Monthly Archive September 27, 2020

1. With the development of science and technology of rotation and temperature rise, the spindle speed of CNC machining of aluminum cavity is higher and higher, and the range of speed change is wider and wider.

Therefore, the requirements of bearing high-speed operation stability are higher and higher. The temperature rise of machine tool spindle bearing is an important factor to limit the bearing speed. Generally, the correct selection of bearing type, worse grade, configuration mode, clearance (preload), lubricant and lubrication mode can improve the high-speed performance of rolling bearing to a certain extent.

1. Service life and bearing capacity for heavy machine tools or heavy cutting machines, the bearing capacity of air filter bearing should be the first.

Because for general machine tools, the life of the spindle assembly refers to the service life to maintain the accuracy of the spindle. Therefore, the bearing accuracy is required to meet the life requirements of the spindle assembly.

1. Stiffness and vibration resistance in order to ensure the machining quality of aluminum cavity CNC machining, the spindle system must have enough stiffness, otherwise there will be a large re mapping error or even vibration.

Anti vibration refers to the ability to resist forced vibration and self-excited vibration. The anti vibration performance of the main shaft depends on the stiffness and damping of the spindle and bearing. The stiffness of the spindle system can be effectively improved by using preloaded rolling bearings.

1. Noise in high-speed grinding machine, the noise of grinding head bearing is an important part of the whole noise, and it is advantageous to select low-noise rolling bearing.

In the fault detection of CNC machining of aluminum cavity, reasoning can be carried out from two aspects: forward and backward. Forward: that is, from the cause of the fault, explore its functional relationship, and check the impact of the cause on the results.

In other words, according to the possible causes of the fault, to see whether it is consistent with the fault phenomenon, to determine the fault point.

By using reasoning method, the object of reasoning analysis is often vague, because in many fault causes or phenomena, we should find out their common characteristics.

So as to determine the fault point, with the deepening of reasoning step by step, we will realize that the personality characteristics of reasoning analysis object is the fault to be found.

Grinding methods can be divided into cylindrical grinding, internal grinding, centerless grinding, surface grinding, form grinding, gear grinding, thread grinding, east-west grinding, general lathe surface grinding, etc. With the development of NC technology, CNC grinding method plays an increasingly important role in grinding.

CNC grinder can process some special parts (such as axis parts with special curve, special-shaped parts with more than three coordinate requirements, mold, etc.) which cannot be processed on general grinder. Therefore, it is used to machining parts in a wide range. In order to maximize the economic benefits of CNC grinding machine, the following processing objects can be given priority.

（1） The parts put into production repeatedly have better benefit

The use of CNC grinding machine process preparation time occupies a higher share. For example, preparation of process analysis, programming, adjustment and trial cutting of the first part of parts.

The sum of these inductive working hours is often dozens to hundreds of times of the working hours of a single part. However, the operation contents of the NC lathe (such as special general lathe fixtures, process documents, programs, etc.) can be saved and used repeatedly. Therefore, when a part is successfully trial produced on a CNC grinder and put into production repeatedly, the production cycle is greatly reduced, and the cost is also less, which can achieve better results Economic benefits.

（2） It is required to guarantee the processing quality and produce the key parts in medium and small batches with high efficiency

Controlled grinding machine can realize high precision, high quality and high efficiency grinding under the control of computer. Compared with special grinding machine, it can save a lot of special process equipment, and has strong flexible manufacturing ability and good economic benefits.

Compared with the general grinding machine, it can remove many artificial disturbing factors in the long process of disorderly processing, and has good accuracy consistency and interchangeability, and high processing efficiency.

（3） The processing batch of parts should be greater than that of general grinder

When NC grinding machine is used to process medium and small batch parts, due to various reasons, the pure cutting time only accounts for 10% – 30% of the actual working hours. When machining on the CNC grinding machine of grinding center, which is a kind of multi process convergence, this share may rise to 70% – 80%, but the preparation adjustment time is often much longer, so the parts batch size will become uneconomical.

（4） The processed parts should fit in with the process characteristics of CNC grinding machine with multi process convergence

When CNC grinding machine is used to process parts, the condition of grinding wheel cutting workpiece is completely the same as that of corresponding non CNC grinding machine, but it can carry out some complex machining with machining accuracy requirements. For example, in the grinding range, the general grinder is mainly used for grinding the end face of cylindrical surface, conical surface or stepped shoulder.

In addition, CNC cylindrical grinder can also grind toroidal surface (including convex and concave surface), as well as the above various forms of disordered combined surface.

（5） Balance of inductive processing capability of parts

As a single CNC grinding machine, it is difficult to complete all the processing contents of a part, and it needs to transfer and cooperate with the processing procedures of other equipment, so it has the requirements of production rhythm and workshop production capacity balance.

Therefore, it is necessary to give full play to the processing characteristics of CNC grinding machine, and reasonably organize matching balance process on other processing equipment.

（6） Some special parts processing considerations

Although the processing batch of some parts is very small, ordinary lathes have disordered shapes, high quality and good interchangeability, which can not meet the above requirements on non CNC grinding machines, and can only be organized to be processed on CNC grinding machines, such as parabola, cycloid cam and special reflector mirror

CNC lathe is a kind of high-precision and high-efficiency automatic machine tool. The use of CNC lathe can improve the processing efficiency and create more value. The emergence of CNC lathe makes enterprises get rid of backward processing technology.

