In the domestic machining industry, CNC machining center is called CNC milling machine processing and computer gong processing. The main features of CNC machining are high precision, high efficiency and stable quality. CNC machining is very suitable for small batch and multi variety products. CNC machining in the production of different parts, only need to change the program, the use is very flexible. In addition to the above features, CNC processing also has the following main features
(1) High rigidity, in order to match the high precision of CNC system, CNC milling machine has high rigidity, CNC machining center can adapt to the high precision machining requirements.
(2) Light drag, turret (table) movement using ball screw pair, small friction, easy to move. The pressure angle of the special bearing for supporting both ends of the precision CNC machining lead screw is larger than that of the ordinary bearing, so it can be selected and matched before leaving the factory; The lubrication part of CNC milling machine adopts oil mist automatic lubrication, which makes CNC milling machine easy to move.
(3) General precision CNC milling machine processing three-axis linkage, according to different machine configuration, there are also four axis, five axis high precision CNC machining center. The main reason is high precision, small batch processing parts can multiple improve production efficiency. These are the main features of precision CNC machining.
In the machining industry, the simplest way to promote cooperation is to understand the processing fee first. In fact, the cost accounting of precision parts processing fee is very simple. It’s just a simple quotation method. You can calculate the price of raw materials and material density of parts. You can roughly calculate the material price of parts by looking at the size of drawings. Let’s take a look at the cost accounting formula of parts processing fee:
In the calculation of parts processing cost, we should know the weight of raw materials: we should also consider the machining allowance of raw materials, and increase the overall size by about 5-8mm. Process requirements: the size of parts requires high, the processing technology will be complex, and the processing cost will increase, especially the single piece processing. Number of machined parts: for the machining industry, small batch parts processing can save clamping time and improve production and processing efficiency. The difference in price is 3-5 times. Single piece processing is not suitable for batch quotation, and the final quotation is based on the processing technology on the drawing.
The above is about the cost accounting of mechanical parts processing fees.
In the mechanical processing industry, the price of general parts processing is calculated through the standard formula, and the processing cost will be appropriately increased in case of complex parts. There is a certain risk in complex precision parts, because if there is any problem in the processing technology, the dimensional tolerance of precision parts will be unqualified. At present, many precision parts are directly processed by CNC lathe or CNC, which can ensure the processing accuracy, save labor and improve the production and processing efficiency. Now many machining manufacturers have added CNC machine tools, let’s see how to calculate CNC processing fee
CNC processing, also known as computer gong processing, is mainly controlled by computer programming code. The main feature is high processing precision, small batch processing parts can improve production efficiency, but also save labor operation. CNC processing fee is generally calculated according to 60-70 yuan / hour. For high-precision parts, the processing fee is determined according to different processing technology.
When CNC processes small batch parts, the processing fee will be quite low. Because the batch parts can be repeatedly clamped, it can reduce a lot of programming time and improve the production efficiency. Machining manufacturers hope to have small batch processing, repeated clamping processing is OK. CNC processing fee how to calculate, generally calculated by the hour price. Precision parts with different requirements can be calculated comprehensively according to the processing technology.
Precision hardware processing technology processes include turning, milling, planing, grinding, clamping, stamping, forging and other methods.
Stamping: the pre made die is used for cold stamping, and the first step is sheet metal processing, that is, most of the processing materials are sheet metal, so the processing efficiency is relatively high and suitable for mass production.
The process of fine hardware processing technology is divided into engineering die and connecting die. Engineering die is also called single punch die. Some more complex parts need several sets of dies, and the connecting die splits the shape of the commodity into several parts in the cavity of the die. In this way, a punch processing stroke is a finished product. High speed continuous punch can process 300 or 400 products per minute.
Lathe: lathe belongs to precision machining machinery, which is divided into general lathe, active lathe, instrument lathe and computer lathe. After holding the material clip, it reverses and processes radially or axially by the turning tool.
Nowadays, active lathe and computer lathe are more and more widely used. Because both of them are fully active processing, the accuracy error caused by human operation is reduced to the lowest point, and the processing speed is fast, which is used for mass production. Most of today’s computer lathes are equipped with side reverse cutter and reverse reverse cutter, that is to say, milling can also be carried out on the lathe. The surface roughness of lathe is about ra0.4-1.6;
Shaft part is one of the most common typical parts. According to the different structural methods of shaft parts, they can be generally divided into three categories: optical axis, stepped axis and special-shaped axis; Or divided into solid shaft, hollow shaft, etc. They are used to support gear, pulley and other transmission parts in the machine to transfer torque or motion.
The machining technology of stepped shaft is typical, which reflects most of the contents and basic rules of shaft parts machining. Next, take the transmission shaft in the gearbox as an example to introduce the processing technology of general step shaft.
The part is the transmission shaft in the reducer. It belongs to stepped shaft parts, which is composed of cylindrical surface, shaft shoulder, thread, thread tail undercut, grinding wheel overtravel and keyway. The shoulder is generally used to determine the axial orientation of the parts on the shaft. The effect of each ring groove is to make the parts have an accurate orientation when they are used in the equipment, and to make it convenient to withdraw the tool when grinding the outer circle or turning the thread; Keyway is used for equipment key to transfer torque; Thread is used for all kinds of lock nuts and adjusting nuts.
