How Gratings Work On CNC Machine Tools


A grating is an optical element that works by utilizing the transmission and diffraction phenomena of light. The grating detection device is widely used, its measurement accuracy can reach plus or minus μm, and has the advantages of high precision, fast response speed, and wide range. There are linear gratings and circular gratings, which are used to measure linear displacement and angular displacement respectively.
 

1. Structure of the grating detection device

 
The structure of the grating device is composed of a scale grating and an indicator grating. There are many of the same density on the scale grating and the indicator grating, which are called grating fringes. For transmission gratings, this line is not I (for reflection gratings, this line does not reflect light), the light is transmitted (or reflected back) by the narrow surface between the two lines.
 

2. The working principle of the grating measuring device

 
Place the indicator grating parallel to the side of the ruler grating, and make their lines relatively inclined by a small angle θ, and place the light on the other side of the ruler grating (take the directional mimeograph as an example). When light passes through them, Nir fringes, which are streaks of light and dark, are created on mimeographs. When the mimeograph is instructed to move, the Nir fringes move, and the moving direction is almost perpendicular to the grating moving direction. The relationship between Moire fringe spacing and line spacing W≈P/θ In the formula, W is the Moiré fringe spacing; P is the distance between two scribed lines; θ is the relative inclination angle (rad) between the two feet.
 
Moyun fringe has a magnifying effect. If P=0.01mm, θ=0.001, then W=10mm, which is equivalent to magnifying the distance between the two-foot engraved lines by 1000 digits. The photoelectric element moves with the instructing mimeograph. When moving, the light received by the photoelectric element is affected by the Moire fringe and changes in a sinusoidal pattern, so the photoelectric element generates a current (voltage 0) that changes according to the sinusoidal law. The displacement of the moving part can be measured by analyzing the change law of the current or voltage. , speed and direction of movement.
 
The structure of the DC servo motor mainly includes three parts.
 
Stator: The magnetic field is generated by the poles of the magnet. According to the way of generating the magnetic field, DC servo motors can be divided into permanent magnet type and separately excited type. The permanent magnetic pole is made of permanent magnet material. The separately excited magnetic pole is made of stamped silicon steel sheets and stacked, and the coil is wound outside, and a DC current is passed to generate a constant magnetic field.
 
Rotor: The rotor is made of silicon steel, with coils embedded on the surface. When DC current is applied, an electromagnetic torque is generated to drive the load to rotate under the action of the stator magnetic field.
 
Brushes and commutator segments: In order to keep the generated electromagnetic torque in a constant direction, the rotor can rotate evenly and continuously in a given direction, the brushes are connected to the external DC power supply, and the commutator segments are connected to the armature conductors.
 
Considering the actual operation, the DC servo motor introduces a mechanical commutation device. The three highs]have many failures and difficult maintenance, often affect production due to sparks generated by carbon brushes, and cause electromagnetic interference to other equipment. At the same time, the commutation capability of the mechanical arrester limits the capacity and speed of the motor. The armature of the motor is on the rotor, which makes the motor inefficient and poor in heat dissipation. In order to change the commutation ability and reduce the leakage inductance of the armature, it is short and thick, which affects the dynamic performance of the system.

 


At Be-cu.com,we use advanced equipment to offer you Unparalleled precision for producing metal and plastic machining parts

  • We combine the latest CNC milling and turning processes with proprietary technology to deliver high quality, on-demand parts.
  • Our team of engineers and machinists program the equipment to optimize cutting time, surface finish, and final tolerance to meet your design specifications
  • We specialize in cnc precision machining, single part prototyping, short to medium production runs, manufacture parts on time, every time, so you can stay ahead of schedule
  • cnc machining can create very similar parts to series parts. It is often more efficient and faster than other rapid prototyping technologies for the manufacture of a quantity of prototypes between 1 and 10 parts . We also recommend CNC machining for parts with large sizes (greater than 600 mm).

The Method Of Inductive Pulse Interference In The Machine Tool Customer Service Network Of CNC Machine Tools


There are many ways to overcome grid pulse interference, the most fundamental way is to eliminate the source of interference. This requires the transformation of various electrical equipment. In the case of AC motors, freewheeling is difficult. In Siemens’ servo system, the alternating current is rectified into stagnant power and then inverted. In this way, the motor is isolated from the grid, and the freewheeling diode can also be connected to the DC current. All kinds of machinery and equipment produced in West Germany now use industrial drive control for electric motors. This not only improves the efficiency of the motor and enhances the protection of the motor, but also avoids it and avoids their interference with the grid.
 
In our country, in order to eliminate the interference in the power grid, it is still difficult to achieve in a short period of time. Usually, the transformer isolation method is used to reduce the influence of the interference pulse on the numerical control system. The principle of this method is to use the characteristics of the inductive reactance of the transformer and the frequency of the signal. Because the frequency of the interference pulse is much higher than 50hz AC. So the transformer transmits much less power to it.
 
Capacitors can also be used to filter interference pulses. Large-capacity filter capacitors are generally installed in DC circuits. These capacitors are usually electrolytic capacitors. Compensate with a non-inductive capacitor. For example, Tangshan Cement Machinery Factory adopts this measure.
 
