Forging

Forgingis amanufacturing processinvolving the shaping ofmetalusing localizedcompressiveforces. The blows are delivered with ahammer(often apower hammer) or adie. Forging is often classified according to the temperature at which it is performed: cold forging (a type ofcold working), warm forging, or hot forging (a type ofhot working). For the latter two, the metal isheated, usually in aforge. Forged parts can range in weight from less than a kilogram to hundreds of metric tons.[1][2]Forging has been done bysmithsfor millennia; the traditional products werekitchenware,hardware,hand tools, edged weapons, andjewellery. Since theIndustrial Revolution, forged parts are widely used inmechanismsandmachines wherever a component requires highstrength; suchforgingsusually require further processing (such asmachining) to achieve a finished part. Today, forging is a major worldwide industry.[3]Forging is one of the oldest knownmetalworkingprocesses.[1]Traditionally, forging was performed by asmithusing hammer andanvil, though introducing water power to the production and working of iron in the 12th century drove the hammer and anvil into obsolescence. The smithy orforgehas evolved over centuries to become a facility with engineered processes, production equipment, tooling, raw materials and products to meet the demands of modern industry.In modern times, industrial forging is done either withpressesor with hammers powered by compressed air, electricity, hydraulics or steam. These hammers may have reciprocating weights in the thousands of pounds. Smallerpower hammers, 500lb (230kg) or less reciprocating weight, and hydraulic presses are common in art smithies as well. Some steam hammers remain in use, but they became obsolete with the availability of the other, more convenient, power sources.Advantages and disadvantageForging can produce a piece that is stronger than an equivalentcastormachinedpart. As the metal is shaped during the forging process, its internalgraindeforms to follow the general shape of the part. As a result, the grain is continuous throughout the part, giving rise to a piece with improved strength characteristics.[4]Some metals may be forged cold, butironandsteelare almost alwayshot forged. Hot forging prevents thework hardeningthat would result from cold forging, which would increase the difficulty of performing secondary machining operations on the piece. Also, while work hardening may be desirable in some circumstances, other methods of hardening the piece, such asheat treating, are generally more economical and more controllable. Alloys that are amenable toprecipitation hardening, such as mostaluminum alloys andtitanium, can be hot forged, followed by hardening. Production forging involves significant capital expenditure for machinery, tooling, facilities and personnel. In the case of hot forging, a high-temperature furnace (sometimes referred to as the forge) is required to heatingotsorbillets. Owing to the massiveness of large forging hammers and presses and the parts they can produce, as well as the dangers inherent in working with hot metal, a special building is frequently required to house the operation. In the case of drop forging operations, provisions must be made to absorb the shock and vibration generated by the hammer. Most forging operations use metal-forming dies, which must be precisely machined and carefully heat-treated to correctly shape the work piece, as well as to withstand the tremendous forces involved.

ProcessesA cross-section of a forged connecting rod that has been etched to show the grain flowThere are many different kinds of forging processes available, however they can be grouped into three main classes.

Drawn out: length increases, cross-section decreasesUpset: length decreases, cross-section increasesSqueezed in closed compression dies: produces multidirectional flowCommon forging processes include: roll forging, swaging, cogging, open-die forging, impression-die forging, press forging, automatic hot forging and upsetting.

