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Transfer Press Line

Transfer Press Line

We manufacture Transfer Press Line. Deep drawing process & Deep drawing press & Double action deep drawing press & Triple action deep drawing press

In the midst of the changing global economic conditions in recent years, the automotive industry has found itself in an environment where together very high expectations (in terms of enhanced product competitiveness in response to the demand for even lower costs, even more, design advances, higher quality, and improved environmental performance) the production systems themselves have also been enhanced because of the shift from large lot production to diversified lot production and the demand for lower energy usage and material usage during production, and production has thus diversified to the point where it has even been evolving in response to
environmental issues.

In terms of its production of automotive body parts using presses, our customer was using conventional transfer and tandem press lines composed of mechanical presses and this resulted in major technological constraints in the production of such parts. Moreover, after considering future difficulties with accommodating major technological
advances and future customer requirements and also its desire to reduce the high energy consumption required for production, our customer decided that it was necessary to revolutionize its press line production systems using next-generation technologies.

Accordingly, the development of a next-generation press production system was initiated in 2005 with the aim of achieving an overwhelming competitive advantage that could serve as a global benchmark for
the next 30 years and enable both the ultimate pursuit of production efficiency and the accommodation of evolutionary changes in its products.

The press line that resulted from this development is a tandem press line composed of 4 servo presses and servo feeders (conveyance equipment that moves panels from one process to the next). Though one of
the goals of using servo technology in its equipment were to improve cycle times via the synchronized control of the presses and associated conveyance equipment and allow the differentially-phased operation of the presses, the primary goal was to optimize the press forming conditions and the panel conveyance conditions for each product.

On conventional press lines, the slide motion of each press in the line is almost uniform, and each parameter is optimized in order to attain the maximum formability characteristics of the press, the maximum flexibility of the conveyance equipment, and the maximum conveyance speed.

This new press line has allowed the achievement of both deep draw-forming which was not possible using conventional methods and the world’s highest level of productivity. The following provides an overview of the development technologies used to make this new system a reality.

Transfer Press Line

Transfer Press Line

A transfer press line is a specialized production line that utilizes a series of synchronized transfer presses to perform multiple forming operations on a workpiece in a continuous sequence. This streamlined process enables the efficient and precise production of high-volume, complex metal components.

Key Components of a Transfer Press Line:

  1. Uncoiler: The uncoiler unwinds the coil of metal stock, typically steel or aluminum, feeding it into the first transfer press.
  2. Straightener: The straightener removes any curvature or warping from the metal strip, ensuring a consistent feeding process.
  3. Feeder: The feeder precisely positions the metal strip at the entrance of the first transfer press.
  4. Transfer Presses: Each transfer press in the line performs a specific forming operation, such as blanking, trimming, drawing, or stamping.
  5. Transfer System: A transfer system, consisting of grippers or arms, moves the partially formed workpiece between the transfer presses, ensuring precise alignment and positioning.
  6. Ejector: The ejector removes the finished part from the last transfer press and deposits it onto a conveyor belt or collection bin.

Working Principle of a Transfer Press Line:

  1. Metal Uncoiling and Straightening: The metal coil is unwound and straightened, ensuring a flat and consistent strip for feeding.
  2. Blanking and Trimming: The first transfer press blanks the desired shape from the metal strip and trims away excess material.
  3. Transferring the Blank: The transfer system moves the blanked part to the next transfer press for further forming.
  4. Drawing and Stamping: Subsequent transfer presses perform various forming operations, such as drawing, stamping, or flanging, to create the desired shape of the workpiece.
  5. Ejection and Collection: The finished part is ejected from the last transfer press and collected onto a conveyor belt or bin.

Advantages of Using a Transfer Press Line:

  1. High Productivity: The continuous sequence of forming operations significantly increases production rates.
  2. Reduced Labor Costs: Automated transfer presses minimize labor requirements and improve overall efficiency.
  3. Consistent Quality: Synchronized presses and precise transfer systems ensure consistent and high-quality parts.
  4. Complex Shape Capability: Multiple transfer presses allow for the production of intricate and complex components.
  5. Material Savings: Optimized blank sizes and minimal waste reduce material consumption.

Applications of Transfer Press Lines:

Transfer press lines are widely used in various industries, including:

  1. Automotive Industry: Producing car body panels, fenders, hoods, and other automotive components.
  2. Appliance Industry: Manufacturing cooking pots, pans, sinks, and other appliance components.
  3. Aerospace Industry: Creating aircraft components, such as fuel tanks, fuselage sections, and engine housings.
  4. Electrical Industry: Producing electrical enclosures, housings, and components.
  5. Medical Device Manufacturing: Manufacturing medical implants, surgical tools, and other medical devices.

