Monthly Archive January 26, 2021

Material selection and heat treatment of CNC computer gong

The first step of CNC lathe processing is to determine the technical requirements of parts and the batch of processed workpieces, formulate the functions that CNC lathe should have, make preparations in the early stage, reasonably select the conditions of CNC lathe, and satisfy the technical requirements of typical parts. The technical requirements of typical parts are mainly the structural dimension, processing range and accuracy requirements of parts. The control accuracy of CNC lathe is selected according to the accuracy requirements, that is, the requirements of scale accuracy, positioning accuracy and surface roughness of workpiece.

Lathe processing is a part of mechanical processing. There are mainly two processing methods: one is to fix the turning tool to process the unformed workpiece in rotation, and the other is to fix the workpiece to process the precision through the high-speed rotation of the workpiece and the lateral and longitudinal movement of the turning tool (tool holder). In the lathe can also be used to drill, reamer, reamer, tap, die and knurled things such as the corresponding processing. Lathe is mainly used to process shaft, disc, sleeve and other workpieces with reverse appearance. It is the most widely used machine tool in machinery manufacturing and repair factory.

There are several points in machining tools

The reasonable or unreasonable selection of machining skills will directly affect the machining accuracy, output power and economic benefits of the workpiece. The selection of technical equipment should be based on local production type, detailed processing conditions, workpiece structure characteristics and technical requirements.

  1. Selection of fixture.

For single piece and small batch production, all kinds of general fixtures and machine tool accessories should be selected, such as chuck, flat vise for machine tool, division number one; for large-scale and large-scale production, special high-efficiency fixtures should be selected to improve the production rate; adjustable fixtures or group fixtures can be selected for multiple types of medium and small batch production.

  1. Selection of cutting tools

Standard cutting tools are usually preferred. If mechanical convergence is selected, various efficient special tools, compound tools and multi edge tools can be selected. The type, standard and accuracy level of the cutting tool should be suitable for the machining request.

  1. Selection of measuring tools.

General measuring tools, such as vernier caliper, micrometer and dial indicator, should be widely used for single piece and small batch production; limit gauge block and efficient special inspection fixture and gauge should be used for large-scale and large-scale production. It is necessary to adapt the accuracy of measuring tools to the machining accuracy.

The selection of the best span l of the spindle and the supporting span l of the spindle. The distance between the front bearing point of the spindle and the rear bearing point of the spindle is called span L. The support span of the spindle assembly has a great influence on the stiffness of the spindle itself and the support stiffness.

(1) Spindle bore diameter. The diameter of the inner hole of the spindle is used to fix the tool through the tool clamping device, drive the pneumatic or hydraulic chuck, etc. The larger the diameter of the spindle, the lighter the relative weight of the spindle components. The aperture size of the spindle is mainly restricted by the stiffness of the spindle.

(2) Spindle diameter. The larger the diameter of the spindle is, the higher its stiffness is, but the size of the bearing and other parts on the shaft increases accordingly. The larger the diameter of the bearing is, the larger the tolerance value of the bearing with the same grade accuracy is, and the more difficult it is to ensure the rotation accuracy of the spindle.

The determination of the spindle overhang a of CNC machining center, the spindle overhang a refers to the distance between the action point of the radial support reaction force of the front support of the spindle and the front end of the spindle, which has a great influence on the stiffness of the spindle assembly. According to the analysis and experiment, shortening the overhanging amount can significantly improve the stiffness and vibration resistance of the spindle assembly. Therefore, on the premise of meeting the structural requirements, the overhanging amount a should be shortened as much as possible.

CNC machining center spindle span diagram, discusses the structure design and progress of CNC machining center mechanical spindle, the influence of span L on the comprehensive stiffness K is not unidirectional. If l is larger, the deformation of the spindle is larger; if l is smaller, the deformation of the bearing has a greater impact on the displacement of the front end of the spindle. Therefore, l has an optimal value. If l is too large or too small, the comprehensive stiffness will be reduced. There is an optimal span l0 for the support span of the spindle, which can minimize the displacement of the front end of the spindle assembly. Due to the structural limitation and the guarantee that the center of gravity of the spindle assembly falls between the two supports, the actual support can be greater than the optimal support span.

