Monthly Archive December 30, 2020

How to choose CNC machine tool system

The numerical control system includes numerical control device, feed drive (feed speed control unit and servo motor), spindle drive (spindle speed control unit and spindle motor) and detection element. The selection of numerical control system should include the following contents.

  1. Selection of numerical control device

(1) Selection of types

Generally speaking, CNC drilling, milling, EDM and other devices should be selected according to their types.

(2) The choice of performance

The performance of different CNC devices varies greatly. The number of input control axes is single axis, 2 axis, 3 axis, 4 axis, 5 axis, or even more than 10 axis, 20 axis; the number of linkage axes is 2 or more than 3 axis, the maximum feed speed is 10m / min, 15m / min, 24m / min, 240m / min; the resolution is 0.01mm, 0.001mm, 0.0001mm. According to the actual needs of machine tools, for example, 2-axis or 4-axis (double turret) control should be selected for general turning, and more than 3-axis linkage should be selected for plane parts processing.

(3) Function selection

A numerical control system has many functions, including the basic function — the essential function of the numerical control device; the selection function — the function for the user to choose. Some of the selection functions are to solve different processing objects, some to improve processing quality, some to facilitate programming, some to improve operation and maintenance performance. Some of the selection functions are related, and you have to select another one to select this one. Therefore, it is necessary to select according to the design requirements of the machine tool, not without analysis, but with too many steps to select the function, and the relevant functions are omitted, which will reduce the function of the CNC machine tool and cause unnecessary losses.

There are two kinds of PLC in the selection function: built-in PLC and independent PLC. It is better to choose the built-in type, which has different models. First of all, it should be selected according to the number of input and output signals between the numerical control device and the machine tool. The selected points should be a little more than the practical points. One cup may meet the needs of adding and changing the control performance. Secondly, the size of sequential program should be estimated and the storage capacity should be selected. With the increase of the complexity of the machine tool, the storage capacity of the program increases, which should be reasonably selected according to the specific situation. There are also processing time, command function, timer, counter, internal relay and other technical specifications, the number should also meet the design requirements.

(4) Xu Ze of price

Different countries, different manufacturers of numerical control devices, produce different specifications of products, the price is very different, should meet the control type, performance, function selection, on the basis of comprehensive analysis of the performance price ratio, choose the numerical control device with high performance price ratio, in order to reduce the cost.

(5) The choice of technical service

When selecting the CNC device that meets the technical requirements, we should also consider the reputation of the manufacturer, whether the product instructions and other documents are complete, and whether the users can be trained in programming, operation and maintenance personnel. Whether there is a special technical service department to provide long-term spare parts and timely maintenance services, so as to give full play to technical and economic benefits.

  1. Selection of feed drive

(1) AC servo motor is preferred, because it has small inertia, good dynamic response, large output power, high speed, simple structure, low cost and unlimited application environment compared with DC motor.

(2) Through the correct calculation of the load conditions on the motor shaft to select the appropriate specifications of the servo motor.

(3) The feed drive manufacturer provides a series of complete products for the feed speed control unit and servo motor, so after the servo motor is selected, the corresponding speed control unit is selected by the product manual.

  1. Selection of spindle drive

(1) The mainstream spindle motor is preferred, because it does not have the limitation of commutation, high speed and large capacity as DC spindle motor, has large range of constant power speed regulation, low noise and low price. At present, 85% of CNC machine tools are driven by AC spindle.

(2) Select the spindle motor according to the following principles:

① According to different machine tools to calculate the cutting power, the selected motor should meet this requirement; ② according to the required spindle acceleration and deceleration time, the calculated motor power should not exceed the maximum output power of the motor; ③ when the spindle is required to be frequent The output power of the motor must be within the range of the required constant power and the constant speed of the surface, which should be controlled continuously.

(3) The spindle drive manufacturer provides a series of complete products for the spindle speed control unit and the spindle motor, so after the spindle motor is selected, the corresponding spindle speed control unit is selected by the product manual.

(4) When the spindle orientation control is needed, the position encoder or magnetic sensor is selected to realize the spindle orientation control according to the actual situation of the machine tool.

  1. Selection of detection elements

(1) According to the position control scheme of the CNC system, the linear displacement of the machine tool is measured directly or indirectly, and the linear or rotary detection elements are selected. At present, the closed-loop pulse rotary encoder and rotary transformer are widely used for angle measurement

(2) According to the accuracy or speed required by CNC machine tools, the position or speed detection elements (test generator, pulse encoder) are selected. Generally speaking, large machine tools mainly meet the speed requirements, while high-precision, medium and small machine tools mainly meet the accuracy requirements. The resolution of detecting element is generally one order of magnitude higher than the machining accuracy.

