How to apply extrusion die casting technology to o

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How to apply extrusion die-casting technology on ordinary die-casting machine

Abstract This paper discusses the application status of traditional die-casting and extrusion casting technology and equipment, introduces the process characteristics and economy of extrusion die-casting technology, and puts forward the method of applying extrusion die-casting technology on ordinary die-casting equipment

key words: Squeeze Casting squeeze casting process squeeze casting machine die forging

I. The application status of squeeze casting process and equipment

squeeze casting technology has been invented for 65 years. It has strong technical advantages and has been valued by the machinery manufacturing process industry. Unfortunately, restricted by the traditional way of thinking and the lagging development of equipment, the advantages of squeeze casting have not been fully demonstrated. At present, the squeeze casting process is basically carried out by open casting and vertical extrusion, which is not compatible with the horizontal cold chamber die casting process with the highest efficiency. The vertical closed mold filling squeeze casting developed in recent years, like the "precision, speed and density" die casting principle invented 40 years ago, is fed by the injection mechanism, and its nominal pressure is limited, which does not meet the feeding specific pressure requirements of squeeze casting. Strictly speaking, it cannot be regarded as squeeze casting in the real sense

compared with die-casting technology, the existing squeeze casting equipment has low efficiency, low dimensional accuracy of parts and relatively high cost. Due to the low degree of automation of the equipment, the requirements for workers' skills are high, the operation is difficult, and the labor intensity is high. For the same parts, the workshop cost of squeeze casting process is about times that of die casting process. In addition, the incomplete injection system makes it difficult to produce parts with complex structure, which limits the wide application of squeeze casting technology

The problems existing in the popularization and application of squeeze casting technology are caused by the lagging development of equipment. At present, the biggest sticking point of the traditional squeeze casting technology and equipment is that it cannot be effectively combined with the injection system of the traditional die-casting device. The key problem is how to combine mold closing, mold locking and extrusion well. Without breaking through this point, the technological potential of squeeze casting can not be fully developed, its alternative advantages to the traditional die-casting process can not be fully expressed, and the traditional die-casting technology can not take this technology to compound and leap to a new level

second, the advantages of applying extrusion die-casting technology to traditional die-casting machines

the traditional die-casting technology and equipment technology have been quite perfect, especially the horizontal cold chamber die-casting machine and horizontal die-casting technology. Its injection and mold closing and locking devices have strong process adaptability. Therefore, if squeeze casting technology cannot be combined with traditional die-casting equipment, its wide application will be restricted. Taking this step, another branch of squeeze casting technology will appear, which is squeeze casting technology. In other words, the application of squeeze casting technology on the basis of traditional die-casting machine is squeeze casting technology. According to the characteristics of the extrusion die-casting process, the traditional die-casting machine is improved accordingly. This set of equipment is a brand-new extrusion die-casting machine

1. Correctly and comprehensively understand the function of die-casting process and traditional die-casting machine

grasp the principle of squeeze casting process, and it is not difficult to simply apply squeeze casting process on traditional die-casting machine. The key is to break through the traditional concept. It requires a comprehensive and full understanding of the performance of the traditional die-casting machine, a deep understanding of the traditional die-casting process, and the elimination of those preconceived fuzzy understandings

in fact, at present, the traditional die-casting machine has quite complete functions. It can not only carry out ordinary die-casting, but also carry out extrusion die-casting and extrusion die-casting with core; It can not only carry out various low-pressure casting, differential pressure casting and gravity casting, but also carry out vacuum suction casting, vacuum die casting and vacuum extrusion die casting after adding vacuum pumping device. If we open our minds a little more and combine semi-solid processing and die forging technology to form a continuous casting and continuous forging process, it can also be effectively realized

there are many models of die casting machines, and the injection force and injection speed of the injection system are "continuously stepless adjustable". In terms of the process characteristics of low-pressure casting, differential pressure casting and gravity casting, there is no problem in carrying out the above processes on ordinary die-casting machines. Installing this kind of mold on the die-casting machine is not as expensive as people think, because it is not necessarily designed as complex as the traditional die-casting mold. Unfortunately, it is difficult for us to see relevant applications and reports in practice. This is a misunderstanding of our understanding, concept and application of traditional die-casting machine and traditional die-casting process

2. characteristics of traditional die-casting process and equipment and adaptability to extrusion die-casting process

traditional die-casting machines are divided into two types, one is full hydraulic master cylinder closing (locking) die-casting machine, and the other is elbow mechanism locking die-casting machine. Due to the low manufacturing cost of elbow mechanism mold locking equipment, this type of model has dominated the market at present

an important feature of traditional die-casting machine is that its model is named after the clamping force as the main parameter. Now we often say that the tonnage of a die-casting machine refers to the tonnage of the clamping force. The extrusion die-casting machine has not only the parameter requirements of clamping force, but also the parameter requirements of extrusion feeding force, and this extrusion force parameter is the most important index

as mentioned above, because the traditional die-casting machine has two different models: full hydraulic and elbow type, there is no difference in traditional ordinary die-casting, but it is different when used as extrusion die-casting. The difference between extrusion die casting and ordinary die casting is that after the casting is filled, extrusion die casting adds a master cylinder power to advance forward for feeding, while ordinary die casting only cools naturally without feeding

