2020 – Page 4 – CNC Machining & Turning, Milling, Metal parts

CNC computer gong processing fault analysis

Fault analysis: after measuring the workpiece, it is found that the relative positions of all dimensions of the parts are correct, but all the coordinate values of X axis are different by 10 mm. By analyzing the causes, the whole pitch deviation of x-axis dimension (the pitch of this axis is 10 mm) is caused by the offset of reference point position.

For most systems, the reference point is generally set on the “zero pulse” of the first programmer after the release of the deceleration iron at the reference point; if the reference point deceleration block is released, the encoder happens to be near the zero pulse, and due to the random error of the deceleration switch action, the reference point position may be shifted by one whole pitch. This fault is especially easy to happen when using small pitch ball screw.

Troubleshooting: for this kind of fault, as long as the position of the deceleration stop at the reference point is readjusted so that the difference between the release point of the stop and the “zero pulse” position is about half a pitch, the machine can resume normal operation. After the above treatment, the fault is removed and the machine returns to normal operation. After the above treatment, the trouble is eliminated, the machine tool returns to normal, and all parts are processed normally.

1、 Machine parts processing plant – types of mechanical parts:

The first type is mainly used in precision machinery, which has high requirements for the stability of the fit. It requires that the wear limit of the parts should not exceed 10% of the dimensional tolerance value of the parts in the process of use or after many times of assembly. This is mainly applied to the surfaces of precision instruments, meters, precision measuring tools, and friction surfaces of extremely important parts, such as the inner surface of cylinder, the main journal of precision machine tools, and the coordinate boring machine Main journal, etc.

The second type is mainly used in ordinary precision machinery, which requires high stability of fit. The wear limit of parts shall not exceed 25% of the dimensional tolerance value of the parts. It is mainly used in machine tools, tools, surfaces matching with rolling bearings, taper pin holes, and contact surfaces with higher relative speed, such as the mating surfaces of sliding bearings and gears Gear tooth working face, etc.

The third category is mainly used in general machinery, which requires that the wear limit of mechanical parts shall not exceed 50% of the dimensional tolerance value. The contact surfaces of parts without relative movement, such as box cover and sleeve, shall be close to each other, the working surface of key and keyway, and the contact surface with low relative movement speed, such as support hole, bushing, working surface with wheel axle hole, reducer, etc.

2、 Mechanical parts processing plant — manufacturability of mechanical parts:

When designing mechanical parts, we should not only make them meet the requirements of use, that is, they should have the required working capacity, but also meet the production requirements. Otherwise, they may not be manufactured, or they can be manufactured, but they are costly and uneconomical. Under specific production conditions, if the designed mechanical parts are easy to process and the processing cost is very low, then such parts are said to have good processability. The basic requirements for processability are as follows:

(1) The method of blank preparation in mechanical manufacturing includes: direct use of profile, casting, forging, stamping and welding. The selection of blank is related to the specific production technical conditions, and generally depends on the production batch, material properties and processing possibility.

(2) When designing the structural shape of parts with simple structure, the simplest surface (such as plane, cylindrical surface and spiral surface) and their combination should be adopted. At the same time, the number of machined surfaces and the area of machining should be minimized.

(3) With the increase of precision, the machining cost of parts increases with the increase of precision, especially in the case of high precision. Therefore, high precision should not be pursued without sufficient basis. In the same way, the surface roughness of parts should also be regulated according to the actual needs of the mating surface.

CNC computer gong machining thin wall parts

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 mechanical 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 technological measures In order to improve the machining accuracy.

What is CNC five axis machining

What is CNC five axis machining center? What are the characteristics of five axis machining center

Definition of five axis: there are at least five coordinates on a machine tool, which are three linear coordinates and two rotation coordinates

Five axis machining features:

a. 3-axis machine tools can not process or need to clamp too long; B. improve the accuracy, quality and efficiency of free space surface

The difference between five axis and three axis; the difference between five axis and three axis; the establishment of five axis coordinate and the expression of its code

Determination of z-axis: the axis direction of machine tool spindle or the vertical direction of worktable for clamping workpiece is z-axis

Or the direction of the axis parallel to the axis of the workpiece in the horizontal plane

Linear coordinate X axis Y axis Z axis rotation coordinate a axis, b axis and C axis

Axis A: axis A is rotated around X axis

B axis: rotate around Y axis to b axis

C axis: rotate around Z axis for C axis

XYZ + A + B, XYZ + A + C and XYZ + B + C five axes

Five axis can be divided into two categories: horizontal and vertical

The five axis linkage is determined by the relationship between the rotating spindle and the linear motion

Double rotary table (a + B as an example)

Add a rotating table of a-axis on the b-axis rotary table, small turbine, impeller and compact die

High rigidity precision of a + B B + C
The double swing head worktable is large and powerful, suitable for processing large workpieces, gantry type

Rotation range of five axis linkage structure:

Rotation range of double rotary table + 20a-100 b360 + 30a-120 C360

Rotation range: 30b-120 C360

Rotation range of double pendulum head is + 90a-90 C360 + 30

ISO knowledge of CNC machining

ISO9000 has several main characteristics, which can be summarized as “one essence and one center, two basic points; three characteristics, four general affairs and four major products, five major modules, six documents and eight principles”. I will simplify it to “112 344 568”

① One essence: speaking, writing and doing are consistent;

② One center: customer centered

③ Two basic points: customer satisfaction and continuous improvement

④ Three characteristics: suitability, sufficiency and effectiveness.

