Monthly Archive June 5, 2020

Analysis of CNC machining structure technology

The structural processability of large CNC machining parts refers to the adaptability of parts to machining methods, that is to say, the designed parts structure should be easy to machining and forming, with low cost and high efficiency. When machining parts on CNC lathe, we should carefully examine the rationality of part structure according to the characteristics of CNC turning. In the structural analysis, if any problem is found, the designer or relevant department shall generally ask for instructions and put forward modification opinions.

When CNC machining CNC lathe turning parts, the tool only makes plane movement, its forming movement form is relatively simple, and the tool path is not too complex. In the process of structural technology analysis, for the parts with narrow space and poor structural rigidity, such as small deep hole, thin-walled part, narrow deep groove and so on, the factors such as tool path, tool type, tool angle, cutting amount, clamping method and so on should be specially considered when arranging the working procedure, so as to reduce the tool loss, improve the machining accuracy, surface quality and labor productivity.

Classification of CNC machining cente

Large CNC machining centers are usually classified into horizontal, vertical and multi axis machining centers according to the relative position of the spindle and the worktable.

A horizontal machining center: refers to the machining center with the spindle axis parallel to the workbench, which is mainly suitable for machining box type parts.

B vertical machining center: it refers to the machining center set vertically between the spindle axis and the workbench, which is mainly used for machining complex parts such as plates, plates, molds and small shells.

C multi axis linkage machining center, also known as universal machining center: it refers to the machining center that can control linkage change through the angle between the machining spindle axis and the rotary axis of the worktable to complete complex space surface machining. It is applicable to the machining of impeller rotor, mould, cutting tool and other workpieces with complex space curved surface.

Construction of CNC machine

1. Casting, which is the most important part of CNC machine, directly affects the accuracy, stability, wear resistance and service life of computer gongs. After the casting is finished, it is not immediately used in production. A good casting is after wind and rain, sun exposure, natural weathering, some of which are soaked by sea water. After the casting does not change, it will be processed. The machine tool is not easy to change. CNC machining can maintain the stability and accuracy of the machine tool for a long time.

2. CNC machine machining spindle, the spindle is used to directly face the workpiece, it is driven by the motor to work, high-speed rotation, on the spindle with a tool handle, it can chip the workpiece, to meet various production needs, the quality of the spindle will directly affect the processing accuracy, if there is wear of the internal bearing, it is easy to cause the spindle swing processing out of the thing accuracy naturally Deviate several wires. At present, the rotating speed of the main shaft is generally around 8000 revolutions, and the high-speed machine can achieve more than 20000 revolutions. In the traditional machining center, each machine has only one main shaft. In recent years, there have been two or more main shaft machining centers.

3. The screw rod is also a part of the fuselage. It is driven by the servo motor. The displacement of the working table is driven by the copper sleeve of the screw rod to meet the processing needs. If there is a gap between the screw rods, it is also directly reflected in the processing accuracy and smoothness.

4. Dongguan machine parts processing motor, there are two kinds of motors: servo motor and frequency conversion motor. The stability of servo motor is good, the power of spindle drive motor is large, and the cooperation rate of three-axis drive motor is small.

5. The coupling is installed between the screw rod and the motor, which is only a linkage.

6. The lubricating cold system is composed of automatic oil pump, spindle oil cooler and chip liquid circulation system. The oil is fed automatically without manual operation. When the machine tool is working, the oil is pumped once every few minutes, and the oil pipe is connected to every corner, such as screw rod, guide rail, etc. if the oil path is blocked, it is easy to cause the guide rail wear and affect the accuracy. Dongguan machine parts processing spindle oil cooling is to cool the spindle and add a cycle of cold power system, 8000 rotation of the spindle can not be, 8000 rotation of the spindle must be equipped with more than. The chip liquid circulation system uses the pumping motor to pump up the oil from the oil tank and rush it to the workpiece being processed.

