2019 – Page 25 – CNC Machining & Turning, Milling, Metal parts

Development and application of laser welding machine welding technology

Laser welding machine welding technology is a combination of laser technology, welding technology, automation technology, material technology, mechanical manufacturing technology and product design as one of the integrated technology, and ultimately embodied as a complete set of special equipment, but also as a supporting process. As an important part of advanced manufacturing technology, laser welding technology has a broad application prospect in the future aviation manufacturing industry. The development direction of laser welding technology is mainly in the following aspects

1. laser welding of filler wire

Laser welding machine generally does not fill the welding wire, but the welding parts assembly gap requirements are very high, sometimes it is difficult to ensure in actual production, limiting its application. Laser welding with filler wire can greatly reduce the requirement for assembly clearance. For example, aluminum alloy sheet with a thickness of 2 mm, if no filler wire is used, the gap between the sheet metal must be zero in order to obtain good forming. For example, if the welding wire with a thickness of 1.6 mm is used as filler metal, even if the gap is increased to 1.0 mm, the weld seam can be well formed. In addition, filler wire can also adjust chemical composition or carry out thick plate multilayer welding.

2. beam rotating laser welding

The method of rotating laser beam for welding can also greatly reduce the requirements of welding assembly and beam alignment. For example, when 2 mm thick high strength alloy steel plate is butted, the allowable butt gap increases from 0.14 mm to 0.25 mm, while for 4 mm thick plate, the allowable butt gap increases from 0.23 mm to 0.30 mm. The alignment error of the beam center to the weld center is increased from 0.25mm to 0.5mm.

3. on line inspection and control of laser welding quality

In recent years, the detection of laser welding process by using the signal of light, sound and charge of plasma has become a hot research topic at home and abroad. A few research results have reached the level of closed-loop control. The sensors used in laser welding quality detection and control system and their functions are briefly introduced as follows:

(1) plasma monitoring sensor

1) Plasma Optical Sensor (PS): Its function is to collect the characteristic light-ultraviolet signal of plasma.

2) Plasma Charge Sensor (PCS): The nozzle is used as a probe to detect the potential difference between the nozzle and the workpiece due to the inhomogeneous diffusion of plasma charged particles (positive ions, electrons).

(2) system functions

1) identify which way the laser welding process is. In stable deep penetration welding process, there are plasma, PS and PCS signals are very strong; in stable thermal conduction welding process, there is no plasma, PS and PCS signals are almost equal to zero; in unstable mode welding process, plasma is produced and disappeared intermittently, and corresponding PS and PCS signals rise and fall intermittently.

2) Whether the laser power transmitted to the welding area is normal or not, and when other parameters are fixed, the intensity of PS and PCS signals corresponds to the power incident to the welding area. Therefore, monitoring the PS and PCS signals can be known whether the light guide system is normal, whether the power of the welding area has fluctuations.

3) automatic tracking of nozzle height. The PCS signal decreases as the distance between nozzle and workpiece increases. The closed-loop control based on this law can keep the distance between the nozzle and the workpiece unchanged and realize the automatic tracking of the height direction.

4) focus position automatic optimization and closed loop control. In the range of deep penetration welding, when the beam focus position fluctuates, the plasma optical signal received by PS changes accordingly, and the PS signal is the smallest at the best focus position (at this time the hole is the deepest). According to this rule, the focus position can be automatically optimized and closed-loop controlled, so that the focus position fluctuation is less than 0.2 mm and the penetration depth fluctuation is less than 0.05 mm.

Summary:

While laser welding technology is widely used, it is also continuously studied in depth. In view of its shortcomings, the heating performance of other heat sources is used to improve the laser heating of workpiece. On the basis of maintaining the advantages of laser heating, laser welding with other heat sources is carried out. There are laser and arc, laser and plasma arc, laser and induction heat source hybrid welding and double laser beam welding. Composite welding can increase welding penetration, improve joint performance, reduce equipment costs, and improve welding speed and productivity. In short, laser welding has high production efficiency, stable and reliable processing quality, good economic and social benefits. In an era of endless and renewal of new equipment, new materials, new technologies and new processes, producers should not only understand the characteristics, advantages and requirements of laser welding, but also recognize the many innovations and future trends in this field. Only in this way can they grasp the trend of technological popularity and keep up with the times.

