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In machining production, it is easy to encounter metal materials that are difficult to cut. However, some workpieces require these materials to be used for processing. In machining, different difficult cutting materials have their own performance characteristics. Corresponding measures should be taken according to specific objects during milling. Milling of common difficult cutting materials 1. Milling of high manganese steel Alloy steel with a nominal content of 13% or more of manganese is called high manganese steel. When milling high manganese steel, tool materials with high hardness, certain toughness, large thermal conductivity and good high temperature performance should be selected. In the process of machining, the feed rate and milling depth should not be too small, so as to avoid the cutting edge or tool tip scratching in the hardened layer formed by the last tool walking and accelerating the wear of the milling cutter. On the premise of ensuring sufficient strength of the cutting edge, the cutting edge should be as sharp as possible to reduce the work hardening layer of the material during milling. 2. Milling of high strength steel High strength steel has high strength and enough toughness, and can withstand high stress; At the same time, the specific strength is large, which can reduce the self weight of the structure. Cutting tool materials with good wear resistance must be selected for milling high-strength steel. 3. Milling of austenitic stainless steel Stainless steel can be divided into five types according to its metallographic structure: ferritic stainless steel, martensitic stainless steel, austenitic stainless steel, austenitic ferritic stainless steel and precipitation hardening stainless steel. Milling austenitic stainless steel requires good rigidity of the machine tool fixture tool system, high power of the machine tool, less teeth of the milling cutter, and good grinding quality. Forward milling is adopted during milling. 4. Milling of Superalloys Alloys with high oxidation resistance and high mechanical properties at high temperatures are called superalloys. When milling superalloys, it is required that the rigidity of the machine tool fixture tool system is good, and the machine tool power is large. The geometric parameters and cutting parameters of the tool should be reasonably selected, and new tool materials with good performance should be used as far as possible. In addition, pressure cooling should be applied to the cutting area during cutting, and forward milling should be adopted for milling. 2、 Measures to be taken when milling difficult cutting materials 1. Select the appropriate tool material Appropriate tool materials should be selected according to the characteristics of difficult cutting materials. Generally, tool materials with good hardness and high temperature hardness and good cutting performance can be selected. Such as cobalt containing high-speed steel and other new high-speed steel, coated high-speed steel. When necessary, new cutting tool materials such as artificial diamond and cubic boron nitride can be used. 2. Choose reasonable geometric parameters of milling cutter For hard cutting materials with low hardness and good plasticity, the milling cutter should adopt larger rake angle and rake angle; For hard cutting materials with high hardness and strength, such as superalloys, smaller rake angle, larger helix angle and the absolute value of increasing blade inclination should be used. 3. Use proper cutting fluid Select the appropriate cutting fluid according to the milling cutter material and processing material. When milling difficult cutting materials with high-speed steel milling cutter, synthetic cutting fluid with good adhesion resistance and cooling performance is generally used; When milling with carbide milling cutter, it is best to use oil extreme pressure cutting fluid, such as extreme pressure emulsion, extreme pressure cutting oil, etc. 4. Select reasonable milling amount Due to the large milling force and high milling temperature when machining difficult cutting materials, the milling amount is smaller than that when milling ordinary steel. 5. Choose a reasonable milling method For some materials with large plastic deformation, high thermal strength and severe cold hardness, forward milling should be used as far as possible (asymmetric forward milling is used for end milling), so that the bonding contact area of chips is small, the pressure on the milling cutter when the chips are separated from the workpiece is small, and it is easy to get rid of it, as well as improve the durability of the milling cutter and obtain a smaller surface roughness value.

