22 Klochok Vcheslv Jurijovuch Kiev 2013 Contens Intro Controlling the Die Csting Process The min benefits of high pressure diecsting re Die csting ve.html
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MINISTRY EDUCATION AND SCIENCE OF UKRAINE
National Technical University of Ukraine
“Kyiv Polytechnic Institute”
Abstract
On: “Controlling the Die Casting Process”
Student 2nd year
EPF
Group FT-22
Klochoka Vacheslava Jurijovucha
Kiev 2013
Contens
Intro
Controlling the Die Casting Process
The main benefits of high pressure die-casting are
Die casting versus. other casting processes
Choosing the proper alloy
Die casting process
History
Die construction
Hot chamber machines
Cold chamber machines
Automation and quality control
Die casting design
Controlling the Die Casting Process
Casting under controlled pressure creates opportunities for management form filling melt. If inside a sealed chamber apodavaty compressed air or gas under pressure wood-> RATM, then by riznytsityskiv melt rises to metalloprovoda 1 and 2 tolevel fill in a form corresponding to H = (pizb-patm) / r. This method of filling nazyvayutlyttyam low pressure. The term "low pressure" is used because for lifting melt and form filling required excess tyskmenshe 0.1 MPa.If in a sealed chamber to create a vacuum installations and Broadcaster atysk maintain equal atmospheric, then fill in the form stanetsyaza the difference of pressure RATM-R. This method is called fill lyttyamvakuumnym absorption. Using a similar procedure to establish this can be done zapovnennyaformy otherwise. Put that in cells a and b initially created equally, alebilshe pressure air or gas Pk> RATM. Then feed povitryav camera would stop, and the camera and continued the pressure in the chamber apidvyschuyetsya to PV + DP.Then the metal will climb metalloprovoduvnaslidok pressure difference Pa-Sat, ie the same way as in lyttyapid low pressure. The same result can be achieved if the camera would znyzhuvatytysk, leaving a constant pressure in the chamber as well. Takiprotsesy called low pressure casting of backpressure. Settings for casting under controlled pressure - complex dynamichnisystemy, allowing widely adjust the speed zapovnennyaformy melt. Using these settings allows you to fill formytonkostinnyh 9600 olive change the length form filling okremyhdilyanok casting complex configuration with variable wall thickness with to managing heat melt and form domahayuchysratsionalnoyi sequence solidification casting parts. Application of pressure on the solidifying melt improves umovyharchuvannya, casting shrinkage, improve quality - mechanical properties tahermetychnist.In the above process after completing the form tyskdiye to melt crucible through which one enters metalloprovoda uzastyhayuchyu cast and nourishes it.This shrink insuch casting porosity decreases, the density and mechanical properties increase. Injection pressure is regulated in plants so thatprocess form filling melt - the most time-consuming and frustrating from the point view of health and safety operation - vykonuyetsyaavtomatychno. Construction plant and machinery for these casting protsesivzabezpechuyut also automate operations of addition and disclosure forms, extrusion molding and its removal from the mold. Thus, the processes lyttyapid controlled pressure can improve the quality of castings and zabezpechytyavtomatyzatsiyu their production. In practice, the greatest use such casting processes pidrehulovanym pressure: Low pressure casting, low pressure casting of backpressure, vacuum suction casting, molding vakuumnymvsmoktuvannyam of crystallization under pressure (vacuum - kompresiynelyttya).
