Cold heading process

Cold upsetting is essential for mass production of automotive fasteners, motorcycles, bicycles, appliances profiled automated production method for producing the same cutting workers compared the metal fibers (metal flow lines) along the product the shape continuous grain no break, thus increasing the strength of the product, particularly excellent in mechanical properties, and raw material savings.

Rising as the environmental voice of the fasteners more industry more attention to environmental issues. Therefore, as a non-cutting forming cold heading technology are increasingly seeking high-strength, high-value-added.

This article lists near cold heading and cold extrusion composite technology developments.

1, the binding of stamping parts

The distance between the shape and the edge of the inner hole is smaller than the thickness of the punch and die, an inner diameter greater than the outer diameter of the half, the height is more than 1.5 times the inner diameter of the punching, the better binding stamping. Since the distance between the edge of the shape and bore closer, the the stamping punch needle force will affect the shape, the size of the shape changes. Must make this part of the shape is bound by the state in order to prevent changes Dimensions. Since the role of the binding force, stamping section is in a compressive stress state, in this punched compressive stress state, to take an appropriate gap can be obtained all bright band stamping effect.

2, cut extrusion

Generally, the bolt head of the plastic processing, of forming cold upsetting cut extrusion forming process has more advantages than rose shaped craft. Before the cut extrusion, rough shaping process requirements can be obtained by shaping rough. Rough size must be seriously rough shape before the squeeze is to be determined according to the situation of the part, using the rough shape of the material flow. Rough size is too large, cut squeeze the margin is too large, cut squeeze force to squeeze easily lead cut to reduce die life, and to increase the possibility of mold accidental damage, and consumption of raw materials; cutting squeezed margin is too small parts easy to cut squeeze off angle, the shape is incomplete, not satisfied with the appearance of quality.

Mold structure is focused on the design of the cut squeeze film processing, cutting edge work size best control in the lower limit, the cut extrusion die angle to the right, the edge must go through the grinding, polishing, the roughness Ra0.025 to Ra0.050 μ m, has the highest life expectancy.

3, drawing and forging forming

Bumps thick-walled parts with cold extrusion and deep drawing goblet shaped pieces into one plate material, drawing and compression the composite molding method and forming fasteners, forming characteristics forming and increased wall thickness of the head projection.

4, the local forming

Upsetting pressure molding there are two concepts, one plenary upsetting pressure, i.e. on the whole end face of the product has force; partial upsetting pressure, i.e. only in the necessary part of the applied pressure. Forming all the processing area, forming load, require large tonnage stamping machines, get the necessary thickness variation can be used for partial forming a lower load, holes, slots forming a wide range of applications.

Of ① steps parts

An example to illustrate the points forming applications, engineering design: design lathe - annealing - phosphorus saponification - extrusion (half sealed extrusion forming steps) to the connector.

② fine local forming

The need for locking and chip 1 to 3, for some set screws scraping groove machining, extrusion processes can be used, a representative is a grooved molding automobile combination bolt shavings.

Research and application technique based on reverse engineering, mold repair

 With the development of modern industry, the mold increasingly prominent position in the manufacturing industry, is widely used in aviation, cars, ships and other industries. High quality, efficient, cost has been the pursuit of the eternal goal of manufacturing technology development, the mold as indispensable to modern industrial process equipment, improve product quality, increase production efficiency, saving energy and raw materials, reflecting the technical and economic aspects of the mold manufacturing products means, has become a key contemporary industrial production process development direction and involved in the production of competitive products. However, due to the natural wear and operating personnel to improper operation and other reasons, it is caused by wear of the mold or severely worn. Mold and imported, often because a certain part of the wear and scrapped, if re-manufacturing the mold is not only time consuming, but also additional manufacturing costs, and seriously affect the production. Therefore, mold repair work is particularly important.