In processing and production, there are three kinds of keyways on the shaft: through groove, half through groove and closed groove. The through groove on the shaft and one end of the groove bottom are arc-shaped half through grooves, which are generally milled with a disk-shaped groove milling cutter. The width of the shaft groove is guaranteed by the width of the milling cutter, and the arc radius of the groove bottom at one end of the half through groove is guaranteed by the radius of the milling cutter. The closed groove on the shaft and the half through groove with right angle at one end of the groove bottom are milled with a keyway milling cutter, and the diameter of the keyway milling cutter is determined according to the width of the shaft groove. 1. Clamping and correction of workpiece When clamping the workpiece, it is not only necessary to ensure the stability and reliability of the workpiece, but also to ensure that the axis position of the workpiece remains unchanged, so as to ensure that the central plane of the shaft groove passes through the axis. Common clamping methods are as follows: (1) Clamping with flat tongs: clamping the workpiece with flat tongs is simple and stable, but when the diameter of the workpiece changes, the axis of the workpiece will change in the left and right (horizontal position) and up and down directions, affecting the depth dimension and symmetry of the shaft groove. Therefore, it is generally suitable for single piece production. (2) Clamping with V-shaped frame: the clamping method of placing the cylindrical workpiece in the V-shaped frame and fastening it with a pressing plate is a common clamping method for milling the keyway on the shaft. (3) Clamping with dividing head: clamp the workpiece with the two centers of the dividing head spindle and tailstock or with the method of one clamping one top of the three jaw self centering chuck and tailstock center. The axis of the workpiece is always on the connecting line between the center of the two centers or the three jaw self centering chuck and the rear center. The position of the workpiece axis does not change due to the change of the workpiece diameter, so the symmetry of the keyway on the axis will not be affected by the change of the workpiece diameter. 2. Adjustment of milling cutter cutting position (to the center) In order to ensure that the keyway on the shaft is symmetrical to the axis of the workpiece, the position of the milling cutter must be adjusted so that the axis of the keyway milling cutter or the symmetrical plane of the disk groove milling cutter passes through the axis of the workpiece (commonly known as centering). Common adjustment methods are: (1) Adjust the centering according to the cut mark: this method is the most commonly used method because of its low centering accuracy and simple use. (2) Wipe the side and adjust the alignment Center: this method has high alignment accuracy and is suitable for occasions where the diameter of the disc groove milling cutter is larger or the keyway milling cutter is longer (relative to the workpiece diameter). When adjusting, first stick a thin paper on the side of the workpiece, start the machine tool, and make the rotary milling cutter gradually lean towards the workpiece. When the edge of the milling cutter rubs the thin paper, lower the workbench to exit the workpiece, and then move the workbench laterally for a distance to realize alignment. (3) Adjust the centering with a lever dial indicator: this method has high centering accuracy and is suitable for vertical milling machines. It can adjust the centering of workpieces clamped with dividing heads, flat tongs and v-frames for clamping workpieces. 3. Milling method of keyway on shaft (1) Milling the through keyway on the shaft: the through keyway on the shaft (such as the keyway on the plain bar of an ordinary lathe) or the half through groove with one end of an arc (such as the keyway on the milling cutter rod), which is generally milled with a disc-shaped groove milling cutter. (2) Milling the closed keyway on the shaft: the keyway on the shaft is a closed groove or a half through groove with one end at right angles, which is milled with a keyway milling cutter. The common methods for milling the closed groove on the shaft with the keyway milling cutter are as follows: A layered milling method: use a milling cutter that conforms to the width of the keyway to mill the keyway in layers. After installing the milling cutter, first try milling on the waste, check that the width of the milled keyway meets the requirements of the drawing, and then clamp, correct and center the workpiece before processing the workpiece. B expanding milling method: first, use the keyway milling cutter with smaller diameter to carry out layered reciprocating rough milling, and then use the keyway milling cutter that meets the width of the shaft groove to finish milling. During finish milling, because the radial forces of the two cutting edges of the milling cutter can be balanced with each other, the deflection of the milling cutter is small, and the symmetry of the keyway on the shaft is good.