Low pressure casting The crucible with the melt in the furnace Transfer (camera) installation hermetychnozakryvayut cap which is set metaloprovod made zzharostiykoho material. Metalloprovoda dipped into the melt so that kinetsyoho not reach to the end of the crucible by 40-60 mm. Uniform on the lid, combine with metaloprovodom gating bushings. The cavity in the casting can beperformed metal, shell and sand core. Air or inert gas under pressure to 0.1MPa systemurehulyuvannya coming through the pipeline into the camera settings iatmosfernym pressure melt comes in the form below due metaloprovod, pouring and collector at a rate controlled by pressure in chamber settings. After filling out a form and solidification casting avtomatychnovidkryvayetsya valve connecting the camera settings with the atmosphere. Tyskpovitrya in the chamber is reduced to atmospheric and Nezatverdilyy zmetaloprovoda melt is poured into the crucible. After this form is revealed vidlyvannyavytyahuyetsya and the cycle repeats. The main advantage of the casting process under low pressure are: automation of time-consuming operations fill forms, the ability rehulyuvannyashvydkosti melt flow in the mold cavity pressure changes kameriustanovky, nutrition casting, reducing consumption of metal nalitnikovuyu system. The main disadvantages of low resistance metalloprovoda, zanurenohov melt, which makes use of methods of casting alloys for hightemperature melting, the complexity of speed control potokurozplavu form caused by dynamic processes occurring vustanovtsi while completing her chamber air leakage instability povitryacherez compaction, reduction in melt to install in miruvyhotovlennya casting, the ability to deterioration of the alloy in the crucible at tryvaliyvytrymtsi installation, operation complexity and configuration settings. Advantages and disadvantages of a rational method of determining the area yohozastosuvannya and prospects. Low pressure casting mostwidely used for the manufacture of complex shapes and especially tonkostinnyhvylyvkiv of aluminum and magnesium alloy castings with simple midnyhsplaviv and steels in serial and mass production. Features of iron casting, low pressure. Filling out forms melt while casting process can be zshvydkostyamy flow, which can be adjusted over a wide range. Dlyaoderzhannya quality castings mostly fill out the form sutsilnympotokom at speeds that provide high-quality form filling ivyklyuchayut capture air melt, casting hazovyhrakovyn education, ingress of oxide films and nonmetallic inclusions. Odnakzmenshennya flow rate needed to maintain its continuity mozhesprychynyty premature cooling and solidification of the melt, ie tocomplete form filling. Therefore, as in other casting processes vazhlyvopohodzhuvaty hydraulic and thermal regimes form filling rassplavom. Depending on the combination of structural and air movement parametrivustanovky metalloprovoda and melt in the mold pryzapovnennya can occur with increasing flow rate, as andwith its vibrational shift. The oscillatory nature of the change shvydkostinehatyvno affect the quality of castings, construction installation as irezhym of its pneumatic and ventilation design should promote systemyformy vibration velocity. The main design parameters settings are: robochohoprostoru volume chamber cross sectional area of the hole metalloprovoda, surface area of the melt in the crucible. Increase workspace camera settings zbilshuyeshvydkist flow promotes vibration, but they completely nevyklyuchaye. Reducing the cross-sectional area of the holes metalloprovoda plants zob'yemom workspace least 0.07 m3 hasinnyakolyvan leads to a sharp increase in flow velocity and melt in installations with space ob'yemomrobochoho more than 0.4 m 3 increase in cross-sectional area otvorumetalloprovoda not affect the nature of the flow and speed of the melt in navhodi form. Increasing the surface area of the melt in the crucible provided sustainability masyrozplavu it helps calm required. Therefore, installation ztyhli tion type in which the melt mirror is large enough, bilshkraschi, as they provide a stable operation. The increase in hydraulic resistance at the input of the melt vmetalloprovod reduces the acceleration of the melt in early filling Tagaste oscillations occur. Important for sustaining the desired speed from zalyvkydo fill, ie decreasing melt level in the crucible has systemmanagement air supply to the camera settings. Povelychynoyu pressure regulation system should be used only in installations vannohotypu. The accuracy of regulation should be within 0.01-0.05MPa, it maintains speed fill with an error of 10-15%. Dlyaustanovok vannogo types use throttle control system. The design of the cavity shape and design of the ventilation system takozhvplyvayut on the motion of the melt in the mold cavity. Pryzapovnenni forms of complex castings with ribs, lugs, the conditions dlyazahoplennya air flow melt. Hydraulic resistance porozhnynyformy has a significant impact on the nature of the flow. Construction ventilating sistemyvliyaet the nature ruhupotokarasplava in oral form and metalloprovoda. Reducing ploschiventylyatsiynyh channels leads to an increase in pressure of the air vporozhnyny shape helps reduce vibration and speed potokurozplavu. Thermal conditions of the possibility of creating spryamovanohozatverdinnya iron castings and nutrition of shrinkage. Of the form are onupper plate working chamber with heated to a temperature higher than the top of the form. Furthermore, due to the lower section of cavity shapes are closer to metalloprovoda, is more fusion than section located at the top of that istotnozbilshuye temperature difference in the lower and upper parts of the casting.Tomumasyvni part of the casting, which require food, have the bottom of the form, connecting them to a massive pouring of metalloprovoda, top formymayut same at their disposal casting parts that do not need food. Static pressure on the melt after filling out the form polipshuyeKontakt hardening crust and surface shape due chohozbilshuyetsya speed solidification of the casting. However, the air pressure melt in the crucible promotes permanent makeup vmoschuyetsya iron, resulting in reduced shrink porosity, density increases ipidvyschuyutsya mechanical properties of the casting. Excessive pressure in the flow of melt in completing the forms more nizhpry gravity casting and hydraulic shock that can vynyknutypry After completing the form, leads to the penetration of the melt in porypischanoho rod, mechanical appearance burnt on the casting. When casting, low pressure tend to fill out the form below zyakomoha melt overheating, good enough to fill out a form. Withdecrease casting wall thickness and increased its size temperaturuzalyvky are higher. Litnikovye of constructing urahuvannyamlyvarnyh properties of the alloy and casting design. Casting prostyykonfihuratsiyi Injection system can consist of one pouring directly adjacent to the solid parts for more skladnyhtonkostinnyh castings - from pouring, litnikovyh moves collector izhyvylnykiv.
