Here are a few reasons:
1. The static sealing surface which matches the outer edge of the oil seal and the cavity is deformed because the dimensional tolerance does not meet the standard specifications;
2. The material cracks due to the harsh working conditions, especially the cracks on the sealing edge of the oil seal;
3. As the working conditions are too harsh and the rubber elastomer is incompatible with the working medium, the hardness of the rubber increases, or the hardness of the elastomer is too high;
4. The sealing medium swells the rubber and reduces the hardness of the rubber, thereby causing premature aging and wear of the oil seal;
5. Corrosion from the shaft to the sealing lip area will leave a permanently hidden trouble of the sealing performance of the sealing system;
6. The lubricant fails and the system is in a dry-running state so that the sealing lip wears quickly;
7. Comprehensive aging of both rubber elastomer and sealing medium.
8. "Oil-carbon" dirt is formed at the sealing lip, which causes the sealing lip of the oil seal to be lifted, causing leakage of the sealing system.
9. The sealing lip of the oil seal no longer follows the vibration of the shaft surface and the beating of the shaft;
10. Contaminants are permanently embedded in the sealing edge from the inside and outside of the seal, causing premature wear of the shaft surface and the sealing lip;
11. Irregular assembly process causes damage to the contact surface of the shaft surface and premature wear of the sealing lip;
12. The sealing edge is damaged during storage, transportation, and assembly.
In Addition To The Above
We can analyze the causes of leakage according to the time course of oil seals being used, such as early-phase damage and leakage at the beginning of use; premature damage and leakage after a short period of use; damage and leakage after a fairly long period of use in work; damage and leakage at the end of the designed service life.
The hydraulic cylinder uses hydraulic oil as the working medium to transfer movement through the change of the sealed volume, and transfer power through the pressure inside the oil. To establish the seal volume and build up the pressure, there must be a good enclosed space and avoid leakage.
Sealing is a mechanism that prevents the leakage of the working medium (internal leakage and external leakage) and prevents foreign objects (such as air, dust, water, etc.) from entering hydraulic components and hydraulic systems. The sealing element plays a decisive role in the design, service life, and function of the hydraulic cylinder. Here are some factors to be considered in the design of a hydraulic cylinder seal.
1) Work Temperature
When choosing a sealing ring, you should consider the temperature of the work environment in which the hydraulic cylinder will work. Low temperature will cause the sealing materials to harden and shrink, which will cause leakage. Whereas, if the temperature is too high, the sealing materials will be carbonized. Therefore, it is very important to choose the right sealing ring which can agree to the working temperature.
2) Work Pressure
If the system pressure is too high and the hardness of the seal is too small, the seal material will be squeezed out of the metal groove. It will affect the sealing effect and probably cause leakage, which will cause environmental pollution and reduce work efficiency. And the applicable working pressure for different types of seals is also different. Therefore, we should choose the right sealing materials according to working pressure.
3) Linear Velocity Of Hydraulic Cylinder
If the linear velocity of the hydraulic rod to stretch and withdraw is too high, it will cause heating up, dry grinding, and carbonization of the seal, which will cause leakage. Sometimes if it exceeds the usable linear velocity range of the seal, it may lead to premature wear and leakage of the seal.
4) The Stress Condition Of The Hydraulic Cylinder At Work
If the hydraulic cylinder rod is subject to lateral force, it is necessary to design a guide support seal ring to withstand the lateral force, otherwise, it will cause the hydraulic cylinder rod and the hydraulic cylinder end cover to touch and rub each other, which may create scratches and cause leakage.
5) Type Of Hydraulic Cylinder Working Medium (Hydraulic Oil)
If the seal is not compatible with the working medium, the seal material and the medium will dissolve in each other, and the seal will be softened or dissolved. Therefore, we should choose sealing rings that are compatible with the working medium.
6) Dust In The Work Environment
Heavy dust in the work environment may cause the seal to wear and cause leakage as a result. This is why we need to design a dust-proof seal to achieve leak-proof performance.
When the dust is particularly serious, it is even necessary to consider adding a corrugated sleeve to the hydraulic cylinder rod.
Secondly, even the correct seal requires a reasonable structural design. If the size of the seal does not match the metal groove, it may cause leakage.
Double-sided high-pressure bulge forming machine is custom designed to achieve the perfect combination of hydraulic pressure and pneumatic pressure.