In addition to grid and electromagnetic interference, there are other factors that can cause downtime failures. For example, the electrical three defenses mentioned in electrical engineering, that is, the influence of humidity, salt spray, and mold should not be ignored. This situation has been encountered in Zhenjiang Hydraulic Parts Factory. The factory is located in the south of the Yangtze River, and the climate is humid. Although a humidifier is used, the circuit board is still corroded, causing downtime.

 


At Be-cu.com,we use advanced equipment to offer you Unparalleled precision for producing metal and plastic machining parts

  • We combine the latest CNC milling and turning processes with proprietary technology to deliver high quality, on-demand parts.
  • Our team of engineers and machinists program the equipment to optimize cutting time, surface finish, and final tolerance to meet your design specifications
  • We specialize in cnc precision machining, single part prototyping, short to medium production runs, manufacture parts on time, every time, so you can stay ahead of schedule
  • cnc machining can create very similar parts to series parts. It is often more efficient and faster than other rapid prototyping technologies for the manufacture of a quantity of prototypes between 1 and 10 parts . We also recommend CNC machining for parts with large sizes (greater than 600 mm).

Machining Properties Of Carbon Fiber Composites


As a new generation of reinforcing material, carbon fiber has superior performance. Its weight is very light, its density is less than a quarter of that of steel, and its strength is four times that of steel. In addition, it has fatigue resistance, shock resistance, low thermal expansion coefficient, High temperature resistance, good dimensional stability and a series of advantages. Usually, carbon fiber materials are not used alone, but combined with resin to make composite materials. In this article, the editor will tell you about the machining characteristics of carbon fiber composite materials.
 
Machining properties of carbon fiber composites:
  • 1. The interlaminar strength is low. If the drilling axial force is too large and exceeds the strength that the resin can bear, defects such as delamination will occur;
  • 2. It is an anisotropic material, which has different performance indicators in different directions, and the laying direction of its fibers has a great influence on the hole making. If the stress is too concentrated, it is prone to breakage and other defects.
  • 3. Its hardness is high, so the tool is easy to wear during machining.
  • 4. Its thermal conductivity is small, the heat generated by friction during machining is difficult to remove, and it is easy to accelerate the wear of the drill bit, and there will be a lock hole phenomenon.
 
At present, the difficulty of machining carbon fiber composite materials is mainly concentrated in the drilling process, which requires strict process parameters and selection of suitable tools. Compared with traditional materials, although carbon fiber composite materials are difficult to process, their accuracy is not bad at all, and can be controlled between 0.05mm and 0.15mm to meet the requirements of use.
 
With the development of technology, carbon fiber production and machining technology has gradually matured and is very popular in the market. China Be-cu Prototype Material Technology Co., Ltd. has more than ten kinds of professional machining equipment, such as large-scale hot presses, hot presses, hydroforming tables, Cnc high-speed milling machines, etc., specializing in machining carbon fiber products. It is an early start-up company in the Yangtze River Delta region. A manufacturer of carbon fiber products in the automotive industry, , medical equipment, and rail transit.
 
As a new generation of reinforcing material, carbon fiber has superior performance. Its weight is very light, its density is less than a quarter of that of steel, and its strength is four times that of steel. In addition, it has fatigue resistance, shock resistance, low thermal expansion coefficient, High temperature resistance, good dimensional stability and a series of advantages. Usually, carbon fiber materials are not used alone, but combined with resin to make composite materials. In this article, the editor will tell you about the machining characteristics of carbon fiber composite materials.
 

 

ISO 9001 certified. BE-CU Prototype Offering CNC machining carbon fiber and other manufacturing services for carbon fiber marterial. Various capabilities include notching, labeling, drilling carbon fiber, grinding, laser cutting carbon fiber, finishing, plating, marking, CNC milling carbon fiber and turning carbon fiber.We stock high quality 3k carbon fiber sheet in a variety of thickness, types and finish. Its a great material used in applications where light weight and strength are needed such as drones. Unlike other workshops, we have no min order and are often filling orders with a single part. We also don’t make you pay for the full sheet and you only get charged for what is used. With a large selection of material, you should find everything you need to make your project come to life. We are also able to handle larger production runs and provide a competitive pricing. If we don’t have the material or finish you require, we are more the willing to look at bringing it in for you.

What Is Carbon Fiber?Carbon fiber is made of polyacrylonitrile (PAN) (or pitch, viscose) and other organic fibers by carbonization (removal of most elements except carbon) by pyrolysis method under inert gas at high temperature above 1,000 °C. Inorganic polymer fibers with a carbon content of more than 90%.

Measures To Improve Wear Resistance Of CNC Machine Tool Guide Rails


The basic idea of ​​improving wear resistance from the design point of view; strive for no wear as much as possible; when wear is unavoidable, try to strive for less wear, uniform wear and compensation after wear, so as to improve the service life.
 