7. When machining sheet metal, the requirements for sheet metal are not too high, as long as there is no oil leakage, but it also involves the problems of beautiful appearance and image

 

How to change tools in CNC operation

When programming a large-scale computer gong, the selection of tool setting point should be considered first. The determination of tool setting point and tool change point is the starting point of tool movement relative to workpiece in the process of numerical control machining. Since the program is also executed from this point, the tool setting point is also called the program starting point or starting point. When the machining accuracy requirements are not high, some surfaces on the workpiece or fixture can be directly used as the tool alignment surface; when the machining accuracy requirements are high, the tool alignment point should be selected on the design basis or process basis of the part as much as possible, for example, for the parts with hole positioning, the axis of the hole taken as the tool alignment point is more appropriate. The tool setting point must have a certain coordinate relationship with the positioning datum of the workpiece. In this way, the relationship between the coordinate system of the machine tool and the workpiece can be determined. The selection of tool setting point in computer gong processing should be convenient for the calculation of coordinate value and the tool setting. During the tool setting, the tool setting point shall coincide with the tool position. The so-called tool point refers to the intersection of the tool axis and the tool bottom surface for the flat end milling cutter; the ball end milling cutter refers to the ball center of the ball head part; the turning tool refers to the tool tip; the drill bit refers to the drill tip; for the machining of Dongguan Mechanical parts, for the WEDM machine, it refers to the focus of the WEDM axis and the part surface. (1) Stress and warpage analysis based on double side flow technology

According to the analysis results of gate solidification effect and pressure and temperature distribution, the stress and warpage analysis module calculates the change of stress with time in the wall thickness and plane direction of the product and the shrinkage of the product in the wall thickness direction at the time of demoulding. A special double-layer shell element is used to predict the warpage of the product at the time of demoulding.

(2) The combination of numerical calculation and artificial intelligence technology

Traditional CAE software is basically a passive computing tool. Before analysis, users need to design the forming scheme and process parameters first, and often do not know how to use the analysis results to guide production after analysis. To a certain extent, this has affected the promotion and popularization of CAE software. In order to play a greater role in CAE software, HsCAE 6.10 successfully introduced artificial intelligence technology. In the simulation system, the parameters with continuous value space, such as injection time and injection temperature, are optimized by the method of artificial neural network, and the interpretation and evaluation of the analysis results are processed by the method of rule-based reasoning.

There are two lights on the power supply of NC machining center unit, one is the power indicator light, which is green; the other is the power alarm light, which is red. The power supply unit here includes the power input unit and the power control part.

When the power of CNC machining center cannot be connected, if the power indicator light (green) is not on.

Fuse F1 and F2 of power supply unit have been blown. This is caused by high input voltage, or the components of the power supply unit itself are damaged.

The input voltage of CNC machining center is low. Please check the voltage entering the power supply unit. The allowable voltage is AC 200V + 10%, 50Hz ± 1Hz.

The power supply unit is poor, and there is damage in the unit

The power indicator light is on and the alarm light disappears, but the power cannot be connected.

This is because the power on condition is not met. By the following switch circuit, the conditions for power on are as follows:

There are three conditions for turning on the power supply of CNC machining center: (1) the source on button is closed. Dongguan Mechanical parts processing (2) power off button is closed. (3) The external alarm contact is open.

In the process of using CNC machining center, there may be tool imbalance. If not adjusted in time, the processing effect will be affected. Therefore, we should always pay attention to the tool balance of CNC machining center. The main reasons for the imbalance of the tool handle are the asymmetry of the tool design, the defects in the tool body, and all the adjustments on the tool. The tool with correct balance can significantly reduce the noise and vibration, which can increase the tool life and improve the accuracy consistency of parts.

The centrifugal force of CNC machining center magnifies the vibration caused by unbalance in proportion to the square of speed. The vibration of CNC machining center caused by this increase minimizes the life of bearing bush, bearing, shaft, spindle and gear.

Before balancing the tool in CNC machining center, it is necessary to measure the unbalance and the angle position of each selected correction plane. These variables are measured on two general types of balancing machines: non rotating or gravity machines for measuring single plane imbalance, and rotating or centrifuge for measuring single plane or two plane imbalance.

After determining the magnitude and angle of the unbalance in the correct plane, you can correct it by adding or removing material from the workpiece. Machining center for components that are not tools, the most widely used material adding method of drilling and tapping center is to weld the counterweight on the components. Other methods for components with slight unbalance include adding solder to the component body or adding weight in pre drilling.

, stable high precision:

The main parts of gantry milling equipment, such as crankshaft, gear, transmission shaft and so on, have high wear resistance after hardening and heat treatment. The long-term performance is stable, ensuring the requirements of high accuracy and stability.

2、 Slider adjustment mechanism:

The sliding speed adjustment is divided into manual adjustment and electric adjustment, which is convenient, reliable, safe and fast with an accuracy of 0.1mm.

3、 Reliable and safe operation performance:

Safety knowledge in CNC operation

1. Effective protective measures shall be taken for the equipment prone to injury accidents in the processing area.

2. The protective measures shall ensure that any part of the operator’s body is prevented from entering the dangerous area under the working condition of the equipment, or that the equipment cannot operate (run) or make emergency braking when entering the dangerous area.