(3) At present, the photoelectric pulse encoder is the most commonly used detection element of CNC machine tools. It selects the corresponding specifications of pulse encoder according to the ball screw pitch of CNC machine tools, the minimum moving speed of CNC system, command rate and detection rate.

(4) When selecting the detecting element, the corresponding interface circuit of the numerical control device should be considered.

High speed Gong processing requirements

The surface quality standard of high speed computer gong parts

1、 The purpose and action of high speed Gong processing temperature control on formability. The appearance of products, physical properties of materials and forming cycle are significantly affected by die core temperature. In general, it is ideal to keep the core temperature low to increase the injection times. However, the forming cycle related to the shape of the product (core structure) and the type of finished material also depends on the need to increase the core filling temperature.

2、 In order to prevent the temperature control of stress, this is the problem of forming material, the only requirement is cooling rate. The cooling time is short. Even if some parts are hardened and some parts are soft, the stress caused by uneven shrinkage can be avoided. That is to say, proper temperature control can improve the properties of cooling stress.

3、 Temperature control of crystallizing degree adjustment of forming material. High molding temperature is usually required to adjust the degree of crystallization and improve the mechanical properties of crystalline materials such as polyamide, polyacetate and polypropylene.

  1. Computer gong processing fastening parts, check whether the fastening parts loose, damage phenomenon, the way is to find the same specification of metal stamping parts for replacement.
  2. The edge of metal stamping must be ground after a long time of use. After grinding, the edge surface must be demagnetized without magnetism, otherwise the metal stamping is prone to material blocking.
  3. The punch is easy to break, bend and gnaw in the process of metal mold processing. The punch sleeve is generally gnawed. The damage of the punch and the punch sleeve of metal stamping is generally replaced with parts of the same specification. The punch parameters mainly include the size of the working part, the size of the installation part and the length size.
  4. High speed Gong processing hardware stamping parts, such as pressure plate, uniglue, etc., discharge parts, such as stripper, pneumatic top material, etc., during maintenance, check the parts of the relationship and whether there is damage, repair the damaged parts, pneumatic top material check whether there is air leakage, and take measures for the specific situation, such as the replacement of air pipe damage.

Basic program of large computer gong processing

  1. Large scale computer gong processing accuracy requirements, a mold is generally composed of female mold, male mold and mold base, some may also be multi-component module. Therefore, the combination of upper and lower die, the combination of insert and cavity, and the combination between modules all require high machining accuracy. The dimensional accuracy of precision die for machining mechanical parts is often up to μ m level.
  2. The shape and surface of some products, such as automobile panels, aircraft parts, toys and household appliances, are complex. The surface of the shape is composed of a variety of curved surfaces. Therefore, the cavity surface of the mold is very complex. Some surfaces must be treated mathematically.
  3. The production of small batch mold is not mass production, in many cases, only one batch is produced.
  4. There are many working procedures for large-scale computer gong, and many working procedures such as milling, boring, drilling, reaming and tapping are always used in mold processing.
  5. The service life of repetitive production mould is long. When the service life of a pair of molds exceeds its service life, it is necessary to replace the new molds, so the production of molds is often repetitive.
  6. In the mold production of copying process, sometimes there is neither drawing nor data, and the copying process should be carried out according to the real object. This requires high imitation accuracy and no deformation.
  7. Large computer gong processing mold material is excellent, high hardness, the main material of the mold is made of high-quality alloy steel, especially high life mold steel. This kind of steel has strict requirements from blank forging, processing to heat treatment. Therefore, the establishment of processing technology can not be ignored, and heat treatment deformation is also a serious problem in processing. The basic operation of high-speed Gong machining requires that the working performance of high-speed Gong machining center is an important prerequisite for mold manufacturing industry to process mold efficiently and accurately. Driven by drive technology, many different types of high-speed machining centers with innovative structure and excellent performance have emerged. Do not place obstacles around the high-speed machining center to ensure that the working space is large enough; do not splash water or oil on the ground to ensure that the working ground is clean and dry; do not move or damage the warning signs installed on the machine tool to ensure that the safety warning signs are bright and eye-catching. Don’t touch the switch with wet hands, otherwise it will cause electric shock; before pressing the switch, make sure it is correct, so as to avoid danger caused by wrong connection; be familiar with the position of the emergency stop button, and make sure that you can press it when you need to use it.