Heat dissipation of inverter

If you want to use the transducer correctly, you must seriously consider the problem of heat dissipation. The failure rate of the transducer increases exponentially with the increase of temperature. The service life decreases exponentially with the increase of temperature. The ambient temperature is increased by 10 degrees, and the life of the converter is reduced by half. Therefore, we should pay attention to the question of heat dissipation. When the inverter works, the current flowing through the inverter is very large, and the heat generated by the inverter is very large, so we can not ignore the effect of its heating.

Generally, the frequency converter is installed in the control cabinet. To know the approximate calorific value of a frequency converter, you can use the following formula: the approximate calorific value = the converter capacity (KW55 [W]) here, if the converter capacity is 150%*60 of the overcurrent capacity based on a constant torque load, if the converter has a DC reactor or a communication reactor, but also in the cabinet, then The heat will be greater. The reactor equipment is better in the front and the top of the inverter. Budget: Inverter capacity (KW60 [W], since the hardware of each inverter manufacturer is almost the same, so the above can be used for all brands of products.

Note: If there is a brake resistance, because the brake resistance has a large heat dissipation, it is best to isolate the device from the inverter, such as installed on the top or side of the cabinet. Then, how to reduce the heat generated in the control cabinet? When the inverter is installed in the control cabinet, the problem of the calorific value of the inverter should be considered. According to the increase of the calorific value in the cabinet, the size of the cabinet should be increased appropriately.

Therefore, to minimize the size of the control cabinet, it is necessary to minimize the heat generated in the cabinet. If the frequency converter is installed, the radiator part of the frequency converter is placed outside the control cabinet, 70% of the heat generated by the frequency converter will be released to the outside of the control cabinet. Because the large capacity inverter has a large amount of heat, it is more effective for large capacity inverters.

The isolating plate can also be used to separate the body from the radiator, so that the heat dissipation of the radiator does not affect the converter body. The effect is also very good. Frequency converter heat dissipation design is based on the vertical device, the horizontal radiation will become worse! About the cooling fan general power slightly larger frequency converter, all have cooling fans. At the same time, it is also recommended to install cooling fans on the control cabinet. The inlet should be added with filter screen to prevent dust from entering the control cabinet. Pay attention to the fans on the control cabinet and inverter.

In addition, we should pay attention to the following two problems of heat dissipation.

At altitude above 1000m, the air density decreases, so the cooling air volume of the cabinet should be increased to improve the cooling effect. In theory, frequency converter should also consider capacity reduction, 1000m per-5%, but in fact, because the design of up-converter load capacity and heat dissipation capacity is generally larger than the actual use, so it also depends on the specific application. For example, in the 1500m area, but periodic loads, such as elevators, do not need to be lowered.

2 switching frequency: the heating of the transducer mainly comes from the moment when the IGBTIGBT heating is concentrated in the opening and closing. Therefore, when the switching frequency is high, the calorific value of the natural frequency converter increases. Some manufacturers claim that reducing the switching frequency can expand the capacity, which is the reason. OMRON inverter first agent company.

Common faults and treatment methods of laser welding machine for top cover

In order to make the laser welding machine work better, reduce the number of breakdowns, increase work efficiency, we must understand the operation process should pay attention to the problems and troubleshooting methods. Below by the manufacturer Jin silk square laser technician for everyone to analyze the top cover laser welding machine common fault treatment methods.

1. Abnormal stop of the laser welding equipment of the cover pre-welding: check the alarm screen related to the alarm, there is an alarm that the equipment will automatically switch to the pause state and the reset button will flicker at the frequency of 0.2s. At the same time, the buzzer will call at the frequency of 1s and the red light of the three-color lamp will always be on, to solve the relevant alarm and press the alarm again. The bit button can reset the alarm and press the start button to continue running.

2. When the laser welding is wrong, press the emergency stop button in time, the system will automatically cut off the laser control, the servo motor power supply, to prevent accidents, emergency stop after the bomb must be initialized;

3. When the equipment of laser welding machine is not working, please check whether the touch screen alarm or the equipment is suspended or waiting for material.

