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CNC machine tool operation

1. Confirm the model, size and machining allowance of the blank according to the program sheet before operation, and sand and grind the blank

2. Confirm the position of the workpiece, computer gong processing, Dongguan computer gong processing, Shenzhen computer gong processing, mechanical parts processing, Guangzhou computer gong processing and the processing sequence to complete the table comparison

3. If it is necessary to “divide the middle rod”, the rotating speed is 501r / m. if the tool is used to divide the center, the speed depends on the tool, such as computer gong processing, Dongguan high speed computer gong processing, Dongguan mold processing, Dongguan Mechanical parts processing, CNC processing. In this process, it should also be noted that the data must be taken at the same height to ensure the accuracy of the separation. After the separation, the “G0 g54 x0 Y0” can be used for inspection

4. Before formal processing, check and confirm whether the position of the workpiece is placed and whether the fetching is correct

C. Precautions in CNC machining

1. Before machining in each program, it is necessary to strictly confirm whether the tool is consistent with the program

2. When installing the tool, confirm whether the length of the tool and the selected tool holder are suitable

3. In the same workpiece, each tool setting should be kept in the same area to ensure the accuracy of tool connection

4. Air blowing should be used as much as possible in roughening procedure, computer gong processing, Dongguan computer gong processing, Shenzhen computer gong processing, mechanical parts processing, Guangzhou computer gong processing, and oil injection in the light knife program

5. Clean the aluminum slag in the machine tool before the smooth knife oil injection to prevent the aluminum slag from absorbing oil

6. During the operation of the machine tool, the operator shall not leave the machine tool or regularly check the operation status of the machine tool. If it is necessary to leave midway, relevant personnel must be designated to check

7. If too much machining allowance is found in the process of processing, computer gong processing, Dongguan high-speed computer gong processing, Dongguan mold processing, Dongguan Mechanical parts processing, CNC processing must use “single section” or “pause” to clear x, y, Z values, and then manually mill them off, and then swing back to “zero” to let them run by themselves

8. In case of tool collision during CNC processing, the operator must stop the machine immediately, such as pressing the “emergency stop” button or “reset key” button or setting the “feed rate” to zero

The steps of working out process specification in machining process

So in the process of machining, what are the steps to formulate the process specification? Let’s take a look at it

1) Calculate the annual production program and determine the type of production.

2) Analyze the part drawing and product assembly drawing, and analyze the process of parts.

3) Select the blank.

4) Draw up the process route.

5) Determine the machining allowance of each process, calculate the process size and tolerance.

6) Determine the equipment and tools, fixtures, measuring tools and auxiliary tools used in each process.

7) Determine cutting parameters and man hour quota.

8) Determine the technical requirements and inspection methods of each main process.

9) Fill in process documents.

In the process of working out the process, it is often necessary to adjust the contents that have been initially determined before in order to improve the economic benefits. Computer gong processing, Dongguan high-speed computer gong processing, Dongguan mold processing, Dongguan Mechanical parts processing, CNC processing, in the process of implementing the process specification, there may be unexpected situations, such as the change of production conditions, the introduction of new technology and new technology, the application of new materials and advanced equipment, which require timely revision and improvement of the process specification.

The technological process of machining includes, generally speaking, the process of changing the overall dimension and performance of the workpiece through a kind of mechanical equipment.

The working principle of machining process regulation is high quality, high yield and low cost, that is, under the premise of ensuring product quality, labor productivity can be improved and cost can be reduced as much as possible. What problems should be paid attention to in the process planning? Here’s a look:

1., the advanced technology.

In the formulation of machining process procedures, computer gong processing, Dongguan high-speed computer gong processing, Dongguan mold processing, Dongguan Mechanical parts processing, CNC processing should make full use of the existing production conditions of the enterprise, as far as possible, use domestic and foreign advanced technology and experience, and ensure good working conditions.

2. Economic rationality

Under the specified production program and production batch, there may be several process schemes that can meet the technical requirements of parts. At this time, the process cost is generally required to be the lowest through accounting or comparison with each other. Make full use of the existing production conditions, spend less and do more.