Processing copper parts with computer gong

Precision copper processing in our daily life, we often encounter a variety of copper, mechanical parts processing, some products for copper processing technology requirements are very high, the process is not the same, for the processing of product scale is also to have a certain understanding, and then according to the sketch to make mold, so the sketch is very important, in the lamp material copper processing This material is not easy to rust, but also has a long service life. This material is not easy to be cut, and can be made into various shapes. The most important point is that it is conducive to the melting treatment of objects.

And copper alloy is easy to oxidize and change color after pickling. After pickling, copper parts can be immersed in anti tarnishing agent for several minutes, which can effectively prevent copper parts from changing color. The commonly used anti tarnishing agent is ab-712. Take 1 liter working solution as an example, take 70 ml ab-712 anti tarnishing agent, add 930 ml distilled water, stir evenly, and then use it.

BH anti discoloration agent can also be used. BH anti discoloration agent for precision copper parts processing is suitable for anti discoloration treatment of copper and copper alloy chemical polishing parts, copper plating and copper alloy (imitation gold, etc.) parts before coating, anti discoloration treatment of barrel nickel plating parts, composite anti discoloration treatment of silver plating, gold plating and electroplating imitation gold parts after electrolytic passivation, so as to improve its anti discoloration effect. It can also be used for fixation of copper and copper alloy parts after dyeing. It is a new process of chromium free, low pollution and environmental protection.

  1. The polishing solution does not contain chromic acid, which meets the requirements of today’s environmental protection and saves the investment of environmental protection equipment and waste water treatment costs.
  2. The current density of polishing is smaller than that of traditional process, so it not only has low power consumption and long service life of polishing solution, but also is more suitable for surface polishing of large aluminum and aluminum alloy parts.
  3. Precision copper processing has a wide range of applications. CNC machine tools are suitable for processing pure aluminum and various types of aluminum alloys with silicon content more than 2%.

Composition and operating conditions of polishing solution

Concentrated phosphoric acid (specific gravity 1.74) 70% (weight)

Yb-66 additive 30% (weight)

Precision copper processing temperature 55 – 65 ℃, the best 60 ℃

Anode current density, Da 2 – 8 A / DM2 (without stirring)

12 – 20 A / DM2 (stirring)

Voltage 10 – 15 V

Polishing time 3 – 5 minutes

Cathode material lead or stainless steel

Cathode area: anode area 2 – 3:1

Operation process of milling head in CNC machining

CNC milling head can increase the application range, if there is no milling head, boring machine can only process one station, and after installing the milling head, it can install more than 8 stations, and the extension range of spindle can also be expanded.

  1. The use of milling head should also be based on the parameter characteristics of each model, in the appropriate processing conditions, that is to select milling head products for processing.
  2. Avoid long time let milling head at the highest speed of continuous processing, this kind of shaft running mode is easy to cause overwork, will damage the service life of the machine.
  3. It should be confirmed several minutes before commissioning. Each time processing, need to select the appropriate speed and feed processing. Pay attention to adjust the speed, feed and cutting depth gradually until the maximum machining efficiency is achieved.
  4. In most cases, the milling head uses non-contact oil seal. If you want to use cooling water in the machining process, you should avoid adding it directly. Instead, you should run for a while before spraying water, and adjust the direction of the cooling water nozzle to spray water towards the tool, so as to prevent the cooling water from penetrating into the body and causing damage to the machine.

In the process of CNC machining center working, intermittent current alarm appears, English prompt appears on the display interface, 12 words appear in the spindle display module, and 0 display appears at the power module, which can be directly understood as zero voltage. From this point, it can be preliminarily inferred that there is current and leakage at the fault part of CNC machining center.

When checking other parts that may cause current alarm, there is no special phenomenon. The material of processing parts is in line with the operating conditions of CNC machining center, and there is no error in speed and processing mode, so there is no current overload phenomenon.

Check the circuit and find no abnormality,

CNC machining center is the use of three-phase power supply, the voltage is normal, so it is not circuit failure.

When observing the current alarm of CNC machining center again, it is found that the main position of the equipment is in the same feeding area every time the alarm is given. Further observation shows that the wire at the end of the threading slot is damaged, so when the spindle of CNC machining center moves to this area, the wire will cause short circuit fault.

After finding the cause of the fault, it is necessary to cut off all the power supply of CNC machining center, replace the damaged wire, and pass the new wire through the bend at the end of the slot.

The common sheet parts such as washer, friction plate, sample plate and thin plate, due to poor rigidity, heat dissipation difficulty, bending after heat treatment, clamping deformation during clamping and warping during grinding, usually use magnetic chuck to grind on the surface grinder. After grinding, the magnetic attraction is removed, and the sheet work is restored to its original state, so it is difficult to ensure the processing accuracy. If the following clamping methods are adopted to ensure the positioning and clamping of the sheet workpiece in the free state, and the double end face is used for grinding, good results can be achieved and the machining accuracy requirements of the parts can be met.