Material selection and heat treatment of CNC machining center spindle

When the main shaft bearing of CNC machining center adopts rolling bearing, the journal can not be hardened. However, in order to improve the contact stiffness and prevent knocking from damaging the matching surface of the journal, many 45 steel main shaft journals are still subject to high-frequency quenching. When using sliding bearing, in order to reduce wear, the journal surface must have high hardness. Therefore, high frequency quenching is usually carried out at the journal; flame quenching can also be used for large diameter spindle to improve its surface hardness; 15 or 20 steel can be used for spindle with large impact, and carburizing, quenching and tempering can be carried out on the journal surface. 45 steel, GCr15, etc. are often used for spindle materials, which need nitriding and induction hardening.

The selection of spindle material is mainly based on the stiffness, load, wear resistance, heat treatment deformation and other factors. The stiffness of the spindle of CNC machining center is related to the elastic modulus E of the material, and the E value of the steel is larger, so the steel should be considered first. Moreover, the value of elastic modulus E of steel has nothing to do with the type of steel and heat treatment method. Therefore, the cheap medium carbon steel should be selected first. Alloy steel should be considered only when high load and large impact or when material deformation is reduced and high strength and wear resistance are required

The nature of CNC computer gong processing

  1. High reliability

The reliability of CNC machine tool is a key index of product quality. Whether the CNC machine tool can play its high performance, high precision and high efficiency, and obtain good benefits depends on its reliability.

  1. CAD design and modular structure design of CNC lathe

CAD can not only replace the manual to complete the tedious drawing work, but also can select the design scheme, analyze, calculate, predict and optimize the static and dynamic characteristics of the whole machine, and can simulate the working parts of the whole machine dynamically.

  1. High speed and high precision

Linear motor has high driving speed, good acceleration and deceleration characteristics, superior response characteristics and tracking accuracy. By using linear motor as servo drive, the ball screw as an intermediate transmission link is eliminated, the transmission clearance (including reverse clearance) is eliminated, the motion inertia is small, the system has good rigidity, and the precision positioning can be achieved at high speed, thus greatly improving the servo accuracy.

The linear rolling guide pair has very good thermal stability because of its zero clearance in all directions and very small rolling friction, small wear and negligible heating, which improves the positioning accuracy and repeated positioning accuracy in the whole process. Through the application of linear motor and linear rolling guide pair, the fast moving speed of the machine tool can be increased from 10 ~ 20m / MIM to 60 ~ 80m / min, and the maximum speed can reach 120m / min.

High speed and precision is the eternal goal of machine tool development. With the rapid development of science and technology, the upgrading speed of mechanical and electrical products is speeding up, and the requirements for the machining accuracy and surface quality of parts are becoming higher and higher. In order to meet the needs of this complex and changeable market, the current machine tools are developing in the direction of high-speed cutting, dry cutting and quasi dry cutting, and the machining accuracy is constantly improving. On the other hand, the successful application of motorized spindle and linear motor, ceramic ball bearing, low-temperature and high-speed ball screw pair with high-precision and large lead hollow internal cooling and ball nut strong cooling, and linear guide pair with ball retainer and other machine tool functional parts have also created conditions for the machine tool to develop towards high speed and precision.

CNC lathe adopts motorized spindle, cancels belt, pulley, gear and other links, greatly reduces the moment of inertia of the main drive, improves the dynamic response speed and working accuracy of the spindle, and thoroughly solves the vibration and noise problems of belt and pulley when the spindle runs at high speed. With the motorized spindle structure, the spindle speed can reach more than 10000 R / min.

Machining path refers to the movement path and direction of the cutter relative to the part in the process of NC machining.

The processing route should be shortened as far as possible to reduce the tool idle travel time

It should be able to meet the requirements of machining accuracy and surface roughness;

At present, under the condition that the CNC lathe has not been widely used, the excessive allowance on the blank, especially the allowance with forging and casting hard skin, should be arranged on the ordinary lathe. If must use the numerical control lathe processing, then needs to pay attention to the program flexible arrangement.

Key points of fixture installation: at present, the connection between hydraulic chuck and hydraulic clamping cylinder is realized by pull rod.