As a commonly used machining method, heat treatment is widely used in production. Therefore, in the heat treatment process, in order to standardize the market economic order of heat treatment and avoid unfair competition, the quotation guiding principles of heat treatment are formulated. It provides a reference basis for heat treatment enterprises to contract processing and formulate processing prices. In the heat treatment industry, the price of processing business should be based on three basic factors: first, the cost of processed parts. Second, the technological content of the processed parts. Third, the risk premium and reasonable profit. The main cost of heat treatment lies in basic energy loss, process materials and auxiliary materials, equipment depreciation, site and plant rent sharing, interest on investment, taxes and labor fees payable, etc. The calculation of heat treatment quotation is mainly carried out by referring to the formula in the comprehensive evaluation index system and management of heat treatment industry. Among them, the basic power consumption, basic fuel consumption, basic industrial power consumption and basic industrial fuel consumption of each process in heat treatment shall be taken as the base. Through ni=nb × K1 × K2 × K3 × K4 × K5，Ri=Rb × K1 × K2 × K3 × K4 × K5。 You can also refer to the unit consumption value evaluated by the industry. Where: Ni - process power consumption quota of a heat treatment. NB -- standard industrial power consumption. RI - basic fuel consumption. RB - basic industrial fuel consumption. K1 -- conversion process coefficient. K2 - heating mode coefficient. K3 - production mode coefficient. K4 - workpiece material coefficient. K5 - loading factor. What are the quotation of heat treatment jpg Price of specific heat treatment items 1. Annealing and tempering (1) Subject to electric furnace, the price will be reduced by 30% for solid fuel furnace heating: High temperature annealing (greater than or equal to 900 ℃): 1.2; Complete annealing (750-900): 0.8. (2) Recrystallization annealing, high temperature tempering: Artificial aging (500-700 ℃): 0.6; Spheroidizing annealing, isothermal annealing: 1.2; Bright annealing and packing annealing: 1.1. 2. Normalizing class The price of solid fuel furnace heating is reduced by 30% (excluding the straightening fee): Box type electric furnace normalizing: 0.7; Well type electric furnace normalizing: 0.8; Salt furnace normalizing: 0.8. 3. Conditioning (excluding the straightening fee) Box type and trolley type electric furnaces less than 950 degrees: 1.5; Box type and trolley type circuits greater than or equal to 950 degrees: 1.8. 4. Salt bath furnace quenching (1) Including tempering, cleaning, excluding straightening fees; Salt bath, alkali bath cooling, 30% markup: Carbon steel and low alloy steel parts: 2.0; High alloy steel parts: 3.0; High speed steel cutting tools (simple parts) including three tempering and cleaning: 15; High speed steel cutting tools (complex parts) including three tempering and cleaning: 20. (2) Die quenching: Carbon steel, low alloy steel, simple mold: 3.0; High alloy steel, complex mold: Negotiable. 5. Electric furnace quenching Carbon steel and low alloy steel less than or equal to 950 degrees: 1.5. 6. Induction quenching and flame quenching (1) With tempering and without straightening: Power frequency quenching: 2.5; Medium frequency quenching and ultra audio frequency quenching: 2.0. (2) High frequency, flame quenching: Shaft and gear: 1.5; Steel guide rail and complex plane parts: 2.0; Flame quenching of special small parts and infiltrated layers: Negotiable; Flame quenching depth greater than 3mm: according to power frequency; Flame quenching depth less than 3mm: press high frequency.

Common cylindrical helical cutters include cylindrical milling cutters, end milling cutters, staggered three face edge milling cutters, etc. The milling of spiral tooth cutter slots is generally carried out on a horizontal universal milling machine, and the milling method is basically the same as that of machining cylindrical spiral slots. Because the tooth surface of the cutter is a spiral surface, in addition to the factors such as the tooth groove angle and rake angle, the spiral angle must also be considered in machining.   Cylindrical helical tooth cutter 1. Selection of working milling cutter Profile selection of working milling cutter: when milling the slots of cylindrical helical tooth cutters, you can choose double angle milling cutter or single angle milling cutter. When milling with a single corner milling cutter, the "over cutting" phenomenon of cutting part of the metal in front of the workpiece cutter teeth is more serious than when milling with a double corner milling cutter, so the asymmetric double corner milling cutter is generally selected for milling. Selection of cutting direction of working milling cutter: except for symmetrical double angle milling cutter, angle milling cutter can be divided into left cutting and right cutting. Viewed from the side of the small cone edge of the asymmetric double corner milling cutter or the end edge of the single corner milling cutter, if the milling cutter rotates clockwise, it is called a left cutting milling cutter; On the contrary, if the milling cutter rotates counterclockwise, it is called right cutting milling cutter. 2. Determination of workbench corner The deflection direction of the workbench is the same as that of milling general spiral grooves, that is, when milling left-hand spiral grooves, the workbench deflects clockwise; When milling the right-hand tooth groove, the workbench deflects in a counterclockwise direction. Only in this way can the direction of the spiral tooth groove be consistent with the rotation plane of the work milling cutter, so that the normal section of the spiral tooth groove of the workpiece is as close as possible to the profile of the work milling cutter. The deflection angle of the workbench should be determined according to the type of milling cutter and the spiral angle of the workpiece. 