1. Strive for no wear

 
The reason for wear is that the mating is in direct contact and relative movement under a certain pressure. Therefore, the condition for no wear is that the mating surfaces are not in direct contact during relative movement, and there is no relative movement when they are in contact.
One of the ways that the mating surfaces are not in direct contact during relative motion is to ensure complete liquid lubrication, so that the lubricant completely separates the friction surfaces. Such as hydrostatic guide rails, hydrostatic bearings or other hydrostatic pairs. The dynamic pressure guide rail and the dynamic pressure bearing can also achieve a complete liquid lubrication state, but the greasy pressure is related to the relative movement speed. Therefore, wear is still inevitable during starting or stopping.
 

2. strive for less wear

 
No wear and tear can only be achieved in a few and special cases, and in most cases, we can only strive for less wear and tear to extend the working period.
 
1) Heat Treatment of Correctly Selecting Materials of Friction Pairs
Appropriate selection of the material and heat treatment of the friction pair can improve the ability to resist wear, such as hardening of the supporting rails, soft plastic tapes on the surface of the moving rails, etc.
 
2) reduce pressure
 
The pressure can be reduced by increasing the contact surface of the guide rail and reducing the load. Improving the straightness of the guide rail surface and refining the surface roughness can increase the reputation. Extending the length of the moving guide rail with the cold wind guide rail surface can also increase the contact area, but it must be adapted to the rigidity of the moving guide rail, otherwise the deformation will be large after being loaded, the contact will be uneven, and the local pressure will increase, although the area will increase. , but it didn’t work. The use of unloading guide rails is a good way to reduce the load on the guide rails and reduce the pressure.
 
3) change friction properties
 
Replacing the sliding pair with a rolling pair can reduce wear. Ensuring sufficient lubrication in the sliding friction pair avoids dry or semi-dry friction and also reduces wear.
4) Strengthen protection
In order to prevent dust, cutting, grinding wheel chips, etc. from entering the friction pair, strengthening protection is an effective measure to improve the wear resistance of the guide rail.
 

3. Strive for even wear

 
Whether the wear is uniform or not has a great influence on the working life of the components. There are two main reasons for uneven wear.
(1) The pressure distribution on the friction surface is uneven.
(2) Each section has different access opportunities.
 
There are the following measures to strive for uniform wear.
 
(1) Strive to make the pressure on the friction surface evenly distributed, for example, the shape and size of the guide rail should make the concentrated load as symmetrical as possible.
(2) Minimize torsional and overturning moments.
(3) Ensure that the supporting parts such as the workbench and the slide have sufficient rigidity.
(4) The hardness of the friction pair with uneven use opportunities over the entire length should be higher. For example, the hardness of the guide rail of the lathe bed should be higher than that of the saddle guide rail.
 

4. After wear, it should be able to compensate for the amount of wear

 
The gap becomes larger after wear, and the design should consider that the gap can be compensated for in structure. The compensation method can be automatic continuous compensation or periodic manual compensation. Automatic continuous compensation can rely on its own weight, such as a triangular guide. Regular manual compensation, such as rectangular and dovetail guide rails by adjusting the inserts, closed guide rails also need to adjust the pressure plate.
 

 


At Be-cu.com,we use advanced equipment to offer you Unparalleled precision for producing metal and plastic machining parts

  • We combine the latest CNC milling and turning processes with proprietary technology to deliver high quality, on-demand parts.
  • Our team of engineers and machinists program the equipment to optimize cutting time, surface finish, and final tolerance to meet your design specifications
  • We specialize in cnc precision machining, single part prototyping, short to medium production runs, manufacture parts on time, every time, so you can stay ahead of schedule
  • cnc machining can create very similar parts to series parts. It is often more efficient and faster than other rapid prototyping technologies for the manufacture of a quantity of prototypes between 1 and 10 parts . We also recommend CNC machining for parts with large sizes (greater than 600 mm).

The Development Of Mechanical Equipment Control Technology


Here to explain some information about Shenyang machine tools, in order to let everyone know more about the development and past history of Shenyang machine tools, and the structure of machinery! Today we talk about the development of mechanical equipment control technology!

The earliest controls were manual controls. The invention of the steam engine in the 18th century marked the arrival of the first technological revolution,Human society has entered the era of industrialized mass production. The application of electricity in the 19th century marked the beginning of the second technological revolution, and human society began to enter the era of electrification. From the 1920s to the 1930s, the relay original contactor control system was used to realize the control of starting, braking, forward and reverse rotation of mechanical equipment. The advantages of relay-contactor control are simple structure, low price, convenient maintenance and strong anti-interference ability, so it is widely used in various mechanical equipment. The relay-contactor control system can not only realize the automation of the production process conveniently, but also realize the centralized control and remote control.

At present, the control of the original contactor of the relay is still one of the most basic electrical control forms of mechanical equipment in my country. The disadvantages of the relay-contactor control system are: due to the fixed wiring form, it is inconvenient to change the control program during program control, and the flexibility is poor; the use of a contact switch, the operating frequency is low, the contacts are easily damaged, and the reliability is poor. From the 1940s to the 1950s, the AC magnetic amplifier – electric pumping appeared, which is a closed-loop feedback system, and the control accuracy and rapidity of the system were improved. In the 1960s, the Transistor-thyristor-powered DC speed control system and AC speed control system not only greatly improved the speed control performance, but also reduced the mechanical equipment and floor space, with less power consumption and high efficiency, completely replacing the AC magnetic field. Amplifier – Motor Control System.