The whole machine reset alarm: it is necessary to reset the top cover pre welding laser welding machine to run the whole machine.

4. Limit alarm: it shows that the motor reaches the soft limit and can only run in the opposite direction without reset.

5. Shaft ALM alarm: simply return the alarm to the reset axis or press the reset button in the function window.

6. When the laser is out of control, it is necessary to press the stop button quickly, stop sending laser signal and break down the welding shaft. After dealing with the snap stop button, the cover pre-welding laser welding machine can be reset and run again.

7. Note: several minutes of the top cover pre welding laser welding machine.

The welding will stop automatically for one minute after stopping and blow nitrogen.

When an alarm occurs, the beep will be repeated after one minute.

Online body feed will last for only one minute, only 1PCS will automatically feed.

After the failure, we can refer to the above contents for operation inspection.

What are the selection principles of lathe cutting tools

The development of modern manufacturing technology and the wide use of NC machining equipment have greatly promoted the progress of cutting technology. With the need of numerical control and automation in the production process, higher requirements for metal cutting tools are put forward, such as high reliability, high precision, long life, rapid displacement replacement and good chip breaking. The design of cutting tool structure and the variety of cutting part shapes have become very diverse, which brings some difficulties to the designers of machining and cutting tools in choosing cutting tools reasonably. It is very important to select the cutting tools according to different machining features for realizing highly automatic cutting or unmanned machining. The following is a brief introduction of the selection principles for cutting tools.

1. Indexable turning tool structure

The indexable turning tool is widely used as a clamping tool. Its geometric parameters are completely guaranteed by the blade and groove, and are not affected by the technical level of workers. Therefore, the cutting performance is stable and suitable for modern mass production.

Two. Characteristics of lathe processing

Machining characteristics refer to the integration of machining information related to the machining process in the part processing. For example, cylindrical turning features may include such characteristics as initial diameter, minimum complete diameter, maximum complete diameter, machining length, tool tip radius and workpiece stiffness. Machining characteristics can describe the machining requirements of the workpiece more accurately, and these requirements are the premise of selecting machine tools, fixtures, cutting tools and their process parameters. Because each processing feature needs to input multiple characteristic parameters, it is simple and convenient for tool selection.

Three. Method of lathe processing

According to the initial diameter and the finished diameter, turning can be divided into rough machining and finish machining. According to the stiffness of parts, turning can be divided into high stiffness and low stiffness. According to the above requirements, the cylindrical turning can be divided into the following four processing methods: 1. turning the outer circle; 2. turning the outer circle; 3. turning the outer circle; 4. turning the outer circle.

Four, the principle of turning tool selection

Machining features for turning the outer circle, because rough or semi-finish machining is mainly to remove excess metal, cutting force is larger, should choose a stable blade clamping method, the blade angle as much as possible to choose a larger, in order to increase the strength of the blade. Because reducing the main deflection angle will increase the radial component, when the stiffness of the process system is strong, the main deflection angle of the tool can be reduced appropriately. Small tool main deflection angle can increase the length of cutting edge, reduce the load of cutting edge per unit length, thereby improving tool life.

Five. The use of special cutting oil.

Special cutting oil is a kind of medium which must be used in lathe cutting technology. It plays the role of lubrication, cooling, cleaning and so on. Due to the continuous improvement of cutting tools, equipment and technology in high-speed cutting, new cutting oil usually uses vulcanized extreme pressure and anti-wear additives as its core component, which can effectively protect the cutting tools and improve the process accuracy in ultra-high-speed cutting process.

Above is the selection of cutting tools need to pay attention to the problem, through constant optimization of tools, equipment, systems and cutting oil to constantly upgrade the process. Yida Borun Petrochemical Company is the largest manufacturer of high-end metal processing oil in China. The series of cutting oil products developed independently are made of lard sulfide and fatty acid sulfide ester as the main ingredients. They have excellent extreme pressure and wear resistance. They can effectively protect lathe tools, improve workpiece surface finish and greatly improve processing efficiency. The rate has been well received by customers at home and abroad in practical applications.