2、 Milling of tooth slots with staggered three face edge milling cutter The staggered three face edge milling cutter is a kind of cylindrical helical tooth groove cutter, and its circumferential tooth groove is helical. The selection of cutter during milling, the determination of workbench angle, the adjustment of milling cutter cutting position, etc. are the same as the calculation and adjustment methods of general cylindrical helical tooth cutters. The difference is that the circumferential spiral groove of the staggered three face edge milling cutter has two rotation directions, that is, the 1/2 cutter teeth are left-hand and the 1/2 cutter teeth are right-hand, and the left-hand cutter teeth and the right-hand cutter teeth are staggered on the cylindrical surface, and the tooth back of the cutter teeth is polygonal. In addition, the staggered three face edge milling cutter has end face teeth. 1. Milling of circular spiral grooves When selecting a working milling cutter, it is best to select two milling cutters with opposite cutting directions to mill spiral grooves with different rotation directions respectively. 2. Milling of end tooth grooves The end tooth slot milling method of the staggered trihedral edge milling cutter is similar to the end tooth slot milling method of the cylindrical straight tooth slot cutter. Because the front of the circumferential tooth of the staggered trihedral edge milling cutter is a spiral surface, which forms a certain intersection angle with the axis of the cutter, its end tooth has a certain rake angle. When milling the end face teeth on the horizontal universal milling machine, in addition to raising the dividing head by an angle and offsetting the workbench laterally by a distance, it is also necessary to tilt the main shaft of the dividing head by an angle in the plane perpendicular to the workbench table along the transverse moving direction, so that the front of the end face teeth can be smoothly connected with the front of the circumferential spiral teeth. 3、 Quality analysis of tool slot milling Tool slot milling is a kind of comprehensive and complex slot milling, which involves a wide range of contents, high operation requirements and certain difficulties. Among them, the slot milling of cylindrical straight slotting tools is the basis of all kinds of tool slot milling.

With the rapid development of sheet metal processing industry, this industry plays an increasingly important role in industrial production. However, the increase in the number of orders has also brought some side effects, such as the increase in the error rate, the increase in the number of problem pieces, and so on. Most of these problems focus on the deformation of sheet metal processing parts and insufficient springback in the processing process. Causes and solutions of sheet metal workpiece problems In the forming process of sheet metal processing parts, a series of treatments are required, especially in the cooling process of parts. There are strict requirements for the type of quenching medium, cooling performance and hardenability. If it does not meet the requirements, it may cause deformation. Experience shows that the change of cooling performance of parts can be adjusted by changing the viscosity, temperature and liquid level pressure of quenching medium, using additives and stirring. The higher the viscosity and temperature of quenching oil, the smaller the elliptical deformation. The deformation of the part in the static state is small. In the heat treatment of forgings, due to the small hardness of parts, incorrect placement may cause uneven stress, resulting in the deformation of parts. Hang the parts vertically as far as possible, or place them vertically at the bottom of the furnace, or use two fulcrums to support them horizontally. The fulcrum position should be between one quarter and one third of the total length of the parts, and the parts can also be placed flat on the heat-resistant steel tooling. Decompression quenching of sheet metal processing is to reduce the liquid pressure of quenching medium and extend the steam film stage, so that the cooling speed of parts in the high temperature zone decreases and the cooling speed of all parts is evenly distributed. In this operation, firstly, the parts should be cooled by oil cooling from quenching temperature to slightly higher than the initial temperature of martensite transformation; Next, keep the parts in the atmosphere for a while to make the overall temperature uniform, and then conduct oil cooling to make the martensitic transformation uniform, and the irregularity of deformation is greatly improved. Technological means to reduce sheet metal processing deformation The processes that can effectively reduce the deformation of sheet metal processing include salt bath quenching, high temperature oil quenching, decompression quenching, one tank three-stage quenching, etc. The process of salt bath quenching is similar to that of high-temperature oil quenching. Both of them are quenched at the martensitic transformation temperature, which increases the uniformity of martensitic transformation. For welded structures with many components, it is necessary to choose the appropriate welding sequence. First, the components should be welded and corrected respectively, and then assembled for overall welding. Using this sequence is smaller than the method of first assembling into a whole and then welding. Individual parts can also be installed and welded at the same time, which is relatively simple to operate. In order to prevent welding deformation, strip welding, back welding and symmetrical welding should be adopted in the welding sequence. Before welding, the weldment shall be given a deformation opposite to the deformation direction after welding, and the deformation of the workpiece before welding is just offset after welding, which is called anti deformation method. Rigid fixation can also be used, which is also very effective in reducing welding deformation. Various welding methods have different energy density and heat input when heating the weld. For thin plate welding, selecting welding methods with high energy density, such as carbon dioxide gas shielded welding and plasma arc welding to replace gas welding and manual arc welding, can reduce welding deformation. When welding aluminum and aluminum alloy structures, the deformation of gas welding is much larger than that of manual argon arc welding.

