Single-source solution

Rosell Werkzeugbau & Stanztechnik is, unusually, involved with die design from the very beginning – through R&D, tool design, prototyping and manufacture. Once a design has been approved and crash tested, a typical delivery time could be from 12-24 weeks, depending on complexity, but the overall process takes over one year. Based in Heiligenstadt, Rosell uses Vero's VISI software (UK - 01242 542040) to support key processes throughout the process, and a recent example is a project for the Audi Q5. Rosell, in partnership with its customer, Griwe Werkzeug Produktions GmbH, a supplier to Audi AG, developed a progression tool for a retainer sill, which is located under the so-called B-column. The retainer sill was to be produced using high-strength steel with a tensile strength of 1,000 N/mm². "Working closely with the customer is an important part of our tool development," explains Franz Rosell, managing director of Rosell Werkzeugbau & Stanztechnik GmbH. "Once the order has been received, we complete a strip layout and preliminary design for all forming stations and present the data to our customer." Previously, such presentations took about an hour, but now there is more detail available to be viewed and understood, these meetings take longer. "Historically, the customer was presented with a pile of A0 drawings that were used to detail the project. It was extremely difficult to demonstrate how the tool would operate and explain the toolmaker's critical ideas," Mr Rossell outlines. Today, at least three hours are scheduled for such a meeting, as a VISI's 3D representation of the tool provides the customer with a much clearer idea of the tool mechanics, and the technical discussions go into much more detail. "VISI [installed in 2003] was a quantum leap from the software that we had installed previously," explains the managing director. "Unlike the old software, VISI is 'close to the tool maker'. All our designers are fully trained, but almost all staff members are able to work with VISI. And there are approximately eight or nine other engineers who are able to use VISI to extract the relevant information they need from a model." Image: Involvement with a project like this right from the beginning is unusual, and the use of a single software package similarly so Initial tool design is based around three typical steps. The first step is to develop the 2D blank shape from the 3D model. This is done using VISI Blank, which provides valuable analysis of material behaviour during the forming process, such as 'thinning' and 'wrinkling', allowing accurate identification of potential problem areas prior to physical die design. Previously, the blank development was calculated using a collection of tables, which often led to errors. Today, blank calculation is based on a material database that includes material strength, density, work hardening rate and yield stress. With the blank development complete, the second step is the design of the bending/forming stages and the production of the 3D strip, using VISI Progress. Step-by-step unfolding allows the designer to plan each forming stage by dynamically adjusting bend angles, allowing complete freedom for unfolding experimentation. Once the forming stages are complete, it is possible to automatically generate a 2D strip plan, which forms the basis of the 3D strip. Tools such as automatic blank alignment and nesting help plan a more efficient strip and provide valuable information, such as material wastage. The 3D strip can be simulated at any point to validate the performance of the punching and forming stages. Once the customer is satisfied with the tool process plan, step three sees the 3D tool design begin. The customer must approve the tool design and it is here that the main difference between the old 2D style presentations becomes most apparent. The company now presents the tool in the form of an individual plate, and 3D details are often adjusted 'live', together with the customer. Once the customer has approved the 3D design, the standard components such as screws, dowels, strip lifters and springs are integrated into the design. Finally, the designer uses the 3D model to automatically generate the 2D views of individual components. OFFICE OR SHOPFLOOR VISI Machining, a 3D CAM solution that can be used either in the CADCAM office or the shopfloor, is employed to generate EDM?programs and also those used to hard mill the pre-milled and hardened forming tools that shape the component. The old 2D designs made it very difficult to see whether a form part would jam during the assembly. Having a 3D model of the tool assembly allows the engineer to easily check the relationship between the individual parts. A VISI viewer has been installed in the assembly workshop for this purpose. The toolmaker cannot change the data, only interrogate the model in 3D and extract the relevant measurements or create plots, if necessary. Fine-tuning of the tool starts with data produced via VISI Blank, which is used to drive a laser to cut a preliminary strip that is then formed and separated inside the tool. This ultimately creates a prototype component that simulates all cutting, bending and forming operations. Image:Digital designs help customers understand more The final component is scanned using a CNC co-ordinate measuring machine, with quality checked against the target model provided by the customer. If there are any deviations, the changes are filtered back through to the 2D blank; a new strip is cut with the laser and then formed until any deviations are within acceptable tolerances. Finally, the completed tool is assembled and a pressing date is arranged with the customer, with the production part again being checked with a co-ordinate measuring machine; any last minute fine-tuning may take place on-site. CADCAM and rapid manufacturing Image: Delcam's CADCAM software (UK – 0121 766 5544) has helped the Northbend Pattern Works, from West Harrison, Indiana, to streamline its casting die manufacturing process and accelerate the turnaround of every mould. The company uses the PowerSHAPE CAD software to convert customers' part designs into tooling designs and the PowerINSPECT inspection system to check both the pattern moulds and the initial sample parts. Over 90 per cent of moulds made by Northbend Pattern are for high-quality, high-volume automotive parts, such as brake callipers. The shop produces from 100 to150 new moulds and patterns each year, and can be working on between 20 and 50 projects at any one time. Northbend's customers must now deliver tolerances in their castings once expected of machined parts. As a result, they have tightened the requirements on their mould suppliers. This increased level of precision is expected on top of the ability to deliver on time and to accommodate design changes almost overnight. The traditional method for incorporating cooling features within mould tools or inserts is to machine or erode cooling ducts in a conventional manner. LaserCUSING (UK – ES Technology, 01865 821818) involves the fusion of a metallic powder by a scanning laser to produce complex and intricate 3D parts. The layer-by-layer construction of the part makes it possible to design and manufacture tool and insert components that would otherwise be impossible or impractical to produce by traditional machining methods. And the opportunity to cool critical regions of the mould tool frees the users of LaserCUSING technology from the traditional constraints of tool design. For example, in one case, two tools with conformal cooling (picture, above) had the capacity to produce the required yearly volume in only a nine-month period. In contrast, three tools using conventional cooling principles would be required to run for the full 12-month period to achieve the same volume of parts – conformally cooled tools were capable of achieving double the output per tool. First published in Machinery June 2009