Application of laser welding in automobile body manufacture

At present, automobile body welding mainly includes resistance spot welding, laser welding, MIG and MAG welding, among which laser welding technology is mainly used for tailor-welded and body welding of unequal thickness plate. Laser welding is mainly used for body frame structure welding, for example, welding of the top and side. The application of laser welding in automobile can reduce the weight of automobile body so as to save fuel; improve the assembly precision of automobile body, increase the rigidity of automobile body by 30%, thus improving the safety of automobile body; reduce the stamping and assembly costs in the process of automobile body manufacturing, reduce the number of automobile body parts, and improve the integration of automobile body. 1. Laser welding frame laser welding uses laser as welding heat source and industrial robot as motion system. The advantage of laser heat source is that it has a very high heating capacity and can concentrate a large amount of energy on very small welding points. Therefore, it has the characteristics of high energy density, concentrated heating, fast welding speed and small welding deformation, and can realize the rapid connection of thin plates.

(1) Laser source: There are mainly two kinds of laser sources for laser welding: CO2 gas laser source and YAG solid-state laser source. The most important performance of laser source is output power and beam quality. Considering these two aspects, CO2 laser source has more advantages than YAG laser source, and is the main laser source for deep penetration welding. (2) photoconductive and focusing system: the photoconductive focusing system consists of circular polarization mirror, beam expander, mirror or optical fiber and focusing mirror, which can change the polarization state, direction, transmission beam and focusing function. The status of these optical components has a very important impact on the quality of laser welding. Under the action of high-power laser, optical components, especially lenses, will deteriorate, resulting in a decrease in transmittance, thermal lens effect, and surface contamination will increase transmission loss. (3) Welding robot: Because of the difference of laser welding, laser-MIG hybrid welding technology and welding joint form, the assembling precision of welding joint is different. Laser welding of lap joints and laser brazing of fillet welds can be done by ordinary welding robots. For the laser brazing and laser welding of butt welds, a kind of welding robot with a winch arm, which is different from the conventional robot, must be adopted. (4) Welding fixture: it can ensure the accurate positioning of the plate or assembly connected by laser welding, ensure the gap between welds, prevent welding deformation, and thus improve the quality of laser welded joints. (5) Laser welding control system: the control system mainly includes the video surveillance system of welding process, the automatic seam tracking system of robot, the correction system, the wire feeding control system and so on. For different laser welding methods, the composition of control system is also the same. Laser welding does not require wire feeding system, automatic seam tracking system and track correction system. 2. The advantages of laser welding are as follows: (1) the heat input is very small, the weld depth-width ratio is large, the heat affected zone is small, resulting in shrinkage and deformation of the workpiece is very small, without post-weld correction; (2) high weld strength, welding speed, weld narrow and generally good surface condition, without post-weld cleaning and other work; (3) welding Welding consistency and stability are generally good without filling metal and flux, and can realize partial welding of dissimilar materials; (4) beam is easy to control, welding positioning is accurate and easy to realize automation; (5) non-contact processing, no pressure on the workpiece and surface treatment; (6) small solder joints, high energy density, suitable for high-speed welding. (7) Short time welding, not only has no thermal effect on the outside world, but also has small thermal deformation and heat affected zone of the material itself, especially suitable for processing high melting point, high hardness, special materials; (8) no processing noise, no pollution to the environment; (9) long distance, difficult to achieve by ordinary methods through optical fiber parts, multi-channel identical. Time-sharing welding; (10) It is easy to change the laser output focal length and solder joint position; (11) It is easy to mount on automatic and robotic devices; (12) Compared with other welding methods, laser welding has a large investment in the early stage; (13) The welded workpiece assembly accuracy is high, and the beam control accuracy is relatively high. Higher requirements; (14) Due to large spatter, the penetration weld is more rough than brazing, but the strength is much higher than ordinary spot welding.

