The machining refers to the process of changing the shape of the workpiece. Engaged in machining for many years, contact with many different parts processing drawings, according to the processing requirements on the drawings to choose different process steps. Let’s take a look at the basic requirements of the production drawings of the machining plant
In the field of machining, it is necessary to know whether the size and accuracy of the drawing are clear before machining parts? It can correctly reproduce the three-dimensional state of the workpiece through the production drawings, and then according to the processing technical requirements, the drawings are displayed from several perspectives, and the perspectives on the standard drawings are divided into the first perspective and the third perspective. What is the surface finish of the drawing? Is the material surface treated? These are the basic requirements of the production drawings of the machining plant. For the workpieces with special requirements, the processing requirements are finally completed according to the processing technology on the drawings!
The above is the basic requirements of the production drawings of the machining plant.
In the field of machining, roughing, semi finishing and finishing are all called machining. Rough machining refers to the pursuit of high efficiency, which requires the maximum cutting amount per unit time. The requirements for machining accuracy and surface quality are not very high, because the amount of cutting tools is large, and the surface allowance of machined parts is not very uniform. Semi finish machining is to smooth the residual machined surface after rough machining, leaving a relatively uniform machining allowance on the machined surface of the workpiece, which provides the best processing conditions for high-speed machining of finish machining.
In the process of machining mechanical parts, the general processing conditions are divided into rough machining and finish machining. Semi finish machining will be used for special precision parts, mainly to ensure the processing accuracy and provide production efficiency. Although the precision of semi finish machining is not high, it can meet the processing requirements of simple mechanical parts. Mainly auxiliary processing technology, to provide conditions for finishing.
The above is the concept of semi finishing machining.
In the automation equipment, non-standard equipment manufacturing industry, equipment parts are often replaced by stainless steel materials. Compared with general materials, the processing technology of stainless steel materials is more complicated. How to process small holes in stainless steel parts is actually not difficult; With the continuous development of economy and technology, the diversity of processing materials of various enterprises is also changing and increasing. In order to help you solve some problems in the work, the following summarizes some skills of how to process small holes of stainless steel parts?
In the field of mechanical processing, first of all, the design of process route and the selection of processing tools: according to the actual situation of stainless steel parts small hole to be processed, the following process route can be formulated: rough turning inner shape – semi finishing turning inner shape – finishing turning inner shape – finishing turning inner hole annular groove – turning end surface groove. The selection of cutting tools should be based on the characteristics of stainless steel itself and comprehensive consideration from all aspects. It includes the following points
In order to avoid the phenomenon of workpiece falling off, it is necessary to choose the right-hand tool which is opposite to the thread of thread mould.
We should try our best to choose the tool shape and cutting groove shape (not smooth) with the smallest cutting force, so as to reduce the impact on the rigidity of parts.
The arc of the tip should be moderate. If the arc is too large, chattering lines will appear; If the arc is too small, the tool tip is easy to be damaged, which affects the service life of the tool.
In the selection of the tool holder, we should choose the form of internal cooling, so that the parts will be fully cooled in the process of processing, and at the same time, we should control the direction of chip removal.
Small hole machining control of stainless steel parts: due to the structure of mechanical parts, the positioning mode of thread mould can only be used for clamping in the internal turning. For the special requirements of workpiece processing, if the center of gravity is irregular, it is easy to be out of balance in the clamping system. At the same time, there are high requirements for dimensional accuracy, coaxiality and perpendicularity. If there is a little error in the process of processing, it may have a serious impact on the practical performance of the parts.
So for the stainless steel parts small hole processing to the tool selection, cutting parameters and process route setting must have strict requirements, these factors will affect the parts after processing is qualified. Machining accuracy of machining equipment itself is also very important!
The above is how to process the small holes of stainless steel precision parts.
In the field of machining, CNC processing is also known as computer gong processing. In the process of precision parts processing, CNC machining workpiece is placed on the foundation, which should be leveled in the free state, and then the anchor bolts should be evenly locked. For ordinary machine tools, the reading of the level meter is not more than 0.04/1000mm, and for CNC machine tools with high precision, the reading of the level meter is not more than 0.02/1000mm. When measuring the installation accuracy, it should be carried out at a constant temperature, and the measuring tool should be used after a period of constant temperature. When installing the machine tool, we should try our best to avoid the forced deformation of the machine tool. When installing the machine tool, some parts of the machine tool should not be removed casually. The removal of the parts may lead to the redistribution of the internal stress of the machine tool, thus affecting the accuracy of the machine tool.
Mechanical equipment processing and manufacturing industry, precision mechanical parts processing workpieces, the general detection equipment is altimeter, two-dimensional imager, three coordinates, precision machining is mainly CNC machining center, CNC lathe, slow wire processing equipment. According to the mechanical automation equipment accessories processing requirements, select the appropriate processing equipment to complete!
The above is how to measure CNC machining precision mechanical parts.