According to the working performance and conditions, the typical parts processing technology, the transmission shaft drawing rules the primary journal m, N, excircle P, Q and shaft shoulder g, h, I, has higher standard, orientation accuracy and smaller surface roughness value, and has the need of heat treatment. These technologies need to be guaranteed in processing. Therefore, the key process of the transmission shaft is the processing of journal m, N and outer circle P, Q. The material of the transmission shaft is 45 steel, because it belongs to the general transmission shaft, so the selection of 45 steel can meet its needs. The transmission shaft of typical parts processing technology belongs to medium and small transmission shaft, and there is little difference in the outer circle diameter standard, so ￠ 60mm hot rolled round steel is selected as the blank.
Determine the processing method of the primary surface:
Most of the transmission shafts are rotary surfaces, which are mainly formed by turning and cylindrical grinding. Because the primary surface M, N, P, Q of the transmission shaft has higher service level (IT6) and smaller surface roughness Ra (RA = 0.8 UM), it needs grinding after turning. The processing plan of cylindrical surface (see table A-3) can be as follows: rough turning → semi finish turning → grinding.
Determine positioning datum:
Reasonable selection of positioning datum has a decisive effect on ensuring the standard and orientation accuracy of parts. As several primary cooperative surfaces (Q, P, N, m) and shoulder surfaces (h, g) of the transmission shaft need radial circular runout and end circular runout for the reference axis A-B, and it is also a solid shaft, the center hole at both ends should be selected as the reference, and the double tip clamping method should be selected to ensure the technical requirements of the parts.
The rough datum of typical parts processing technology is the blank outer circle of hot rolled round steel. Three jaw self centering chuck is used to clamp the outer circle of hot rolled round steel blank, turn the end face and drill the center hole. However, it is necessary to pay attention to the fact that it is generally not possible to drill the center hole at both ends by clamping the outer circle of the blank twice. Instead, it is necessary to take the outer circle of the blank as the rough datum, first process an end face, drill the center hole, and turn out the outer circle at one end; Then, take the turned outer circle as the benchmark, clamp it with the three jaw self centering chuck (sometimes set up the center frame at the turned outer circle in the previous step), turn the other end face and drill the center hole. Only in this way can the two center holes be coaxial.
In the field of CNC processing industry, CNC processing is also known as CNC machine tools. It mainly refers to the path of feed processing. It refers to the path through which the turning tool starts to move from the tool setting point (or the fixed origin of the machine tool) until it comes back to this point and completes the processing program, including the path of cutting processing and the path of non cutting empty stroke such as cutting in and cutting out of the tool. These are NC commands to complete the operation automatically.
In the process of finishing, the feeding path is basically carried out along the order of parts generalization. Therefore, the key point of determining the feeding path is to determine the feeding path of rough machining and empty stroke.
In the process of NC machine tool machining, the machining process should follow the following rules.
It should be able to ensure the accuracy and surface roughness of the workpiece to be processed.
Make the processing path shortest, reduce the empty travel time and improve the processing power.
Simplify the amount of numerical calculation and the processing procedure as much as possible.
Subprogram should be used to save processing time for some repeated programs.
In the mechanical processing industry, there is such a processing machine, the operation process is completely ordered by the technician with computer programming code, which belongs to precision processing equipment, which is often referred to as CNC processing. Today to a simple understanding of CNC machining parts in the clamping method which
Before CNC machining parts, the size of parts need to choose different clamping methods. What kinds of clamping methods are there in the process of parts processing? The first is to clamp the parts with the jaw, which is suitable for processing the parts with small appearance and not exceeding the scope of the jaw; The third is directly fixed to the platform for processing, which is generally large and complex parts processing, because fixed on the platform can also improve the processing quality; Finally, the use of fixture fixture to clamp parts processing, this for some batch parts or mass parts processing, the main advantage is accurate positioning processing, improve production and processing efficiency!
The above is about the clamping method in CNC machining parts.
Precision machinery parts processing first station (engaged in precision parts processing, professional CNC processing manufacturers)! In the machining circuit, the parts with high precision are often encountered. Now let’s understand the analysis of the positioning error in the processing technology
In terms of machining process, positioning error can be divided into various situations. The following should be paid attention to during operation:
Positioning error is the positioning error of a processing precision parameter in the processing of a part. It is a part of the machining error of the machining accuracy parameter.
A process and positioning scheme can produce different positioning errors for several machining accuracy parameters of the process. Therefore, the positioning errors of these machining accuracy parameters should be calculated respectively.
The premise of analyzing and calculating the positioning error is to ensure the accuracy of processing requirements by using fixture clamping and processing a batch of parts with adjustment method.
The positioning error obtained by analysis and calculation refers to the maximum range of positioning error that may occur when processing a batch of workpieces. It is a limit value, not a specific value of the positioning error of a workpiece.
The most important position change of the design datum of machining a batch of parts relative to the fixture tool adjustment datum is the cause of the positioning error, not necessarily the positioning error.