  Traditional mold repair common measurement instruments detect, limit the amount of regulatory measurement, measurement of straightness error, flatness error measurement, roundness error of measurement and manufacturing special measuring tools and other wear areas conducted measurements, and then according to the mold wear to develop a rehabilitation program. Mold repair cost, low efficiency, repair precision is difficult to meet the requirements, far from being able to meet the needs of modern mold. And the structure is more complex mold helpless.Repair mold technology based on reverse engineering is a more advanced mold repair, and has good prospects for development in the field of mold repair.

1 Reverse Engineering

  "Reverse engineering" (Reverse Engineering RE), also known as reverse engineering, reverse engineering, namely the entity transformation CAD ​​models of digital technology, the general term of the geometric model reconstruction technique, model punch and die manufacturing technology. For items or samples, the use of digital measuring instrument measurement point cloud data, and then point cloud point cloud data preprocessing, model reconstruction, and then the use of CNC machine tools or rapid prototyping technology of its manufacturing, and ultimately finished the generation, reverse engineering process Reverse engineering, product design downstream to the design upstream information feedback loop. Reverse engineering usually include geometry Reverse to craft anti summation Reverse, widely used in the engineering field, geometry inverse.

  

  Reverse engineering technology is so widely used, mainly used in:

  ① the design of new products;

  ② imitation of existing products, copy, reproduce design intent;

  ③ damage or breakage reduction and repair;

  ④ product detection.

  Reverse engineering applications in the mold industry mold design and manufacture and mold repair, reverse engineering that only design prototypes and design drawings and design documents, the innovative design of the original mold structure and wear die wear parts repair.

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The use and maintenance of CNC Stamping machine

Current, in the field of sheet metal stamping, CNC turret punch press with its fast punching speed, high precision machining, mold versatility, flexible product characteristics are widely used. CNC turret punch mold, stamping speed, high accuracy and quality requirements.User in the purchase of a certain quality mold, the level of use and maintenance, directly affecting the quality of machining of the work piece and the life of the mold. The mold is also an important part of the running costs control equipment. Therefore, to learn and master some knowledge and applied to practice to improve efficiency, reduce costs, and will also play an important role.

  Discussed below CNC turret punch mold should be followed in the use and maintenance of a number of technical points, and put forward the corresponding solutions for practical problems, likely has a good role in guiding the user.

, To ensure the best die gap

  Die gap means to punch into the lower mold, and both sides of the gap. It is related to the thickness, material as well as stamping process, the appropriate choice of die clearance, to ensure good quality of punching, reduce burrs and collapse, maintain a flat sheet, effectively prevent the belt material to extend the life of the die.

  Check stamping waste, it can be determined whether the die gap suitable. If the gap is too large, the waste will fracture surface roughness and small shiny surface. The greater the gap, the greater the fracture surface and the angle formed by the shiny surface of the bead is formed when the punching and fracture, even a thin edge protrusion. Conversely, if the gap is too small, the waste will appears the fracture surface of the small angle and large shiny surface.

  Notching, nibbling, shearing and other local punching, lateral force will punch deflection and cause unilateral gap is too small, sometimes blade edge offset Assembly scratches to the lower die, resulting in rapid wear of the upper and lower mold.

  Mold to the optimum gap when punching, the fracture surface and the shiny surface of the scrap has the same angle and overlap each other, so that the punching force can be minimum, the punching burr is also small.

Timely sharpening can effectively extend the life of the mold

  If the workpiece is large burr or stamping abnormal noise may be passivated mold. Check the punch and lower die when its edge wear arc radius of about 0.10mm, we must sharpening.

  Practice often trace sharpening, rather than wait until Unground not re-sharpening, will not only maintain a good quality of the workpiece is reduced blanking force, and extend the life of the die can be more than doubled.

  In addition to know the mold when sharpening is particularly important to master the correct method of sharpening. Mold sharpening procedures are as follows:

1) sharpening punch vertically within the V-groove sandwiched plane magnetic grinding chuck or fixture, each grinding amount of 0.03 ~~ 0.05mm repeated grinding until the punch is sharp, the maximum grinding amount generally 0.1 to 0.3 mm.