Injection of backpressure Development of Low pressure casting is the casting of backpressure. Installation for casting backpressure consists of two chambers. The camera, a device which is like a sealed chamber under low pressure molding installation, located crucible with the melt. The cell shape is certainly metallic. Cameras razdelny tight cover through neyiprohodyt metalloprovoda connecting the crucible and form. These cameras mitsnoz'yednani together clips. Air pressure at which the melt is filling out a form, will be under equal pressure difference in Pa lower and upper Rbkamerah settings: DP = Ra-Sat. Lifting speed melt in metalloprovoda iporozhnyny form as well as in low pressure die casting, zalezhatymevid the totality of the above structural and pnevmatychnyhharakterystyk of determining the rate of increase of pressure difference DP, during the installation. Injection of backpressure to reduce the emission of gas from the melt, improve nutrition castings and consequently increase their integrity, and also mechanical properties. This method of casting gives the greatest effect inmanufacture castings with massive walls of uniform thickness zalyuminiyevyh and magnesium alloys crystallized in a wide rangetemperatures. Use the second stage of the process - crystallization pidvsebichnym overpressure for thin-walled castings zavzhdypryzvodyt not to a noticeable improvement of the properties. This is because schotryvalist crystallization small and thin-walled castings vidlyvannyatverdne before the pressure in the upper chamber installation dosyahneneobhidnoyi value.
Vacuum suction casting The essence of vacuum suction casting process is that rozplavpid dilution effect generated in the oral form, fill it itverdne to form castings. By changing the difference between atmosphericpressure and pressure in the cavity shape can be adjusted shvydkistzapovnennya forms melt by controlling the process. Pumping porozhnynyform when casting allows you to fill the form of thin-walled castings tovschynoyustinky 1-1.5 mm, prevent ingress of air into the melt, improve accuracy, and mechanical properties of castings. In production use setting two basic varieties. Plants of the first type have two chambers: the lower and upper. Lower kamerayavlyaye a handout oven with electric or gas heating, which houses the crucible with the melt. The upper chamber is nakryshtsi lower chamber, the lid set metalloprovoda. Formuvstanovlyuyut and fixed in the chamber so that the pouring connected prytyskamyz cover. The cavity of the upper chamber through a vacuum drive connected zresyverom, which creates a discharge pump, adjustable systemmanagement. At the initial moment control valve opens to discharge verhniykameri created and melt due to the pressure difference ukamerah metalloprovoda rises and fills the mold cavity. Pislyazatverdinnya casting valve control system connects the cavity verhnoyikamery with the atmosphere, the pressure in both chambers is the same, azalyshky Nezatverdilyy merge with metalloprovoda melt in a crucible. The upper chamber is removed, the shape of the casting is removed and the cycle mozhepovtoryatsya. Plants of this type are usually used to improve the filling formtonkostinnyh complex shaped castings of aluminum and magnesium alloys ztovschynoyu wall 2-2.5mm, and sometimes up to 1-1.5mm. Plants of the second type is used to cast sleeves, bars and zahotovokprostoyi configuration in water-cooled engines mold. Nosokmetalevoho water-cooled mold is immersed in rassplav, located in the crucible furnace dispensing. Working cavity mold, Oraz casting, wire-connected vacuum with a vacuum receiver. Dilution in the system creates a vacuum pump and regulated leak. Turn the servo valve cavity krystalizatoraz'yednuyetsya working in a vacuum receiver. In the cavity of the mold stvoryuyetsyarozridzhennya and melt absorbed into the mold, rising navysotu proportional dilution hrt and inversely proportional to yiyischilnosti. After solidification of the casting mold sock pull rank melt, turning the tap, the working cavity connects with the atmosphere ividlyvannya fall out of the mold in the receiver box. Features of the casting. Form can zapovnyatsya melts ztebuemoy speed smoothly without splashing sutsilnymfrontom, melt filled form solidifies under vacuum, gases contained vrozplavi can stand with him, so that the conditions forobtaining castings without gas shells and porosity. For schilnyhvylyvkiv no shrinkage defects must agree intensyvnostizatverdinnya iron and board. Typically vacuum suction casting ingots, bushings, rozplavzasmoktuyut in thin-walled water-cooled metal catalyst, thereby casting casting solidifies at high speed.