In actual production, because there are a large number of simple program control processes controlled by switching quantities, and the actual production process and process are often changed, the traditional relay-contactor control system often cannot meet this need. In the 1960s, an automatic device that can easily change the control program according to needs, has a simple structure and a price, the sequence controller, which realizes the control function through the insertion or programming of the combinational logic elements, can meet the needs of the program frequently. The changed control requirements make the control system have greater flexibility and versatility, but it still uses convenient means, and various functions are also limited. With the development and application of another large-scale integrated circuit and microprocessor technology, a new type of industrial controller with microprocessor as the core appeared in the 1970s, the programmable logic controller (PLC), This kind of device can fully adapt to the harsh industrial environment. Because it has the advantages of computer control and relay control system, it has been widely used in industrial control as a standardized general equipment.

Since the advent of microcomputers in 1971, it has been widely used in the local control of mechanical equipment or the control of the whole machine, reducing mechanical parts, improving production efficiency, and reducing the labor intensity of workers, of which Cnc machine tools are a typical example. In order to solve the automation of single-piece and small and medium-sized batch production, which accounts for about 80% of the total mechanical processing, to improve labor productivity, product quality and reduce labor intensity, the world’s first 3-coordinate vertical CNC milling machine was produced in 1952, which marked the The beginning of CNC technology. With the rapid development of computer technology, the application of CNC machine tools is increasingly widespread, and further promote the development of CNC systems, resulting in automatic programming system (APS), computer numerical control system (CNC), computer group control system (DNC) and flexible manufacturing System (FMS). Computer Integrated Manufacturing System (CIMS) and Computer Aided Design and Manufacturing Integration (CAD/CAM) are the advanced stages of mechanical manufacturing integration, which can realize all automation from design to manufacturing.
To sum up, the generation of mechanical equipment control technology is not isolated, but the result of the mutual penetration of various technologies. It represents a new generation of production technology in the making, has shown and will show more and more powerful power.

 


At Be-cu.com,we use advanced equipment to offer you Unparalleled precision for producing metal and plastic machining parts

  • We combine the latest CNC milling and turning processes with proprietary technology to deliver high quality, on-demand parts.
  • Our team of engineers and machinists program the equipment to optimize cutting time, surface finish, and final tolerance to meet your design specifications
  • We specialize in cnc precision machining, single part prototyping, short to medium production runs, manufacture parts on time, every time, so you can stay ahead of schedule
  • cnc machining can create very similar parts to series parts. It is often more efficient and faster than other rapid prototyping technologies for the manufacture of a quantity of prototypes between 1 and 10 parts . We also recommend CNC machining for parts with large sizes (greater than 600 mm).

What Is The Production Process Of Carbon Fiber Tubes?


Carbon fiber tubes, as the basic carbon fiber products, are currently used in many structural parts. Compared with traditional tubes, carbon fiber tubes show excellent properties such as light weight, high strength and corrosion resistance, and gradually replace traditional tubes. As you know, carbon fiber tubes How is the tube produced? Commonly used carbon fiber tubes include pultrusion and roll forming. Let’s take a look at this article.
 
Pultrusion process: The pultrusion process is a continuous production method of composite material profiles. It is an automatic production process of pultrusion products formed by forming a molding die with a cross-sectional shape, and making it solidified and formed in the die and continuously ejected from the die. Pultrusion dies are expensive and generally limited to producing constant cross-section products.
 
Coil forming process: cut the carbon fiber prepreg according to the specifications of the required pipe and select a suitable inner core mold, apply a release agent on the surface of the mold, and then use the hot pressing of the prepreg to make the prepreg. The prepreg is softened so that it can be rolled onto the mold evenly and tightly. When all the prepregs are rolled, the surface is covered with a layer of OPP, and finally sent to the oven for curing at high temperature.
 
China Be-cu Prototype Material Technology Co., Ltd. has advanced production lines for fiber reinforced composite material sheets, pipes, molding, autoclave, Cnc machining, etc., and is equipped with standardized production workshops such as 10,000-level clean rooms. Production provides the perfect foundation.

 

ISO 9001 certified. BE-CU Prototype Offering CNC machining carbon fiber and other manufacturing services for carbon fiber marterial. Various capabilities include notching, labeling, drilling carbon fiber, grinding, laser cutting carbon fiber, finishing, plating, marking, CNC milling carbon fiber and turning carbon fiber.We stock high quality 3k carbon fiber sheet in a variety of thickness, types and finish. Its a great material used in applications where light weight and strength are needed such as drones. Unlike other workshops, we have no min order and are often filling orders with a single part. We also don’t make you pay for the full sheet and you only get charged for what is used. With a large selection of material, you should find everything you need to make your project come to life. We are also able to handle larger production runs and provide a competitive pricing. If we don’t have the material or finish you require, we are more the willing to look at bringing it in for you.