⑤ Four things: everyone is responsible for everything, there are rules to follow for everything, there is evidence for everything, and there is someone to supervise everything.

⑥ Four products: service, software, hardware and process materials.

⑦ Five modules: (1 total process, 4 major processes)

Quality management system; management responsibility; resource management; product realization; measurement, analysis and improvement

⑧ Six documents: the six procedure documents clearly put forward by ISO9000:2000 standard must be formulated

Document control procedures, quality record management procedures, internal audit procedures

Control procedures of unqualified products, corrective measures and preventive measures.

⑨ Eight principles: customer centered, leadership role, CNC computer gong processing in Dongguan

Staff participation, process method, system management, continuous improvement, fact based, mutually beneficial relationship with suppliers.

Seven techniques of IE

① Program analysis;

② Time analysis;

③ Movement analysis

④ Pipeline analysis;

⑤ Dynamic analysis of crops;

⑥ Material analysis;

⑦ Environmental analysis

Types of common surface treatments:

① Grinding (polishing)

② Electroplating

③ Spraying / baking

④ Heat treatment

⑤ PVD (vacuum coating)

⑥ Sandblasting

⑦ Vehicle pattern

⑧ Scratch (wire drawing)

⑨ Oxidation (coloring)

⑩ Matte

Making black

(12) trimming

The flower of the flower`

Ten steps to RoHS compliance

The first step is to determine the correlation between enterprise products and ROHS directive. (if it is determined that the products produced by the enterprise are within the jurisdiction of RoHS, then go to the second step

Step 2: set up a company wide “compliance” team within the enterprise.

Step 3: establish RoHS compliance statement.

Step 4: establish the implementation plan of RoHS compliance within the enterprise.

CNC computer gongs processing design basis

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. For the surface (or line, point) as positioning reference, only the rough surface can be selected in the first working procedure. This positioning surface is called rough datum. The machined surface can be used as the positioning datum in the following processes, and the positioning surface is called the precise datum.

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:

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 ensure the quality of the premise

Surface accuracy of CNC computer gong machining

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.

① 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, 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 cannot meet the requirements, that is, the possibility of various original errors, and take effective technological measures to overcome them, So as to improve the machining accuracy.

Common problems of CNC computer gong processing

First question:

The injection head is stuck in the gooseneck

Solution:

When the equipment is at normal temperature, try to rotate the hammer head. If it cannot be rotated, replace the sleeve and take out the hammer head.

If you want to quickly solve the problem of jamming, the best is the refueling pot. Precision mold processing

Second question:

In the process of punching, it will not be able to produce dozens of die materials. It will take a few minutes to continue to punch the precise mold processing

Solution:

Check whether there are bright spots on the top of the blanking head. If the cross-section is gray, it indicates that the nozzle is blocked. The temperature of the nozzle can be moderately increased. The time of leaving the nozzle can be reduced by 0.1 to 0.2 seconds, and the cooling water of the fixed mold is slightly turned down.

Third question:

It is easy to crack when casting thin-walled products

Solution:

This problem may be due to material problems, poor mold setting or improper selection of process parameters,

The proportion of waste material should not exceed 30%. The mold retention time should not be too long, about 3S per mm wall thickness, and the ejection delay should not be long, generally 0.5-2s.

Fourth question:

The material is hard and the tool is easy to wear

Solution:

The raw material ratio is used, and the gem blade specially produced for cemented carbide is used instead of recycled material.

Advantages of CNC computer gong processing

CNC computer gongs processing refers to the processing with CNC tools. CNC index controlled machine tool is programmed by NC machining language, usually G code.

The accuracy of the work is relatively high, and the quality of the processed products is guaranteed.
Even if there are multiple coordinates, there is no need to worry, because it can realize the linkage between the coordinates, and can process parts with complex geometry structure.
It is necessary to replace the processed parts, but only need to change the relevant data to realize the work and simplify the work
Because the computer gong is automatic, it can reduce the labor force and increase the productivity

Formulation of machining process flow

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? Let’s take a look at it

1., the advanced technology.

When working out the machining process specification, we should make full use of the existing production conditions of the enterprise, adopt the advanced technology and experience at home and abroad as far as possible, and ensure good working conditions.

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.

Computer gongs processing how to score

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

After operation, confirm the position of the workpiece and the processing sequence, and complete the table comparison

In the process of centring, if it is necessary to “split the rod”, the rotating speed is 501r / m. if the tool is used to divide the center, the speed depends on the tool. In this process, it should be noted that the data must be taken at the same height to ensure the accuracy of the split. After the separation, the “g0g54 x0y0” can be used for inspection

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

C. Precautions in CNC machining

Check whether the tool is consistent with the machining procedure

When installing the tool, confirm whether the length of the tool and the selected tool holder are suitable
In the same workpiece, each tool setting should be kept in the same area to ensure the accuracy of tool connection

In the program, use the gas blowing knife as much as possible

Clean the aluminum slag in the machine tool before the smooth knife oil injection to prevent the aluminum slag from absorbing oil
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
If too much machining allowance is found during machining,

You 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 on their own