SinteringSinteringis the process of compacting and forming a solid mass of material by heat[1]and/or pressure[2]without melting it to the point of liquefaction. Sintering happens naturally in mineral deposits or as a manufacturing process used with metals, ceramics, plastics, and other materials. The atoms in the materials diffuse across the boundaries of the particles, fusing the particles together and creating one solid piece. Because the sintering temperature does not have to reach the melting point of the material, sintering is often chosen as the shaping process for materials with extremely high melting points such astungstenandmolybdenum. The study of sintering in metallurgy powder-related processes is known aspowder metallurgy. An example of sintering can be observed when ice cubes in a glass of water adhere to each other, which is driven by the temperature difference between the water and the ice. Examples of pressure driven sintering are the compacting of snowfall to a glacier, or the forming of a hard snowball by pressing loose snow together.The word "sinter" comes from theMiddle High Germansinter, acognateof English "cinder".Sintering is effective when the process reduces the porosity and enhances properties such as strength, electrical conductivity, translucency and thermal conductivity; yet, in other cases, it may be useful to increase its strength but keep its gas absorbency constant as in filters or catalysts. During the firing process, atomic diffusion drives powder surface elimination in different stages, starting from the formation of necks between powders to final elimination of small pores at the end of the process.The driving force for densification is the change in free energy from the decrease in surface area and lowering of the surface free energy by the replacement of solid-vapor interfaces. It forms new but lower-energy solid-solid interfaces with a total decrease in free energy occurring on sintering 1-micrometre particles a 1 cal/g decrease. On a microscopic scale, material transfer is affected by the change in pressure and differences in free energy across the curved surface. If the size of the particle is small (and its curvature is high), these effects become very large in magnitude. The change in energy is much higher when the radius of curvature is less than a few micrometres, which is one of the main reasons why much ceramic technology is based on the use of fine-particle materials.[3]For properties such as strength and conductivity, the bond area in relation to the particle size is the determining factor. The variables that can be controlled for any given material are the temperature and the initial grain size, because the vapor pressure depends upon temperature. Through time, the particle radius and the vapor pressure are proportional to (p0)2/3and to (p0)1/3, respectively.[3]The source of power for solid-state processes is the change in free or chemical potential energy between the neck and the surface of the particle. This energy creates a transfer of material through the fastest means possible; if transfer were to take place from the particle volume or the grain boundary between particles, then there would be particle reduction and pore destruction. The pore elimination occurs faster for a trial with many pores of uniform size and higher porosity where the boundary diffusion distance is smaller. For the latter portions of the process, boundary and lattice diffusion from the boundary become important.[3]Control of temperature is very important to the sintering process, since grain-boundary diffusion and volume diffusion rely heavily upon temperature, the size and distribution of particles of the material, the materials composition, and often the sintering environment to be controlled.[3]

Rotary forgingIn this process the punch is given orbital rocking motion while pressing the workpiece. As a result of this the area of contact between work and punch is reduced. Therefore lower forging loads are sufficient. The final part is formed in several smaller steps. Example of parts produced by this process include bevel gears, wheels, bearing rings.

Fig. 1.9: SwagingHubbing: It is a pressing operation in which a hardened steel block, with one end machined to the form, is pressed against a soft metal. This process is used for making mold cavities. Hardened steel form is called hub. Hubbing is advantageous because it is easy for machining the positive form than machining the negative cavity.