1 elastic gasket clamping mode, {i5 E3 U8 d * [9 F

When grinding the sheet workpiece on the surface grinder, the elastic clamping mechanism is adopted to realize the positioning and clamping of the sheet workpiece in the free state. A layer of rubber with thickness of 0.5mm is padded between the workpiece and the magnetic worktable. When the workpiece is affected by the magnetic attraction, the rubber is compressed and the elastic deformation becomes smaller, so that the flat plane of the workpiece can be ground. Repeated grinding for several times can meet the requirements of machining accuracy.

  1. Using temporary measures to strengthen the rigidity of sheet workpiece: Z8 V2 I6 s * U2 E. I – [7 V

Epoxy resin is used to bond the sheet to a flat plate in free state. Place the plate and the sheet on the magnetic chuck. After grinding the plane of one end of the sheet, remove the sheet from the flat plate, put the flat side on the magnetic chuck, and then grind the plane of the other end of the sheet. Due to the fluidity of epoxy resin before hardening, it can fill the gap between the sheet workpiece and the flat plate. When the epoxy resin is hardened, the workpiece and the plate are bonded together to form a whole, thus greatly enhancing the rigidity of the workpiece. Under the magnetic force attraction, the sheet workpiece will not produce clamping deformation in CNC machining, which creates the conditions for grinding out the flat plane. Thick grease can also be used instead of epoxy resin to fill the gap between the sheet workpiece and the magnetic chuck, so as to enhance the rigidity of the workpiece, and good results can also be obtained.

  1. Mechanical clamping mode ‘H9’) g% B x / J

Therefore, the small flat tongs of the worktable with magnetic force can absorb the workpieces. The feed rate is gradually reduced to grind one plane of the sheet workpiece and then take it off. At this time, the ground plane is put on the magnetic worktable, and then the other plane of the sheet workpiece is grinded again and again, and the flatness of the two planes meets the requirements. (Y4 @ 7 F. Z0 F “S9 X4 vacuum clamping mode ‘d0 L1 Q0 | 3 {8 h” g (V / K: l)

The pressure of atmosphere is used to clamp the workpiece for grinding.

Its working principle is: the clamp is provided with a rubber sealing ring, and the sheet workpiece is placed on the rubber sealing ring, so as to form a sealing cavity between the workpiece and the clamp. The vacuum pump is used to draw the indoor air from the air extraction hole, and the workpiece is clamped. Because of the small clamping force, the circular grinding method can be used for grinding. When one end of the workpiece is ground and the other end of the workpiece is ground, the above method can be used and satisfactory results can also be obtained.

How to deal with oil leakage of CNC machine tools

  1. Design reasons

One of the main reasons for machine tool leakage is due to unreasonable design. Due to the neglect of the particularity of sealing technology, the design of sealing structure is unreasonable, resulting in the leakage of machine tool. Its performance is that the design scheme of the sealing structure is not suitable for the working pressure, working temperature, medium characteristics and environmental conditions; ventilation, oil return, liquid guide device and other measures are not considered in the design, such as the place where the oil return labyrinth groove should be set is not set; computer Gong processing | mechanical parts processing | Dongguan CNC machining center | Dongguan high-speed computer gong processing bearing seat is lubricated with thin oil and the limit value is high The rotation speed is very high, the oil temperature is very high, but there is no vent. Wechat for metal processing, with good content, is worthy of attention. In the design of sealing structure, we did not pay attention to anti-corrosion, anti vibration, pressure equalizing and dredging measures, but only one-sided considered plugging; the screw holes on the box were designed as through holes without sealing measures; the box cover did not take corresponding sealing gasket; the matching relationship between the shaft and the box hole was unreasonable, the gap was too large; the interference between the sealing ring and the shaft did not meet the standard requirements; the design of the sealing groove was not up to standard All these will cause oil leakage.

  1. Manufacturing reasons

This is one of the important reasons for the leakage. The main problems are machining accuracy and surface roughness. For example, only turning is used in the place where grinding treatment is needed, resulting in the surface roughness of the processing place not meeting the requirements, resulting in leakage; for various pumps and valves in the hydraulic system, the leakage is controlled by clearance. If the manufacturing accuracy is out of tolerance and does not meet the design requirements, the internal leakage will be increased and the work efficiency will be reduced; the leakage often occurs in castings If preventive measures are not taken, these defects are often the source of oil leakage in the process of equipment use.