What Is Carbon Fiber?Carbon fiber is made of polyacrylonitrile (PAN) (or pitch, viscose) and other organic fibers by carbonization (removal of most elements except carbon) by pyrolysis method under inert gas at high temperature above 1,000 °C. Inorganic polymer fibers with a carbon content of more than 90%.

A Stamping Die Integrated With Small Hole Punching Technology


In order to ensure product quality and production efficiency, it is necessary to optimize the product structure and redesign the mold structure, and ensure the accuracy of processing and assembly and parts, in order to achieve the goals of product quality and quantity and reducing manufacturing costs.

1 Description of integrated small hole punching die

The blanking die is shown in Figure 1 and Figure 2. The description is as follows: Optimize the small holes of the product and reduce the types. The diameter of the punch ⑩ D≥2.5T is suitable (T=material thickness). Add the small guide post ⑾ of the stripper plate to improve the guiding accuracy; the length of the small hole punching needle ⑩ is shortened from 60mm to 24.5mm; the punching insert of the lower die is made into a double-layer block, and the first layer of inserts ⑭The thickness is 10mm, the material is SKH-9, the back side is left 2mm straight, and the whole body is discharged and hollowed out to prevent the needle from breaking due to blockage. The second layer of inserts ⑮The thickness of 15mm is made of D2 material; the screw ②quick release device is locked and placed on the machine. It is easy to replace; all the small holes should be in the same step as far as possible, centralized punching, centralized waste suction, and increased waste suction equipment.

2 Structure specific implementation plan

The small hole is concentrated in the punching step, and the stripper plate ⑤ is made into a double-layer structure ⑧ and ⑨. According to the position of the corresponding hole on the product tape, the punching needle fixing plate ⑧ is cut on the line, and the punching needle ⑩ is fixed on the punching needle. In the wire cutting hole of the fixing plate ⑧, punch through the punching needle stripping plate ⑨. ; When the punching needle is broken and needs to be replaced, first loosen the anti-locking screw ②, take out the punching needle stripping plate ⑨, then loosen the equal-height screw ①, take out the punching needle backing plate ⑦ and the punching needle fixing plate ⑧, so as to avoid dismantling the whole set The die can be replaced on the punch press.

The punching needle ⑩ is mounted on the punching needle fixing plate ⑧, and the punching needle backing plate ⑦ and the punching needle fixing plate ⑧ are fixed by small screws ⑫, which play the role of fixing and resisting the punching needle ⑩, preventing the punching needle from retreating during the punching process; Therefore, both the punching backing plate ⑦ and the punching needle fixing plate ⑧ need heat treatment. In order to ensure the smooth disassembly and assembly of the punching needle backing plate ⑦ and the punching needle fixing plate ⑧, the corresponding position of the stop plate ④ needs to make way through holes. This structure is also separate The precision small guide post ⑪ is used to guide up and down. The precision small guide post ⑾ is also mounted on the punching pin fixing plate ⑧, and passes through the punching pin stripping plate ⑨ into the guide post guide hole ⑬ of the lower die, so as to improve the guiding accuracy of the structure [2].

When the upper and lower dies are separated, the stripper plate ⑤, the stop plate ④ and the punching needle stripping plate ⑨ will be separated with the ejection of the spring assembly ⑥, while the punching needle backing plate ⑦ and the punching needle fixing plate ⑧ ①Fixed on the fixing plate ③, the punching needle ⑩ fixed on the punching needle fixing plate ⑧ returns to the punching needle stripping plate ⑨, so as to achieve the purpose of stripping after punching.

When the upper and lower dies are closed, the small precision guide post ⑾ will first enter the lower die together with other guide components, the die will continue to descend, and the punching needle ⑩ will pass through the punching needle stripper plate ⑨ and press the material before punching.

3 Conclusion

To sum up, through verification, the length of the punching needle is shortened, from the conventional punching needle length of 60-65mm to 24-28mm, which increases the strength and life of the punching needle, and reduces the maintenance frequency and punching cost by more than 50%. . The structure concentrates the small holes in one step, and is designed as a quick-release structure, which saves the time of replacing the punching needle without disassembling the whole set of molds. The quality and quantity are guaranteed, the operation is simple, and the practicability is very strong.

Sheet fabrication services for mild steel, high strength low alloy (HSLA) steel, cold/hot rolled steel, galvanized steel, stainless steel, aluminum, copper and brass. Capable of fabricating parts up to 12 ft. length and +/-0.001 in. tolerance. Various capabilities include contract manufacturing,custom stamping,edge rolling, forming,top laser cutting, roll bending and welding. Finishing and secondary services such as hardware installation, tapping, deburring, cleaning, heat treating, plating, anodizing and painting available. Sheet Metal Prototype and low to high volume production runs offered. Suitable for commercial/residential architectural, aluminum brake shape parts, wall Panel systems, brackets, general flashings, rails, call button plates and ship building component parts.