The process of making raw materials into mechanical parts by processing equipment is called mechanical parts processing, and the process is called machining process. In the field of mechanical processing, the materials of automatic equipment accessories and hardware mechanical parts are different, or the processing requirements are different, which directly affects the selection of processing technology and processing equipment. In the surface treatment of mechanical equipment parts is the same, different raw materials need to choose a reasonable treatment process. Let’s take a look at the mechanical parts processing industry, what materials are suitable for surface drawing treatment
In the mechanical parts processing industry, there are many raw materials processing, such as steel: Cr12, S45C, Q235, s316, etc., plastic: POM saigang, bakelite, ESD, peek, etc., aluminum: aluminum profile, al5052, Al6061, imported al7075, etc., stainless steel: sus303, SUS304, etc., and many raw materials. Used in the automation equipment parts, plastic materials generally do not require surface drawing treatment. Most of them are aluminum and stainless steel. If there are no special requirements for the surface, the surface drawing treatment will be selected. The main drawing effect is beautiful, so that the surface looks good.
The above is in the mechanical parts processing industry, what material is suitable for surface drawing treatment to share.
In the field of mechanical parts processing, parts of automation equipment, medical equipment and other accessories use stainless steel materials more, and the machinability of stainless steel materials is much worse than that of medium carbon steel. The relative machinability of austenitic stainless steel 1Cr18Ni9Ti is 40%; 48% for ferrite stainless steel 1cr28; 55% for martensitic stainless steel 2Cr13. Among them, the machinability of austenitic and austenitic + ferritic stainless steels is the worst. In the cutting process of stainless steel, the following factors should be paid attention to:
The work hardening of stainless steel is serious: in stainless steel, the work hardening of austenite and austenite + ferrite stainless steel is the most prominent. For example, the strength of austenitic stainless steel after hardening σ B is 1470 ～ 1960mpa, and it increases with time σ B, yield limit σ S increased; Austenitic stainless steel in annealed state σ S not more than σ B 30% ～ 45%, and 85% ～ 95% after work hardening. The depth of work hardening layer can reach 1 / 3 or more of cutting depth; The hardness of the hardened layer is 1.4-2.2 times higher than that of the original one. Because of the large plasticity of stainless steel, the character of plastic deformation is distorted, and the strengthening coefficient is very large; The austenite is not stable enough, and part of austenite transforms into martensite under the action of cutting stress; In addition, compound impurities are easy to decompose and disperse under the action of cutting heat, resulting in hardened layer during cutting. The work hardening phenomenon caused by the previous feed or the previous process seriously affects the smooth progress of the subsequent process.
Large cutting force of stainless steel: large plastic deformation of stainless steel in the cutting process, especially austenitic stainless steel (its elongation is more than 1.5 times of 45 steel), which increases the cutting force. At the same time, the work hardening of stainless steel is serious and the heat intensity is high, which further increases the cutting resistance and makes it difficult to curl and break the chip. Therefore, the cutting force for machining stainless steel is large. For example, the unit cutting force for turning 1Cr18Ni9Ti is 2450mpa, which is 25% higher than 45 steel.
The cutting temperature of stainless steel is high: the plastic deformation and friction between stainless steel and cutting tool are very large, resulting in more cutting heat; In addition, the thermal conductivity of stainless steel is about 1 / 2 ~ 1 / 4 of that of 45 steel. A lot of cutting heat is concentrated in the cutting area and the tool chip contact interface, and the heat dissipation condition is poor. Under the same conditions, the cutting temperature of 1Cr18Ni9Ti is about 200 ℃ higher than that of 45 steel.
Stainless steel chip is not easy to break, easy to bond: stainless steel plasticity, toughness are very big, turning chip continuous, not only affect the smooth operation, chip will crush the machined surface. Under high temperature and high pressure, the affinity between stainless steel and other metals is strong, so it is easy to produce adhesion phenomenon and form chip accumulation tumor, which not only aggravates tool wear, but also causes tearing phenomenon and worsens the machined surface. This characteristic is more obvious in martensitic stainless steel with lower carbon content.
Stainless steel tools are easy to wear: the affinity effect in the process of cutting stainless steel makes the tool chip bond and diffuse, resulting in the tool bond wear and diffuse wear, resulting in crescent depression on the tool rake face, and micro spalling and notch on the cutting edge; In addition, the hardness of carbide particles (such as TIC) in stainless steel is very high, and the tool wear will be aggravated by direct contact, friction, tool scratch and work hardening.
Large coefficient of linear expansion of stainless steel: the coefficient of linear expansion of stainless steel is about 1.5 times that of carbon steel. Under the action of cutting temperature, the workpiece is easy to produce thermal deformation, and the dimensional accuracy is difficult to control.
The above are the basic elements of stainless steel cutting in mechanical parts processing.
In the machining industry, aluminum profiles can be called aluminum alloy and aluminum. According to the manufacturing process of automation equipment in different industries, there are a lot of aluminum processing for spare parts. There will be some deformation during the processing of aluminum alloy parts. Let’s see why the aluminum parts are deformed during the processing? Generally, aluminum alloy materials are divided into profiles and plates, which have large metal removal and low rigidity. In the process of machining, deformation will be caused by residual stress, clamping force and cutting motion.