  1. Reasons for equipment installation

The quality of equipment installation also has a greater impact on leakage. In practical work, equipment installation personnel do not assemble according to the correct assembly process, computer gong processing, mechanical parts processing, Dongguan CNC machining center, Dongguan high-speed computer gong processing or equipment installation personnel do not install correctly, assembly errors, or assembly process confusion, etc. are easy to cause equipment investment Leakage occurs after use. Moreover, when the equipment installation personnel carry out the assembly operation, if they use the big hammer and other tools to operate the place that should be knocked lightly, it will cause oil leakage due to the damage of individual parts of the equipment. Wechat for metal processing, with good content, is worthy of attention. Because the installation personnel do not pay attention to the working principle of the equipment or ignore the technical requirements of the drawings, the reverse installation of the framework oil seal and other seals will inevitably lead to leakage.

  1. Reasons for sealing elements and materials

Improper selection of sealing elements and materials will shorten the service life of the sealing device, lead to poor sealing performance and easily lead to equipment leakage. For example, the use of hardness and working pressure does not adapt to the sealing rubber, or the selection of internal and external diameter is not suitable for the sealing ring. In addition, the oil resistant rubber products used for oil pipes and pipe joints will be aged, hardened and brittle due to long-term use, resulting in oil leakage at the joints of oil pipes and pipe joints.

  1. Operational reasons

Improper operation and poor maintenance are the most direct causes of equipment leakage. If too much oil is added, the transmission shaft of the spindle box of the machine tool is completely immersed in the oil, the computer gong processing, mechanical parts processing, Dongguan CNC machining center, Dongguan high-speed computer gong processing, when the gear rotates, the pressure in the box increases and causes oil leakage; or the vent hole is blocked but not treated, the packing gland is not compacted, and the micro leakage is not treated in time, and the sealing element cannot be replaced after damage If the sealing parts and sealants are not used correctly, there are paint, burr, impurity or bruise on the joint surface of the upper and lower boxes of the reducer, which makes the joint surface not tight. If the sealants are not used after the equipment is sealed, the equipment will leak.

Basic introduction of drilling and tapping machine

Drilling and tapping center is a kind of metal cutting equipment. Its style and function are basically similar to machining center, but it is smaller than machining center. Generally, the stroke is no more than (x / y) 800 × 400mm. It is mainly used for drilling and tapping of nonferrous metals, 3C industry, aluminum substrate, etc. Although it can realize boring and milling, due to the low power of main motor, it can’t carry out heavy tapping of ferrous metals Cutting, but the efficiency and quality of drilling and tapping speed is more than 10 times of that of ordinary machining center. For 3C, communication industry and other industrial customers, it is the most ideal processing equipment.

Current overall market analysis:

Due to the rise of mobile phone industry, communication industry and tablet computer industry in recent years and the continuous upgrading to please consumers, the accompanying supporting processing industry is also rising, especially the demand for drilling machine is growing.

In the early stage of drilling and tapping center, the water-based cutting fluid (water-based) was used in the separate cooling water tank, and both stations were used. However, after a period of time, it was found that the water-based cutting fluid of drilling and tapping center was not good for drilling and tapping threads, especially for taps, which were “astringent” during machining and were very easy to break, and the quality of the tapped holes was not good. Therefore, we changed the drilling center to dry machining. When we arrived at the tapping station, kerosene was used for lubrication (kerosene was supplied by the pump alone, and the electrical control) to produce good thread quality, and the tap was rarely broken. The processing form of drilling and tapping Center: manually push the material to the conveying position, press the “swing up” button to enter the automatic cycle, and the two headstocks act at the same time. After the second feeding, the two headstocks return to the original position.

CNC machine tool is a widely used drilling and tapping center. CNC machine tool is a kind of advanced equipment with excellent performance, wide range of technology, high precision of drilling and tapping center and high production efficiency. One time clamping can complete drilling, reaming, boring, grooving and plane milling. In addition, it can also process holes with high precision. CNC machining is used for heavy machinery, engineering machinery, rolling stock, mining equipment, large motor and water turbine , steam turbine, shipbuilding, steel, military and other industrial sectors essential processing equipment. The CNC machine tool has the characteristics of good rigidity, high precision, strong reliability, convenient operation, beautiful appearance, etc., especially in the end face of square ram, it can also install various accessories or cooperate with the rotary table, which can further expand the application scope of CNC machine tool. CNC machine tools are mainly used for boring large and medium-sized parts of the hole, but also can complete drilling, expanding, reaming, milling plane and other work. The CNC machine tool is equipped with a change gear device, which can process metric or English internal thread. The end face can be turned by using the flat disc radial tool rest, which can be used online with the rotary table, and the inner hole and outer circle with large diameter and short length can be processed.