2) the use of sintered alumina grinding wheel, the hardness D ~~ J, the abrasive grain size of 46 ~ 60, preferably selected applicable to high-speed steel grinding wheel.

3) When the grinding force large or mold near the wheel, add coolant to prevent mold from overheating and cracking or annealing, selection of high-quality multi-purpose coolant should be in accordance with the manufacturers requirements.

4) grinding wheel down into the knife amount of 0.03 to 0.08mm infeed to the amount of 0.13 ~~ 0.25mm cross feed rate of 2.5 ~ 3.8m/min.

5) Sharpening oil stone polished edge, burr, and grind a radius of 0.03 ~ 0.05mm rounded edge crack, can prevent.

6) punch demagnetization process and sprayed with a lubricant to prevent rust.

  Third, eliminate and reduce the sticky material

  Due to the pressure and heat when the stamping will plate material fine particles adhered to the surface of the punch, resulting in poor quality punching. The removal of adhesive material can be used a thin whetstone grinding, polishing the direction should be the same as the direction of movement of the punch, so that light will avoid the generation of the further viscous material. Do not use coarse gauze polished, so as to avoid the rough surface of the punch, more prone to sticky material.

  Reasonable mold gap, the stamping process, as well as the necessary sheet lubrication will reduce the generation of the sticky material. Prevent overheating, general lubrication, this will reduce the friction. If you can not lubrication or waste rebound may take the following methods:

  Alternately using a plurality of the same size punch turns stamping allows it to have a longer cooling time before being reused.

  Stop the overheating mold used. Be programmed to control other mode, to interrupt long duplication of work, or to reduce its stamping frequencies.

, Punch a lot of holes to prevent the sheet deformation measures

  If you punch a lot of holes in a board, because the punching stress accumulated sheet can not be kept flat. Each punching holes surrounding material is deformed downward, causing the material on the surface of the plate to tensile stress, while the lower surface of the compressive stress appears. For a small amount of punching, its impact is not obvious, but when punching the number increases, the tensile and compressive stress accumulated somewhere until the material deformation.

  A method to eliminate such deformation is: first every punching a hole, and then returns punching remaining holes. Although this will produce stress, but it alleviate the stress accumulated in the order in the same direction when punching, also make before and after the stress of the two sets of holes offset each other, thereby preventing the deformation of the plate material.

  Avoid punching too narrow strip

  Molds for sheet metal punching width less than the plate thickness, due to the lateral force of the punch bending deformation, so that one side of the gap is too small or wear exacerbate serious scratching the lower die, so that the upper and lower mold damage.

  Not recommended nibbling narrow strip of sheet width of less than 2.5 times the sheet thickness. Shear too narrow strip, sheet would tend to bend into the lower die opening, rather than being completely cut off, or even the side of the wedging the die. If you can not avoid the above situation, it is recommended to use a stripper hedge head support-oriented mold. , Punch surface hardening its Scope

  Although the heat treatment and the surface coating may improve the surface characteristics of the punch, but not the solution to the stamping parts problem and the general method to extend the life of the die. Generally, coating improves the lubricating properties of the surface hardness and to the side of the punch is improved, but when large tonnage, hard material stamping, these advantages disappear in about 1000 times stamping tools after.

VI can be used for surface hardening of the punch:

  Punch soft or viscous materials (such as aluminum);

  Punch thin abrasive material (such as glass epoxy sheet);

  Punch thin hard material (such as stainless steel);

  Frequent point of red;

  The non-normal lubrication situation.

  The surface hardening is usually titanium, nitriding, etc., the surface-hardened layer of the molecular structure of the thickness of 12 ~ 60 μ m, which is a part of the punch base, and not only is the coating.

  The surface hardening of the mold can be the usual way sharpening. Will reduce the wear of the mold punch the stainless steel plate when hardened by the surface, but does not extend its service life, appropriate lubrication, timely sharpening and operate according to rules, but it is an effective method.