Powder metallurgy

Powder metallurgyis the process of blending fine powdered materials, pressing them into a desired shape or form (compacting), and then heating the compressed material in a controlled atmosphere to bond the material (sintering). The powder metallurgy process generally consists of four basic steps: powder manufacture, powder blending,compacting, and sintering. Compacting is generally performed at room temperature, and the elevated-temperature process of sintering is usually conducted at atmospheric pressure. Optional secondary processing often follows to obtain special properties or enhanced precision.[1]The use of powder metal technology bypasses the need to manufacture the resulting products by metal removal processes, thereby reducing costs.Powder metallurgy is also used in "3D printing" of metals. Seeselective laser meltingandselective laser sintering.The history of powder metallurgy and the art of metal andceramicsinteringare intimately related to each other. Sintering involves the production of a hard solid metal or ceramic piece from a starting powder. "While a crude form of iron powder metallurgy existed inEgyptas early as 3000 B.C, the smiths of India produced the famous "Iron pillar of Delhi", weighing about 6.5 tons, and other objects even larger as early as 300 A.D, and the ancient Incas made jewelry and other artifacts from precious metal powders, mass manufacturing of P/M products did not begin until the mid- or late- 19th century".[2]In these early manufacturing operations, iron was extracted by hand from metal sponge following reduction and was then reintroduced as a powder for final melting or sintering.A much wider range of products can be obtained from powder processes than from directalloyingof fused materials. In melting operations the "phase rule" applies to all pure and combined elements and strictly dictates the distribution of liquid and solidphaseswhich can exist for specific compositions. In addition, whole body melting of starting materials is required for alloying, thus imposing unwelcome chemical, thermal, and containment constraints on manufacturing. Unfortunately, the handling of aluminium/iron powders poses major problems.[3]Other substances that are especially reactive with atmospheric oxygen, such astitanium, are sinterable in special atmospheres or with temporary coatings.[4]In powder metallurgy or ceramics it is possible to fabricate components which otherwise would decompose or disintegrate. All considerations of solid-liquid phase changes can be ignored, so powder processes are more flexible thancasting,extrusion, orforgingtechniques. Controllable characteristics of products prepared using various powder technologies include mechanical, magnetic,[5]and other unconventional properties of such materials as porous solids, aggregates, and intermetallic compounds. Competitive characteristics of manufacturing processing (e.g., tool wear, complexity, or vendor options) also may be closely controlled.Powder production techniquesAny fusible material can be atomized. Several techniques have been developed which permit large production rates of powdered particles, often with considerable control over the size ranges of the final grain population. Powders may be prepared bycomminution, grinding, chemical reactions, or electrolytic deposition.Powders of the elements titanium, vanadium, thorium, niobium, tantalum, calcium, and uranium have been produced by high-temperaturereductionof the correspondingnitridesandcarbides. Iron, nickel, uranium, and beryllium submicrometre powders are obtained by reducing metallicoxalatesandformates. Exceedingly fine particles also have been prepared by directing a stream of molten metal through a high-temperatureplasmajet orflame, simultaneously atomizing and comminuting the material. Various chemical and flame associated powdering processes are adopted in part to prevent serious degradation of particle surfaces by atmospheric oxygen.In tonnage terms, the production of iron powders for PM structural part production dwarfs the production of all of the non-ferrous metal powders combined. Virtually all iron powders are produced by one of two processes: the sponge iron process or water atomization.Sponge iron processThe longest established of these processes is the sponge iron process, the leading example of a family of processes involving solid state reduction of an oxide. In the process, selected magnetite (Fe3O4) ore is mixed with coke and lime and placed in a silicon carbide retort. The filled retort is then passed through a long kiln, where the reduction process leaves an iron cake and a slag. In subsequent steps, the retort is emptied, the reduced iron sponge is separated from the slag and is crushed and annealed.The resultant powder is highly irregular in particle shape, therefore ensuring good green strength so that die-pressed compacts can be readily handled prior to sintering, and each particle contains internal pores (hence the term sponge) so that the good green strength is available at low compacted density levels.Sponge iron provides the base feedstock for all iron-based, self-lubricating bearings and still accounts for around 30% of iron powder usage in PM structural parts.AtomizationAtomization is accomplished by forcing a molten metal stream through an orifice at moderate pressures. A gas is introduced into the metal stream just before it leaves the nozzle, serving to create turbulence as the entrained gas expands (due to heating) and exits into a large collection volume exterior to the orifice. The collection volume is filled with gas to promote further turbulence of the molten metal jet. Air and powder streams