Cutting conditions of CNC machining

The three elements of cutting conditions: cutting speed, feed and cutting depth directly cause damage. With the increase of cutting speed, the point temperature will rise, resulting in mechanical, chemical and thermal wear. If the cutting speed is increased by 20%, the tool life will be reduced by 1 / 2.

Back feed conditions and tool wear are kept to a minimum. But feeding behind, cutting temperature rise, wear. Computer gong processing, Dongguan computer gong processing, Shenzhen computer gong processing, mechanical parts processing, Guangzhou computer gong processing, it is less than the impact of cutting speed. Cutting depth has no effect on cutting speed and feed, small cutting depth, but cutting material in hardened layer will also affect tool life.

According to the user’s processing material, hardness, cutting conditions, material selection, feed and cutting depth, the cutting speed is used.

Based on the selection of the most suitable process conditions, these factors are selected. Regular life and stable wear are the most ideal conditions.

However, in practice, the selection of tool life and tool wear, through machining size, surface quality, noise reduction, heat and so on. Under certain processing conditions, it is necessary to study according to the actual situation. Difficult to machine materials such as stainless steel, heat-resistant alloy, can use coolant or choose a good rigid blade.

Reasonable selection of cutting tools

1。 Rough rotation, should choose high strength, good durability knife, in order to meet the large car turning, feedback.

2。 The essence of automobile is to select high precision, durable and good cutting tools to ensure the machining accuracy.

3。 Reduce the conversion time and knife convenience, should try to use machine knife and machine clip blade.

Select fixture

1。 Choose general fixture to clamp workpiece as much as possible, avoid using special fixture; computer gong processing | Dongguan computer gong processing | Shenzhen computer gong processing | mechanical parts processing | Guangzhou computer gong processing

2。 The coincidence of parts positioning datum reduces the positioning error.

Determine the processing route

Machining path is the part of tool path and direction relative to each other in the process of exponential control.

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

2。 Shorten the processing route as far as possible and reduce the idle travel time of the tool.

Heat treatment process of CNC machining metal

According to the different heating medium, heating temperature and cooling method, each category can be divided into several different heat treatment processes. The same metal with different heat treatment process can obtain different microstructure and different properties. Computer gong processing | Dongguan computer gong processing | Shenzhen computer gong processing | mechanical parts processing | Guangzhou computer gong processing

Steel is the most widely used metal in industry, and the microstructure of steel is also the most complex. Therefore, there are many kinds of heat treatment processes for steel.

Integral heat treatment is a metal heat treatment process that heats the workpiece as a whole and then cools it at a proper speed to change its overall mechanical properties. There are four basic processes of heat treatment of iron and steel: annealing, normalizing, quenching and tempering.

Annealing is to heat the workpiece to the appropriate temperature, adopt different holding time according to the material and size of the workpiece, and then cool it slowly. The purpose is to make the internal structure of the metal reach or close to the equilibrium state, and obtain good process performance and performance. Computer gong processing, Dongguan computer Gong processing, Shenzhen computer gong processing, mechanical parts processing, Guangzhou computer gong processing

Or to prepare for further quenching. Normalizing is to heat the workpiece to a suitable temperature and then cool it in air. The effect of normalizing is similar to that of annealing, but the microstructure is finer. It is often used to improve the cutting performance of low-carbon materials, and sometimes used as the final heat treatment for some parts with low requirements.

Quenching is the rapid cooling of the workpiece in water, oil or other inorganic salt, organic water solution and other quenching media after heating and holding. After quenching, the steel parts become hard but brittle at the same time. In order to reduce the brittleness of steel parts, the quenched steel parts are kept at a proper temperature higher than room temperature but lower than 650 ℃ for a long time, and then cooled. This process is called tempering. Annealing, normalizing, quenching and tempering are the “four fires” in the whole heat treatment. Quenching and tempering are closely related and often used together.

With the different heating temperature and cooling methods, different heat treatment processes have evolved. In order to obtain certain strength and toughness, quenching and high temperature tempering process is called quenching and tempering. Computer gong processing | Dongguan computer gong processing | Shenzhen computer gong processing | mechanical parts processing | Guangzhou computer gong processing

Some alloys are quenched to form supersaturated solid solutions, which are kept at room temperature or a little higher temperature for a long time to improve the hardness, strength or electrical magnetism of the alloys.