Reasonable selection of cutting parameters

For high efficiency metal cutting, the processed materials, cutting tools and cutting conditions are the three major elements. These determine the processing time, tool life and processing quality. The economic and effective machining method must be reasonable selection of cutting conditions. The three elements of cutting conditions: cutting speed, feed and cutting depth directly cause tool damage. With the increase of cutting speed, the temperature of tool tip will rise, which will produce mechanical, chemical and thermal wear. If the cutting speed is increased by 20%, the tool life will be reduced by 1 / 2.

The relationship between the feed condition and the tool wear is very small. But when the feed rate is large, the cutting temperature rises, and the back wear is large. It has less influence on the tool than the cutting speed. Although the influence of cutting depth on the tool is not as big as the cutting speed and feed rate, the hardened layer of the material to be cut will also affect the life of the tool

Regular and stable wear is the ideal condition. However, in the actual operation, the selection of tool life is related to tool wear, dimension change, surface quality, cutting noise, processing heat and so on. In determining the processing conditions, it is necessary to study according to the actual situation. For stainless steel and heat-resistant alloy and other difficult to machine materials, you can use coolant or choose a rigid blade.

Reasonable selection of cutting tools

In order to reduce the tool changing time and facilitate tool setting, the machine clamping tool and machine clamping blade should be used as far as possible.

In rough turning, the cutting tools with high strength and good durability should be selected, so as to meet the requirements of large back feed and large feed.

When finishing turning, the cutting tools with high precision and good durability should be selected to meet the requirements of machining accuracy.

Reasonable selection of fixture

Try to use general fixture to clamp workpiece, avoid using special fixture

In order to reduce the positioning error, the positioning datum of parts coincides.

Processing principle of CNC computer gong

CNC processing is specialized in mechanical processing. With many years of practical experience, I would like to talk about the specific processing principles of mechanical processing

(1) In order to ensure the machining accuracy, rough and finish machining should be carried out separately. Because of the large amount of cutting during rough machining, the cutting force and clamping force on the workpiece are large, the heat value is large, and there is a significant work hardening phenomenon on the machined surface. There is a large internal stress in the workpiece. If rough machining and rough machining are carried out continuously, the precision of the parts after finish machining will be quickly lost due to the redistribution of stress. For some parts with high machining accuracy. After roughing and before finishing, low temperature annealing or aging treatment should be arranged to eliminate the internal stress.

(2) Reasonable selection of equipment. Rough machining is mainly to cut off most of the machining allowance, and it does not require high machining accuracy, so rough machining should be carried out on the machine tool with high power and low accuracy, while finish machining requires high accuracy. High speed computer gong rough and finish machining in different machine tools, not only can give full play to the equipment capacity, but also can extend the service life of precision machine tools.

(3) Heat treatment process is often arranged in CNC machining process. The location of heat treatment process is as follows: in order to improve the cutting performance of metal, such as annealing, normalizing, quenching and tempering, it is generally arranged before machining. Mechanical parts processing to eliminate internal stress, such as aging treatment, quenching and tempering treatment, generally arranged after rough machining, before finishing. In order to improve the mechanical properties of parts, such as carburizing, quenching, tempering, etc., it is generally arranged after machining. If there is large deformation after heat treatment, the final processing procedure must be arranged.

Industrial control aluminum panel processing

  1. Understand the shape, structure and corresponding graphic position of parts.
  2. Look at the benchmark of the parts. Axis line, hole center line, surface, etc.
  3. Look at important dimensions, accuracy, roughness, form and position tolerance, etc.
  4. Look at the technical requirements, materials, etc.
  5. Look at the three views, left view, right view, top view, section view, detail drawing, etc. to understand the outline structure and facilitate cutting.
  6. Focus on the tolerance accuracy requirements of machining, including roughness, etc.
  7. Heat treatment and hardness requirements in technical requirements.