are segregated using gravity orcyclonic separation. Most atomized powders are annealed, which helps reduce the oxide and carbon content. The water atomized particles are smaller, cleaner, and nonporous and have a greater breadth of size, which allows better compacting. The particles produced through this method are normally of spherical or pear shape. Usually, they also carry a layer of oxide over them.There are three types of atomization:1. Liquid atomization2. Gas atomization3. Centrifugal atomizationSimple atomization techniques are available in which liquid metal is forced through an orifice at a sufficiently high velocity to ensure turbulent flow. The usual performance index used is theReynolds numberR = fvd/n, where f = fluid density, v = velocity of the exit stream, d = diameter of the opening, and n = absolute viscosity. At low R the liquid jet oscillates, but at higher velocities the stream becomes turbulent and breaks into droplets. Pumping energy is applied to droplet formation with very low efficiency (on the order of 1%) and control over the size distribution of the metal particles produced is rather poor. Other techniques such as nozzle vibration, nozzle asymmetry, multiple impinging streams, or molten-metal injection into ambient gas are all available to increase atomization efficiency, produce finer grains, and to narrow the particle size distribution. Unfortunately, it is difficult to eject metals through orifices smaller than a few millimeters in diameter, which in practice limits the minimum size of powder grains to approximately 10 m. Atomization also produces a wide spectrum of particle sizes, necessitating downstream classification by screening and remelting a significant fraction of the grain boundary.Centrifugal disintegrationCentrifugal disintegration of molten particles offers one way around these problems. Extensive experience is available with iron, steel, and aluminium. Metal to be powdered is formed into a rod which is introduced into a chamber through a rapidly rotating spindle. Opposite the spindle tip is an electrode from which an arc is established which heats the metal rod. As the tip material fuses, the rapid rod rotation throws off tiny melt droplets which solidify before hitting the chamber walls. A circulating gas sweeps particles from the chamber. Similar techniques could be employed in space or on the Moon. The chamber wall could be rotated to force new powders into remote collection vessels,[6]and the electrode could be replaced by a solar mirror focused at the end of the rod.An alternative approach capable of producing a very narrow distribution of grain sizes but with low throughput consists of a rapidly spinning bowl heated to well above the melting point of the material to be powdered. Liquid metal, introduced onto the surface of the basin near the center at flow rates adjusted to permit a thin metal film to skim evenly up the walls and over the edge, breaks into droplets, each approximately the thickness of the film.[7]Other techniquesAnother powder-production technique involves a thin jet of liquid metal intersected by high-speed streams of atomized water which break the jet into drops and cool the powder before it reaches the bottom of the bin. In subsequent operations the powder is dried. This is called water atomization. The advantage of water atomization is that metal solidifies faster than by gas atomization since the heat capacity of water is some magnitudes higher than gases. Since the solidification rate is inversely proportional to the particle size, smaller particles can be made using water atomization. The smaller the particles, the more homogeneous the micro structure will be. Notice that particles will have a more irregular shape and the particle size distribution will be wider. In addition, some surface contamination can occur by oxidation skin formation. Powder can be reduced by some kind of pre-consolidation treatment as annealing used for ceramic tool.Powder compactionPowder compactionis the process of compacting metal powder in a die through the application of high pressures. Typically the tools are held in the vertical orientation with the punch tool forming the bottom of the cavity. The powder is then compacted into a shape and then ejected from the die cavity.[8]In a number of these applications the parts may require very little additional work for their intended use; making for very cost efficient manufacturing.The density of the compacted powder is directly proportional to the amount of pressure applied. Typical pressures range from 80 psi to 1000 psi (0.5MPa to 7MPa), pressures from 1000 psi to 1,000,000 psi have been obtained. Pressure of 10 tons/in to 50 tons/in (150MPa to 700MPa) are commonly used for metal powder compaction. To attain the same compression ratio across a component with more than one level or height, it is necessary to work with multiple lower punches. A cylindrical workpiece is made by single-level tooling. A more complex shape can be made by the common multiple-level tooling.Production rates of 15 to 30 parts per minutes are common.There are four major classes of tool styles: single-action compaction, used for thin, flat components; opposed double-action with two punch motions, which accommodates thicker components; double-action with floating die; and double action withdrawal die. Double action classes give much better density distribution than single action. Tooling must be designed so that it will withstand the extreme pressure without deforming or bending. Tools must be made from materials that are polished and wear-resistant.Better workpiece materials can be obtained by repressing and re-sintering.