These simple understanding of the positioning error analysis and calculation, in the process of precision CNC machining parts, mechanical parts processing, there are many reasons affecting the size of the error.
In the hardware processing and manufacturing industry, slow wire cutting and fast wire cutting both refer to WEDM, so what’s the difference between these two processing technologies? Let’s take a look at the following:
Development status of low speed wire processing technology
Multiple cutting technology is the fundamental means to improve the machining accuracy and surface quality of slow wire. Generally, it is formed by one cutting, the accuracy is improved by two cutting, and the surface quality is improved by more than three cutting.
Because of the lag of the electrode wire when cutting the corner, the corner will collapse. In order to improve the corner cutting accuracy, more dynamic corner processing strategies are adopted. Such as: automatic change of processing speed, automatic adjustment of water pressure, control of processing energy, etc.
The high precision finishing circuit adopted by the advanced slow moving machine tool is an effective technology to improve the flatness of the workpiece, which significantly improves the accuracy of thick workpiece processing; In order to carry out micro finish machining of small fillet, narrow slot, narrow groove and micro parts, the NC low speed WEDM machine tool can use 0.02 ~ 0.03 mm electrode wire for cutting.
In order to ensure high-precision machining, the mechanical accuracy, pulse power supply accuracy and servo control accuracy of the machine tool (including the control of mechanical motion, pulse parameters, wire feeding system and working fluid system) have reached a very high level. Using water temperature cooling device, the internal temperature of the machine tool is the same as the water temperature, which reduces the thermal deformation of the machine tool; The closed-loop digital AC (DC) servo control system ensures excellent dynamic performance and high positioning accuracy. The machining accuracy can be controlled within several microns, and the precision positioning can achieve 0.1 μ The control of m equivalent; Immersion machining is used to reduce the thermal deformation of the workpiece; Motor servo, closed loop electrode wire tension control; Using voltage modulation tool setting power supply to achieve high-precision tool setting, tool setting accuracy can reach 0.002 mm, no damage to the workpiece, no matter dry or wet.
Advantages of 2-wire processing technology
Medium speed wire cut electrical discharge machining (ms-wedm) belongs to the category of reciprocating high-speed WEDM, which realizes multiple cutting function on high-speed reciprocating WEDM, and is commonly known as “medium speed wire cut”. The so-called middle wire cutting does not mean that the wire cutting speed is between high speed and low speed, but the compound wire cutting machine. That is to say, the wire cutting principle is to adopt high speed (8-12m / s) wire cutting in rough machining and low speed (1-3m / s) wire cutting in finish machining. In this way, the work is relatively stable and the jitter is small, and the error caused by material deformation and molybdenum wire loss can be reduced through multiple cutting, The processing quality can be between high speed wire feeder and low speed wire feeder. Therefore, the user’s “medium wire” is actually a reciprocating WEDM, which uses the processing technology of some low-speed wire cutting machines for reference, and realizes the stripless cutting and multiple cutting.
As for the second cutting, low speed wire feeding and speed limited feeding are adopted. In the process of machining, the deformation treatment should be paid attention to for many times of cutting, because when the workpiece is online cutting, with the effect of the original internal stress and the influence of the processing thermal stress produced by spark discharge, the non directional and irregular deformation will be produced, which makes the cutting depth uneven and affects the processing quality and accuracy. Therefore, it is necessary to reserve different machining allowance according to different materials, so as to fully release the internal stress and complete torsion deformation of the workpiece. In the subsequent multiple cutting, there is enough allowance for finishing machining, so that the later size of the workpiece can be guaranteed.
▌ advantages of fast wire processing technology
As the name suggests, fast wire processing is named for the high speed wire running of electrode wire in the cutting process. Fast moving machine tool is an electric machine tool created by Du in China. After decades of continuous improvement and development, it has become an important processing means in the manufacturing industry. It can meet the requirements of medium and low-grade mold processing and other complex parts manufacturing, and occupies a considerable proportion in the medium and low-grade market.
At present, the technical index of fast cutting machine tool: the efficiency of one cutting is 180 mm ²/ The surface roughness is RA ≤ 1.0 μ m. The average efficiency is 50 mm ²/ The machining precision is 0.01mm, and the loss of electrode wire is less than or equal to 0.01mm/200000 mm ² 。 These performance indicators seem to be quite good, but it should be noted that to obtain these indicators, we need to ensure all aspects. Once there are differences, such as the concentration of working fluid and the loss of electrode wire, the stability of processing quality will be affected.
Due to the stronger social demand for product diversification, the proportion of multi variety, medium and small batch production has increased significantly, and the traditional ordinary processing equipment used in middle walking processing has been difficult to adapt to the requirements of high efficiency, high quality and diversification. However, middle walking processing has the characteristics of simple structure, low cost and low consumption, so it also has its living space. Compared with fast-moving machine tool, slow-moving machine tool has obvious advantages in processing efficiency, precision and surface quality. Although the price of the machine tool is more expensive, with the rapid development of the manufacturing industry, it will be more and more used in various processing fields.