3. The following protective measures shall be taken for machining equipment separately or simultaneously:

(1) Completely fixed and semi fixed airtight cover;

(2) Mechanical or electrical barriers;

(3) Mechanical or electrical interlocks;

(4) Automatic or semi-automatic feeding and discharging device;

(5) Hand limiter, hand release device;

(6) Mechanical or electrical hands off device;

(7) Automatic or manual emergency stop device;

(8) Limiting devices that cause dangerous travel, feeding, or feeding;

(9) Prevent misoperation or misoperation of the device;

(10) Warning or alarm device;

(11) Other protective measures.

CNC machining selection and positioning reference

① Try to choose the design basis as the positioning basis;

② When the positioning datum and the design datum cannot be unified, the positioning error shall be strictly controlled to ensure the machining accuracy;

③ When the workpiece needs to be clamped for more than two times, the selected benchmark can complete the processing of all key precision parts in one clamping and positioning

④ The selected benchmark shall guarantee to complete as many processing contents as possible;

⑤ In batch machining, the positioning datum of parts should coincide with the tool setting datum of workpiece coordinate system as much as possible;

⑥ When it is necessary to clamp several times, the benchmark shall be uniform.

Contents and scope of CNC machining self inspection

Contents and scope of CNC machining self inspection

1. Before processing, the processor must clearly see the contents of the process card, clearly know the parts to be processed, shapes, dimensions of drawings and know the processing contents of the next process.

2、 Before clamping the workpiece, measure whether the blank size meets the drawing requirements. When clamping the workpiece, carefully check whether the placement is consistent with the programming operation instruction.

3. After rough machining, self inspection shall be carried out in time so as to adjust the data with errors in time and effectively. The content of self inspection is mainly the position and size of processing parts. For example: (1). Whether the workpiece is loose; (2). Whether the workpiece is correctly divided; (3). Whether the dimension from the processed part to the reference edge (reference point) meets the drawing requirements; (4). Position and dimension of machining parts. After checking the position and dimension, measure the rough machined shape ruler (excluding arc).

4. Finish machining can only be carried out after rough machining and self inspection. After finishing, the workers shall conduct self inspection on the shape and size of the processed parts: inspect the basic length and width of the processed parts of the vertical surface; measure the base point size marked on the drawing for the processed parts of the inclined surface. 5。 The workers can remove the workpiece and send it to the inspector for special inspection after completing the self inspection of the workpiece and confirming that it is in conformity with the drawings and process requirements.

What are the processing methods of CNC milling machine

With the continuous development and innovation of high technology, there are more and more CNC milling machine processing methods. What are the specific processing methods? People may not know how to process it. If there is anything else you don’t know, you can pay attention to the following information!

1. Flat hole system parts

It is commonly used to process point and line controlled computer gongs (such as CNC milling machine and drilling machine). When selecting the process route, two principles of processing accuracy and efficiency are mainly considered.

2. Rotating parts

Commonly used CNC lathe or grinder processing.

a. Consider machining efficiency: when machining on lathe, the machining allowance is usually large, so the rough machining route must be reasonably arranged to improve the machining efficiency. In practical programming, it is generally not suitable to use cycle command (otherwise, there are too many empty knives with working speed). Shenzhen computer gongs processing a better way is to use a rough car as soon as possible to cut materials, and then fine car.

b. Consider the tip strength: the CNC lathe often uses low strength tools to process small grooves.

3. Flat profile part

a. Direction control of cut in and cut out: radial cut in, with pits left on the workpiece surface; horizontal cut in and cut out, with smooth workpiece surface.

b. Selection of the first approximation method: when the computer gong machine tool which only has the function of line and arc interpolation processes the irregular curve contour, it needs to use the small straight line segment or arc segment to approximate the processed contour (its error is called the first approximation error). When approaching, the Shenzhen computer gong processing should make the workpiece error within the qualified range and the number of program segments less.

What are the classifications of machining centers for large CNC milling machines

There are many kinds of machining centers for large-scale gantry CNC milling machines. Here is a brief introduction:

A horizontal machining center: refers to the machining center with the spindle axis parallel to the workbench, which is mainly suitable for machining box type parts.

B vertical machining center: it refers to the machining center set vertically between the spindle axis and the workbench, which is mainly used for machining complex parts such as plates, plates, molds and small shells.