Applications of Forging Process:Wide variety of uses in different kinds of Industries: Automobile Industry: Wheel spindles, kingpins, axle beams and shafts, torsion bars, ball studs, idler arms and steering arm. Agro-Industries: Engine and transmission components, levers, gears, shafts and spindles to tie-rod ends, spike harrow teeth and cultivator shafts. Aerospace: Bulkheads, hinges, wing roots, engine mounts, brackets, beams, shafts, landing gear cylinders and struts, wheels, brake carriers and discs and arresting hooks, blades, buckets couplings etc. Hand Tools: Sledges, pliers, hammers, wrenches and garden tools, as well as wire-rope clips, sockets, hooks, turnbuckles and eye bolts are common examples. Industrial Equipment: Connecting rods, blanks, blocks, cylinders, discs, elbows, rings, T's, shafts and sleeves.

Advances in Forging TechnologyThe customers demands for individual solutions are constantly increasing, especially from the automotive industry. Despite the platform strategies and modular designs of automobile manufacturers, forgers are faced with producing an increasing number of variants of aluminum forgings, increasingly complex parts, high steel costs, and sagging prices.These developments also affect us as equipment suppliers. We have to offer different units in our product range to provide for more complex forging operations. There also is a need for increased use of suitable pre-forming units, which offer a potential for saving material, as well as producing a part with higher complexity.Also, the number of automated lines will increase across all products. This requires forging of very different parts with a single forging line at a high degree of automation and with a competitive cost/performance ratio.The following discussion covers new developments in pre-forming technology and automation of hammers, new drive concepts designed for reducing the contact time, and a new generation of control systems.Pre-forming forgings Many different processes are available from Muller Weingarten for pre-forming aluminum or steel forgings. They can be essentially subdivided according to two basic process variants:Continuous Pre-forming With the continuous pre-forming method, the forging is given a defined pre-shape in a single forming movement. Some of the traditionally used pre-forming units are hydraulic or mechanical presses as well as cross rolls. The continuous process offers the advantage, especially for aluminum, that the short process involves only little cooling for the component and high cycle times can be reached. A disadvantage is that the degree of forming is often limited in the pre-forming process, since only a limited amount of energy and a limited forming capability are available for the component within a single stroke (of the press) or a single revolution.Discontinuous Pre-forming The discontinuous pre-forming method is characterized by producing a pre-shape by means of several forming movements. The typical forming equipment used for this process is the reducer roll. However, it is also possible to use mechanical or hydraulic presses as discontinuous pre-forming units. This is usually the case if several pre-forming phases are necessary, e.g. upsetting and bending. The advantage is a high degree of forming in the pre-forming phase. A disadvantage is that it may be necessary to re-heat the workpiece, especially aluminum, before the main forging phase.The various processes and their specific requirements for the pre-forming of aluminum forgings are described in more detail below in order to provide a deeper understanding of the different pre-forming technologies available.