Selection Of Common Lathe Cutting Fluid


The cutting fluid should be selected according to the specific conditions of workpiece material, tool material, processing content and process requirements.
(1) According to the workpiece material selection
1) For rough machining of steel parts, generally use low-concentration emulsion, and when finishing, use mineral oil or extreme pressure cutting oil.
2) When roughing gray cast iron and other brittle metals, due to the low tensile strength of the material and the small plastic deformation, when the tool cuts, it is squeezed into chipping chips on the sliding surface, and the contact friction with the front of the tool The force is very small, and the cutting temperature in the front is relatively low. Therefore, ordinary lathes generally do not use cutting fluid. When finishing, in order to reduce the surface roughness value and cutting heat of the workpiece, kerosene or 5%~10% high concentration emulsion can be used.
3) When roughing non-ferrous metals such as copper or aluminum and their alloys, generally do not add cutting fluid. When the ordinary lathe is finished turning, the aluminum can be filled with an appropriate amount of kerosene, and the copper can be filled with 7% N10% emulsion.
4) When cutting magnesium alloys, it is strictly forbidden to use cutting fluid to prevent burning and fire.
(2) Select according to the processing content
1) During rough machining, due to the large amount of cutting, more cutting heat is generated, the temperature of the cutting area is higher, and the tool wear is larger. At this time, a cooling-based cutting fluid should be used to reduce the cutting temperature.
2) When finishing, the precision and surface quality of the workpiece are required to be high, and mineral oil or extreme pressure cutting oil mainly for lubrication should be selected.
3) When processing precision tools and measuring tools such as taps, wrench teeth, thread plug gauges or thread ring gauges, ordinary lathes should use vegetable oil or vulcanized oil that has been diluted and added with active agents due to the high strength and precision requirements of the material.
“During deep hole machining, the tool is working in a semi-closed state, which makes chip removal difficult, easily causes chips to wrap around and gather, affect the normal operation of cutting, and may damage the cutting edge and the surface of the workpiece. At this time, a lower viscosity should be used. The extreme pressure cutting oil is injected with sufficient pressure and flow, and the blasting force will flush out the chips in time.
(3) Select according to the tool material 1) High-speed steel tool. Select according to workpiece material and processing content.
2) Carbide cutting tools. Ordinary lathe cemented carbide is made of carbides with high hardness and melting point and bonding metals such as cobalt and molybdenum, which are pressed and sintered by powder metallurgy, and have high thermal hardness, so cutting fluid is generally not added. Ordinary lathes should use cooling-based cutting fluids when processing some materials with high hardness, high strength and poor thermal conductivity. Ordinary lathes must be poured continuously from the beginning to avoid sudden cooling of cemented carbide inserts. produce brittle cracks.

 


At Be-cu.com,we use advanced equipment to offer you Unparalleled precision for producing metal and plastic machining parts

  • We combine the latest Cnc milling and turning processes with proprietary technology to deliver high quality, on-demand parts.
  • Our team of engineers and machinists program the equipment to optimize cutting time, surface finish, and final tolerance to meet your design specifications
  • We specialize in cnc precision machining, single part prototyping, short to medium production runs, manufacture parts on time, every time, so you can stay ahead of schedule
  • cnc machining can create very similar parts to series parts. It is often more efficient and faster than other rapid prototyping technologies for the manufacture of a quantity of prototypes between 1 and 10 parts . We also recommend CNC machining for parts with large sizes (greater than 600 mm).

Be-cu Recommended – Technology丨What Is The Thermal Runaway Of The So-called High-safety Lithium Iron Phosphate Battery?


Introduction: Compared with ternary lithium-ion batteries with higher energy density, lithium iron phosphate batteries are considered to have higher safety, so what is the experience of thermal runaway of safer lithium iron phosphate batteries?

In 2018, under the background of the first decline in the entire automobile market in more than 20 years, new energy vehicles still bucked the trend and increased by more than 60%, becoming a group of dark horses in the automobile market. With the large-scale popularization of new energy vehicles, the safety of power batteries has also attracted more and more attention. Compared with ternary lithium-ion batteries with higher energy density, lithium iron phosphate batteries are considered to have higher energy density. Safety, so what is the experience of thermal runaway in a safer lithium iron phosphate battery?

Recently, PeterJ. Bugryniec (first author) and Solomon F. Brown (corresponding author) of the University of Sheffield in the United Kingdom used accelerated calorimetry (ARC) and hot box experiments for LFP batteries in different SoC states leading to thermal runaway The main reasons for the occurrence are analyzed, and the study shows that under high SoC, the decomposition reaction of cathode and anode is the main cause of thermal runaway of LFP battery, but the decomposition reaction of anode is the main cause of thermal runaway of LFP battery at lower SoC state. reason.

The LFP material has an olivine structure. We believe that due to the presence of more stable PO bonds, the LFP material has high stability at high temperatures. We take the 18650 structure battery as an example. If the LFP material is used, it can be at most in thermal runaway. 0.5g of O2 is released, but if we use LCO as the cathode material, as much as 3.25g of O2 can be released in thermal runaway, less O2 release means that the combustion reaction of the electrolyte is inhibited, releasing less heat, thus Suppresses the severity of thermal runaway in LFP cells.