CNC machine tools are widely used in production and processing because of their high precision and high efficiency. CNC machine tools cut metal through programming, which ensures the error caused by manual operation and improves the production accuracy. At the same time, mechanical processing is faster than manual processing, which also improves the processing efficiency to a certain extent. Reasonable selection of cutting parameters For high-efficiency metal cutting, the three elements are: processed materials, cutting tools, and cutting conditions. These have a certain impact on processing time, tool life and processing quality. Among them, if you want to process economically and effectively, you need to choose reasonable cutting conditions. Cutting conditions are also composed of three elements: cutting speed, feed rate and cutting depth (cutting depth). Cutting speed will have a serious impact on the tool. The increase of cutting speed will lead to the increase of tool tip temperature, resulting in mechanical, chemical and thermal wear. Data shows that cutting speed increases by 20%, and tool life will be reduced by 1/2. The feed rate has little to do with tool wear, but if the feed rate is large, the cutting temperature will rise and the subsequent tool wear will increase. However, the feed rate has less effect on tool wear than cutting speed. Although the cutting depth has less influence on tool wear than the first two, when cutting with small cutting depth, the hardened layer of the material to be cut will also affect the service life of the tool. Therefore, during production, users need to choose the appropriate cutting speed according to the processed material, hardness, cutting state, material type, feed rate, cutting depth and so on. How to determine the three elements of machining 1. Cutting speed: to select the revolutions per minute of the spindle, you must know the linear speed of cutting. The choice of this linear speed depends on the tool material, workpiece material and processing conditions, etc. (1) Cutting tool material: selecting cemented carbide cutting tools can obtain higher linear speed, generally more than 100m/min. For high-speed steel, the linear speed can only be low, generally not more than 70m/min, and in most cases, it is less than 20-30m/min. (2) Workpiece material: the workpiece material with high hardness has low linear speed. The linear speed of cast iron is low, and the use of cemented carbide tools is 70-80m/min. (3) Processing conditions: rough processing, low linear speed; Finish machining, and the linear speed is higher. 2. Feed rate The feed rate mainly depends on the requirements for the machined surface roughness of the workpiece. When finishing, the surface requirements are increased and the feed rate is taken as small. During rough machining, the feed rate can be larger. It mainly depends on the tool strength, which can generally be more than 0.3. When the main rear angle of the tool is large, the tool strength is poor, and the feed amount cannot be too large. 3. Cutting depth (cutting depth) Generally, it can be less than 0.5 (radius value) when finishing. During rough machining, it is determined according to the conditions of workpiece, cutter and machine tool. Generally, when turning No. 45 steel in normalized state, the cutting depth in radius direction is generally not more than 5mm.