Injection molding process of CNC machining mold

After the injection molding, the film and plastic are integrated. The wear-resistant material is on the outside. This process is often used in the mobile phone display screen. Dongguan computer gong Processing Factory Dongguan machine parts Processing Factory Dongguan mold processing factory Shenzhen computer gong processing plastic materials are mainly PC, PMMA, PBT, etc., which mainly have the function of wear resistance and scratch resistance. There is also a technology called IML (in-mold-lable), which is roughly the same as IMD, except that flim is pulled out like a punched tape after injection molding, which just transfers the printed pattern to the plastic parts, also known as in mold transfer.

There are two main types of IMD. One is PC and single chip. The other is pet, chain like (like film or printed instant noodle pockets).

The former finished product is merge PC chip, the latter only takes the ink on the pet chain, but PET material (chain, also known as foil) is not imported into parts by merge.

For example, the front shield of Motorola v66 is very delicate,

The latter because of the thin pet, can be offset printing, very fine, especially electroplating and transparent, metal and surface fine texture are very good, such as Motorola V60 pre plating and black texture effect.

For example, the control panel on Matsushita rice cooker mold is a typical IMD, which puts a silk screen printed PET film into the injection mold for injection molding. The materials are PC, transparent ABS and PMMA. After injection molding, the film and plastic are combined into one.

Nowadays, most of the outer screen lenses of mobile phones adopt IMD technology, and the cost is correspondingly increased. The requirements of mobile phone molds, especially transparent molds, are more stringent.

Generally speaking, there are two background reasons for using IMD,

1. Some effects of injection molding are difficult to simulate, such as the walnut automobile dashboard (car parts mold).

2. It is very difficult to integrate several effects on small pieces of parts. Dongguan computer gong Processing Factory Dongguan Mechanical Parts Processing Factory Dongguan mold processing factory Shenzhen computer gong processing, such as the front triangle of moto V60 mold, concentrates electroplating, transparent, screen printing, but it also requires exquisite. Imagine using real electroplating, transparent pieces are injected separately and then splicing is very difficult.

Another method is to make the outer surface smooth and the inner surface rough, but there are some requirements for the mold.

CNC machining blank surface or rough machining steps

When machining the surface of blank or rough machining hole, the end milling cutter or corn milling cutter inlaid with cemented carbide can be selected for strong cutting.

The end mill C is often used when machining the peripheral contour of a plane workpiece.

In order to improve the accuracy of the groove width and reduce the number of tool changes, the milling cutter with a diameter of 7 than the groove width can be used to mill the middle part of the groove first, and then use the tool radius compensation function to mill the two sides of the groove.

Ball end milling cutter, ring milling cutter, drum milling cutter, cone milling cutter and disc milling cutter are often used in machining solid curved surface or variable bevel profile.

When the machining allowance is small and the requirement of surface roughness is high, the face milling cutter with cubic boron nitride blade or ceramic insert blade can be selected for high-speed cutting.

According to the principle of NC machining, the overall consideration is made according to the requirements of workpiece processing drawings, and the format specified by CNC milling machine is used for editing. Computer gong processing, Dongguan high-speed computer gong processing, Dongguan mold processing, Dongguan Mechanical parts processing and CNC machining are input according to the action sequence. Thus, we can know the precise machining technology of CNC lathe while compiling the NC program It is also necessary.

1. Determine the process flow. The processing technology of CNC milling machine is very similar to that of ordinary machine tool. Through analyzing the workpiece, specify the processing route, select the processing procedure, select the machine tool, fixture and cutter. Determine the equipment baseline position and cutting amount. The difference is that CNC machine tools need to program the operation process.

2. Calculate the tool coordinate value. In order to facilitate the programming and calculation of tool path coordinates. The coordinates of the workpiece and the size and shape of the part must be calculated first, so as to determine the whole machining path of the tool.

3. Write processing program, for simple workpiece can be written manually, but for complex processing workpiece, automatic programming is needed.

4. There are many ways to input program into CNC system, such as computer gong processing, Dongguan high-speed computer gong processing, Dongguan mold processing, Dongguan Mechanical parts processing, CNC processing, which are mainly completed by the operation panel of the CNC control system, and the interface between the computer and the CNC system can be connected to input the program through the computer.