  Seven, the punch die bit of neutral bad overhaul

  The punch die bit neutral bad, caused by the mold quickly passivation workpiece quality in respect of the following overhaul:

  Check the machine level, if necessary, re-adjust;

  Check and lubricate the die hole on the dial and guide key, timely repair any damage;

  Clean dial mold base, so that the lower mold accurate installation, and check its key or keyway wear and replace if necessary;

  Use the special mandrel calibration tool stations timely adjustments, if any deviation.

  The above content is often the case, in view of the specific type of punch and die specifications differ, the user but also with the actual understanding and sum up experience, play the best use of the performance of the mold.

viper process use in marking aircraft engine

Aircraft engine manufacturing is a highly competitive industry, market demand for cyclical, it requires a lot of investment and development costs. Although complexity means that the finished engine aircraft and airframe manufacturers must bear the time interval between ordering and delivery of long history, but competitive pressures are forcing people to look for more sophisticated and faster response of the market to make The method of manufacturing. In the United Kingdom, the engine manufacturer Rolls-Royce has a unique process of this challenge response - Flexible grinding of nickel alloy wheel with equipment processing center. 

This process is referred to as the "Viper", "Vitreous Improved Performance Extreme Removal" Abbreviated from. The 1990s as a method for processing nickel alloy alternative CBN super abrasive and strong creep feed grinding technology, high-performance technology developed. The process has been applied in the Rolls-Royce factory, but it is the most comprehensive application of a worm blade factory in Derbyshire city, which has 10 processing center for the Viper. The process plant will each set to high pressure worm gear leaves from order to delivery time reduced from about 100 days to 15 days.

Viper grinding process involves the use of pre-formed small diameter grinding wheel - used on CNC machining centers "tool" 
The various features used in precision machining nickel alloy worm blade

Viper grinding diameter of not more than 200mm of alumina grinding wheel, grinding wheel mounted on the after special adaptive processing Makino (Makino) or Bridge Fort (Bridgeport) machining center spindle. Replacement of the wheel with the ordinary cutter. For a specific blade, the processing "cedar" root form "shroud" end features may need to 15 different types of wheel shape. 

Rolls-Royce claims, under suitable conditions, the process of metal removal rate can reach 80 mm3 / s / mm of wheel width. This is in the ordinary grinder of nickel plated CBN grinding wheel by super abrasive machining technology machining nickel alloy metal removal rate can be achieved. The process can also fining alternative way much higher than other metal removal. 

Phil Hopton, Rolls-Royce worm Systems Director. He said : Used strong creep feed grinding technology to the processing of these characteristics. Goal of this technology is to be mass-produced, machine set-up times must be counting days, each blade needs to be completed through a large machine to processing. These. process kinds of technology, high-pressure blade production is a bottleneck problem exists. "the company consider the use of CBN grinding wheel as an alternative, but the the Viper process in terms of performance to achieve a great improvement, thus changing the entire blade processing mode. 

The Viper's origins can be traced back to the Rolls-Royce engineers Peter Hill, he noticed that the special strength creep feed machine can sometimes be in a continuous wheel dressing satisfactory processing in order to maintain the shape and sharpness case. Subsequently, in a high pressure coolant cleaning tool cutting edge titanium milling project experience, he considered such a possibility, that the development of a suitable general milling and drilling tool change machining center will set become one of the "pure grinding wheel grinding process.

This grinding device equipped on a horizontal machining center. Equipped with a suitable for the job 
Machine tool changes including the installation of the dresser, and coolant nozzle CNC control

Cooperative development projects carried out by professional manufacturers Tyrolit, machining center manufacturers the Makino and Bridge Fort consumable parts and grinding up to four years, the company developed last today. May Unsurprisingly, the most important factor proves grinding consumable parts and coolant. The project also eliminate people suspected of ordinary milling spindle can cope with the grinding wheel imbalance. 
Mr. Hill said: "We have to consider a lot of factors and we must make sure that the open wheel connection not grip the fine grinding produces chip must also develop a support ratio of high velocity and high pressure coolant system and coolant able to withstand, but does not produce foam in the case of fine filtration process. " 

The coolant filter the Viper grinding success is very critical. The process uses a specially developed nozzle to a pressure of 1000psi of sprayed cooling liquid and interface maintains a precise angle relative to the grinding wheel and the workpiece. By filtration and removal of particles above 10 microns in diameter, Viper process thus avoiding to produce corrosion of the grinding wheel cutting edge. 