Cylindrical spiral groove is the combination of several spiral lines on the cylinder. When milling a cylindrical spiral groove on a milling machine, the relative motion of the milling cutter and the workpiece must conform to the spiral forming motion law. Cylindrical spiral grooves are common in some parts. Then, how to process the cylindrical spiral groove? Now let's talk about the milling method of cylindrical spiral groove. 1、 Technological characteristics of cylindrical spiral groove milling 1. Milling cylindrical spiral groove, milling cutter and workpiece conform to the law of spiral forming motion. That is, in addition to the rotary motion of the milling cutter, the workpiece must also rotate at a uniform speed while the workbench drives the workpiece for longitudinal feed, and ensure that when the workbench moves a distance equal to the lead of the helix, the workpiece rotates at a uniform speed for one cycle. During the longitudinal feeding, the spindle of the dividing head is driven by the table lead screw through the exchange of gears to realize the rotation of the workpiece. When milling multi line spiral grooves, it is also necessary to Realize indexing adjustment according to the number of lines. 2. Due to the different uses of workpieces with spiral grooves, the cross-sectional shapes of spiral grooves are also diverse. For example, the section of the tooth groove of the cylindrical spiral groove cutter is triangular or curved, the normal section of the spiral groove of the constant speed cylindrical cam is rectangular, and the axial section of the Archimedes worm is trapezoidal, etc. The profile of milling cutter for machining spiral groove should be consistent with the normal section shape of spiral groove. Therefore, the correct selection of milling cutter is the key to ensure the section shape of spiral groove. 3. When milling a cylindrical spiral groove, because the spiral angles on the surface of cylinders with different diameters are not equal (large diameter, large spiral angle; small diameter, small spiral angle), there is interference in the processing, which causes the side of the spiral groove to be overcut and the groove shape distortion. The overcut phenomenon is more serious when using disc milling cutter than when using end milling cutter. Therefore, the spiral groove with rectangular normal section can only be milled with end milling cutter. When the disk-shaped milling cutter is used to process spiral grooves with other cross-section shapes, the diameter of the milling cutter should be as small as possible to reduce the overcut of interference. 4. When using a disk-shaped milling cutter to mill a cylindrical spiral groove on a horizontal milling machine, in order to make the normal section shape of the processed spiral groove as close to the profile of the milling cutter as possible, the workbench of the milling machine must be turned by an angle in the horizontal plane, so that the rotation plane of the disk-shaped milling cutter is consistent with the tangent direction of the spiral. 2、 Milling of cylindrical spiral groove 1. Exchange gear calculation When milling the cylindrical spiral groove, the workpiece is clamped on the dividing head, and the relative motion law of the milling cutter and the workpiece is realized by connecting the table screw and the dividing head with the exchange gear. Usually, the side shaft change gear method is adopted. 2. Selection of milling cutter Correct selection of milling cutter is the key to ensure the section shape of cylindrical spiral groove. The profile of milling cutter should be consistent with the normal section shape of spiral groove. The commonly used milling cutters are end milling cutter, angle milling cutter, forming milling cutter, etc. 3. Interference phenomenon in milling rectangular groove When milling the spiral groove on the milling machine, when the workpiece rotates for one cycle, the distance that the milling cutter moves in the axial direction relative to the workpiece is equal to the lead. On a spiral groove, the lead of both the notch and the spiral at the bottom of the groove is equal, that is, the lead of all parts on a spiral groove is equal.

As a revolutionary equipment in the sheet metal processing industry, the application of laser cutting machine undoubtedly promotes the rapid development of this industry. Compared with traditional shears, punches, flame cutting, plasma cutting and water cutting, what are the obvious advantages of laser cutting? Now let's make a collective appearance of all cutting equipment, which is better or worse at a glance. Shearing machine The biggest advantage of the shearing machine is its high cutting efficiency. The cutting distance of one knife can reach 4 meters. However, this kind of equipment can only cut along a straight line, so its use is greatly limited. Punch Punches are processed by punches. A punch can be equipped with multiple sets of punches of different shapes, and even customized punches according to processing requirements. Therefore, it can have more flexibility and repeatability for the processing of curves and complex shapes. This kind of processing equipment is often used in the chassis and cabinet industry. However, the punch often performs poorly when processing steel plates with a thickness of more than 2mm and stainless steel plates with a thickness of more than 1.5mm, which is not only easy to cause surface defects of the workpiece, but also easy to damage the punch. In addition, although the customized punch can complete the processing task, the customization process itself is not easy, the development cycle is long, and the cost is high. Therefore, unless it is a mass and high profit processing activity, the customized punch may lose money. flame cutting Flame cutting is one of the most traditional cutting methods, but it still has its market today. Because this cutting equipment has low investment cost and can cope with the cutting of thicker steel plates, it has strong adaptability. Of course, flame cutting equipment also has its obvious shortcomings. First, the processing speed is slow, which will slow down the production progress; Second, the cutting seam is wide, which wastes materials; Third, the cutting quality is poor, and it is also prone to thermal deformation. Although the cutting quality can be remedied to a certain extent through the subsequent machining process, it will further slow down the processing speed. Plasma cutting Plasma cutting and fine plasma cutting can