1. The appearance of the equipment is unique and beautiful. The main body adopts a four-column three-plate cylinder under-mounted structure. The pneumatic system, electric control system, and hydraulic system are scientifically arranged in different sections; The four posts are made of high-quality 45# forging materials, and the surface is hard chrome-plated and polished after intermediate-frequency quenching, and the hardness reaches HRC45-50 degrees, which can improve the wear resistance of the columns during the movement of the slider, while ensuring the guiding accuracy (parallelism and perpendicularity), and the ability to withstand strong eccentric loads.
2. The double-sided high-pressure bulge forming machine adopts servo-hydraulic system technology and the German-imported quantitative pump to accurately set the pressure, which has no overflow compared with the conventional hydraulic system, and saves power and energy by more than 50%;
3. Two-stage speed control of the movable plate, which can realize fast approaching speed, slow-closing speed, and fast return speed;
4. Mold customization and one-stop technical service support;
5. The equipment has passed the market test in batches. The advantages of the products: the corners of the composite material don’t turn whitish, and the layer is not separated.
6. The double-sided high-pressure bulge forming machine uses configuration software to compile. It has a friendly HMI enabled by a high-color touch screen, which greatly facilitates the user's visual input and use of production parameters and direct monitoring of on-site production process data including equipment status. The main cylinder pressure, heating time, template temperature, vacuum suction time, air pressurization pressure, pressure holding time, etc. can be directly input through the touch screen, and each running value is dynamically displayed, with a friendly and visual interface, simple and convenient operation;
7. The touch screen has an Ethernet interface, USB interface, data storage, and input/output functions;
8. The press-fitting data can automatically generate production reports, and the data can be exported for easy query;
9. Equipment I/O input and output signal monitoring function with signal input displayed in red and no signal input displayed in green, which is convenient for troubleshooting the equipment;
10. The machine has a fault alarm function. When a fault occurs, the corresponding cause identification turns yellow, and the corresponding troubleshooting can be done quickly according to the fault information;
11. The operating table is equipped with photoelectric protection, which is safe and reliable
12. This equipment adopts a single-station design, which makes it more convenient to place in the workshop.
For some manufacturers, how to choose a servo press has become an issue of great concern. As long as you fully understand the process requirements of the products you make and know the fixing method and the size of the mold, it is not difficult to choose the appropriate servo press. In fact, when choosing a servo press, we basically need to consider tonnage, table size, stroke, opening daylight, etc.
(1) Pressure: the required pressure of the selected press-fitting product should be 10%-90% of the range of the servo press machine;
(2) Opening daylight: it is the distance between the worktable and dies head/die platen. Usually, when we could have the data of your shut height requirement, we could judge if the daylight and stroke of the designed servo press are suitable for your application.
(3) Press-fitting stroke: it refers to the distance that the die head/die platen moves from the top limited position to the bottom position. Please note that the servo press can perform full-scale press-fitting in the whole stroke, and there is no idle stroke without force, in order to improve the work efficiency, we don’t need to over-enlarge the stroke;
(4) The effective worktable: the size should be enough for convenient mold installation and workpieces loading and unloading.
(5) Mold installation mode: the mold is usually fixed at the upper and lower ends (usually the upper end uses the die head/die platen, and the lower table surface is machined with T-slot mode installation).
Accuracy refers to the measurement of precision with which the pressure and position reach the specified point. It is related to the resolution of the drive, the resolution of the pressure transmitter, the accuracy of the servo motor, and the response speed of the reaction device. By virtue of the mature complete set of servo motors and integrated drive-control, the servo press is getting a higher and higher repeated accuracy and is applied in more and more fields.
It is particularly important to ensure the quality of the explosive devices. As you may already, the production process has a decisive influence on the performance of the explosive device. Therefore, in addition to factors such as the materials used and product design, the quality of the explosive device must be guaranteed by a reliable production process. In the entire production process of explosive devices, the powder pressing process is one of the key processes. Parameters such as pressure accuracy, pressurization speed, and pressure-holding time in the process of powder pressing have an important influence on the quality of explosive devices. At present, the traditional powder pressing machine generally has disadvantages such as low accuracy, poor stability, inconvenient equipment adjustment when changing products, and low digitization, which ultimately leads to a low yield of explosive devices and many potential safety hazards. Therefore, the development of an explosion-proof servo press for the production of explosive devices with high reliability and flexibility is of great significance for improving the production capacity and level of explosive devices.
