all the parts that can be completed. Use the second knife and the third knife to complete other parts they can complete. This can reduce the number of tool changes, compress the idle time, and reduce unnecessary positioning errors

(2) for parts with a lot of processing content, the processing part can be divided into several parts according to its structural characteristics, such as inner shape, shape, curved surface or plane. Generally, the plane and positioning surface are processed first, and then the hole is processed; First process simple geometry, then complex geometry; First process the parts with low accuracy, and then process the parts with high accuracy requirements

(3) for parts prone to machining deformation by rough and finish machining sequence method, shape correction is required due to the possible deformation after rough machining, so generally speaking, the processes of rough and finish machining should be separated

to sum up, when dividing the process, we must flexibly grasp it according to the structure and manufacturability of the parts, the function of the machine tool, the number of NC machining contents of the parts, the installation times and the production organization of the unit. In addition, it is suggested to adopt the principle of centralized process or decentralized process, which should be determined according to the actual situation, but we must strive to be reasonable

II. Question: what principles should be followed in the arrangement of processing sequence

answer: the arrangement of processing sequence should be considered according to the structure of parts and the condition of blanks, as well as the needs of positioning and clamping, and the key point is that the rigidity of the workpiece will not be destroyed. Generally, the sequence should be carried out according to the following principles:

(1) the processing of the previous process should not affect the positioning and clamping of the next process, and the general machine tool processing process interspersed in the middle should also be comprehensively considered

(2) first carry out the inner cavity processing procedure, and then carry out the contour processing procedure

(3) the process of processing with the same positioning, clamping method or the same knife is best connected to reduce the number of repeated positioning, tool changing and moving the pressing plate

(4) for multiple processes in the same installation, the process with little damage to the rigidity of the workpiece should be arranged first

III. Q: what aspects should be paid attention to in determining the clamping mode of the workpiece

answer: when determining the positioning reference and clamping scheme, we should pay attention to the following and set the upper and lower temperature (20 ⑷ 5 ° C):

(1) strive to unify the design, process and programming calculation

(2) try to reduce the clamping times, and try to process all the surfaces to be processed after one positioning

(3) avoid using manual adjustment scheme

(4) the fixture should be open, and its positioning and clamping mechanism should not affect the tool walking in processing (such as collision). In such cases, it can be clamped with a vise or with a bottom plate to extract screws

IV. question: how to determine the tool setting point is more reasonable? What is the relationship between workpiece coordinate system and programming coordinate system

1. the tool setting point can be set on the machined part, but pay attention to that the tool setting point must be the reference position or the part that has been precision machined. Sometimes the tool setting point is damaged after the first process, which will make it impossible to find the tool setting point in the second process and after. Therefore, when setting the tool in the first process, pay attention to setting a relative tool setting position where there is a relatively fixed size relationship with the positioning reference, In this way, the original tool setting point can be retrieved according to the relative position relationship between them. This relative tool alignment position is usually set on the machine tool workbench or fixture. The selection principles are as follows:

1) it is easy to find it. With more and more packaging garbage

2) convenient programming

3) small tool setting error

4) it is convenient to check during processing

2. The origin position of the workpiece coordinate system is set by the operator himself. It is determined by tool setting after the workpiece is clamped. It reflects the distance position relationship between the workpiece and the zero point of the machine tool. Once the workpiece coordinate system is fixed, it is generally not changed. The workpiece coordinate system and the programming coordinate system must be unified, that is, during machining, the workpiece coordinate system and the programming coordinate system are consistent

v. ask: how to choose the cutting route

tool path refers to the motion path and direction of the tool relative to the workpiece during NC machining. The reasonable selection of machining route is very important, because it is closely related to the machining accuracy and surface quality of parts. When determining the cutting route, the following points are mainly considered:

1) ensure the machining accuracy requirements of parts

2) facilitate numerical calculation and reduce programming workload

3) seek the shortest processing route and reduce the empty tool time to improve the processing efficiency

4) try to reduce the number of program segments

5) ensure the requirements of the roughness of the workpiece contour surface after machining, and the final contour should be processed continuously with the last tool

6) the forward and backward (cut in and cut out) route of the tool should also be carefully considered, so as to minimize the knife marks caused by stopping at the contour (elastic deformation caused by sudden change of cutting force) and avoid scratching the workpiece by cutting vertically on the contour surface

VI. ask: how to monitor and adjust in the processing process

the high end of the electronic universal experimental machine configured at the high end of workpiece alignment and program debugging is mainly reflected in the completion of high-precision photoelectric encoder, which can enter the automatic processing stage. In the process of automatic machining, the operator should monitor the cutting process to prevent abnormal cutting from causing workpiece quality problems and other accidents

the following aspects are mainly considered in monitoring the cutting process:

1. The main consideration of rough machining is the rapid removal of excess allowance on the workpiece surface. In the automatic machining process of the machine tool, the tool automatically cuts according to the predetermined cutting path according to the set cutting parameters. At this time, the operator should pay attention to observing the change of cutting load in the automatic machining process through the cutting load table, and adjust the cutting amount according to the bearing capacity of the tool to give full play to the maximum efficiency of the machine tool

2. monitoring of cutting sound in the process of cutting in the process of automatic cutting, generally when cutting, the tool cuts the workpiece

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