Pay attention to tolerance, fit tolerance, finish and concentricity

Computer gong processing equipment

How much do you know about computer gong processing equipment? Let’s make it up for you

  1. Casting, which is the most important part of the computer gong, directly affects the accuracy, stability, wear resistance of the computer gong and the service life of the machine tool. After the casting is finished, it is not immediately used in the production. The good casting is that it is after wind and rain, sun exposure, natural weathering, and some of them are soaked in sea water. After the casting does not change, it is taken to the processing. The machine tool made in this way is not easy to change, and can maintain the stability and accuracy of the machine tool for a long time.
  2. There are two kinds of motors: servo motor and frequency conversion motor. The servo motor has good stability, high power of spindle drive motor and low coordination rate of three-axis drive motor.
  3. The coupling is installed between the screw rod and the motor, which is just a linkage function.
  4. Spindle, the spindle is used to directly face the workpiece, it is driven by the motor to work, high-speed rotation, the spindle is equipped with a tool handle, it can chip the workpiece, meet various production needs, the quality of the spindle will directly affect the processing accuracy, if the internal bearing is worn, it is easy to cause the swing of the spindle, the accuracy of the processed things naturally has a few deviations . At present, the rotation speed of the spindle is generally about 8000 rpm, and the high-speed machine can achieve more than 20000 rpm. In the traditional machining center, each machine has only one spindle. In recent years, there have been double spindle or even multi spindle machining centers.
  5. The screw rod is also a part of the fuselage. It is driven by a servo motor and drives the displacement of the worktable through the copper sleeve of the screw rod to meet the processing needs. If there is a gap in the screw rod, it is also directly reflected in the processing accuracy and finish.
  6. The lubrication cooling system consists of an automatic oil pump, a spindle oil cooler and a chip liquid circulation system. When the machine tool is working, the oil can be pumped once every few minutes, and the oil pipe is connected to every corner, such as screw rod, guide rail, etc. if the oil circuit is blocked, the guide rail will be easily worn and the accuracy will be affected. Spindle oil cooling is a circulating cooling system added to cool the spindle. It is necessary or not for the spindle with 8000 revolutions, and it must be equipped for the spindle with more than 8000 revolutions. In the chip liquid circulation system, the oil in the oil tank is pumped up by the oil pumping motor and flushed to the workpiece being processed.
  7. Sheet metal, sheet metal requirements are not too high, as long as there is no oil leakage on the line, but also involves the appearance of beautiful, image problems.

Whether the accuracy of computer gong processing analysis and various technical requirements are complete and reasonable; whether the CNC turning accuracy of this process can meet the drawing requirements. If not, other measures (such as grinding) should be taken to make up, then allowance should be left for the subsequent process.

  1. Horizontal machining center: it refers to the machining center with the spindle axis parallel to the workbench, which is mainly suitable for machining box parts.

Computer gong machining center is usually classified by the relative position of spindle and workbench, which is divided into horizontal, vertical and multi axis linkage machining center.

  1. Vertical machining center: it refers to the machining center with the spindle axis perpendicular to the workbench, which is mainly suitable for processing complex parts such as plates, plates, molds and small shells.
  2. Multi axis linkage machining center, also known as universal machining center, refers to the machining center that can control linkage change through the angle between the spindle axis and the rotary axis of the worktable to complete the machining of complex spatial surface. It is suitable for machining impeller rotor, mould, cutting tool and other workpieces with complex space surface.

CNC computer gong processing sub center

CNC processing novices often encounter the situation of inaccurate points, sometimes it takes more than ten times to get accurate points. To this end, today I will introduce the reasons and solutions of inaccuracy in CNC machining.

Reasons for inaccurate CNC machining

  1. The operator’s manual operation is not accurate, and the manual operation number is wrong.
  2. There are burrs around the mold.
  3. The center bar has magnetism.
  4. The four sides of the mold are not vertical.

The solution to the inaccuracy in CNC machining is as follows:

  1. The manual operation should be carefully checked repeatedly, and the points should be at the same point and at the same height as far as possible.
  2. Deburring the periphery of the mould with oilstone or file, wiping it with rag, and finally confirming with hand.
  3. Demagnetize the center bar before centring the mold (ceramic center bar or others can be used).
  4. Check whether the four sides of the die are vertical (the verticality error is large, so we need to review the scheme with the fitter).

Points are not complex, according to the above method can operate several times, I hope to help you.

CNC Lathe Feed processing path refers to the path that the turning tool starts to move from the tool setting point (or the fixed origin of the machine tool) until it returns to the point and ends the processing program, including the path of cutting and the path of non cutting empty travel such as cutting in and cutting out.