 

The battery used in the experiment is a commercial LFP 18650 battery with a capacity of 1500mAh, and the thermal runaway behavior of the LFP battery is studied by ARC and hot box experiments respectively (as shown in the figure below), and the SoC of the LFP battery is controlled to be 0%, 28%, 63%, 100% and 110% were tested for ARC (accelerated calorimetry), and the control SoC was 100% for hot box test.

 

The ARC test is a common method to study the thermal stability of lithium-ion batteries. The basic operation method can be divided into three steps. The first step is to heat to a predetermined temperature, the second step is to wait, and the third step is to search, that is, the battery is at a certain temperature. When the heating rate of the battery temperature reaches a certain rate, it means that the battery starts to release heat. If the heating rate of the battery reaches a certain rate, it is considered that the battery starts to thermally runaway. Here, the author sets the starting temperature of ARC to 50°C and the end temperature to 315°C. The temperature increases by 5°C in each step, and waits for 60 minutes. If the heating rate of the battery reaches 0.02°C/min at this temperature, the temperature is the battery If the heating rate of the battery reaches 1°C/min, the temperature is the thermal runaway trigger temperature of the battery.

Figure a below is the ARC test curve of a 100% SoC battery. From the figure, it can be seen that the self-heating temperature of a 100% SoC LFP battery starts at 95 °C, and then the heating rate of the battery increases continuously, and reaches 3.7 °C at 230 °C /min, but then the heating rate of the battery began to decline, and a new high point appeared around 280 °C – 1.6 °C/min. Figure a below can be divided into four regions, in which region 1, 95-150 ℃, the battery starts to heat itself, which mainly corresponds to the decomposition of the SEI film on the surface of the negative electrode, accompanied by the negative electrode-electrolyte reaction, in region 3 At 150-255℃, the heat generated in this stage mainly comes from the side reactions of negative electrode-electrolyte and positive electrode-electrolyte, among which the heat released by negative electrode-electrolyte occupies most of it. In region 4 (>255 °C), the internal heat generation of the battery at this stage mainly comes from the oxidation reaction between the electrolyte and the O2 generated by the decomposition of LFP.

As can be seen from Figures b and c below, the shape of the ARC curve of the battery under 110% SoC and 63% SoC is basically the same as the shape of the ARC curve of the 100% SoC battery, but when the SoC of the battery drops further to 28%, Then the shape of the ARC curve of the battery will change significantly (as shown in Figure d below). From the start of self-heating of the battery until 190 ° C, the heating rate of the battery has been increasing, and reached a peak at about 190 ° C, and then began to heat up. decreased, and then the heating rate of the battery began to slowly increase again. In the low SoC state, the LFP positive electrode is relatively stable, so the heat production of the first half of the battery mainly comes from the decomposition reaction of the negative electrode and the electrolyte. decomposition reaction, but due to the relatively high stability of the positive electrode under this SoC, the heating rate of the battery is relatively slow.

At 0% SoC, the shape of the ARC curve of the LFP battery is further changed. It can be noticed from the figure that on the one hand, there is a significant delay in the self-heating start temperature of the battery, and secondly, the heating rate peak of the battery near 190 °C also disappears. It shows that under low SoC, the battery is in a relatively stable state, and the negative electrode has been completely delithiated, so the speed of the negative electrode-electrolyte decomposition reaction is also greatly reduced. Basically the same, a small amount of O2 released from the decomposition of the LFP cathode promotes the decomposition of the electrolyte, which makes the heating rate of the battery increase slowly.

 

The figure below shows the battery’s self-heating trigger temperature, maximum heating rate temperature and temperature corresponding to the maximum heating rate based on the ARC test results. It can be seen from the figure that as the SoC of the battery increases, the maximum heating rate of the battery also increases. It rises accordingly, mainly because more energy is stored in the battery under the higher SoC, and the higher SoC also means that the stability of the positive and negative electrodes of the battery is also lower, mainly because the stored Li in the negative electrode is more. Therefore, the decomposition reaction of the negative electrode with the binder, the electrolyte, etc. releases more heat, thereby accelerating the temperature increase of the lithium-ion battery.

 

Since the maximum heating rate can reflect the stability of the positive and negative electrodes inside the lithium-ion battery, the maximum heating rate can well reflect the risk of thermal runaway in the lithium-ion battery. The following figure compares several common lithium-ion battery positive systems in different The maximum heating rate in the state of Other types of batteries offer significant safety advantages.

 

The figure below shows the change curve of the surface temperature of the LFP battery in the hot box test (solid line), and the temperature inside the hot box (dotted line). During the process of temperature increase under heating, the surface temperature of the battery is lower than 95°C, and the battery has not yet begun to release heat. In area B, the surface temperature of the battery continues to rise to about 180°C. At this stage, the SEI film begins to decompose, the negative electrode-electrolyte and positive electrode-electrolyte decomposition reactions begin to occur, the battery begins to heat itself, and the battery temperature rises rapidly and quickly exceeds Hot box temperature, and eventually the battery’s pressure relief valve burst due to overpressure. In area C, the battery thermal runaway reaches the peak temperature after the battery pressure relief valve is activated, and in area D, the battery thermal runaway ends, and the temperature of the battery finally returns to the temperature of the hot box.