In the grinding process, with the cooling liquid can reduce the chip temperature, to prevent the fine chips are adhered to the grinding medium, while the jet may also be washed clean the cuttings. This can prevent the wheel "passivation", thus obviating the need for intermediate trimming. This in turn helps to keep the lower wheel wear rate, thus the "tool" of the small diameter grinding wheel life can be maintained within the acceptable range. 

In order to a processing center for Viper grinding process, the need for a large number of manufacturing changes. These changes include the coolant delivery, installation, and sealing and protection of the diamond dresser problems. From the process in this regard, the need to maintain the same cooling liquid transport track, while using the the interpolation axis grinding machine up to 5. Makino company has developed a two-axis CNC-controlled coolant nozzle mounted on the spindle end around. Provided by an axis (U) of rotation, so as to either horizontal grinding the vertical grinding may be performed; nozzle radial positioning provided by another axis (V), thereby to compensate for wear of the grinding wheel - this wear the machining cycle sometimes the grinding wheel diameter reduced by half. 

Even after these changes, the Makino A55 machining center equipped this way, the cost is still lower than the cost of the strong creep feed grinder. Moreover, with the tool change function, all characterized by grinding can be done in two operations, and by means of the machining center has a flexible, between different parts of the conversion can be achieved within 2 hours, or less than 2 hours . 

Look ahead 

In the the Viper process is complete, the challenges faced by the Rolls-Royce is a comprehensive infer leaf processing and the advantages of the process. 

Hopton said Mr. : "Viper technology has advantages help us to move forward the process of reform. Worm blade machining factory Go to the sophisticated manufacturing process from batch manufacturing machining practices as well as the development of the worm blade machining method has 'Rolls-Royce production systems' practices and methods for providing a model for reducing customer from order to delivery between the time it is very useful. " 

British subcontractor to provide services to Rolls-Royce, a common saying is "40-day engine. Today worm blade machining process played a major role in achieving the goal. Pressure vane 15 days of the order to the delivery time, in fact, only 4-5 days of processing time, and have found that the time can be further shortened. 

Each of the engine's high-pressure the worm leaves, such as Rolls-Royce Trent, it generates horsepower racing engines to produce the same. These blades are composed of the finished engine with about 28% of the blade, and the company has maintained its production in-house. Worm gear blade factory in Derbyshire city built on a the same high-tech precision casting factory near the casting plant mainly produces leaves blank, at the same time near a heat treatment plant operated by a third party contractor. Only to complete the operation is not in the factory floor is coated with a special heat-resistant coating on the finished blade.

In the the Viper grinding machine unit, a robot in the processing center and 
Transmitted between the blade is mounted on the jig in the coordinate measuring machine

Blade machining and design in Derbyshire City an expansion of the building, through a glass wall separates between them. Relatively low due to the cost of installation of a the Viper production unit of Rolls-Royce has a whole production line for leaf development. Traditional designers from production machinery must "request or borrow" time to develop new products, but such a development unit to change this situation. Therefore, Hopton said: "We hope that the convenience of the new aspects of the design and production of high pressure vane can bring great benefits." 
The worm leaves processing in manufacturing systems and methods development is the team of led by Mark Hulands, responsible for the, now he is the manager of the worm gear systems company Rolls-Royce sophisticated manufacturing. The President of Hulands, an important goal is to keep the production flow, to the advantage of the Viper process can not be interrupted in the entire manufacturing process. In order to achieve this, the team is scheduled to target offline for part clamping and automate this process when possible. The team also strive to avoid reliance on batch processing technology. One such technique is the zinc alloy to encapsulate the blade, so that during the grinding process can be more easily clamping. This encapsulation not only with the queue, and also must be implemented by the two-stage process of removing. 
The plant currently has 5 of the same production lines (one for development, for the production of four), and also set aside space for the sixth production line. Each production line and equipment are the same, both for the blade machining, and claims can be processed in any one of the 18 kinds of blade type. The general routine includes four stages, including cedar shaped grinding one Viper unit and the shroud, and the seal band and the opening shroud cooling device EDM gas film and the shroud portion EDM drilling of the cooling holes, the pair of positioning pins EDM removal processing, and the TIG welding of the hole of the core used in the casting process, the blowing hole drilling, and final polishing process on a CNC surface grinder . 

