Monthly Archive August 24, 2021

Application method of CNC fast wire cutting

For the current processing industry, wire cutting is a very common cutting process. For fast cutting wire cutting, the same mechanical equipment will have certain differences in product quality after being operated in the hands of different people, which will also have a certain impact on the normal use of machine tools. Here, the methods for fast wire cutting will be briefly introduced. First, find the line you are cutting.

The line method is correct. If you are working on a multi-layer thin-walled sheet metal part because it will be affected by dimensions such as welding or blanking, the edges of the plate will not be neat. At this time, if the cutting accuracy is not high. In this case, it can be done by using the chemical fiber arrangement method or by manual method.

The alignment method of paper pattern is also a common method. When the multi-layer thin-walled bow and arrow is used for cutting shape processing, the inner contour or hole must be operated. Then, it is necessary to carry out silk pre threading in multiple places. At this time, we can paste one-to-one paper pattern on the workpiece to be processed, which will not only lead to the deviation of wire hole, but also lead to wire cutting. It will also become easier. Rapid cutting wire cutting is also a technology for cutting internal control, keyway or outer circle, which makes it possible to cut tooth shaped workpiece.

For the process hole to be corrected, many workpieces should be processed according to the machining steps. Generally, this process shall be carried out on the left and right sides of the plate and at the diagonal. At this time, the size or surface quality of the machined hole is a better case. You can use the corresponding hole on the bridge tool, and then use the position of the tip to perform alignment.

Universal table alignment is also a common alignment method using rapid cutting line cutting technology. The most important feature of this correction method is that the accuracy is relatively high, so the probability of using it is relatively large. Rapid cutting line is one of the cutting methods used at present. This cutting method requires higher cutting technology, but the cutting technology is actually based on cutting experience, so for the operator, we must accumulate some experience.


What is the usual speed of CNC machine tools

With the improvement of the performance of the core processor of CNC system, the feed speed limit of high-speed machining center can reach 80m / min and the empty running speed can reach about 100m / min. At present, many automobile factories in the world, including China’s Shanghai General Motors Company, have adopted the production line composed of high-speed machining centers to partially replace the modular machine tools. The feeding speed limit of the hypermach machine tool of Cincinnati is 60m / min, the fast speed is 100M / min, the acceleration is 2G, and the spindle speed has reached 60000r / min. It takes only 30min to process a thin-walled aircraft part, while the same part takes 3 hours in general high-speed milling machine and 8 hours in general milling machine. Due to the specialization of the division of labor among the components of the mechanism, the high-speed spindle is becoming more and more popular with the development of professional spindle factories. In the past, the models used only for High-speed Automobile Industry (models with more than 15000 revolutions per minute) have become an essential element of mechanical products.


How to select hard rail processing and wire rail processing for iron parts?

In the machining industry, iron parts belong to common processing workpieces. When using machining centers to process iron parts, should we choose hard rail machining centers or wire rail machining centers?

When selecting hard rail machining center and wire rail machining center, machining manufacturers need to understand the size of iron parts processed by themselves, whether they are finish machining or rough machining,

Only by understanding these details can a manufacturer specializing in the production of CNC machining centers give an accurate answer.

Generally, large-size iron parts have high quality and large cutting amount. In this case, it is more appropriate to select the hard rail machining center. The hard rail machining center has strong rigidity, earthquake resistance and load-bearing capacity, which is more suitable for heavy-load cutting.

In this case, if the wire rail machining center is used for processing for a long time, the guide rail may be damaged. Customers are generally advised to use hard rail CNC machining centers, such as table group finishing machines T-8, T-10, T-12, T-13 and T-15, which are hard rail machining centers, compared with 850, 1060 and 1270 in the market. These hard rail CNC machining centers are generally suitable for heavy-duty cutting.


How to ensure the accuracy of CNC machining

For many non-standard parts processing customers, when selecting suppliers, they are most concerned about the machining accuracy of mechanical precision parts. In the precision machining industry, it is easy to find suppliers, but it is difficult to find CNC machining center suppliers with appropriate accuracy, so we must be cautious. In short, precision is risky and processing needs to be cautious.

Machining of mechanical precision parts

In the machining center of non-standard parts, more cutting tools are generally used in the machining process. In order to ensure the machining accuracy of precision parts, the replacement sequence of cutting tools must be arranged reasonably. The corresponding replacement of machining tools is the machining sequence. The general process principle is to make the datum first, then punch holes, and then divide the primary and secondary rough and then fine.

In the machining process of mechanical precision parts, the machining of datum surface is the best, which provides positioning reference for the machining of other surfaces. The benchmark of this process positioning is the benchmark of the next process positioning. Therefore, when the positioning datum of all processes of machining a non-standard part is determined, the sequence arrangement of the whole machining process can be pushed forward.

When arranging the processing sequence of mechanical precision parts, it must be clear whether non-standard parts need to be processed and processed. Pre machining is also usually done by CNC lathes. If the workpiece has high rough accuracy, the positioning is guaranteed, or the processing volume is sufficient, it can be processed directly in the machining center without pretreatment. This needs to consider the difference between the accuracy of the rough datum and the process of the machining center, which can be completed by several processes or one process.

Similarly, if the pretreatment surface has different standard requirements from the operation surface of the machining center, sufficient machining allowance must be reserved during pretreatment. At the end of one-time clamping in the machining center of non-standard mechanical precision parts, all machining contents including the pre machined surface must also be included to ensure the final machining accuracy of precision parts.