The mechanical part of the explosion-proof servo press for explosive devices is mainly composed of the C-frame machine body, the explosion-proof cover, the dust cover, etc. The C-frame body is the core functional component of the equipment, which is used to realize the precise control and output of pressure during the suppression process of explosive devices. The explosion-proof servo motor and the servo-electric cylinder are arranged and installed horizontally. Equipped with a high-precision explosion-proof pressure sensor and position sensor, the machine can realize the real-time high-precision closed-loop control of the output pressure during the suppression process throughout its entire stroke.
Based on the specific process requirements and technical indicators in the process of powder pressing, the overall structure of the press and the design of the electrical control system are determined; combined with the characteristics of the pressure-controlled object in the powder pressing process, the powder pressing pressure control method which is based on the variable-speed integral PID algorithm is designed, and the experiment of powder pressing is conducted. The explosion-proof servo press can achieve a pressure accuracy of more than 0.3%. The pressing force is adjustable in the range of 100-2000KG, and the pressure holding time can be freely set according to the requirements, which truly realizes the flexibility and digitization of the explosive device suppression process.
1. Logic and motion control system: It mainly completes human-computer interaction, signal acquisition, and control output, closed-loop control of suppression pressure, and logic control required by other systems.
2. Servo driver: it responds to the control output signal of the motion controller and converts it into a drive output that the servo motor can accept, completing the semi-closed loop motion control of the motor end.
3. Explosion-proof servo motor: the power source for the pressure output of the explosion-proof servo press.
4. Explosion-proof pressure sensor: It detects the real-time pressure on the die head/slider of the machine and converts it into a standard electrical signal that can be recognized by the motion controller as the feedback input of the pressure closed-loop control system.
5. Other mechanical devices: mainly include deceleration booster mechanism, servo-electric cylinder, etc.
1. The rapid-approaching stage.
2. Material suppression pressing stage.
3. Pressure holding stage.
4. Quick return stage.
The IMT high pressure forming machine is a brand-new numerical control device. It is written by configuration software and uses a high-color touch screen as a carrier to form a friendly human-machine dialogue window, which greatly facilitates users’ visual input and use of production parameters and direct monitoring of on-site production process data including equipment status, forming integrated equipment of oil pressure, position, air pressure, and IR hot pressing.
IMT (Inner Molding Translate label) or (Insert Molding Three-dimensional) is a synthesis and extension of in-mold injection molding technology and in-mold transfer printing technology.
It brings together the advantages of a variety of decoration processes: it adopts the advantages of the IML process in the production of the film, absorbs the advantages of the IMR process, and combines the digital printing and offset printing effects with the traditional screen printing process, which makes it highly adjustable and widely applicable, and makes up for the limitations of traditional exterior decoration technology and meets the high-level innovation requirements of product exterior decoration. The 3D effect and product stretching meet the in-mold decoration process of more products.
The advent of the IMT technology process will replace oil spraying, UV overprinting, electroplating, vacuum color plating, silk screen printing, pad printing, transfer printing, and other processes, and will drive leapfrog innovation in the product appearance industry. It has realized three-dimensionality, color gradients, R angles, and other irregular product appearance decoration effects. It has also provided better innovation and realization platform for the exterior design industry.
The name of the traditional IMT process appeared in China back in 2006. In fact, it is similar to the IMR process in Japan. The process at that time was equivalent to the PET carrier of the IML process after its color is removed and left in the plastic part. The radian of products was then not large(2D), and the appearance is not varied enough; basically there were only silkscreen and color layers, and very few metallic colors.
The new IMT technology is combined with the most popular 3D optical texture + PVD decoration method. Products processed by this new technology have a more beautiful appearance and larger radian compared with products processed by the traditional method. Currently, the new IMT technology has evolved from 3D optical texture + PVD to double 3D optical texture +PVD.
For mobile phone housing made of plastic + metal middle frame, it is the amount of metal CNC processing that determines the price of the whole housing. Compared with the high-pressure composite plate which was very popular last year, the IMT back cover can not only serve as a decorative part, but also a part of the structural part as well, and so as to reduce the processing time of the middle frame. Therefore, it is quite competitive in the 5G era.
The 5G era is coming, and the mobile phone housing materials will change from plastic to metal and then back to non-metallic materials. Plastics are favored by the low-end market because of their low cost. But now the new IMT process has made plastic the favorite choice of many CMF designers. We cannot evaluate the specific cost of the back cover material alone but should integrate it with the middle frame as a whole to position the price of the product. There are several types, from low-end to high-end mainly including plastic + metal middle frame, 2.5D glass + metal middle frame, and 3D glass (ceramic) + metal middle frame.
1. The four-column structure of a small hydraulic press, is simple, economical, and practical. The frame structure has good rigidity, high precision, and strong anti-fraud load ability.