This way you can get thin casting type rods without sleeves. In this case, the absorption of the melt in the mold and namorazhivaniya on the inner walls kristalizatora crust solid metal thickness specified vacuum is turned off and Nezatverdilyy melt is discharged back into the pot. So get thick piece sleeves with gas and shrinkage cavities and porosity. The Method to Obtain allows CASTINGS of light colored and Alloys copper, iron and steel. Often this Method ispolzuetsyadlya casting sleeves, LINERS, bearings of expensive copper steels. The Most apparent main advantages of this Method: The calm completing form melts at a rate Controlled , reducing costs due to elimination of metal runners and profits, automation of form filling.
The main benefits of high pressure die-casting are :
• Die casting is an economical process offering a broader range of shapes and components than any other manufacturing technique.
• Parts have long service life and may be designed to complement the visual appeal of the surrounding part. Designers can gain a number of advantages and benefits by specifying die cast parts.
• High-speed production – it provides complex shapes within closer tolerances than many other mass production processes.
• Little or no machining is required and thousands of identical castings can be produced before additional tooling is required.
• Dimensional accuracy and stability - Die casting produces parts that are durable and dimensionally stable, while maintaining close tolerances.
• They are also heat resistant.
• High strength and low weight - Thin wall castings are stronger and lighter than those of other casting methods.Plus, because die castings do not consist of separate parts welded or fastened together, the strength is that of the alloy, rather than the joining process. The low weight not only saves on the metal cost, but also on general transport costs In some markets this is a must such as in the automotive industry.
• Multiple finishing techniques - Die cast parts can be produced with smooth or textured surfaces and they are easily plated or finished with a minimum of surface preparation.
• Simplified Assembly - Die castings provide integral fastening elements, such as bosses and studs. Holes can be cored and made to tap drill sizes, or external threads can be cast, as can slots, etc …
• Interchangable Inserts - The same part can me casted with different bran names,logos, serie numbers, without having to make ...additional tool invesments, or without engraving costs.
• Fast, large & flexible delivery - It is ideal to produce large amounts of perfectly equal products in a minimum of time. ( of some products we produce 30 000 pieces a day on a single machine ). Saving you high stock costs, transport and logistical costs; as making quick efficient deliveries of large unexpected orders possible.
• Tool life – The tool life is extremely long ( up to 400 000 shots in some cases )
• Combination casting : Because of its high perfect degree, two or more materials/pieces can easy be casted upon or on each other.Lowering or eliminating the final cost of the product treamandously.
• Rapid and flexible delivery: customers require less or no stock.
Die casting versus. other casting processes:
• Die casting vs. plastic molding : Die casting produces stronger parts with closer tolerances that have greater stability and durability.
Die cast parts have greater resistance to temperature extremes and superior electrical properties.
• Die casting vs. sand casting : Die casting produces parts with thinner walls, closer dimensional limits and smoother surfaces.
Production is faster and labor costs per casting are lower. Finishing costs are also less.
• Die casting vs. permanent mold : Die casting offers the same advantages versus permanent molding as it does compared with sand casting
• Die casting vs. forging : Die casting produces more complex shapes with closer tolerances, thinner walls and lower finishing costs.
Cast coring holes are not available with forging.
• Die casting vs. stamping : Die casting produces complex shapes with variations possible in section thickness.
One casting may replace several stampings, resulting in reduced assembly time.
• Die casting vs. screw Die casting produces shapes that are difficult or impossible from bar or tubular stock, ..
• machine products : while maintaining tolerances without tooling adjustments. Die casting requires fewer operations
and reduces waste and scrap.
Choosing the proper alloy :
Each of the metal alloys available for die casting offer particular advantages for the completed part.
• Aluminum : These alloys are lightweight, while possessing high dimensional stability for complex shapes and thin walls. Aluminum has good corrosion resistance and mechanical properties, high thermal and electrical conductivity, as well as strength at high temperatures.
• Pewter : This alloy offers high density and are capable of producing parts with extremely close dimensions. It is also used for special forms of corrosion resistance.
• Zamak : .
These alloys offers high ductility, high impact strength and is easily plated. Zinc is economical for small parts, has a low melting point and promotes long die life.
• Lead : This mettal offers a high density, heavy weighted pieced that are extreemly economical.