C multi axis linkage machining center, also known as universal machining center: it refers to the machining center that can control linkage change through the angle between the machining spindle axis and the rotary axis of the worktable to complete complex space surface machining. It is applicable to the machining of impeller rotor, mould, cutting tool and other workpieces with complex space curved surface

How to add the fourth and fifth axis in CNC machining

CNC is a typical set of high-tech in one machining equipment, its development represents the level of a country’s manufacturing industry, has been highly valued at home and abroad.

Compared with general CNC machine tools, CNC has the following outstanding features:

1. Fully enclosed protection all CNC have protective doors. When processing, closing the protective doors can effectively prevent personal injury accidents.

2. In the process of centralized processing, CNC processing is connected with multiple feeding shafts (more than three shafts), even multiple spindles, and the number of linked shafts is also very large, such as three-axis linkage, five axis linkage, seven axis linkage, etc., so it can actively complete the processing of multiple planes and multiple view points, and complete the high-precision processing of disordered parts. The last clamping in CNC can finish milling, boring, drilling, expanding, reaming, tapping and other processing, with highly centralized process.

3. With the use of multiple tools, the active AC CNC with tool magazine and active tool change equipment, the required tools are loaded into the tool magazine before machining, and the active tool change can be controlled by the program during machining.

4. If there are active communication worktables on the worktable active communication CNC machining, one worktable can be finished together and the other worktable can be finished to clamp the workpiece, and then greatly shorten the auxiliary time and improve the processing power.

5. It has powerful functions and tends to compound machining. CNC machining can compound turning and grinding functions. For example, the circular worktable can drive the workpiece to rotate at high speed, the cutter only makes the main movement without feeding, and the turning process is similar. This makes CNC have a wider processing scale

6. High active, high-precision and high-power CNC has high spindle speed, feed speed and rapid positioning accuracy, which can be reasonably selected by cutting parameters, fully show the cutting performance of the tool, reduce the cutting time, and all the processing processes are connected, all kinds of auxiliary actions are fast, high degree of initiative, and reduce the auxiliary action time and shutdown time. Therefore, the production power of CNC is very high High.

7. Due to the high level of intelligence, messy structure and powerful function of CNC, the cost of one-time investment and routine maintenance of CNC computer gongs is much higher than that of general machine tools.

8. It is very important for the rational application of CNC to show the best efficiency of CNC machine tools under proper conditions, that is, to show the advantages of CNC machine tools in the process of application, and to fully reflect the efficiency of CNC machine tools.

Composition of automatic tool change device for large CNC machining

The large CNC machining center is developed from the basic CNC milling machine. It integrates all the features and functions of the CNC milling machine. The only difference between the CNC milling machine and the large CNC machining center is that the machining center has an automatic tool change device, which can realize the automatic tool change function during machining. The CNC milling machine has no automatic tool change device, which can not realize the automatic tool change function, which is the only difference between CNC milling machine and machining center.

Today, Xiaobian will introduce the automatic tool change device. Automatic tool change device of machining center: the automatic tool change device of machining center is composed of parts such as tool magazine, mechanical arm and driving mechanism. The tool magazine is used to store the tools needed for machining. There are many types of magazine, mainly according to the shape, there are many kinds of magazine, such as hat magazine, disc magazine and chain magazine. The capacity of these magazine is several to hundreds of knives. In the market, there are two kinds of tool magazine commonly used in machining centers, i.e. hat magazine and disc magazine, while chain magazine is not used by many manufacturers because of its high price.

Here is a brief introduction to the tool change method. The tool change method of large-scale CNC tool magazine is relatively simple. There is no mechanical arm in this kind of tool magazine, so it is not necessary to use the mechanical arm to complete the tool change. The tool change mode of the tool magazine is as follows: the tool magazine moves to the spindle to realize the tool change. This type has the advantages of high cost performance, convenient maintenance, simple structure and so on, but the disadvantage is that the tool change speed is slow. Tool change mode of disc type magazine: the tool change mode of disc type magazine is relatively complex, which is mainly completed by the manipulator, which takes out the tool from the magazine 180 ° and rotates it into the spindle to complete the tool change. This kind of tool magazine has the advantages of fast tool change, its disadvantages are complex structure, inconvenient maintenance, and high failure rate. Although there are different ways of tool changing, tool selecting and tool structure in large-scale computer gong processing disk type tool magazine, they are all controlled by numerical control system, and the selection and exchange of tools are realized by motor, air pressure or hydraulic pressure and manipulator.