The processing technology of CNC lathe is similar to that of ordinary lathe. However, since CNC lathe is a kind of clamping device, which can complete all turning process continuously and automatically, attention should be paid to the following aspects.

For efficient metal cutting, machining materials, cutting tools and cutting conditions are the three main factors. These factors determine the processing time, tool life and machining quality. An economical and effective machining method must be a reasonable choice of cutting conditions.

Three factors of cutting conditions: cutting speed, feed and cutting depth directly lead to tool damage. With the increase of cutting speed, the tool tip temperature increases, resulting in mechanical, chemical and thermal wear. When the cutting speed is increased by 20%, the tool life is reduced by 1 / 2.

The relationship between feed condition and tool wear is very small. However, when feeding, the cutting temperature increases and the wear occurs. It has less effect on the tool than on the cutting speed. Although the influence of cutting depth on cutting speed and feed rate is not as great as that of cutting speed and feed rate, the hardened layer produced by cutting material will also affect the tool life when cutting at small cutting depth.

The user should select the cutting speed according to the material, hardness, cutting state, material type, feed rate and cutting depth.

According to these factors, select the most suitable processing conditions. The ideal state is to wear regularly and stably to reach the service life.

But in practice, the choice of tool life is related to tool wear, size change, surface quality, cutting noise, processing heat and so on. When determining the processing conditions, it is necessary to study according to the actual situation. For refractory materials such as stainless steel and heat resistant alloy, coolant or hard blade can be used.

(1) Point control CNC lathe processing robot. The CNC lathe robot of CNC equipment can only control the moving parts of the lathe from one position to another accurately, that is to say, only the value of controlling the end point of coordinate travel does not have any reduction in the moving process, as for the speed and path between the relevant two points depends on the productivity.

In order to locate accurately on the basis of as high productivity as possible, the movement between the two related points is first to move quickly to the new position, and then slow down the 1-3 stage, let it slowly locate the point, so as to ensure its positioning accuracy.

(2) Point line control CNC lathe processing robot. This kind of NC lathe robot processing, not only to control the position between the two related points, but also to control the movement speed and route between the two related points.

Its route usually consists of straight lines parallel to each axis. The difference between the control and the point of NC lathe robot is that when the moving parts of the machine tool move, it can be processed along an axis direction (generally it can be cut at 45 ° oblique line, but not any slope linear cutting). The auxiliary function is the position control of the NC lathe robot, such as improving the spindle speed control, feed processing cycle, tool selection, and other functions.

(3) Contour control CNC lathe processing robot. The control device of this kind of CNC lathe can control two or more coordinate axes continuously at the same time.

In the process of machining, we should not only control the starting point and the end point, but also control the speed and position of each point in the whole processing process, so that the CNC lathe robot can process complex shaped parts according to the drawing requirements. Its auxiliary functions are also relatively complete.

CNC machining is to use the automatic control system to install digital program flow commands to control the automatic start stop, direction change and speed change of CNC machine tool bearings. NC blade can be selected, the drilling amount and moving track of NC blade can be changed, and all kinds of auxiliary posture needed for lifetime machining can be carried out. CNC machining can greatly reduce the number of work clothes, and produce parts with complex processing methods, only need to change the process flow. CNC machining is relatively stable and will not cause machining error. What are the reasons that affect the accuracy of CNC machining? Let’s take a look at it

From the long-term data analysis and practical operation of parts processing, we can see the machining accuracy error caused by CNC machine tool positioning. The positioning of machine tools has a great influence on the machining accuracy of CNC machine tools. From the perspective of structure, the machining error of CNC machine tools is mainly caused by the accuracy grade, and the feed system of machine tool is the key stage affecting the accuracy level. The feed system of CNC machine tool is generally composed of mechanical transmission system and electrical control system. In the overall design, the accuracy level is related to the mechanical transmission system. In the closed-loop control system, CNC machine tools can generally avoid the position error of key components (such as ball screw and other components) according to the positioning inspection equipment. However, for the open-loop system, because of many factors and complex conditions, it is impossible to carry out positioning detection, so the machining accuracy of CNC machine tools is greatly affected.

The influence of CNC machining position error on machining accuracy. Position error refers to the transformation or offset level of the specific surface layer, center line or symmetry face of the machined part relative to its ideal position, such as flatness, symmetry, symmetry, etc. Position error in NC machining generally refers to over-current protection error. The key reason for the position error is the machining error caused by the gap and elastic deformation caused by the transmission system in the whole machining process of machine tool parts, and the position error caused by the sliding friction force that the special tool head needs to get rid of in the production process. In the open-loop system, the position precision is greatly affected, while in the closed-loop control system, the key to the position precision is the offset test.

The machining accuracy error caused by geometric figure error of CNC machining. In the processing of CNC machine tools, because of the influence of external factors such as external force, heat generated during processing, the geometric precision of the machine tool is affected, and the geometric shape deformation of parts processed on the machine tool will cause geometric error. According to scientific research, there are two reasons for the geometric error of CNC machine tools: internal factors and external factors. The internal factors causing geometric errors of machine tools refer to the geometric errors caused by the machine itself, such as the flatness of the machine tool table, the flatness and parallelism of the guide rail of the machine tool, and the geometric precision of the special tools and fixtures of the machine tool. The key of external factors refers to the geometric error caused by environmental factors and thermal deformation in the production process. For example, the geometric error caused by thermal deformation and deformation of NC blade or parts in the whole drilling process will affect the machining accuracy of machine tools and parts.