Die casting process :
The basic die casting process consists of injecting molten metal under high pressure into a steel mold called a die. Die casting machines are typically rated in clamping tons equal to the amount of pressure they can exert on the die. Machine sizes range from 10 tons to 4000 tons. Regardless of their size, the only fundamental difference in die casting machines is the method used to inject molten metal into a die. The two methods are hot chamber or cold chamber. A complete die casting cycle can vary from less than one second for small components weighing less than an ounce, to two-to-three minutes for a casting of several pounds, making die casting the fastest technique available for producing precise non-ferrous metal parts.
History :
The earliest examples of die casting by pressure injection - as opposed to casting by gravity pressure - occurred in the mid-1800s. A patent was awarded to Sturges in 1849 for the first manually operated machine for casting printing type. The process was limited to printer's type for the next 20 years, but development of other shapes began to increase toward the end of the century. By 1892, commercial applications included parts for phonographs and cash registers, and mass production of many types of parts began in the early 1900s. The first die casting alloys were various compositions of lead, but their use declined with the introduction of aluminum alloys in 1914. Magnesium, zinc and copper alloys quickly followed, and by the 1930s, many of the modern alloys still in use today became available. The die casting process has evolved from the original low-pressure injection method to techniques including high-pressure casting — at forces exceeding 4500 pounds per square inch — squeeze casting and semi-solid die casting. These modern processes are capable of producing high integrity, near net-shape castings with excellent surface finishes. N.V. Riskin was the first company in the world to diecast pewter on a high pressure die casting machine, back in 1967.
Die construction :
Dies, or die casting tooling, are made of alloy tool steels in at least two sections, the fixed die half, or cover half, and the ejector die half, to permit removal of castings. Modern dies also may have moveable slides, cores or other sections to produce holes, threads and other desired shapes in the casting. Sprue holes in the fixed die half allow molten metal to enter the die and fill the cavity. The ejector half usually contains the runners (passageways) and gates (inlets) that route molten metal to the cavity. Dies also include locking pins to secure the two halves, ejector pins to help remove the cast part, and openings for coolant and lubricant. When the die casting machine closes, the two die halves are locked and held together by the machine's hydraulic pressure. The surface where the ejector and fixed halves of the die meet and lock is referred to as the "die parting line." The total projected surface area of the part being cast, measured at the die parting line, and the pressure required of the machine to inject metal into the die cavity governs the clamping force of the machine.
Hot chamber machines :
Hot chamber machines are used primarily for zinc, copper, magnesium, lead and other low melting point alloys that do not readily attack and erode metal pots, cylinders and plungers. The injection mechanism of a hot chamber machine is immersed in the molten metal bath of a metal holding furnace. The furnace is attached to the machine by a metal feed system called a gooseneck. As the injection cylinder plunger rises, a port in the injection cylinder opens, allowing molten metal to fill the cylinder. As the plunger moves downward it seals the port and forces molten metal through the gooseneck and nozzle into the die cavity. After the metal has solidified in the die cavity, the plunger is withdrawn, the die opens and the casting is ejected.
Cold chamber machines :
Cold chamber machines are used for alloys such as aluminum and other alloys with high melting points. The molten metal is poured into a "cold chamber," or cylindrical sleeve, manually by a hand ladle or by an automatic ladle. A hydraulically operated plunger seals the cold chamber port and forces metal into the locked die at high pressures.
Automation and quality control :
Modern die casters as Riskin use a number of sophisticated methods to automate the die casting process and provide continuous quality control. Automated systems can be used to lubricate dies, ladle metal into cold chamber machines and integrate other functions, such as quenching and trimming castings. Microprocessors obtain metal velocity, shot rod position, hydraulic pressure and other data that is used to adjust the die casting machine process, assuring consistent castings shot after shot. These process control systems also collect machine performance data for statistical analysis in quality control.
Die casting design :
Die casting is one of the fastest and most cost-effective methods for producing a wide range of components. However, to achieve maximum benefits from this process, it is critical that designers collaborate with the die caster at an early stage of the product design and development. Consulting with the die caster during the design phase will help resolve issues affecting tooling and production, while identifying the various trade-offs that could affect overall costs. For instance, parts having external undercuts or projections on sidewalls often require dies with slides. Slides increase the cost of the tooling, but may result in reduced metal use, uniform casting wall thickness or other advantages. These savings may offset the cost of tooling, depending upon the production quantities, providing overall economies. Many sources are available for information on die casting design, including textbooks, technical papers, trade journals and professional associations. While this section is not intended to provide a comprehensive review of all the factors involving die casting design, it will highlight some of the primary considerations.Of course Gieterijen Riskin is always available, and ready to give you the expertise advice of over 50 years that you need. Not only increasing your quality and efficiency, but also saving you money.
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