Conclusion:

Transfer press lines represent a sophisticated approach to high-volume metalforming, offering exceptional productivity, consistent quality, and the ability to produce complex shapes. Their versatility and efficiency make them essential tools in modern manufacturing, particularly for industries that require the production of high-quality, complex metal components.

The Primary Goals of a Transfer Press Line

The primary goals during the development stage of the servo press forming machines were the ability to perform deep draw-forming and to achieve high press stroking speeds (27 SPM when running in Continuous
mode).

First, a slide stroke length of 1100 mm was selected to accommodate the deep draw-forming target values. An eccentric crank motion system was adopted for the slide drive mechanism because of the importance of high slide speed during the forming portion of the press stroke, especially in the vicinity of the bottom dead center. The slide of this long-stroke press is driven at high speed, and rapid acceleration and
deceleration is also achieved via the servo controls.

Compared with a link mechanism, the eccentric crank mechanism design is simpler, which also simplifies the motion controls. On the other hand, a great deal of torque is required to drive such a press and to attain the requisite forming tonnage, and thus it was necessary to develop a low-speed, high-torque servo motor for these large-capacity servo presses.

The servo motors for this development project (Photograph 2) were manufactured by the press machinery manufacturer EMS Metalworking Machinery, using its independently developed technologies. Based on the specification requirements provided by our customer, EMS Metalworking Machinery optimized the structural designs, the magnetic circuit designs, the cooling architecture, and the CNC controls of its servo motors

This resulted in the achievement of unique large-capacity servo presses (Photograph 3) that operate at high speeds with high accuracy. Additionally, the highest capacity draw-forming press (23000 kN
rated capacity) in the line is powered by 4 servo motors, and it also contributes to a smaller installation footprint and lower equipment investment costs.

Servo Motors in a Transfer Press Line

At the same time, in order to achieve the targeted deep draw-forming requirements, high-precision variable controls were also necessary for the die cushion pressure to enable it to track with the press motion. The die cushion equipment used in the draw-forming press in this new line utilizes a hybrid motorized hydraulic system equipped with NC controls.

Small high-speed servo motors are used to control the pressure inside hydraulic cylinders to enable high responsiveness to die cushion pressure fluctuations during the forming portion of the press stroke and high-precision pressure controls that are within ± 2.5% of the commanded pressure value. Additionally, the electrical power regeneration feature in the die cushion enables 70% of the working force to be recaptured, which also helps to lower energy consumption.

In order to achieve the targeted line SPM, the ability to complete a 5~6 meter conveyance stroke within 1.5 seconds was required. However, it would be difficult to achieve this requirement using a simple sliding-type
the mechanism, and as a consequence, it was necessary to combine a long arm with a swiveling pivot shaft. The drive method for the arm is based on the well-known Scott Russell linear linkage, and it has a newly developed link mechanism that enables motion in the lift direction by replacing the connection point between the feed arm and the drive arm with a short linkage.

Hydraulic Deep Drawing Transfer Press Line
Hydraulic Deep Drawing Transfer Press Line

Transfer Press Line Manufacturer

In the case of a conventional Scott Russell linkage, it is customary
to raise the entire unit in order to achieve motion in the lift direction, which means that as the conveyance distance lengthens the unit as a whole becomes larger and larger. However, this newly developed mechanism
does not require the lifting of the entire unit–the additional short linkage only needs to be actuated–and this is extremely advantageous for the high-speed motion required for tandem lines.

Additionally, because the linkage in the linear direction is achieved by controlling 2 axes on one side plus 1 tilt axis, even when multiple conveyance equipment units are connected the total number of controlled axes can be kept to a minimum. This press-to-press conveyance equipment was the result of a joint development project with EMS Metalworking Machinery.

A comprehensive control system is crucial to achieving high-speed synchronous control of the entire press line, and a priority has been placed on selecting systems based on their synchronization control performance with respect to the servo press machines. In order to derive the maximum benefit from the high-speed, high-accuracy control of the position of the servo press slide throughout its entire motion range from top dead center to bottom dead center, this synchronized control system not only provides synchronized controllability of the conveyance equipment it also constantly monitors its positional relationship with the press slide.

It is also equipped with interference prevention features to deal with a wide variety of possible risks. Moreover, the conveyance equipment drive mechanism incorporates know-how obtained during the development of the servo presses, and just like a servo press it uses a low-speed, high-torque servo motor in combination with a gear drive system to achieve the power performance required for high-speed operations.