5. Comprehensive inspection of procedures. Through the function of graph magic shadow display or NC milling machine equipment running without load, the machine tool running track can be checked, whether the tool movement meets the requirements of capping, or the method of single step program execution can be used for cutting

CNC machining thin wall mold processing

In a broad sense, it refers to the process that all products can be manufactured by mechanical means; in a narrow sense, it refers to the process of making parts by special machinery such as the lathe, milling machine, drilling machine, grinding machine, stamping machine, die-casting machine, etc.

There will be some errors in machining. Let’s talk about the original error related to the initial state of the process system itself

① Principle error is the error of machining method.

② Geometric error of process system

The relative position errors between workpiece and tool exist in static state, such as manufacturing error of tool and fixture, adjustment error and installation error;

The relative position error of workpiece and cutter exists in the motion state, such as the spindle rotation error of machine tool, the guide error of guide rail, the transmission error of transmission chain, etc.

The deformation caused by the force effect of the process system, such as the deformation caused by the stress deformation of the process system and the deformation caused by the generation and disappearance of the internal stress of the workpiece.

② Deformation caused by thermal effect of process system, such as the error caused by thermal deformation of machine tool, cutting tool and workpiece. In the machining process of Dongguan machine parts, when the position relationship between the tool and the workpiece processing surface is reasonable, the machining surface accuracy can meet the processing requirements, otherwise it can not meet the processing requirements. CNC machining accuracy analysis is to analyze and study various factors when the machining accuracy can not meet the requirements, that is, the possibility of various original errors, and take effective measures In order to improve the machining accuracy.

The process of CNC machining blank into finished product

Design datum: the datum used to determine the position of other points, lines and planes on the part drawing, which is called design datum.

Process datum: the datum used in the process of machining and assembling parts, which is called process datum. According to different uses, process datum can be divided into assembly datum, measuring datum and locating datum.

(1) Assembly datum: the datum used to determine the position of parts in parts or products during assembly, which is called assembly datum.

(2) Measurement datum: the datum used to check the size and position of machined surface, which is called measuring datum.

(3) Positioning datum: the datum used for workpiece positioning during machining, which is called positioning datum. Computer gong processing, Dongguan high speed computer gong processing, Dongguan mold processing, Dongguan Mechanical parts processing, CNC machining as the positioning reference surface (or line, point), in the first process, only the rough surface can be selected. This positioning surface is called the rough datum. In the following processes, the machined surface can be used as the positioning reference, and the positioning surface is called the precise reference.

In the process of turning a blank into a finished product, the total thickness of the metal layer cut off on a machining surface is called the total machining allowance of the surface. The thickness of the metal layer cut by each process is called the machining allowance between processes. For the rotating surface such as outer circle and hole, the machining allowance is considered from the diameter, so it is called symmetrical allowance (i.e. bilateral allowance), that is, the actual thickness of the metal layer cut off is half of the machining allowance on the diameter. The machining allowance of the plane is the unilateral allowance, which is equal to the actual thickness of the metal layer removed. The purpose of leaving machining allowance on the workpiece is to remove the machining errors and surface defects left by the previous process, such as the surface cold and hard layer, air hole and sand inclusion layer on the casting surface, oxide scale, decarburization layer and surface crack on the forging surface, internal stress layer and surface roughness after cutting. The precision and surface roughness of the workpiece are improved. The size of machining allowance has great influence on machining quality and production efficiency. If the machining allowance is too large, it not only increases the labor of machining, reduces the productivity, but also increases the consumption of materials, tools and power, and increases the processing cost. If the machining allowance is too small, it can not eliminate all kinds of defects and errors in the previous process, and can not compensate for the clamping error in this process, resulting in waste products. The selection principle is to make the allowance as small as possible on the premise of ensuring the quality. Generally speaking, the more finish machining, the smaller the process allowance.