3. The application of laser welding to automobile body can be divided into two ways: one is welding without filler material, and the other is filler welding, which is commonly called brazing, mainly used in automobile roof cover welding. 3.1 according to the energy density of laser beam, fusion welding can be divided into heat conduction welding and penetration welding. (1) Heat conduction welding (HTW) is a kind of heat conduction welding, because the laser converges at a point and produces a very high temperature (related to the energy density). When the temperature reaches 1490 C, the steel plate will melt. The heat conduction welding is carried out by using this heat effect. The process is as follows: firstly, the surface of the workpiece is heated to the melting point by laser, and the metal melts. After melting, a hemispherical molten pool will be formed, and the radius and depth of the molten pool will gradually increase. When the absorbed laser energy reaches a balance with the heat diffused around the molten pool, the molten pool will not expand any more. As the laser beam moves along a predetermined trajectory, the molten pool moves, the metal in front of the molten pool melts and the metal in the rear cools.

The use of spot welder

How to use spot welding machine:

1. The position of electrode rod should be adjusted before welding, so that the electrode arm keeps parallel with each other when the electrode is just pressed into the weldment.

2. The choice of series of current regulating switches can be selected according to the thickness and material of weldments. After power on, the power indicator should be on, and the electrode pressure can be adjusted to change the compression degree of the spring pressure nut.

3. After the above adjustment is completed, the cooling water can be first connected to the power source and ready for welding. Welding procedure: the welding piece is placed between the two electrodes, step down the pedal, and make the upper electrode contact with the welding piece and pressurize it. When the pedal continues to be pressed, the power contact switch is connected, so the transformer starts working secondary circuit energized to heat the welding piece. When the electrode rises when the pedal is loosened after a certain time of welding, the power supply is cut off first and then restored to its original state by the pulling force of the spring, and the single point welding process ends.

4. Welding preparation and assembly: Before welding, all dirt, grease, oxide scale and rust should be removed. For hot-rolled steel, it is better to wash, sandblast or remove oxide scale with grinding wheel. Uncleaned weldments can be spot welded, but the service life of the electrode is seriously reduced, and the production efficiency and quality of spot welding are also reduced. For medium and low carbon steel with thin coating, it can be directly welded.

In addition, users can refer to the following process data when using:

1. Welding time: In welding medium and low carbon steel, this welding machine can use strong specification welding method (instantaneous power) or weak specification welding method (long time power). Strong standard welding method should be adopted in mass production, which can improve production efficiency, reduce electric energy consumption and reduce workpiece deformation.

2. Welding current: the welding current depends on the size, thickness and contact surface of the weldment. In general, the higher the conductivity of metal is, the greater the electrode pressure and the shorter the welding time. The required current density also increases.

3. Electrode pressure: The purpose of applying pressure to the weld is to reduce the contact resistance at the solder joint and to ensure the pressure needed for the formation of the solder joint.

How to operate sander

How to operate the sander? The following is a detailed description of its operation steps:

1. Operators must be familiar with the performance and use of the machine and operation precautions before operating. Fresh hands are strictly prohibited to operate alone on the machine and non-related personnel must not be near the machine.

2. Operators are not allowed to wear machine-involved clothes, such as loose Necklace clothes and other long hair, please curl their hair, or wear headgear and gloves to operate the machine.

3. The safety device on the sander should not be removed at will, and any non-work objects should not be placed on the worktable, such as wrenches, so as to avoid the damage of the machine caused by foreign bodies.

4. Make sure all switches are in OFF position before switching on the power supply switch. Check the cleaning sharpness of the abrasive belt before normal operation, check the installation direction of the abrasive belt correctly (the arrow on the back of the abrasive belt points to the same direction as the rubber wheel steering), whether the abrasive belt specifications are suitable, whether the abrasive belt swings properly, whether the abrasive belt is loose and conveyed moderately. The track of the belt conveyor is moderate, whether the conveyor belt is tight or not, and whether the blade is properly installed.

Fifth, all the cover must not be removed before processing to determine whether the size of wood within the scope of the machine, adjust the correct thickness of processing, wood too thick will lead to conveyor belt stuck fracture, the equipment can only be used for uniform thickness of wood sanding can not be used for horizontal correction of wood bending, and triangle Neither rhombic nor circular curved wood can be processed. It must be noted that there are no metal accessories on the workpiece to avoid damage to the machine.