Flexible process 

The the Viper unit includes two suitable Viper technology Makino A55 machining center as well as two Mitutoyo coordinate measuring machine (Mitutoyo), all of these machines are equipped with Fanuc (Fanuc_ robot input of the unit using a a scroll conveyor belt - with a video installation, and jig identification system. 

The blade casting is a separate standard code, with a customer-designed air metering station to install them in a flexible fixture, in order to be processed. The blade through a casting pin is fixed in the fixture (fixed position of the bottom of the cedar shaped portion), but can be by the freedom of movement of the mechanically fixed ball joints. The feature position on the terminal by the metering table with respect to the blades of the gas film portion the best-fit analysis, and when all the measured characteristics are automatically in its nominal position within the range of 30 microns at the position clamping. Located at the input to the imaging system on the conveyor blade will automatically read the serial number and jig ID, automatically storing data (to be processed for each blade automatically created) in the history file.

For grinding the blade is mounted in a toggle-type flexible fixture. 
This conditioning systems through customer development the blade shape relative to the correct clamping parts cedar shaped shroud end. 
When the optimum adjustment, the fixture is automatically lock in place

The characteristics of the blade is completed by two operations, a total of 17 minutes. First 12 minutes of operation, the second operation of 5 minutes, the unit allows a single machine to complete the two operations, and let the other only the first operation, in this way to be balanced on the machine workload . With the clamping position of the the Erowa fixture on the machine tool and the clamping device, the positioning of the workpiece in the processing center and the coordinate measuring machine can be highly repetitive. All processing by using a series of pre-formed the wheel completed grinding process. These wheels are installed in the same manner as with ordinary cutter shape model for a computer-generated checks, and in the clamping process. 

After the completion of the first operation, the blade to be checked on a coordinate measuring machine. Rolls-Royce at this stage adaptive processing software automatically with characteristic, it can automatically adjust the parameters of the CNC program for the second operation. Terry Shaw, members of the group, said the process to achieve a 1.42 Cpk tolerance for cedar root the shape ± 14 microns. 

After the completion of the grinding, the various parts are cleaned, and then sent them to Charmilles EDM machine tools - for processing sealing tape slot and opened shroud cooling characteristics. Compare the unique aspects of the operation is the Rolls-Royce normal EDM practices turn: Part jig is mounted to the spindle sleeve, for machining the electrode is mounted to the fixed position in the cutting fluid within the three. In a stacked manner for processing blades are mounted on the four universal fixture. These fixtures are then mounted on the electrode replacing apparatus of the machine tool, and extracted by the spindle sleeve and the workpiece, and using the positioning function of the C-axis is aligned with the desired electrode. All clamping can thus be done in the case of off, thereby improving the processing efficiency. 

Similarly, the cooling hole EDM drilling must be carried out in a blade clamping and also to achieve a fully automated. Each production line 12 EDM drilling machine tools, they are arranged in a fully automatic unit. Each machine can be used equipped with a plurality of preformed tubular brass electrode apparatus of one type of hole drilling. The drilling process with deionized water as a dielectric to achieve a high drilling speed. When drilling is completed, through the eye and video scan mode to check each leaf, in order to determine the required grooved its appearance and the correct position - in less than 25 microns. And then the blade sent for final finishing operation. 

The President of Hulands said, an important advantage of the entire system having a high flexibility. He said : Within 2-3 hours of the production line to switch from one type of leaf processing to another type of volume can also be processed in technology as a blade. "(End)

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