The main core component of CNC machining center
Time : 2023-08-02
A CNC machining center is composed of multiple core components and related connectors. Any problem in any link may cause serious damage to the CNC machining center. So, we need to start with the core components first:
1. Spindle
The spindle is a major core component of machine tools, and the surface accuracy of machining is largely related to the spindle, so the quality of the spindle is crucial. At present, the spindle produced in mainland China is not commonly used in CNC machining centers, indicating that the quality of high-speed spindle units produced in mainland China still needs to be improved. The spindle units produced in Taiwan are widely used in the market, and their prices vary greatly based on their brand awareness and market share.
At present, there are several commonly used spindle brands for CNC machining centers on the market: Danquan, Jianchunlong, Pusen, and Luoyi. Their prices are also on the rise, and Jianyi can choose according to their own product requirements. Generally, CNC machining center manufacturers can modify the configuration according to your requirements, and specific details should be further discussed with CNC machining center manufacturers.
2. Ball screw
The most commonly used transmission component in precision machinery, whose main function is to convert rotational motion into linear motion or torque into axial reciprocating force, while also possessing the characteristics of high precision, reversibility, and high efficiency. Its manufacturing requirements are also relatively high, including materials and assembly accuracy.
The ball screw determines the transmission accuracy of the equipment, and its material, accuracy, preload force, cutting resistance, lubrication, load, etc. may cause rapid wear of the ball screw, resulting in gaps or other irreparable problems. So, this is also the key point.
The commonly used ball screws in CNC machining centers can be divided into P2/C2, P3/C3, P4/C4 according to accuracy, and a small number of CNC machining center manufacturers choose P5/C5 (the smaller the number, the higher the accuracy). According to the process, they can be divided into rolling grade and grinding grade, with the latter having higher accuracy than the former.
3. Knife magazine
The tool magazine of CNC machining center is divided into three types: bucket hat type, disc type, and chain type, and the number of tool capacities increases in order.
The conical hat style tool magazine is usually located near the spindle head, and when changing tools, it requires up and down movements in the direction of the spindle, which takes up working time and reduces work efficiency It also affects the working stroke range of the spindle direction, but due to its simple structure, the failure rate is relatively low.
The disc tool magazine adopts a mechanical arm for tool changing, which has a fast tool changing speed but a relatively high failure rate. There are also a few disc type tool magazines and bucket hat type tool magazines that directly change tools through the spindle. The chain type is generally applied to models that accommodate a large number of cutting tools, and its price increases accordingly. At present, common knife magazine brands include First Round, Jifu, Shengjie, and Deda. Choosing the appropriate brand and type is quite important.
4. Guide rail
The commonly used guide rails for CNC machining centers can be roughly classified into three categories based on accuracy: C ordinary level, H high-precision level, and P ultra precision level. Generally, the guide rails used for CNC machining centers are above H level. According to their types, they can be divided into three types: hard rails, linear rails, and embedded steel rails, with the first two being the most common.
The characteristic of hard rails is good rigidity, but the disadvantage is that due to high frictional resistance, the accuracy and speed are relatively low. Suitable for large cutting volume machining.
There are two common types of linear guides used in CNC machining centers: ball guides and roller guides. As the name suggests, ball guides achieve linear sliding through the rolling of steel balls, while roller guides achieve linear sliding through the rolling of cylindrical rollers, with lower frictional resistance than hard rails. Ball guides have point contact, while roller guides have line contact. Therefore, the frictional resistance of roller guides is greater than that of ball guides, and their rigidity is stronger than that of ball guides. Therefore, CNC machining centers generally use two types of guide rails: hard rails and roller rails, while small engraving and milling machines use more ball rails.
When choosing a hard rail, users should pay attention to the following points: 1. The quenching hardness of the guide rail is generally above HRC50 °. 2. Whether the workbench is coated with plastic or not. (When the guide rail is rubbed, small iron powder or cutting will be generated. The coated guide rail has strong wear resistance and soft material, which can be accommodated in the plastic rail to reduce the wear of the guide rail. Therefore, the service life of the coated guide rail is longer than that of the non coated guide rail.) Users can choose between hard rail or linear guide rail according to their own situation.
5. Bearings
Machine tool spindle bearings are generally equipped by spindle unit manufacturers. In terms of brand, the selection of this bearing brand is not very controlled by CNC machining center manufacturers, and currently can meet the needs of the vast majority of users. As long as the brand of spindle unit is chosen well, it is sufficient.
In addition to the spindle bearing, the screw bearing is also crucial here. Ball screw bearings for CNC machining centers generally use angular contact ball bearings, but major bearing manufacturers generally have ball screw specific bearings based on their usage characteristics. Their characteristic is a 60 degree contact solution, which can withstand higher axial forces and has relatively high accuracy and rigidity.
6. Bearing locking nut: These two parts have a small volume, but they also play an important role. From the above content, we know that bearings and screws used in CNC machining centers are high-precision parts, so the selection of bearing locking nuts is also very important. Some manufacturers have the conditions to produce them themselves.
7. Couplings: Couplings are the connecting parts between motors and lead screws, and are also used for connecting spindle motors and spindles in some direct coupled enclosures. Its function is not only to connect, but also to transmit torque. So, whether on the spindle or the screw, its quality cannot be ignored. At present, there are many brands of couplings used in CNC machining centers, including those produced in mainland China, those produced in Taiwan, and other imported brands, with price differences several times greater.