The feed route of finishing machining is basically carried out along the contour of the parts. Therefore, the key point of determining the feed route is to determine the feed route of rough machining and empty stroke.

In the CNC lathe processing, the determination of the processing route should generally follow the following principles.

① It should be able to ensure the accuracy and surface roughness of the workpiece to be processed.

② The processing route is shortest, the idle travel time is reduced, and the processing efficiency is improved.

③ The workload of numerical calculation should be simplified as much as possible.

④ For some repeated programs, subroutines should be used.

Advantages and disadvantages of CNC CNC CNC machining has the following advantages:

① The number of tooling is greatly reduced, and complex tooling is not needed to process complex parts. If we want to change the shape and size of the parts, we only need to modify the processing program of the parts, which is suitable for the development and modification of new products.

② The machining quality is stable, the machining accuracy is high, and the repetition accuracy is high, which can meet the machining requirements of aircraft.

③ In the case of multi variety and small batch production, the production efficiency is high, which can reduce the time of production preparation, machine adjustment and process inspection, and reduce the cutting time due to the use of the best cutting quantity.

④ It can process complex surface which is difficult to be processed by conventional methods, and even process some parts which cannot be observed.

The function of CNC computer gong processing

Computer gong processing is now widely used in daily life

The parts with complex structure and shape, which are difficult to be processed by ordinary machine tools, need multi coordinate linkage processing when the main surface is composed of complex curves and curved surfaces, which is difficult or even impossible to be completed on ordinary machine tools. Numerical control processing equipment is the most effective equipment for processing such parts. The common typical parts of computer gong processing are cam, integral impeller and mold.

① There are various kinds of curved disc cam, cylindrical cam, conical cam and end face cam. When machining, according to the complexity of the cam surface, three axis, four axis or five axis machining center can be selected.

② Integral impellers are commonly used in aero-engine compressors, air compressors, marine underwater propellers, etc,

In addition to the characteristics of general curved surface machining, there are many special machining difficulties in mold machining, such as narrow channel, easy tool contact with machined surface and adjacent curved surface.

The CNC center of parts with both plane and hole system has automatic tool changing device. In one installation, it can complete the milling of the upper plane of parts and the multi-step machining of hole system, such as drilling, boring, reaming, milling and tapping. The processing part can be on one plane or on different planes. The pentahedron machining center can complete the machining of five surfaces except the clamping surface. Therefore, the parts with both plane and hole system are the preferred processing objects of computer gongs. The common parts include box parts and plate, sleeve and plate parts.

① There are plane, curved surface and hole system on the end face of parts, and some radial holes are often distributed in the radial direction. The vertical processing equipment should be selected for the disc, sleeve and plate parts whose processing parts are concentrated on a single end face, and the horizontal processing equipment should be selected for the parts whose processing parts are not located on the surface in the same direction.

② Box parts are common box parts. Box parts generally need multi station hole system and plane processing, with high accuracy requirements, especially the shape accuracy and position accuracy. They usually need to go through milling, drilling, expanding, boring, reaming, countersinking, tapping and other steps, and need more tools. It is difficult to process on ordinary machine tools, and the number of tooling sets is large. It needs multiple clamping and alignment, and manual measurement times are many, so the accuracy is not easy Guarantee. The last installation of CNC machining center can complete 60% ~ 95% of the process content of ordinary machine tool, with good consistency of parts precision, stable quality and short production cycle.

Now, the middle and low-grade CNC has such a large function that it may also be accepted by users to process molds. It is generally considered that CNC is the limiting factor to determine the maximum feed rate of die processing, but now, the limiting factor is often the structure of the machine tool itself. If the machine itself is already running at its performance limit, a better CNC will not transmit more functions

CNC five axis computer gong processing technology

It is a difficult point for five axis parts to process multi-dimensional surface parts. In addition to the application of multi axis machine tool, multi axis programming technology is the key. Reasonable setting of machining tool path is an important guarantee for the surface accuracy and dimensional accuracy of parts. Five axis parts processing taking human head image processing as an example, this paper discusses and analyzes the practical application of five axis cutting to multi-dimensional surface parts processing.