Applicability:

The total thickness of the metal layer cut off on a machining surface is called the total machining allowance of the surface. The thickness of the metal layer cut by each process is called the machining allowance between processes. For the rotating surface such as outer circle and hole, the machining allowance is considered from the diameter, so it is called symmetrical allowance (i.e. bilateral allowance), that is, the actual thickness of the metal layer cut off is half of the machining allowance on the diameter. The machining allowance of the plane is the unilateral allowance, which is equal to the actual thickness of the metal layer removed. The purpose of leaving machining allowance on the workpiece is to remove the machining errors and surface defects left by the previous process, such as the surface cold and hard layer, air hole and sand inclusion layer on the casting surface, oxide scale, decarburization layer and surface crack on the forging surface, internal stress layer and surface roughness after cutting. Computer gong processing, Dongguan high speed computer gong processing, Dongguan mold processing, Dongguan Mechanical parts processing, CNC processing, so as to improve the accuracy and surface roughness of the workpiece. The size of machining allowance has great influence on machining quality and production efficiency. If the machining allowance is too large, it not only increases the labor of machining, reduces the productivity, but also increases the consumption of materials, tools and power, and increases the processing cost. If the machining allowance is too small, it can not eliminate all kinds of defects and errors in the previous process, and can not compensate for the clamping error in this process, resulting in waste products. The selection principle is to make the allowance as small as possible on the premise of ensuring the quality. Generally speaking, the more finish machining, the smaller the process allowance.

报错笔记

Conventional digital position control in CNC machining

1、 Conventional digital position control

At present, digital AC servo system is widely used in CNC machine tools. The basic composition of the position control system composed of mechanical parts processing is shown in Fig. 1. In the figure, the digital servo drive module and servo motor constitute a high-precision angle closed-loop servo system, whose input is the command pulse given by the CNC system, and the output is the motor angle. Under the closed-loop control with optical encoder as feedback, the rotation angle of motor shaft will strictly follow the command value. Computer gong processing | Dongguan computer gong processing | Shenzhen computer gong processing | mechanical parts processing | Guangzhou computer gong processing is driven by gear pair and screw nut pair, and the angular displacement of motor is converted into the required linear displacement of worktable.

It can be seen from the figure that although the digital servo system with angle as output is a closed-loop system, the position control system composed of it is an open-loop system (or semi closed-loop system) from the perspective of taking the displacement of the machine table as the final controlled quantity. Therefore, the position control accuracy is not only related to the performance of the control system, but also largely depends on the mechanical structure of the machine tool. In this way, the error of information transmission link, the error of mechanical transmission link and the influence of various non-linear factors in the system will make the table displacement deviate from the command value, and the open-loop system can not effectively correct it. Therefore, even if the conventional CNC machine and the machine use high-performance digital servo system, it is difficult to achieve high machining accuracy.

2、 Composition of digital full closed loop position control system

In order to solve the above problems, this paper proposes a digital full closed-loop position control method. Its basic idea is: on the basis of the digital drive of the moving parts of the machine tool, the digital measurement link which directly detects the final displacement of the moving parts is introduced to fully obtain and use the system information to count the motion of each coordinate of the machine tool from the perspective of feedback control The digital closed-loop system consists of various error sources and nonlinear links. This system can not only make the positioning accuracy of the moving parts determined by the measurement accuracy of the detection link, but also effectively dynamically correct the influence of various interference and nonlinear factors on the displacement of the moving parts, so that the actual displacement of the moving parts at any time can be achieved It strictly follows the change of the command value, so as to ensure the high dynamic and steady-state accuracy of the machine tool.

The basic composition of the digital closed-loop position control system is shown in Fig. 2. The system uses grating as the linear displacement detection device to directly obtain the displacement information of the machine tool table. After preprocessing, the two-way displacement pulse signals with phase difference of 90 degrees are obtained. The frequency is directly proportional to the displacement speed of the worktable, and the number is the actual displacement of the worktable divided by the pulse equivalent. The displacement pulse is sent to the reversible counter for counting, and the count value in the counter represents the current actual position of the worktable. The function of the position controller in the system is to control the operation of the whole system according to the difference between the given position value and the position feedback value according to the digital control law designed in advance, so as to ensure that the displacement of the worktable strictly follows the instruction value.