Cross-roll formingThe cross-roll pre-forming method is characterized by a rotating movement of the workpiece between two rotating rolls (round dies) or vertically reciprocating plates (flat dies) rolling a contour into the workpiece with matched profiled tools. The specific tool contour produces a tapering of the workpiece, with the material being predominantly pressed either from the middle of the workpiece toward the ends or into a non-forming zone between the rolls.Forming speeds for steel and aluminum can be 600 mm/sec. The resistance to flow of the workpiece material during the forming process makes it necessary to minimize any torsion of the workpiece during rolling or at least obtain a homogeneous distribution around the neutral line by suitable design of the tools.Cross-rolls can only be used to produce rotationally symmetric pre-shapes. The degree of forming is limited because of the 360 rotary motion of the rolls, where only about 280 have a forming effect. An advantage is that the edges of the pre-formed forgings can be trimmed in the final phase of the process, which can prove beneficial for the further process with a view to constant material charges.To obtain a reliable process for aluminum forgings, a new generation of cross-rolls was developed on the basis of the Bch design. Highest priority was given to controlled tool heating on a rotating tool holder by adding electrical heating cartridges to maintain the temperature of the tools within an acceptable range for reliable aluminum forming. The cartridges are designed so they can be automatically coupled during die changes.The bearings and other susceptible parts of the machine must be protected against excessive heat input from the rolls. For this reason, an efficient cooling arrangement was developed for the roll bearings that prevents excessive transmission of heat from the tools to the machine bearings and the drive.Furthermore, a quick-tool-change mechanism was developed that allows simply pulling the tools from the carrier rolls to minimize setup time, reducing downtime for the overall line.Our clients also use our Type RBQ equipment for the production of ready-made shafts or other rotationally symmetric components with high precision requirements.Reducer-roll formingIn the reducer-roll process, the workpiece is introduced between a rotating pair of rolls and led through them by rotation of the two rolls. In contrast with the cross-roll process, the workpiece is not rotated and therefore a suspected torsion of the pre-formed forging does not take place. Forming is usually performed in several passes with different profiles engraved on the rolls. The workpiece can be rotated from one step to the next in order to obtain a more homogeneous pre-forming result. Reducer rolls are not limited to producing rotationally symmetric pre-shapes. It is also possible to produce square symmetric shapes.The new reducer-roll generation of the PWS series combines state-of-the-art control technology with long-term experience in mechanical engineering for forging lines. Pass selection and rotation angle are freely programmable. The feed height can be adjusted and the latest handling technologies permit fast, precise, and bidirectional reducer-roll processes, where the workpiece runs through the rolls completely in each pass and is received by the handling unit on the other side.With regard to the application to aluminum, we were able to successfully transfer the experience gathered with the heating technology for the tools and with cooling the machine body from the developments in the cross-roll design described above.The first reducer-roll delivered is additionally provided with a new spraying system and a quick-change feature for the rolls. Mller Weingarten is convinced that the reducer roll equipment will prove to be an efficient solution in the market for aluminum pre-forming just as is the cross-roll equipment. The use of a suitable reducer or cross-rolling unit is especially useful for travel-based main forging units, with a view to the constantly increasing complexity of aluminum forgings and because of the limited forming energy of these units.Rolling pre-formingEver-increasing requirements for forging line process speed made it necessary to develop a low-cost alternative specifically for simple pre-shapes. The objective was to develop a technology that equals the forming and the material/structural requirements of the reducer-roll method while permitting high forming speeds at the same time.The new process was to be suitable for integration into the press cycle of an automatic forging line, e.g. with 60 strokes/minute, and produce constant, flash-free pre-forming results.Finally, many customers wanted a method with substantially lower investment and tooling costs compared to the reducer or cross-roll processes.As a result of an analysis of the existing technologies, the rolling pre-forming method was conceived. Two rolls move in parallel along the workpiece, guided by two parallel contour blocks with matching profiles, displacing the material in the direction of motion. The material is upset in front of the rolls and flows in the opposite direction after rolling. This could be referred to as upset-stretch forming or extruding.Since this is a single-axis forming process, there is very little risk of structural cracks, as opposed to the cross-roll process. The tooling costs (rolls and contour blocks) are relatively low. The maximum process speed is not determined by the automation or mechanical equipment of the unit, but depends exclusively on the maximum acceptable forming speed.The rolling pre-forming method patented by Mller Weingarten AG is available as a standalone unit or integrated into a mechanical press and offers extremely competitive production of preformed parts.Presses as pre-forming unitsIt is obviously desirable to integrate a simple pre-forming operation as the first step into the main press because of the advantages this offers for process and cycle times, production costs, and reduced cooling down of the forging. An upsetting or pre-bending operation can easily be imagined at this point.Generally, hydraulic and mechanical presses are possible solutions for pre-forming units. The disadvantage of the travel-based mechanical press is the limited energy (energy capacity). Hydraulic presses have recently had a renaissance for some time because of their flexibility in use. The slogan hydraulic means slow is no longer true, which is evidenced by process speeds of up to 180 mm/min. Hence, it is not necessarily a disadvantage