Installation process of CNC machining

The automatic tool changing device of machining center is composed of tool magazine and tool changing mechanism. There are many kinds of tool magazine, including disc type and chain type. The storage capacity of chain magazine is large.

In order to further shorten the non cutting time, some machining centers are equipped with two pallets which automatically exchange workpieces. One is loaded with workpieces for processing on the worktable, and the other is loaded and unloaded outside the worktable.

The tool change mechanism exchanges tools between the machine tool spindle and the tool magazine, commonly known as the manipulator; there are also no manipulator and the spindle directly exchanges tools with the tool magazine, known as the armless tool change device.

Machining center is divided into vertical type and horizontal type according to the arrangement of spindle. Horizontal machining center generally has indexing turntable or numerical control turntable, which can process all sides of the workpiece; it can also make joint movement of multiple coordinates to process complex space surface. The vertical machining center generally does not have a turntable, only for the top surface processing.

In addition, the machining center and spindle can be adjusted into horizontal axis or vertical axis of the vertical and horizontal adjustable machining center, they can process five surfaces of the workpiece.

The common lathe has a wide range of processing objects, a wide range of spindle speed and feed adjustment, and can process the internal and external surfaces, end faces and internal and external threads of the workpiece. This kind of lathe is mainly operated by manual workers with low production efficiency. It is suitable for single piece, small batch production and repair workshop.

Turret lathe and turret lathe are equipped with turret turret or return wheel turret which can hold multiple cutters. Workers can use different cutters to complete a variety of processes in one clamping process, which is suitable for batch production.

The automatic lathe can automatically complete the multi process processing of small and medium-sized workpieces according to a certain program. It can automatically load and unload materials and repeatedly process a batch of the same workpieces. It is suitable for mass production.

Multi Tool semi-automatic lathe can be divided into single axis, multi axis, horizontal and vertical. The layout of the single axis horizontal lathe is similar to that of the ordinary CNC lathe, but the two groups of tool holders are respectively installed in the front and back or up and down of the spindle, which are used to process disc, ring and shaft workpieces, and their productivity is 3-5 times higher than that of the ordinary CNC lathe.

The lathe can imitate the shape and size of the template or sample, and automatically complete the processing cycle of the workpiece. It is suitable for small batch and batch production of the workpiece with complex shape. The productivity is 10-15 times higher than that of the ordinary lathe. There are multi turret, multi axis, chuck type, vertical and other types.

The spindle of the lathe is perpendicular to the horizontal plane, the workpiece is clamped on the horizontal rotary table, and the tool rest moves on the beam or column. It is suitable for machining larger, heavier workpieces which are difficult to install on ordinary lathe. It is generally divided into single column and double column.

When lathe is turning, the tool rest makes radial reciprocating motion periodically, which is used for forming tooth surface of forklift milling cutter, hob, etc. Usually with grinding accessories, a small grinding wheel driven by a separate motor is used to grind the tooth surface.

Lathe is used to process a certain kind of workpiece specific surface lathe, such as crankshaft lathe, camshaft lathe, wheel lathe, axle lathe, roll lathe and ingot lathe.

The lathe is mainly used for turning, but after adding some special parts and accessories, it can also carry out boring, milling, drilling, inserting, grinding and other processing, with the characteristics of “one machine with multiple functions”, which is suitable for the repair work of engineering vehicles, ships or mobile repair stations.

Processing 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 some parts which cannot be observed.

The working principle of CNC machining is divided into several points

Firstly, in the process of clamping, in order to simplify the machining origin of each positioning surface relative to the work center, there should be accurate coordinate dimensions. Secondly, the orientation of mechanical parts installation is consistent with the orientation of workpiece coordinate system and machine coordinate system selected in programming, and directional installation. In the production and processing of batch precision mechanical parts, it should be considered that the fixture suitable for new workpiece can be changed after a short time of disassembly. As the auxiliary time of machining center has been compressed very short, the loading and unloading of supporting fixture can not take up too much time.

In the production of the fixture, should have as few workpieces and higher stiffness. The fixture should be open as far as possible, the space position of clamping workpiece can be low as possible, and the installation fixture should not interfere with the tool path. In order to avoid affecting the processing process, ensure that the processing content of the workpiece is completed within the stroke range of the spindle!

When there is an interactive worktable, the fixture design must prevent the space interference between the fixture and the machine tool due to the movement, up support, down support and rotation of the worktable. Try to complete all the processing contents in one clamping. When it is not necessary to replace the clamping point, special attention should be paid not to damage the positioning accuracy due to replacing the clamping point. If necessary, it should be explained in the drawing processing technology.