3、 Dynamic structure and controller design of the system

The dynamic structure of the system in Fig. 2 is shown in Fig. 3, which includes three parts: digital position controller, generalized object and feedback channel. The generalized object is composed of zero order holder, pulse generator, digital AC servo system and mechanical moving parts. Among them, the zero order holder plays a bridge style of connecting discrete link (digital controller) and continuous link. The task of pulse generator is to generate command pulse to control the operation of AC servo system according to the control signal given by the position controller, so this link is a proportional link.

AC servo system is a digital driving device in the system. From the macroscopic point of view, there is an integral relationship between the angle θ of servo motor and the command pulse frequency f, but the inertial characteristics between θ and F should be further considered from the microscopic point of view. The function of mechanical moving parts is to convert the rotation angle of the motor into the linear displacement of the worktable. If the influence of transmission error and nonlinear factors is treated as the dynamic disturbance to the system, the link can also be regarded as a proportion link. In this way, the transfer function of the generalized object can be expressed as a feedback channel after proper processing, although it includes detection device, pre-processing, information transfer, reversible counting and many other links, involving more complex information processing process.

However, from the point of view of taking the actual position of the worktable as the input and the position feedback value (the count value in the reversible counter multiplied by the pulse equivalent) as the output, the feedback channel can be regarded as a proportional link in computer gong processing, Dongguan computer gong processing, Shenzhen computer gong processing, mechanical parts processing and Guangzhou computer gong processing, and the transfer function GF (s) = l can be made by proper design. Considering that the generalized object is a third-order system with an integral link, in order to make the closed-loop system composed of it have fast dynamic performance and no steady-state error of tracking slope input, PID controller is used as position controller

Selection of surface machining methods for CNC machining

1、 Selection of surface processing method selection of surface processing method selection of surface processing method selection of surface processing method:

The selection of surface processing scheme shall be based on the machining accuracy required for each surface of the part

According to the surface roughness and structural characteristics of parts, the corresponding processing methods and schemes are selected.

1. According to the technical requirements of the machined surface, the economical machining precision scheme should be adopted as far as possible.

2. According to the properties of workpiece material and heat treatment, select the corresponding processing method.

For example: quenching steel finishing to use grinding, computer gongs processing, Dongguan computer gongs processing, Shenzhen computer gongs processing, mechanical parts processing, Guangzhou computer gongs processing of non-ferrous metals, in order to avoid blocking the grinding wheel during grinding, adjust the cutting method such as fine turning or fine boring.

Consider the structure, switch and size of the workpiece.

4. Productivity and economy are considered in combination with production type.

5. Consider the existing equipment and technical conditions of the plant (or workshop).

2、 Division of processing stage division of processing stage division of processing stage division of processing stage:

When the machining quality of parts is high, the whole processing process should be divided into the following stages:

1. Rough machining stage rough machining stage rough machining stage rough machining stage

The main task is to remove most of the machining allowance, so how to obtain high productivity should be considered.

2. Semi finishing stage. Computer gong processing, mechanical parts processing, CNC machine tool processing, Dongguan high-speed computer gong processing, complete the secondary surface processing, and prepare for the finishing of the main surface.

3. Finishing stage finishing stage finishing stage finishing stage finishing stage finishing stage. Make the main surface meet the quality requirements specified in the drawing.

Finishing stage finishing stage finishing stage finishing stage finishing stage finishing stage finishing stage. In order to further improve the dimensional accuracy and reduce the surface roughness value, it is necessary to finish the surface with high quality requirements.

3、 Process centralization and decentralization process centralization and dispersion process centralization and dispersion: process centralization and process dispersion are two different principles for determining the number of operations when drawing up a process route.

4、 Arrangement of processing sequence arrangement of work sequence arrangement of work sequence: the machining process route of complex workpiece must go through cutting, heat treatment and auxiliary processes.

Therefore, when drawing up the technological route, the technologists should take the cutting, heat treatment and auxiliary processes into consideration.

5、 Selection of machine tool and process equipment selection of machine tool and process equipment selection of machine tool and process equipment

1. Selection of machine tool equipment selection of machine tool equipment selection of machine tool equipment selection of machine tool equipment.

2. Computer gong processing, mechanical parts processing, CNC machine tool processing, Dongguan high speed computer gong processing, process equipment selection, process equipment selection, process equipment selection.