Five axis parts processing has the characteristics of high efficiency and high precision, the workpiece can complete complex processing with one clamping. It can adapt to the processing of modern molds such as auto parts and aircraft structural parts. There is a big difference between five axis machining center and pentahedron machining center. Many people don’t know the five axis machining, and mistakenly regard the pentahedron machining center as the five axis machining center. Five axis machining center has x, y, Z, a, C five axis, XYZ and AC axis form five axis linkage processing, good at space surface processing, special processing, hollow processing, drilling, oblique hole, oblique cutting and so on. Five axis parts processing and “pentahedron machining center” is similar to the three-axis machining center, but it can do five faces at the same time, but it can’t do special-shaped processing, oblique hole, cutting slope, etc.

A five axis machining type for mechanical parts relates to a five axis manipulator. Its main features are that the shoulder mechanism and the reducer shaft of the waist mechanism fixed on the fixed seat are fixedly installed to realize the radial swing of the shoulder mechanism and the reducer shaft of the fixed seat, the elbow mechanism and wrist mechanism for five axis mechanical parts processing realize the relative swing between the shoulder mechanism and the elbow mechanism, and the elbow mechanism and wrist mechanism respectively, and the five axis mechanical parts processing claw mechanism is installed on the bevel gear shaft of the wrist mechanism and passes through A pair of gears installed on the wrist mechanism reducer are meshed with the bevel gears of the claw mechanism.

Five axis machine parts processing type has simple structure, comprehensive functions, good reliability, stability and accuracy of the whole machine. It can perfectly replace the existing manipulator, and is suitable for welding, assembly, processing and other industrial systems. Five axis mechanical parts processing CS Series manipulator is suitable for 500 ~ 3000 tons of various types of horizontal injection molding machine products and nozzle extraction. The upper and lower arm type is variable section type; the up and down stroke is 800 ~ 3000mm, and the X, y, Z three axes are driven by AC servo motor. The installation can increase the production capacity (20 ~ 30%), reduce the defective rate of products, ensure the safety of operators, reduce labor, accurately control the production volume, and reduce waste.

The five axis mechanical parts processing is driven by drive components such as motor, reducer, pulley mechanism, sprocket mechanism, etc. it is characterized in that: the manipulator includes waist mechanism, shoulder mechanism, elbow mechanism, wrist mechanism and claw mechanism. The five axis mechanical parts processing shoulder mechanism and the reducer shaft of waist mechanism fixed on the fixed seat are fixed together The elbow mechanism and wrist mechanism are respectively installed in the shoulder mechanism and the reducer in the elbow mechanism to realize the relative swing between the shoulder mechanism and the elbow mechanism, and between the elbow mechanism and the wrist mechanism. The five axis mechanical parts processing claw mechanism is installed on the bevel gear shaft of the wrist mechanism, and is installed on the reducer of the wrist mechanism The engagement of a pair of bevel gears with the claw mechanism realizes the swing or rotation of the claw mechanism.

Five axis impeller machining supports four axis roughening, and some manual settings can be made in the control of the axis. Of course, in the process of generating the program, automatic avoidance can adjust these parameters. Channel finishing method is mainly used to finish the channel surface of five axis impeller. Various finishing strategies provide different optimization path distribution and tool inclination calculation methods for tasks. Similarly, the five axis impeller machining also supports the four axis mentioned above and the manual setting of tool tilting and other functions.

Five axis impeller machining point is to use the tool point contact method to process the blade surface with continuous and spiral circular action. In this method, a variety of machining modes and feeding strategies are provided to adapt to different tasks, such as the cavity mode of five axis impeller machining to reduce the vibration of adjacent blades. The strategy also supports the four axis and manual tool tilting functions mentioned above.

Five axis impeller machining is a kind of typical free-form surface parts. If the traditional cam machining strategy is adopted, different machining directions need to be tested repeatedly, and the paths of different directions need to be connected through human intervention, which will take a lot of time to adjust. Traditional machining methods are time-consuming and difficult to ensure accuracy. HyperMILL? Provides professional machining modules for both open and closed five axis impeller machining, so that even users with less experience in machining can program NC programs of this kind of parts which are difficult to complete by using conventional programming strategy in a short time through simple settings. This specialized module is commonly used in various fields of five axis impeller processing.