Influence of spindle speed on large CNC machining center

Since the development of large CNC machining centers, the total output value has gradually increased, and the domestic machine tool industry is becoming more and more prosperous. According to the appearance design of most machining centers in the market, the slicing conveyor can be adjusted to the back of the production line, which is suitable for customizing the arrangement of the production line, which is also one of the reasons why customers like it. The machine adopts high torque motor. The output of the motor can fully reflect the characteristics of the main shaft. The indexing disc has high efficiency and high precision, including 8 oil circuit joints. One air pressure is tightly confirmed and has high mobility. It can be used with oil pressure fixture.

The main shaft of the large NC machining center is a vertical machining center, the structural form is a fixed column, the worktable is rectangular and has no indexing rotation function. It is suitable for machining disc, sleeve and plate parts. It has three linear motion coordinate axes, and it can be installed on a rotary table rotating along the horizontal axis on the worktable to process spiral parts. The replacement of the machine tool adopts pneumatic mode, which is fast and convenient. The machine adopts automatic lubrication to ensure the good operation of all parts of the machine tool.

The structure of the machine tool adopts the form of horizontal carriage, and the layout is reasonable. The three-axis feed adopts precision ball screw connected with servo motor to improve the transmission accuracy. The X and y-axis guide rails of the machine adopt precision rolling linear guide rails with high feed sensitivity; The z-axis adopts rectangular hardened cast iron plastic sliding guide rail pair, which has good vibration absorption; The machine control system adopts AC servo system, which is suitable for the processing of complex parts, especially complex molds.

The machine tool spindle adopts servo spindle motor, and the spindle box is equipped with counterweight device to ensure the smooth operation of z-axis. As we all know, the spindle speed of large CNC machining center is generally high, but with the continuous improvement of spindle speed, especially the rapid and various random vibrations, the instability of rotating shaft will increase. When the anti fatigue strength of spindle is exceeded, the spindle rotation error will increase reversibly, and finally affect the machining accuracy of machine tool. Therefore, the selection of spindle speed is very important.


Skills of avoiding Tool Collision in CNC machining center

What are the tips for avoiding knife collision in CNC machining center? With the development of computer technology and the continuous expansion of CNC machining teaching, there are more and more NC machining simulation systems, and their functions are becoming more and more perfect. Therefore, it can be used in the preliminary inspection program to observe the movement of the tool to determine whether a collision may occur.

1、 Using the simulation display function of CNC machining center

Generally, advanced CNC machining centers have graphic display function. When inputting the program, you can call the graphic simulation display function to observe the tool path in detail, so as to check whether there is possible collision between the tool and the workpiece or fixture.

2、 Using the empty running function of CNC machining center

The idling function of CNC machining center can be used to check the correctness of tool path. When the program is in the NC machining center, you can install it on the tool or workpiece, and then press the empty operation button. At this time, the axis does not rotate, and the automatic operation is tracked according to the planned worksheet. At this time, you can find out whether the tool may contact the workpiece or fixture. However, in this case, it must be ensured that the tool cannot be installed when the workpiece is installed; When the tool is installed, the workpiece cannot be installed, otherwise collision will occur.

3、 Using the locking function of CNC machining center

General CNC machining center has locking function (full lock or single shaft lock). After entering the program, lock the z-axis, and you can use the coordinate value of the z-axis to judge whether there will be a collision. When applying this function, avoid tool change and other operations, otherwise the program cannot pass.

4、 Improve programming skills

Programming is the most important part of large CNC machining center. Improving programming skills can avoid some unnecessary collisions to a great extent.


Problems in high speed machining

In the machining and manufacturing industry, high-speed machining is often used to process the automobile transmission housing. Although high-speed cutting technology has the advantages of high machining efficiency, small cutting force, reduced influence of cutting heat on workpiece, high machining accuracy and intensive process, the following problems are encountered at present:

  1. Lack of reasonable processing parameter selection scheme

As a new cutting method, high-speed cutting has no complete machining parameter table to choose from, and there are not many machining examples for reference. In high-speed cutting, most of them still rely on previous experience or carry out a large number of trial cuts to select parameters to achieve the best cutting effect. Finding reasonable machining parameters is a primary problem in the application of high-speed cutting.

  1. Lack of proper tool selection method

Cutting tool is a key problem in the popularization and application of high speed cutting. Because the cutting mechanism of high-speed cutting is completely different from traditional cutting, the wear mechanism and failure form of machining, the stress state of cutting tool and the cutting shape are different. In traditional milling, the main failure form of tools is flank wear, while in high-speed cutting, its failure form is completely different according to the processing conditions and workpiece materials, such as tool tip breakage, flank wear, tool rod fracture and other forms, and the effects of different combinations of tools and different workpiece materials are also different. How to choose a reasonable high-speed cutting tool, prolong the service life of the tool as much as possible and give full play to the performance of the tool is a very key technology for high-speed cutting technology.

Tempering treatment of steel in CNC processing

In the machining of machinery industry, steel generally needs heat treatment, and the allowance will be indicated in the process drawing for grinding and finishing. In the process of steel heat treatment, tempering is required to harden the steel parts, then heat them to a temperature below AC1, hold them for a certain time, and then cool them to room temperature. Common tempering processes include low temperature tempering, medium temperature tempering, high temperature tempering and multiple tempering. The purpose of tempering: it is mainly to eliminate the stress generated by steel parts during quenching, so that the steel parts have high hardness and wear resistance, as well as the required plasticity and toughness.