2. The hydraulic control system adopts the integral cartridge valves. The leakage point of the hydraulic system is reduced. The small hydraulic press acts smoothly and reliably, yet with long service life.
3. PLC control which is sensitive, reliable, and flexible. The working pressure and stroke can be adjusted within the specified range according to the process requirements. The machine operation is simple.
5. There are three operation modes: manual adjustment, two-hand semi-auto cycling, and automatically continuous working cycle (with an automatic feeding device).
6. Rotary selector switch of the three processing operations optional: cycles with cushion, without cushion, ejecting.
1. The design of this model adopts four-column and three-plate open space, and the four columns are respectively equipped with self-lubricating bearings.
2. The working area is sufficient. It is suitable for the installation of larger molds, and suitable for large-area leveling, punching, bending, etc.
3. The hydraulic circuit design is simple. The motor power demand is small, and the maintenance is easy. The circuit design can also be changed according to the customer's work requirements to achieve the purpose of the work.
4. The machine can be moved freely with wheels.
5. Two-hand operation, safety light curtain, and interlocked safety mesh shield are installed to ensure safe operation.
6. The rotary indexing plate, automatic feeding devices, and returning devices are optional.
At present, there are still many difficulties in the direct drive of hydraulic pumps by high-power servo motors. The main reason is that the speed range of the hydraulic pump is very large. The minimum speed of the general hydraulic pump is 600 r/min, and the hydraulic pump can work normally even if it is below 10 r/min.
High-power AC servo motor and its control technology
The advent of the high-power AC servo motor is a new product that came into being in the past 10 years. At present, the technology mainly adopts switched reluctance motor (SMR), SMR is well known for being simple and reliable, and it also has other noticeable advantages including high-efficiency operation in a wide range of speed and torque, four-quadrant operation, fast response speed, and low cost. But it also has disadvantages which include high control costs and low power density due to the system’s nonlinear characteristics, large torque fluctuations, large vibration, etc.
The AC servo motor drive control unit is composed of large-scale integrated circuits, high-power rectifier modules, and other electronic power components. With the development of electronic technology, the performance of high-power AC servo motor drive control units has been improving, while the prices have been decreasing, which facilitates the realization and promotion of high-power AC servo drive technology, and makes it possible to adopt AC servo drives in the field of forging equipment. The focus of the research is to pull scientific research energy to develop high-power AC servo motor control technology and related application technologies with independent intellectual property rights, which will provide a solid foundation for the development of servo-hydraulic presses.
The closed-loop control technology of hydraulic pressure and position through servo motor is not mature yet. Traditional hydraulic presses control hydraulic pressure and position through proportional valves and proportional servo valves. It is necessary to study a special control algorithm to achieve the high stability and high accuracy of hydraulic pressure between 1 and 25 MPa.
In order to save more energy and reduce energy loss as much as possible, it is necessary to recover and reuse the potential energy of the sliding block's own weight and the energy generated by the pressure relief of the oil cylinder. Currently, there is no mature practice and experience in this regard yet. In terms of energy management, since instantaneous power is many times larger than average power, energy must be deployed properly in large-scale servo-hydraulic machines to avoid impact on the power grid.
Most of the existing hydraulic presses are controlled by PLC, but the servo-hydraulic presses are controlled by hydraulic pressure and speed closed-loop program, which requires a large amount of calculation, so ordinary PLC can hardly meet the needs. Therefore, the control system of the servo-hydraulic press is controlled by an industrial PC, and a special control system must be developed.
Since the materials and shapes of different kinds of stamping parts are different, the stamping processes are also different. As for the silent blanking process, for example, the control of the shifting point is the key; in reverse extrusion forming of the magnesium alloy cup-shaped part, the slider needs to experience 4 different speeds in a working cycle, and the extrusion process is under constant- pressure control. Therefore, only when the servo-hydraulic press is optimized in combination with various forming processes, can it exert its superiority. To achieve the goal of improving product quality and production efficiency and reducing production costs, it is very important to study the forming mechanism of various forming processes and establish optimized parameters suitable for each forming process.
Compared with traditional hydraulic presses, servo-hydraulic presses have more advantages such as energy-saving and noise reduction. When designing their machine body, more factors need to be considered so as to achieve these advantages, such as various possible extreme working conditions, working frequency, the complexity of stamping parts, etc. For a long time, Chinese engineers and technicians have mainly adopted empirical methods and analogy methods when designing products, and the forging machine tools have disadvantages such as large volume, heavyweight, poor control accuracy, etc. Steel consumption has been one of the key factors in product cost control for forging machine tool manufacturers.