Comparing the battery surface temperature curves obtained from two hot boxes with different temperatures, it can be found that the peak temperature of the battery in the 220 °C hot box during thermal runaway is significantly higher than that of the battery in the 180 °C hot box, which indicates that in the 220 °C hot box Additional reactions will occur in the thermal runaway of the battery. The previous ARC analysis shows that the LFP cathode decomposition reaction will only occur when the battery surface reaches 210 °C, while the electrolyte decomposition reaction will only occur when the battery surface temperature exceeds 255 °C. Occurs, and the maximum temperature of the battery surface in the 180°C hot box test is less than 230°C, so at least the battery has not yet reached the decomposition temperature of the electrolyte, and the O2 released by the LFP positive electrode will also be significantly reduced at lower temperatures, which are all significant It reduces the heat generation rate of the lithium-ion battery, thereby suppressing the increase of the battery temperature.

 

Peter J. Bugryniec’s research shows that SoC has a significant impact on the thermal runaway behavior of LFP batteries. With the increase of SoC, the severity of thermal runaway of the battery increases significantly, and the stability of the battery decreases significantly. The analysis of the specific causes of thermal runaway shows that the main cause of battery thermal runaway in 100% and 110% SoC states is the decomposition reaction of anode-electrolyte and cathode-electrolyte, but the battery thermal runaway in lower SoC states The main trigger factor is the decomposition reaction of the anode-electrolyte. When the SoC is lower than 28%, the thermal stability of LFP is significantly improved, and thermal runaway will not occur. The hot box test shows that higher hot box temperature will lead to more serious thermal runaway of Li-ion batteries, mainly because better hot box temperature triggers the decomposition reaction of electrolyte and the decomposition of cathode to release O2 reaction, which intensifies the battery Rise in temperature.

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CNC Machining of Carbon Fiber Composites


carbon fiberIt has the characteristics of high temperature resistance, friction resistance, and electrical conductivity that ordinary carbon fibers have, but also has flexibility and anisotropy that carbon materials do not have. It is often compounded with resin matrix to make carbon fiber composite materials. Although carbon fiber composite materials are light in weight and high in strength, they are brittle and difficult to machine. In this article, I will talk about cnc machining of carbon fiber composite materials.
Tool material:Carbon fiber composite materials have high hardness, so high-hardness tools should be selected during machining, such as CVD diamond, cemented carbide, PCBN, and high-property ceramics.
Front and rear corners:According to the material properties, the rake angle of the tool should be selected as a smaller value to enhance the cutting strength and heat dissipation volume. However, at the same time, carbon fiber composite materials have high strength and toughness, and the cutting edge should be kept sharp. Generally, γ=° is selected; in order to reduce the friction and wear of the flank surface and prolong the service life of the tool, the flank angle is easy to choose. Larger value, but in order to ensure the strength of the cutting edge of the tool and not cause chipping, generally choose α=°
Number of teeth and helix angle:The number of tool teeth and the helix angle can be appropriately selected to be larger, so that multiple teeth can participate in cutting at the same time during the machining process. Generally, the number of teeth is Z=, and the helix angle β=°
Amount of knife eaten:The amount of tool wear during cutting is large. In order to ensure the surface quality of the machined surface, the axial non-layered cutting method is adopted, and the depth of cut a= mm. In order to avoid excessive cutting force, a is not easy to be too large.
Cutting speed and feed:In order to reduce the cutting force and improve the surface quality and cutting efficiency of the parts, high-speed cutting is adopted. The general speed is S= rpm, and the feed rate is F= mm.
When machining carbon fiber composite materials, the specific parameters should be determined according to the actual situation. China Be-cu Prototype Material Technology Co., Ltd. is a professional carbon fiber manufacturer with strong technical force. The drawings are made of fine carbon fiber CNC machining, the surface has no pinholes, no white spots, no scratches, and the quality is good.

ISO 9001 certified. BE-CU Prototype Offering CNC machining carbon fiber and other manufacturing services for carbon fiber marterial. Various capabilities include notching, labeling, drilling carbon fiber, grinding, laser cutting carbon fiber, finishing, plating, marking, CNC milling carbon fiber and turning carbon fiber.We stock high quality 3k carbon fiber sheet in a variety of thickness, types and finish. Its a great material used in applications where light weight and strength are needed such as drones. Unlike other workshops, we have no min order and are often filling orders with a single part. We also don’t make you pay for the full sheet and you only get charged for what is used. With a large selection of material, you should find everything you need to make your project come to life. We are also able to handle larger production runs and provide a competitive pricing. If we don’t have the material or finish you require, we are more the willing to look at bringing it in for you.

What Is Carbon Fiber?Carbon fiber is made of polyacrylonitrile (PAN) (or pitch, viscose) and other organic fibers by carbonization (removal of most elements except carbon) by pyrolysis method under inert gas at high temperature above 1,000 °C. Inorganic polymer fibers with a carbon content of more than 90%.