CNC computer gong processing tool

The work of determining the tool path is the focus of machining programming. Because the tool path of finishing cutting program is basically carried out along the contour sequence of parts, the main content is to determine the tool path of rough machining and empty stroke. Tool path generally refers to the path that the tool moves from the tool setting point until it returns to the point and ends the machining program. It includes the path of cutting and the non cutting empty stroke such as tool introduction and cutting out.

The shortest tool path can save the execution time of the whole machining process, and also reduce some unnecessary tool consumption and the wear of the sliding parts of the feed mechanism of the machine tool. The following figure 1 shows three taper turning methods, which are processed with rectangular circular command to analyze the reasonable determination of tool path. This method is that after each feed, the moving path of the turning tool is parallel to the generatrix of the cone. With each feed, the z-phase size increases in a certain proportion, which is the same as the common turning method, so that beginners can understand it easily. The calculation method of Z-direction dimension is based on the formula C = D-D / L. If C is 1:10, it means that 1 mm is removed from diameter x and 10 mm is added to length Z. According to this ratio, it is easy to program, and can ensure the same turning allowance every time, so that the cutting is uniform. The taper angle turning method is to keep the z-direction dimension as the drawing dimension with each X-direction feed. The taper angle of each cut is changed, and only the last cut is the taper angle required by the drawing. This taper turning method does not need to calculate the Z dimension every time, but because of the same Z dimension in machining, the machining path is longer, and the cutting allowance is not uniform, which affects the surface size and roughness of the workpiece. It is generally suitable for the taper with short taper and small allowance. Step table processing cone method, this processing method is that each time the tool path is parallel to the axis of the workpiece, many small steps are processed, and the last turning tool moves along the bevel of the cone. This processing method needs to make a 1:1 scale diagram first, otherwise it is easy to turn the waste workpiece, because it is a step shape, so the allowance is not uniform, which affects the processing quality of the cone.

Obviously, in the above three cutting routes, if the starting point is the same, the parallel turning cone route is the most reasonable, which is commonly used in production. The analysis of part drawing is the primary work in the process preparation, which directly affects the preparation and processing results of parts. It mainly includes the following contents:

Analysis of the geometric conditions of machining profile: the main purpose is to deal with the unclear dimension and closed dimension chain on the drawing.

Analyze the dimensional tolerance requirements on the part drawing to determine the processing technology to control the dimensional accuracy, such as the selection of cutting tools and the determination of cutting parameters.

Analysis of shape and position tolerance requirements: for CNC machining, the shape and position errors of parts are mainly affected by the accuracy of machine tool mechanical motion pairs. In turning, if the direction of movement along the z-axis is not perpendicular to the axis of its main axis, the shape tolerance requirement of cylindricity cannot be guaranteed; if the direction of movement along the x-axis is not perpendicular to the axis of its main axis, the position tolerance requirement of perpendicularity cannot be guaranteed. Therefore, before programming, we should consider the relevant scheme of technical processing.

Analysis of the surface roughness requirements of parts, material and heat treatment requirements, blank requirements, the number of pieces requirements is also the process arrangement and the determination of the tool path are parameters that can not be ignored. In NC turning, the program runs through the whole process of parts. Because each person’s processing method is different, the programming is also different, but the ultimate goal is to improve the production efficiency of CNC lathe, so it is particularly important to choose the most reasonable processing route. This paper will analyze the programming method in NC turning from the details of determining the tool path and selecting the appropriate g command. According to each individual geometric element (i.e. straight line, oblique line, arc, etc.), the corresponding processing program is worked out, which constitutes each program of the processing program, i.e. program segment. In the process of programming, we always hope to process the parts with the least number of program segments, so as to make the program concise, reduce the probability of error and improve the efficiency of programming.