Especially in the case of the above-mentioned link drive mechanism, the drive power is transmitted internally via the swivel arm, which enables motors and other heavy items to be mounted in a stationary position, which enables the feed arms and drive arms to swivel at high speed. The body panel conveyance system incorporates the high-speed conveyance configurations used on transfer press lines, i.e., a crossbar cup feed system.

Transfer Press Line Parts

The end of the feed arm is equipped with a tilt feature that swivels in the vicinity of the crossbar center axis and a tool section mounted on the crossbar is used to handle the other swiveling and/or shifting motions required in the vicinity of the axis.

Optimized press forming conditions are required in order to maximally leverage the capabilities of a servo press and to achieve the goal of deep draw-forming. Formability is improved by optimizing the press speed during the forming portion of the stroke by controlling the speed of the press slide and by optimizing the material flow characteristics by controlling the die cushion pressure (Figure 2) shows the target deep draw-forming values and the degree to which each parameter contributes to the final result

However, based on prior tests, we knew that the forming conditions required to achieve deep draw-forming that was 50 mm deeper than
conventional techniques were only found in an extremely narrow range, and additionally, we knew that the forming conditions varied depending on the shape of the part being formed.

The most rudimentary method for finding optimal forming condition solutions is to actually manufacture dies and then perform forming trials under various conditions, but this involves a tremendous amount of time and expense. Moreover, when forming automotive body parts and especially when deciding upon the design of exterior body panels.

It is necessary to ascertain whether forming is possible or not at a very early stage in the development process, and it was a real problem because it is not possible at that early stage to determine whether such forming would be possible through a trial and error process that uses dies. In this development project, press forming simulations were used instead of trial and error testing in order to develop a system that would deliver optimal forming conditions.

Press Forming with a Transfer Press Line

Press forming simulations are analyzed and the results are evaluated by dividing the press forming process into a number of discrete stages and then using optimization software to fine-tune the press forming speed parameters and the die cushion pressure parameters at each stage. Based on the final analysis results of the minimum primary strain and the results of the material thickness reduction rate, the optimal forming conditions are determined by selecting a central value within a range that has a good balance between both factors, and then the servo press motion controls and the die cushion pressure controls are converted into data.

However, in existing press forming simulation software, the analysis function assumes that the relationship between the material stress and strain and the frictional coefficients are always uniform, and thus there were problems because even when the forming speeds were changed in the simulation software the resulting analysis results remained the same. As such, we also developed the servo press forming simulation software used for this system.

When simulating the speed-dependent relationship between material stress and strain, the relative speed of the adjacent contact points of the forming model during the forming process was calculated, and that was used as the strain speed, and a module was added that varies the relationship between stress and strain depending on this calculated strain speed. And a method was also incorporated for the frictional coefficient that correctly simulated the effects of relative speed and contact surface pressure.

This resulted in a press forming simulation that would correctly output the forming results based on variations made to each of the forming parameters. This system enables us to determine during an early stage of new automobile development whether a design that approaches the maximum capabilities of a servo press can be used or not, and it allows the press forming conditions for each part to be automatically set during the production preparation stage.

EMS Metalworking Machinery

We design, manufacture and assembly metalworking machinery such as:

  • Hydraulic transfer press
  • Glass mosaic press
  • Hydraulic deep drawing press
  • Casting press
  • Hydraulic cold forming press
  • Hydroforming press
  • Composite press
  • Silicone rubber moulding press
  • Brake pad press
  • Melamine press
  • SMC & BMC Press
  • Labrotaroy press
  • Edge cutting trimming machine
  • Edge curling machine
  • Trimming beading machine
  • Trimming joggling machine
  • Cookware production line
  • Pipe bending machine
  • Profile bending machine
  • Bandsaw for metal
  • Cylindrical welding machine
  • Horizontal pres and cookware
  • Kitchenware, hotelware
  • Bakeware and cuttlery production machinery

as a complete line as well as an individual machine such as:

  • Edge cutting trimming beading machines
  • Polishing and grinding machines for pot and pans
  • Hydraulic drawing presses
  • Circle blanking machines
  • Riveting machine
  • Hole punching machines
  • Press feeding machine

You can check our machinery at work at: EMS Metalworking Machinery – YouTube

Applications:

  • Beading and ribbing
  • Flanging
  • Trimming
  • Curling
  • Lock-seaming
  • Ribbing
  • Flange-punching