How to achieve control balance in CNC machining

CNC (numerical control machine tool) is the abbreviation of computer numerical control machine tool, which is a kind of automatic machine tool controlled by program. The control system can logically process the programs with control codes or other symbolic instructions, and decode them by computer. Thus, the machine tool can perform the specified action, and the blank can be processed into semi-finished parts by cutting tools.

The computer gong machining center is a highly mechatronic product. After the workpiece is clamped, the CNC system can control the machine tool to automatically select, change the tool, set the tool, change the spindle speed and feed rate according to different processes. It can continuously complete drilling, boring, milling, reaming, tapping and other processes, thus greatly reducing the workpiece clamping time, measuring and machine tool adjustment and other auxiliary processes It has good economic effect for the parts with complex machining shape, high precision and frequent variety replacement.

CNC milling machine is developed on the basis of general milling machine. The processing technology and structure of the two machines are basically the same. However, CNC milling machine is an automatic processing machine controlled by program, so its structure is very different from that of ordinary milling machine. Considering the limitation of traditional reliability method, the superiority evaluation principle of extension engineering method is applied, This paper defines and calculates the influence degree and influence factor of each subsystem and its failure mode of machining center on the reliability of machining center. Combined with the failure example of a machining center, the detailed calculation is carried out under the condition of comprehensively considering all failure factors, and the reliability improvement measures are put forward.

It is correct that not all tools need to be balanced, especially when the process results in increased costs and additional steps. Whether to balance the cutting tools depends on the specific situation. At high speed, the balance effect is the most prominent, but at any speed, the balance tool produces better shape and position accuracy, improves surface finish and prolongs tool life.

How to improve wear resistance in parts processing

  1. Avoid sliding friction pairs made of the same materials

Avoid too large thickness of white alloy

  1. Avoid increasing the requirements for the whole part in order to improve the wear resistance of the part surface
  2. Avoid local wear of large parts and scrap the whole parts
  3. When white alloy is used as bearing liner, attention should be paid to the selection of bearing material and the design of bearing structure
  4. The lubricant supply is sufficient, covering the working face
  5. The lubricating oil tank should not be too small
  6. Do not let the filter filter out the additive in the lubricant
  7. The size, position and shape of oil groove of sliding bearing shall be reasonable
  8. The amount of grease added into the rolling bearing should not be too much
  9. Add a certain amount of wear allowance to the easily worn surface of parts
  10. Pay attention to the adjustment of worn parts
  11. The velocity and pressure difference between different points on the same contact surface should be small
  12. Adopt dust-proof device to prevent abrasive wear
  13. Avoid step wear
  14. Contact oil seal cannot be used for sliding bearing
  15. The easily worn parts shall be protected
  16. For easily worn parts, the structure of automatic wear compensation can be adopted
  17. Avoid the distance between the force point and the support point
  18. Avoid cantilever structure or reduce cantilever length
  19. Don’t ignore the beneficial effect of working load
  20. Avoid using friction to transfer force for parts under vibration load
  21. Avoid the unbalanced force in the mechanism
  22. Avoid considering only one way of force transmission
  23. High speed computer gong processing should not ignore the influence of part deformation on stress distribution during working
  24. Avoid large tensile stress on iron castings
  25. Avoid bending stress on thin rod
  26. Avoid excessive rigidity of parts under impact load
  27. Avoid rough surface or scratch of parts under variable stress
  28. Residual tensile stress should be avoided on the surface of parts under variable stress
  29. The stress concentration of parts under variable load should be avoided or reduced
  30. Avoid that the local structures that affect the strength are too close to each other
  31. Avoid pre deformation in machining of mechanical parts, and the deformation direction is the same as that produced by working load
  32. The diameter of pulley and drum of wire rope shall not be too small
  33. Avoid too many times of wire rope bending, and pay special attention to avoid repeated bending during machining of mechanical parts
  34. Allowance shall be left at the joint of wire rope and drum during lifting
  35. The intermediate parts of CNC machining center that can not transfer force should be avoided as far as possible
  36. Try to avoid additional force caused by misalignment of axis during installation
  37. Minimize the force acting on the foundation.

The reason why the machining center does not grasp the tool

There are two ways of tool change in vertical machining center: manipulator tool change and direct tool change. There are many reasons why the tool magazine can not grasp or change the tool correctly. To sum up, there are the following 7 points.