Residual stress: in the process of forming aluminum alloy materials, the arrangement of metal crystals is not in the ideal state, and the size and shape of crystals are not the same. There is original residual stress, which releases slowly with time and produces certain deformation. In addition, in the process of machining precision mechanical parts, the plastic deformation of metal cutting and the friction heat between the tool and the workpiece make the temperature difference between the machined surface and inner layer larger, resulting in greater thermal stress and thermal stress plastic deformation.
The deformation of mechanical parts in the process of machining and cutting is not caused by a single reason. It is often the structure of the combined action of several reasons, and this combined action is not invariable in the process of machining. With the continuous change of machining, it is difficult to judge which reason has the greatest impact on the deformation. We can only start from the causes of deformation, The corresponding process method is adopted to reduce the machining deformation as far as possible.
Clamping force: due to the thin wall of thin-walled cavity parts in aluminum alloy processing, both bench vice and chuck clamping will produce transverse or radial clamping force, which will inevitably lead to clamping deformation. The degree of clamping deformation is related to the clamping force. If the clamping force is large, it will form irrecoverable plastic deformation.
If it is small, it will form elastic deformation, and the elastic deformation will recover after unloading, but the cutting process is carried out when the elastic deformation is not recovered. The recovery of single elastic deformation will bring new deformation to the processed parts.
Cutting motion: the cutting process of mechanical parts is the process of the interaction between the tool and the workpiece, which makes the tool remove part of the material from the workpiece. The cutting movement makes the crystal particles of the material squeeze, stretch, break and other phenomena, these phenomena will make the crystal atoms displacement, forming irrecoverable plastic deformation!
The above is about the machining of aluminum parts why deformation.
In the field of hardware machining industry, there will be dimensions and processing steps on the machining drawings of mechanical parts, and the machining accuracy, that is, tolerance requirements, is required for the special position. The precision marked on the production drawing is to ensure that the actual geometric parameters of the hardware after machining are consistent with the size specified on the drawing, and the degree of inconsistency between them is called machining error. In the hardware machining line, the following three aspects should be paid attention to in order to ensure the accuracy tolerance of the production and processing drawings and avoid the machining error:
Datum: select the same datum plane for processing, so as to reduce certain error range in clamping processing of hardware machining parts.
Workpiece shape: for workpieces with special shape, fixture can be designed for positioning processing, so as to continuously achieve accuracy tolerance and improve production and processing efficiency.
Processing technology: in the process of hardware machining, selecting reasonable machining technology can ensure the quality of production and processing, and also improve efficiency!
Reasonable arrangement: according to the machining accuracy on the drawing, different machining equipment can be selected to complete the machining process. While ensuring the workpiece tolerance, it can also show the advantages of machining machine tools!
The above is the basic tolerance concept of hardware machining
In the mechanical parts processing industry, the selection of a reasonable machining process steps, the use of machine tool processing equipment and the selection of tools is also very important, today to see the understanding of cutting conditions in machining tools
Before automatic equipment parts processing or fixture processing, first find the necessary tools and tools, and prepare to start production and processing. In the aspect of cutting, the service life of the cutting tool is affected by the machine tool forward milling and reverse milling. The cutting vibration of forward milling is smaller than that of reverse milling. The cutting thickness of the cutting tool is reduced from the maximum to zero in down milling. After the cutting tool cuts into the workpiece, there will be no springing phenomenon caused by not cutting the chip. The process system has good rigidity and small cutting vibration; In reverse milling, the cutting thickness of the tool increases from zero to the maximum. At the initial stage of cutting, due to the thin cutting thickness, a path will be scratched on the surface of the workpiece. At this time, if the cutting edge meets the hard points in the graphite material or the chip particles remaining on the surface of the workpiece, it will cause the tool to bounce or chatter, so the cutting vibration of reverse milling is larger.
In the process of machining parts, when special materials are encountered, the cutting materials on the surface of the workpiece should be cleaned in time, which is conducive to reducing the secondary wear of the tool, prolonging the service life of the tool, and reducing the influence of some waste materials on the lead screw and guide rail of the machine tool. In the process of machining, select the appropriate high speed and the corresponding large feed.
Based on the above points, the material, geometric angle, coating, edge strengthening and cutting conditions of the cutting tool play different roles in the service life of the tool. A good machining tool should have smooth chip removal groove, long service life, be able to carry out rough and finish machining, and save processing cost.
The above is the understanding of machining conditions of cutting tools.
In the mechanical processing industry, ordinary machining equipment includes lathe, milling machine, grinder, wire cutting, etc., while precision machining equipment includes precision grinder processing, CNC lathe processing, CNC processing, slow wire processing, etc; According to the accuracy requirements of production drawings, to choose a reasonable processing technology and different processing equipment. General processing equipment will be auxiliary accessories, auxiliary accessories also have a different role. Let’s take a look at the application of rotary top of processing equipment accessories
In the process of machining mechanical parts, sometimes auxiliary parts are needed to complete the processing of complex or high precision workpiece. For example, lathe processing shaft parts, with the help of center hole positioning, rotary center is widely used. Because of the high precision of mechanical parts, it is a necessary machine tool accessory for high-speed cutting on small precision lathe.
The above is the application of the rotary center of processing equipment.