here, we need to subdivide and clarify two concepts, namely, clamping force and clamping force (or mode locking resistance). The clamping force refers to the forward force required to advance the moving mold, while the clamping force refers to the resistance required to resist mold filling and expansion. It can be just a static force (reaction force). Therefore, the direct application of extrusion die-casting process with traditional die-casting machine can only use its clamping force, and only the clamping force is a driving force to move forward. The clamping force determines the squeezing and feeding force. Therefore, the maximum clamping force of the full hydraulic traditional die casting machine is its maximum clamping force, which can also be used as its extrusion and feeding force. The maximum forward extrusion force of elbow die-casting machine is equal to the force of its clamping cylinder multiplied by the lever ratio of the clamping mechanism, but the maximum compressive strength that the clamping mechanism can bear cannot be exceeded. When using this kind of equipment for extrusion die casting, because its initial position of clamping does not reach the self-locking "dead point" of the clamping mechanism, and the extrusion end position is the "dead point" of its maximum clamping resistance, if the same die-casting is compared with pressure filling, the projection area of the parts that can be produced will be reduced

3. Define the main technical characteristics of squeeze casting

the highest squeeze feeding specific pressure of squeeze casting is about times that of ordinary die casting. Measured by the extrusion specific pressure of squeeze casting, at present, except that the vertical open mold pouring squeeze casting machine transformed by four column hydraulic press meets the main technical indicators of squeeze casting, the realization of other devices only belongs to the process scope of traditional die casting, which is not squeeze casting in the real sense. This concept, we want to define 18 The sand content is calculated

4. it is infeasible to use the injection device of traditional die-casting machine for extrusion die-casting process

at present, no matter what kind of clamping mechanism the traditional die-casting machine is, the designed injection force is about one tenth of the clamping force, which is restricted by Pascal's law. The current die-casting process generally requires that the specific pressure of injection is roughly between 80MPa and 130Mpa, and each 100 tons of clamping force can bear the projection area of die-casting is about square centimeters. As the squeeze casting process requires feeding specific pressure rather than die-casting specific pressure, the maximum requirement of extrusion feeding specific pressure is between 500MPa and 1000MPa. For die-casting parts with small inner gate, we can't use injection cylinder or auxiliary cylinder to squeeze or "pressurize" for cold feeding, and it must be powered by the main cylinder to squeeze and feed. If extrusion die casting is really carried out in the way of "precision, speed and density", it is necessary to increase the size of the inner ring to make it have the characteristics of sequential solidification. Since the ingate is generally cooled before the casting, it is impossible to realize extrusion feeding without increasing the size of the ingate. This method is not applicable to many die castings. In order to achieve the above extrusion feeding specific pressure, the projection area of the extrusion die casting produced by the die casting machine is only one tenth of the original. The "diecasting projection area" of the blank produced by the traditional die-casting machine is not large, and it is obviously uneconomical to reduce it by 90%. In practice, it has lost its significance of application. At present, all die-casting machines have the "pressurization" link at the later stage of die-casting filling, but the air tightness defects of die-casting parts remain the same. The effect of the "big cow pulling small car" method of producing small parts with an enlarged model is not much better. The so-called "precision, speed and density" die-casting is only a beautiful name. There has been no substantive progress in 40 years. The commercial publicity of the manufacturer of this kind of die-casting machine, Instead, it strengthens the misunderstanding of engineering technology and application personnel, and makes people lose their way

5. Understand the main technical characteristics of extrusion die casting technology and its strong technical and economic advantages

the main technical characteristics of extrusion die casting embody the principle of "ordinary die casting filling, squeeze casting feeding". It uses the perfect injection system of the existing die casting machine to fill the mold, and at the same time, it avoids the restriction of Pascal's law on the filling conditions (the filling area of parts) when filling the metal liquid phase as far as possible. This is of great significance, and it is also an important feature of the extrusion die-casting process: the extrusion die-casting process emphasizes the lowest filling specific pressure and speed as far as possible under the conditions of satisfying the filling conditions. This process idea is a great advantage for all kinds of thick parts that need low-pressure filling and the successful realization of die-casting with core. This is the reason why it can replace low-pressure, differential pressure, gravity casting and some sand casting processes with core. The introduction of extrusion die-casting technology has greatly expanded the scope of application of traditional die-casting machines and die-casting processes. Its major economy lies in that if a traditional die-casting machine is filled with 1.4mpa low pressure, the projection area of the parts produced is 80-100 times that of the original. It can be said that the size of the mold that can be installed on the workbench of the existing equipment can produce parts. A traditional j1140 full hydraulic 400 ton die-casting machine is transformed into an extrusion die-casting machine with 400 ton extrusion feeding force at the same time, which can basically meet the technological requirements of large-scale parts such as automobile and motorcycle hubs. Based on the technology of extrusion die-casting, an extrusion die-casting machine with both 500 tons of clamping force and 500 tons of extrusion force can cope with more than 90% of the current die-casting production. Using a traditional die-casting machine with more than 500 tons of clamping force is already a very uneconomical practice, and it has great investment risks for small die-casting plants

the technical and economic energy contained in the extrusion die casting process is amazing. An extrusion die-casting plant of the same scale will reduce its equipment investment by more than two-thirds compared with the traditional die-casting plant, but its process adaptability can cover most of the casting molding except foundry. The concept breakthrough of extrusion die casting technology may be deeper than the breakthrough of its technology itself

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