if a hydraulic pre-forming unit is installed before a mechanical main forging press.The advantage is obvious. There are almost no restrictions with regard to the geometry (rotational or symmetrical) when designing the pre-forming operations. The number of pre-forming steps is only limited by the pressing force of the unit, the forming properties of the part and the specific cooling coefficient, which is an important factor in forging as mentioned above.A multi-dimensional pre-forming process is possible, involving hydraulic or mechanical pusher tooling and subsequent bending. We consider this a modern pre-forming unit, the potential of which has been underrated in this field of application to date.Introducing SpeedForgeIn practical application of a Mller Weingarten forging crank press of type PK 3150 with a rated force of 31,500 kN and stroke rates from 30 to 60 strokes per minute, die service life increased decisively with the same parts when the stroke rate was doubled. In connection with the given sine kinematic characteristics, this is also the case when the die spraying time is reduced to the same degree. At a stroke rate of 30 per minute, a nominal spraying time of about 300 milliseconds remains for die protection; at 60 strokes/ minute, this is only 150 milliseconds.In view of the constant pressure towards reducing the costs in the production of forgings, Mller Weingarten was urged again and again by customers and technical institutes to give more attention to the issue of reduced contact time when developing a new crank press, since there is still a potential for cost reduction inherent in closed-die forging. Furthermore, a die with less thermal stress would make it possible to produce forgings with fine structures, e.g. gear wheels, in large quantities with small tolerances and nearly ready for installation.Many concepts were considered and assessed. The objective was to design a press with a rated force of 12,500 kN and a cycle rate of 60/minute with a very high ram speed in the bottom dead center (BDC) zone and a low ram speed in the top dead center (TDC) zone. The issue was to find a low-energy and low-wear solution while keeping the investment costs low.Existing know-how made it possible to develop a drive concept referred to as SpeedForge, which is available as an option for every PK press. It costs only a little more than the standard drive concept and permits a freely programmable kinematic characteristic. With a cycle rate of 30 to 60 per minute, analog ram speeds at BDC of 60 to 120 strokes/minute can be freely set in combination with analog ram speeds at TDC of 6 - 12 strokes/minute.Compared with a traditional eccentric drive, the contact time is less than half with the same cycle time. The machines clutch/brake assembly operates virtually without wear both in continuous mode and single-stroke mode. The press offers a kinematic characteristic with regard to the freedom of movement which is optimally suited for automation with transfer equipment.Technological description: The press is provided with two drives. One auxiliary drive is for those sections of the kinematic characteristic where no forming operation is performed and the tried and tested PK main drive with planetary gear, high-speed flywheel and a hydraulic clutch/brake assembly with free-wheel position. The main drive is only engaged with the eccentric shaft for the actual forming operation.The flywheel of the PK main drive has the necessary speed corresponding to the maximum ram speed at BDC. The main drive engages with the eccentric shaft just before the forming operation and disengages from the eccentric shaft after the forming operation. The ram movements before engaging and after disengaging are driven by the frequency-controlled auxiliary drive. In this phase, the clutch/brake assembly of the main drive is in free-wheel mode, i.e. neither engaged nor braked.The auxiliary drive decelerates the ram during upstroke and accelerate the ram to the required speed during downstroke. The auxiliary drive, the eccentric shaft and the main drive have the same speed at the engaging/disengaging points, i.e. engaging/disengaging is fully synchronized, virtually without slip or wear. A kinematic characteristic as shown in the chart is thereby achieved. This can be freely programmed, depending on the cycle time required, forming travel, material flow characteristics, and transfer kinematic characteristics. To illustrate the improved kinematic characteristics, the chart shows the traditional eccentric kinematic characteristics as well.The new SpeedForge drive concept makes it possible to use high cycle rates safely because of the improved freedom of movement for the transfer system. The energy taken from the flywheel is nearly limited to the actually required forming energy and the flywheel can be recharged very quickly in the disengaged phase.Moreover, additional die spraying time is available for cooling and lubricating the dies. Of course, a customized kinematic characteristic for forging aluminum or other light metal materials can be programmed, which allows a slower forming process while maintaining a high cycle rate.The press built with this design also includes an integrated low-energy closing mechanism for flash-free forging. It offers a closing force of 4,000 kN and implements a specially designed hydraulic concept, feeding the major part of its potential energy back into the main drive flywheel after the forming operation and before disengaging the main drive. The reduced power requirements make it possible to use a smaller drive, which is a direct benefit with regard to the investment costs for a PK press with SpeedForge.New FCS generationTo meet market requirements, Mller Weingarten has developed a new control system generation. In addition to implementing a real-time core in the functional unit, it is now possible to integrate the system with various standards at low cost, e.g. Siemens S7 or Allen Bradley. It can be used for screw presses, hammers and mechanical presses alike.The new concept includes thickness measurement of the forgings and the resulting energy regulation for the hydraulic short-stroke hammer as well as process control and measurement of cpk and cmk values during the forging operation. The outline curve technology for force characteristics familiar from sheet metal forming is now also available for all forging units.This is supplemented by possible automation of hammers and screw presses, and optional extension of the system with production data acquisition functions or external modules.