be regarded as the upgraded version of flame cutting. Its cutting speed and accuracy are much higher than flame cutting equipment, and are very close to laser cutting equipment. Therefore, it is widely used in the cutting of medium thickness metal plates. However, the thermal deformation caused by this equipment is too large, and the slope is not accurate enough, which cannot meet the requirements for parts cutting tasks with high accuracy requirements. In addition, some consumables in plasma cutting equipment, such as electrodes, nozzles and vortex rings, are expensive and expensive to use. High pressure water cutting High pressure water cutting is a process of cutting sheet metal with the help of carborundum doped in high-speed water jet. Its biggest advantage is that it has strong adaptability, and there are almost no restrictions on the materials to be cut. Whether it is metal materials such as iron and copper, or non-metallic materials such as ceramics and glass, it can be cut in this way. There is no need to worry about the bursting of the material when it meets heat, nor is there any need to worry about the reflectance of the material to light. Therefore, in terms of processing range, high-pressure water cutting is even better than laser cutting. And its cutting thickness can also reach more than 100 mm. However, the disadvantages of water cutting are also obvious. The slow cutting speed is on the one hand, and it is not clean and environmentally friendly enough, and the consumables are also relatively expensive. laser cutting Of course, the last one is our protagonist - laser cutting equipment. It has the advantages of high flexibility, fast cutting speed, high production efficiency and short production cycle. Not only that, laser cutting will not produce cutting force on the workpiece, so there will be no machining deformation, let alone tool wear; This cutting method has good material adaptability, and can be competent for various parts of different shapes, and the processing process is completed at one time; Laser cutting has extremely high precision, narrow weld and low surface roughness, so there is no need for subsequent "tool repair"; In addition, this processing method is simple to operate, with a high degree of automation. It will not cause pollution and is harmless to workers' health. Based on the above advantages, the market prospect of laser cutting has been unanimously favored by experts and insiders. This technology will play an increasingly important role in the sheet metal processing industry in the future.

A gear with a conical indexing surface is called a bevel gear. According to the shape of the tooth line, bevel gears can be divided into straight teeth, helical teeth and curved teeth. Bevel gears are used for cross shaft gear transmission and cross shaft gear transmission. For the processing of milling straight bevel gears, let's introduce it in detail below. Geometric characteristics of spur bevel gears 1. The top conical surface (top cone), indexing conical surface (sub cone) and root conical surface (root cone) of straight bevel gear intersect at one point. 2. The teeth of spur bevel gears are distributed on the conical surface, and the grooves are wide and deep at the big end and narrow and shallow at the small end. The teeth gradually shrink from the big end to the top of the cone. 3. In the developed surface of the back cone of a spur bevel gear (usually the big end face of the bevel gear tooth, and the prime line of the back cone is perpendicular to the sub cone), the tooth profile curve of the tooth is an involute. 4. The module of straight bevel gear is different from big end to small end. In the design and calculation of bevel gear, it is stipulated to take the big end module as the basis and adopt the standard module. Straight bevel gear milling cutter and its selection The teeth of straight bevel gear are distributed on the conical surface, and the tooth shape gradually shrinks from the big end to the top of the cone. The diameters of the big end and the small end of the bevel gear are not equal, and the diameters of the base circle are not equal. The base circle diameter of the big end is large, and the curvature of its involute tooth profile curve is small (that is, the tooth profile curve is relatively straight); The diameter of the base circle at the small end is small, and the curvature of the involute tooth profile curve is larger (that is, the tooth profile curve is more curved). The tooth profile of straight bevel gear milling cutter can only be designed according to a certain section of the prime line of the indexing conical surface, and the tooth profile of the processed gear can only be more accurate in a certain section, while there are certain errors in other sections. Therefore, the precision of straight bevel gear formed by bevel gear milling cutter is low. The less the number of teeth or the larger the width of bevel gear, the greater the error. Usually, the tooth profile curve of the straight bevel gear milling cutter is designed according to the tooth profile curve of the big end, and the thickness of the milling cutter is designed according to the slot width of the small end, so as to ensure that the blade can pass through the small end in the milling process. Therefore, the straight bevel gear milling cutter is thinner than the straight cylindrical gear milling cutter with the same modulus. Milling of straight bevel gear Straight bevel gears can be machined on horizontal or vertical milling machines with disk bevel gear cutters. When machining on a horizontal milling machine, it can be divided into longitudinal (horizontal) feed milling method and vertical feed milling method according to the feed direction. When using the longitudinal feed milling method, first adjust the spindle of the dividing head to be parallel to the worktable and the rotation plane of the milling cutter, and check the radial circular runout of the big end and the small end after the gear blank is installed. Then make the main shaft of the dividing head tilt up by an angle, which should be equal to the root cone angle of the processed bevel gear. When the root cone angle of the bevel gear is large, and the length and diameter are also large, it is possible that even if the workbench is at the lowest position (the lifting table will touch the base), the tooth groove bottom of the bevel gear cannot pass under the milling cutter. At this time, the vertical feed milling method can be used for processing.