Introduction of cam processing with computer gong

For the processing of camshaft and large crankshaft, we hope that the equipment has better controllability, multi-functional and flexible turn milling head, and strong anti-collision protection function. Generally, in addition to the advanced and stable CNC system, the static geometric accuracy should be reliable, stable and have a long retention. The dynamic positioning accuracy should be implemented according to the vdi3441 standard, especially exaggerating the acceptance and assessment of the repeated positioning accuracy PS. since the positioning accuracy and reverse clearance can be compensated by the CNC system, the repeated positioning accuracy is the manufacturing precision It can’t compensate for the combination of degree and transmission chain precision.

When machining slender shaft, it is required to be able to measure the bending degree in the middle of crankshaft during clamping, and compensate the center frame through the numerical control system. At the same time, it is required to realize the function of online measurement through the instrument during machining. The key points to be achieved in Camshaft machining are: the perpendicularity of the two outer faces of flange relative to the camshaft axis, the runout of flange is 0.02mm, and the distance between the two flanges is 0.02mm The position degree of two road holes relative to the axis of the boss on the same side, the coaxiality of one hole relative to the other, the dimensional accuracy of each cam profile, and the shape and position accuracy include the profile degree, the runout of the base circle relative to the axis of the boss at both ends of the camshaft, and the parallelism of the generatrix of the cam profile relative to the axis of the boss at both ends of the camshaft. Similarly, for the crankshaft connecting rod neck processing, it is necessary to maintain a number of requirements such as coaxiality and parallelism.

Generally, it doesn’t need a lot of complex process equipment. The parts with complex shape and high precision can be processed by programming. When the product is modified and the design is changed, as long as the program is changed, there is no need to redesign the tooling. Therefore, CNC lathe processing can greatly shorten the product development cycle, and provide a shortcut for new product development, product improvement and modification.

CNC lathe processing is mainly aimed at the characteristics of wood products processing industry, combined with the operating habits, using the Chinese character operation, easy to learn and use (primary school education can operate the CNC system), can process cylinder, cone, arc, spherical and other complex shapes of rotary wood parts, can be set flexibly at any time, quickly change the processing style, the processing batch of parts should be more than For various reasons, the pure cutting time only accounts for 10% – 30% of the actual working time when machining medium and small batches of parts on non CNC grinding machine by ordinary lathe and batch CNC lathe.

CNC computer gong processing workpiece overcut

Computer gong processing has become an important development direction of modern processing, with high degree of automation, high processing accuracy and strong adaptability to parts, so it is widely used in modern machining. But CNC machining will also occur on the workpiece overcut phenomenon. Overcutting will directly affect the machining accuracy of the workpiece, and even lead to the scrapping of the workpiece.

Causes of workpiece overcutting in CNC machining:

  1. Improper operation of the operator.
  2. The cutting allowance is not uniform.
  3. Improper cutting parameters.
  4. The strength of the tool is not enough, too long or too small.

CNC machining workpiece overcutting solution:

  1. Reasonable adjustment of cutting parameters, large allowance, corner rounding.
  2. Using SF function of machine tool, the operator can fine tune the cutting speed to achieve the best cutting effect.
  3. The principle of using a knife: big but not small, short but not long.
  4. Add the corner cleaning procedure, the allowance should be as uniform as possible, and the allowance on the side and bottom should be the same.

CNC processing problems can not be as easy as ordinary machine tools can be manually adjusted, so we must pay attention to every detail of the processing process, careful consideration, strive to be accurate, avoid overcutting problems, do not waste, improve resource utilization. Novices often encounter the situation that the score is not accurate, sometimes they have to score more than ten times to be accurate. To this end, today I will introduce the reasons and solutions of inaccuracy in CNC machining.

Reasons for inaccurate CNC machining

  1. The operator’s manual operation is not accurate, and the manual operation number is wrong.
  2. There are burrs around the mold.
  3. The center bar has magnetism.
  4. The four sides of the mold are not vertical.

The solution to the inaccuracy in CNC machining is as follows:

  1. The manual operation should be carefully checked repeatedly, and the points should be at the same point and at the same height as far as possible.
  2. Deburring the periphery of the mould with oilstone or file, wiping it with rag, and finally confirming with hand.
  3. Demagnetize the center bar before centring the mold (ceramic center bar or others can be used).
  4. Check whether the four sides of the die are vertical (the verticality error is large, so we need to review the scheme with the fitter).

Points are not complex, according to the above method can operate several times, I hope to help you.