There are three FCS configurations:FCS BasisLow-cost with small visualization moduleFCS Stand AloneLow-cost with large visualization moduleFCS CustomizedCustomer-specific design with Siemens S7 or Allen Bradley module and large visualization module.The basic functions of each unit comprise:

Energy measurement and controlHammer speed, ram speedPart thickness measurementProgram preselections (strokes, blow energy, die and part data, etc.)Data memory for at least 100 parts/diesPlain text fault displayAll basic functions (e.g., rolling blows for hammers, production data acquisition with cpk and cmk data output for each forging, etc.)A new user interface with a large visualization module was developed completely in a web-based design. In addition to a substantially improved remote maintenance capability via modem, this facilitates the preparation of on-line training documentation which can even be made available through the Internet. Both involve a substantial economic advantage for the customer during the implementation and commissioning of the unit or control system on his premises.

Mller Weingarten focused on the process analysis module. The performance capacity of the new MW FCS is illustrated with the following example of energy control for hammers.

With its data-scanning frequency of up to 600 kHz and MWs sensing concept, the MW FCS is able to precisely determine the thickness of the forging with a tolerance of +/- 0.1 mm. With a stroke program of 5 strokes, for example, it is possible to control the thickness of the forging to match the target value. We discussed with our customers whether a blow-to-blow control would not erase the traces for assessing the process stability. The thickness of a forging and the energy actually input into the forging are closely related to each other in a successful process resulting in a part according specification. This relationship can be used to calculate coefficients from the stroke program characteristics at different energy levels, resulting in a fixed pair of coefficients in a stable process. These can be recorded as digital cmk or even cpk values and compared. After a certain number of strokes to be defined by the customer, the MW FCS calculates a correction stroke automatically. With varying coefficients, when the intervention limits to be defined are violated, this is referred to as an unstable process which can be determined only indirectly via the control variable or not at all in a blow-to-blow control design.

In the FCS, the customer decides which control method should be used.

The new control concept can be retrofitted to existing systems.

Economical forging with an automated hammer line

The forging hammer, especially with a hydraulic drive, is competitive thanks to its low capital cost and above-average energy and force capacity. Increasing demand led to an automated version with robots, especially for the production of flat parts such as connecting rods or hand tools.

The latest line delivered is equipped with a flexible gripper design that allows turning the forging during the forging process and prevents the gripper or robot from being damaged when parts stick to the upper die.

In combination with the FCS control concept, we developed a solution that is resistant to dirt, vibration, and elastic effects from the hammer. The reproducibility of this line is substantially improved in comparison with manual hammer forging.