A flat plate or straight bar is called a rack when it has a series of equidistant teeth. A rack whose tooth line is a straight line perpendicular to the direction of tooth movement is called a straight rack; A rack whose tooth line is a straight line inclined to the direction of tooth movement is called an inclined rack. There are many processing methods for rack, and milling is commonly used. What are the methods of milling rack? 1、 Milling of straight rack The straight rack is milled on a horizontal universal milling machine with a disc gear cutter. 1. Milling of short rack (1) Selection of milling cutter: the milling cutter for milling rack generally selects a set of No. 8 disc straight tooth cylindrical gear milling cutter among 8. When the rack accuracy is required to be high, a special rack milling cutter can be used. (2) Clamping of workpieces: workpieces are clamped with flat tongs or directly pressed on the worktable. When there are a large number of workpieces, special fixtures can be used for clamping. No matter which clamping method is adopted, the tooth top surface of the rack blank must be parallel to the workbench, The positioning reference surface on one side of the blank must be parallel to the transverse feed direction of the workbench. (3) Control of tooth pitch: when milling the rack, after each tooth is milled, the workbench moves one tooth pitch horizontally, which is called shift distance. Common displacement methods are: Dial method: use the horizontal feed handle of the workbench to turn the dial by a certain number of grids to realize the displacement. This method is only applicable to short racks with low accuracy requirements and a small number. Dividing disc method: refit the dividing disc and dividing handle of the dividing head on the head of the transverse feed screw of the workbench. 2. Milling of long rack (1) Clamping of workpiece: when machining long rack, because the horizontal movement distance of milling machine workbench is not enough, the longitudinal movement distance of workbench must be used to divide the teeth, that is, the positioning reference surface on one side of workpiece is required to be parallel to the longitudinal feed direction of workbench. The workpiece can be directly pressed on the worktable or clamped with a special fixture. (2) Installation of milling cutter: when processing long racks, the tooth pitch is controlled by the longitudinal lead screw of the workbench, so the direction of the original milling cutter rod on the horizontal milling machine cannot meet the processing requirements. The direction of the milling cutter rod must be parallel to the longitudinal feed direction of the workbench. Therefore, the spindle of the milling machine must be refitted. 2、 Milling of inclined rack The helical rack can be regarded as a part of a helical cylindrical gear with infinite base circle diameter. The helical rack is milled on a horizontal universal milling machine with a disk-shaped gear milling cutter. The milling method is basically the same as that of milling the straight rack, except that the workpiece rotates a spiral angle relative to the cutter during milling. There are two milling methods for inclined rack: 1. Workpiece tilting clamping method When the workpiece is installed, make one side of the reference surface form a spiral angle with the direction of the dividing tooth displacement of the workbench. After milling one tooth, the shift distance shall be equal to the normal tooth distance of the helical rack. This method is limited by the horizontal stroke of the worktable, so it is only suitable for milling inclined rack with small helix angle. 2. Workbench rotation method When installing the workpiece, the reference surface on one side of the workpiece is parallel to the longitudinal displacement direction of the workbench, and at the same time, turn the workbench by a spiral angle to make the inclined rack slot parallel to the milling cutter rotation plane. After milling one tooth, the workbench moves one end tooth pitch longitudinally. This method is suitable for milling long inclined rack on universal milling machine.