6. In the normal operation, please pay attention to the electric load of the ammeter at any time to prevent the occurrence of jumping machine or sandpaper overload, resulting in sand belt cracking or fracture. Correction methods: 1 to slow down the sanding belt; 2 to replace the sanding paper with coarse sand; 3 to rubber wheel or sanding plate position increased a little more to reduce the amount of sanding.

7. When the operator works, once the workpiece is put on the conveyor belt, both hands must leave immediately. The workpiece should be evenly distributed on the conveyor belt. It means that the abrasive belt and the rubber wheel have uniform force, avoid unilateral wear and tear, and shorten the service life of the abrasive belt and the rubber wheel.

Eighth, the sand machine table adjustment using computer digital lift controller operation, table adjustment is strictly prohibited beyond the controller adjustment range, not altruistic manual adjustment table height, in order to avoid table tilt or lift controller data errors, conveyor belt speed adjustment speed using infinitely variable speed to adjust in machine operation.

9. Be sure to clean up the inside of the machine and remove the sandpaper when you clean up the inside, and then install the sandpaper when you finish cleaning up. It is recommended that the abrasive belt be loosened after the work is finished, so that the belt is kept in a tight state for a long time, resulting in gradual relaxation.

10. The new employee must be trained to operate the machine, and the old employee must accompany the work before the employee is fully familiar with the performance of the machine. If the operator wants to leave his job, he must turn off the machine and stop talking with others in the operation.

The advantage of compound machining is obvious.

At present, the performance of some composite machines has been close to and reached the level of imported equipment. Due to the continuous improvement of functions and the continuous improvement of automation, the cost performance of domestic equipment is high, and the competitive advantage is increasingly obvious. Some packaging and printing enterprises that used to import equipment began to use domestic equipment, and the purchase of domestic equipment as a future direction of investment.

Composite CNC machining will be more diversified, more and more powerful functional configuration, such as glazing, die cutting, cross cutting, soft standard cutting and so on. Accordingly, gravure press management system and remote technology support system will be used more and more. At the same time, in order to meet the needs of personalization, from unwinding, printing to wire processing, winding and other parts will be modularized, the most important of which will be gravure trolley or gravure and flexographic printing interchange trolley.

Design principle of micro switch for electric tractor

Electric tractor is widely used in railway, airport and other logistics systems because of its battery power, good environmental protection performance and high production efficiency.

At present, the forward and backward motion of electric tractor is mainly controlled by the forward and backward switch, accelerator, electronic control unit and motor on the direction switch assembly. This control method has three shortcomings: firstly, when the tractor and the pallet truck are towed and trailed, it can not accurately adjust the position of the tractor pin and the pallet truck hook, so it is easy to damage the tractor body; secondly, the tractor forward, backward time and speed control precision is low; thirdly, when the vehicle frequently forward, backward and brake, the motor. The damage of components such as ECU and tires is large.

The principle of the micro-motion control system of the electric tractor is as follows: when the tractor and the pallet truck are towed, the tractor approaches the pallet truck first; when the tail of the tractor is very close to the pallet truck, the driver alights to observe the distance between the tractor pin and the pallet truck hook; two electric mounted on the right rear hood of the tractor car body The movable switch is used for adjusting the micro adjustment of the towing vehicle’s forward or backward motion so as to complete the hook operation accurately. When the tractor needs to be decoupled from the pallet truck, the operation method is basically the same.

The micro-motion control system of electric tractor greatly shortens the towing operation time, improves work efficiency, and reduces the damage caused by motor, electronic control unit, tire and other components of towing operation team.

Can aluminum be plated with nickel

Recently many customers came to consult whether the aluminum parts can be plated with nickel or chemical nickel.

After our practical experience, it is confirmed that it can be plated with nickel.

However, not all aluminum materials are the same, aluminum is divided into pure aluminum plate, aluminum alloy, national standard aluminum plate, non-standard aluminum plate, die-casting aluminum, extruded aluminum and so on, different aluminum materials, processing characteristics and color difference is different.

Many customers sent samples and workpieces to be processed, proofing back to our Yinhua Xin gave a high evaluation, but also established the basis for cooperation.