  1. It is caused by solenoid valve or magnetic induction switch of tool magazine

Vmc750 vertical machining center adopts direct tool change mode, and the tool magazine has two actions: swing and rotation. A three position five way solenoid valve is used to control the cylinder to drive the tool magazine to swing, and a single-phase tool magazine motor is used to realize the rotation of the tool magazine. There is a progressive switch in the magazine for counting. When changing the tool, the tool magazine should be placed at the spindle position first, put the original tool back into the tool sleeve, and then rotate the tool magazine to find the next tool. The spindle position and original position of Dongguan high-speed computer gong machining tool magazine are determined by two magnetic switches on the cylinder of the tool magazine. When the solenoid valve and magnetic switch fail and give an alarm [39-12], the tool magazine does not move to the spindle position within the specified time; when [39-15], the tool magazine does not move to the original position within the specified time. At this time, check whether the solenoid valve has action. If the swing magazine can’t hear the action sound of the solenoid valve all the time, check the valve manually (at this time, it’s better to disconnect the output end of the valve). If it’s broken, replace it.

  1. The three switch values in the headstock are incorrect

Whether the state of the spindle after grasping the tool is correct or not is judged by the three progressive switches (sq7 clamping switch, SQ8 release switch, sq9 no tool switch) in the spindle box. The three switches are distributed in a triangle and sense different parts of the loose broach cylinder. The correct position switch value should be (1) normal no knife: sq9 and sq7 lights on; (2) normal knife: only sq7 lights on; (3) press the knife release key: only SQ8 lights on. Usually, the three switch states are not correct. The alarm code is [39-4]: rod failure; [39-13]: rod loosening failure; [39-14]: rod clamping failure; [39-34]: tool not clamped. These kinds of alarms are related to the three progressive switches. It is necessary to check whether the switches are good or bad and adjust them to the appropriate position to make the switch indication correct.

  1. Damage of light board

If the valve is correct, it is necessary to check the status of I / O switch value: whether the signal of spindle position slidrum spdl000:00 / 15 or original position slidrum park000:00 / 16 has been given. Check whether the corresponding 24 V level signal on the light disaster board, the fuse on the board and the 110 V voltage signal from the light disaster board are sent to the solenoid valve, and check the signal voltage all the way to find out the fault point. Vertical CNC machine tools are usually more likely to damage the safety tube and light tube. Just buy the same glass safety tube or light tube and replace it.

  1. Mechanical jamming

If the handle of the knife is stuck, you can hear the pressing sound of the cylinder by pressing the release key, but the knife just can’t come off. This is due to the tool handle not pay attention to maintenance and rust, or due to the spindle taper hole or tool handle with iron chips caused by stuck. At this time, just press and hold the release key. Under the condition of confirming that the cylinder of the release broach is pressed down, use wood to act on the edge of the handle and knock the tool off gently. Another problem is that the pull rod is stuck. It is necessary to remove the spindle and knock out the pull rod. At this time, there are usually scratches on the surface of the pull rod. If it is serious, you need to mill off the scratches and knock them in again.

Sometimes the cutterhead is mechanically jammed. In addition to mechanically cleaning the iron filings stuck in the cutterhead, the operator is required to remove the iron filings in the cutterhead in time to keep the cutterhead and the handle clean.

  1. It is caused by incorrect counting switch of tool magazine

Incorrect counting switch of tool magazine can also lead to incorrect tool change or grabbing. There are [39-38] alarms: the tool sleeve does not turn to the correct position; [39-44] the tool magazine cannot be placed to the spindle position. Check whether the switch is damaged and adjust the switch state to the correct sensing position.

  1. CNC system failure

During the maintenance, some strange phenomena have been encountered, such as normal start-up of the equipment, self inspection, loading system, secondary power on, calibration of the mechanical zero point, and then calibration of the tool magazine, the tool magazine can neither rotate nor swing. After checking the I / O switch value, it is found that the switch value pridrum Park and pridrum SPDL are both 0 when pressing the fl key (Park home position) and the F2 key (SPDL spindle position), indicating that the signal is not given and the magazine will not move naturally. Check the self-test table, computer gong processing, mechanical parts processing, CNC machine tool processing, Dongguan high-speed computer gong processing found that the left main board, right main board, bridge board, servo board, I / O board, touch screen and keyboard board passed normally. However, when the electrical cabinet was opened for inspection, it was found that the bridge board indicator of CNC system was incorrect. Through the exchange and comparison test of two machine tools, the fault point is finally locked on the bridge plate and recovered after replacement.

  1. Machine tool protection

Sometimes, due to misoperation, the protection action of the machine tool makes it impossible to grasp the knife correctly. At this time, just press the emergency stop switch to power on again, or directly shut down the machine and restart it.