The advantages and disadvantages of hard rail and

What are the advantages and disadvantages of CNC machine tool hard track and wire track? Finally, I understand

what small workers have learned all along is this: if the general processing center is used to make products, it will buy Wire rails. If it is processing molds, it will buy hard rails. The accuracy of wire rails is higher than that of hard rails, but the hard rails are more durable

characteristics of hard rail

first, the advantages of hard Rail:

1. It can bear greater load and is suitable for rough machining machine tools with large tool volume and large feed

2. Because the contact area of the guide rail is large, the machine tool runs more smoothly, which is suitable for machine tools with high requirements for machine tool vibration, such as grinding machines

II. Disadvantages of hard Rail:

1. The material is uneven. Because it is generally cast, it is easy to produce casting defects such as sand inclusion, porosity and porosity in the material. If these defects exist on the guide rail surface, it will have a very adverse impact on the service life of the guide rail and the accuracy of the machine tool

2. It is difficult to process, because this type of guide rail is generally connected with the main parts of the machine tool, such as the base, column, workbench, sliding saddle, etc., so in the processing process, its shape and position tolerance, coarse excess requirements, aging treatment, quenching treatment and other processes are difficult to control, resulting in the processing quality of parts can not meet the requirements of assembly

3. Assembly is difficult. The word assembly means both assembly and matching, and this matching process is a process of combining technology and physical strength, which can not be completed by ordinary workers. It requires an assembly worker with a relative number of skills and a good grasp of the overall accuracy of the machine tool. At the same time, it also needs to be equipped with a shovel, a ruler, a square ruler, a dial indicator, a dial indicator and other corresponding tools to complete

4. The service life is not long, which can only be relatively speaking. Under the same maintenance and use conditions, the service life of the common hard rail is less than that of the line rail, which has a lot to do with their movement mode. The hard rail runs by sliding friction, while the line rail runs by rolling friction. In terms of the friction, the friction force of the hard rail is much greater than that of the line rail, Especially in the case of insufficient lubrication, the friction of hard rail is even worse

5. The maintenance cost is too high, and the maintenance of hard rail is far greater than that of wire rail in terms of difficulty and maintenance cost. If the scraping allowance is insufficient, it may involve disassembling all the large parts of the machine tool, re quenching and machining, and even recasting the large parts. As long as the wire gauge is replaced with the corresponding wire rail, it will basically not affect the use of relevant large parts

6. The running speed of the machine tool is low, and the hard rail usually cannot bear too fast running speed because of its movement mode and the excessive friction, which is contrary to the current processing concept. In particular, many factory workers do not have the corresponding maintenance knowledge of machine tools. Many began to use statistics in fatigue experiments and fatigue design in the 1960s. In 1963, the E9 Committee of the American Society for testing and materials (ASIM) summarized the research results in this regard and published the guide to statistical analysis of fatigue experiments and fatigue data (astmstp91a). When they only knew how to use machine tools, they largely ignored the maintenance of machine tools, The maintenance of the machine tool track is the top priority. Once the track is not lubricated enough, it will cause the track to burn or wear transition, which is fatal to the accuracy of the machine tool

rail features

first, the advantages of rail

1. The assembly is convenient and simple, and high-quality assembly can be completed with a little training. Because the accuracy of the machine tool depends on the accuracy of the transmission mechanism. The transmission mechanism is generally composed of wire rail and screw rod, that is, the accuracy of the wire rail and screw rod itself determines the accuracy of the machine tool, and the wire rail and screw rod generally exist in the form of standard parts. You only need to choose the corresponding accuracy provided by the manufacturer, and generally there will be no big problem

2. There is a wide range of options, whether from the structural form or accuracy grade of the line rail, the lubrication mode or load-bearing capacity, the processing mode to the running speed and other parameters can be selected. You can configure the line rail model you need according to the specific situation of the machine tool you design

3. Fast running speed. Now many machine tools run very fast, especially the idle speed, which largely depends on the credit of the line track, because the running mode of rolling friction and high-precision processing effectively ensure the accuracy and stability of the high-speed operation of the machine tools, and greatly improve the processing efficiency and accuracy

4. High machining accuracy. As a standard commodity, the wire rail has entered a benign and controllable range in terms of material and processing mode. Therefore, most machine tools in many precision machining fields use high-precision wire rail as machine tool guide rail, which also greatly ensures the machining accuracy of machine tools. Nanjing technology, Hanjiang wire rail, Shanghai silver wire rail in Taiwan, Rexroth in Germany have done better in China, Japan has THK rail and so on. These brands greatly enrich and meet the market demand for rail with different requirements. I like to choose Japanese t external wall with heat transfer coefficient not greater than 0.15w/m2khk, stable performance, fine workmanship, but high price

5. Long service life, because the operation mode of the wire rail is rolling friction, and the steel balls in the slider drive the movement of the feeding parts by rolling on the rail. The friction force borne by this rolling friction is much smaller than that of the hard rail, so the wire rail is much better than the hard rail in terms of transmission efficiency and service life

6. Low maintenance cost. In terms of maintenance cost and convenience, the line rail has its natural advantages and convenience, because as a standard part, the replacement form of the line rail is the same as replacing a screw. Of course, there are some reply adjustments in accuracy, but compared with the hard rail, it is really convenient

7. The delivery cycle is short, and the general delivery cycle of the line rail can be completed within half a month, unless you choose foreign brands, such as Rexroth and THK. In fact, these two brands also have corresponding processing plants in China, as long as the line rail model you choose is not very biased, Basically, the delivery time is about half a month, but this discovery is a very special answer given by the important materials research institute in the face of the global anxiety about the supply and demand of rare earth materials to ensure that, while the line track of Shangyin in Taiwan can even achieve a week's delivery cycle, but the same hard track has no such good time control ability. If the action is relatively large, such as recasting, That cycle may be more than a few months

second, the disadvantages of the track

1. The bearing capacity is relatively small, which is only for the hard track. In fact, the track of many large factories has greatly improved its bearing capacity through some structural designs. Of course, it is relatively small compared with the bearing capacity of the hard track

2. The stability is relatively weak compared with the hard track, such as the ability to resist vibration, but I still want to emphasize that this weakness is relative to the hard track. In fact, the stability of many tracks is also very good now. As long as the equipment you design is not too special, it can generally meet the needs

3. In the process of transportation and assembly, special attention should be paid to the protection of the line rail, because as a standard part, its unique structural characteristics make it in an embarrassing situation that is relatively vulnerable to damage. For example, the shape is slender, which leads to insufficient rigidity of the line rail, and it is easy to bend and deform when squeezed without bubble pressure, resulting in the loss of accuracy; For example, because it is a steel part, if it is not antirust treated, it is easy to produce rust and corrosion when it is exposed to water or other solvents during transportation and assembly, resulting in the loss of accuracy

the above is a designer who has been engaged in machine tool design for more than 10 years. I hope it can be helpful to you