Through a lot of effort, Chinese scholars and engineering technicians have developed relevant optimization software for partial optimization of forging machine bed components. However, they have been mainly lingering in the static design stage, and have not considered much of the dynamic machining process of the machine tool system. Therefore, the corresponding issue of machine tool reliability has not been fundamentally solved, resulting in a reduction in the service life of the machine tool and an increase in the maintenance cost of the machine tool. Therefore, it’s imperative to form a design method and technical system under the constraints of the rigidity, strength, and dynamic performance of the forging machine tool, so as to narrow the gap between our own country and developed countries in the design and manufacturing of products.
C frame hydraulic presses play different roles for different products. For shaft parts, profiles, etc., the C frame press is mainly used to complete the pressing of the parts; for metal materials, it is mainly used for the stretching, blanking, bending, flanging, correction, pressing, and cold & hot extrusion of the material. It is also indispensable for compression molding of such products as powder products, plastic products, etc. How much do you know about the application and features of C frame presses? Let’s take a look!
1. The C frame hydraulic press is mainly used for correction and press-fitting of shaft sleeve parts, and can also be used for other processing purposes.
2. As the C frame press stands upright, and its equipment parts are inside the machine body, the appearance is neat and beautiful.
3. The C frame hydraulic press can be used for handle and pedal operation. The pressure of the hydraulic press can be adjusted within the specified range. The stroke can be controlled with a relatively simple operation.
1. The integral welded solid open structure of the press can keep the body rigid enough while having a convenient operating space.
2. The press has noticeable advantages such as good structural rigidity, good guiding performance, fast speed, etc.
3. The convenient manual adjustment mechanism of the press can adjust the position of the pressure head or can press any position in stroke, and it can also arbitrarily adjust the distance between a fast forward stroke and a pressing stroke。
It’s optional to have an additional pressure sensor to convert into a press-fitting force value and display it digitally through data acquisition and system processing composed of the PLC. When the force exceeds the limit, it will send out a sound and light alarm and shutdown signal, so as to achieve automatic control of press-fitting force. The load display controller can control the value accurately and display it clearly; it has a fast response speed and stable and reliable working conditions. Different sensors and application software can be replaced for different forging equipment with different tonnages. By using a counter, every operator knows the total number and the unqualified number. And the two-hand start button is added to make the operation of the machine safer.
The four-column hydraulic press drives the operating mechanism by the motor through the transmission mechanism, applies pressure to the workpieces, and completes its processing process. The transmission mechanism is a reduction mechanism driven by a belt or gear. The transmission mechanism is a belt-drive or gear-drive decelerating mechanism; the operating mechanism is divided into a screw mechanism, a crank connecting rod mechanism, and a hydraulic cylinder. The transmission mechanism of a hydraulic press can not only complete various forms of complex motion and compound motion but also complete a large-scale continuous step-less speed regulation. Now let’s have a look at the issues that should be paid attention to when adjusting the pressure and reducing the vibration of the press.
The pressure of debris cannot be higher than the pressure of the pump unless the hydraulic machine has a supercharging device. The actual pressure of the pump depends on the load size and is generated automatically rather than adjusted. The set pressure of a four-column hydraulic machine is the maximum pressure for normal operation. Lower the pressure of the overflow valve, adjust the overflow valve, and the pump outlet pressure will rise to the required value.
After the four-column hydraulic press is used for a period of time, every time it starts or stops, there will be a vibration of the machine with noise. This is not good for the hydraulic press in the long run; it also affects the production efficiency and causes concern for the operator. Therefore, we
have to think of some methods to reduce the vibration.
The vibration caused by the alternating internal and external cycles of the hydraulic press process system, also known as forced vibration, is mainly caused by external interference. The vibration source must be eliminated first. Prevent the exciting force frequency of the four-column hydraulic press from approaching the natural frequency of the system to avoid resonance. the motor speed is changed or the spindle speed is changed to avoid resonance. Adopt the forward contact surface accuracy, reduce the roughness of the joint surface, and eliminate the gap and the forward contact stiffness, which can eliminate vibration.
The motor and the bed can use flexible connections to isolate the vibration of the motor itself. the hydraulic buffer device can be used to reduce the shock when the components are reversed. thick rubber and wood can be used to isolate the machine from the foundation; consider using anti-vibration ditch separation equipment connected to the ground to prevent the surrounding vibration source from being transmitted to the hydraulic press through the ground.
