Papers by Keyword: Cold Extrusion

Abstract: This study investigates an adaptive die concept for cold extrusion that actively modulates radial preload during the main forming and ejection phases. A Gaussian process regression (GPR) surrogate, trained on fewer than 400 finite-element simulations, provides a highly data-efficient model capable of accurately predicting geometric tolerances, residual stresses, and process forces. Experimental spot measurements validate the physical trends captured by the surrogate, demonstrating reliable reproduction of the underlying mechanical interactions. The results show that increased preload during forming enables micrometer-level calibration of final diameters, while higher preload during ejection promotes beneficial compressive residual stresses at the cost of elevated ejector forces. A part-to-part control strategy effectively improves accuracy by independently steering two target properties through separate preload adjustments. Furthermore, a reinforcement learning-based controller, enhanced by flow stress estimates derived from hardness measurements, reduces variance and compensates for stochastic fluctuations in material and friction conditions. Overall, the adaptive die system, combined with surrogate-and RL-based control provides a robust foundation for achieving high dimensional precision and stable product properties under future variability scenarios, such as green steel and sustainable lubrication systems.

Abstract: In this paper, the cold extrusion process of aluminum alloy with multi-ribs was studied. The target part is formed by one-step closed cold extrusion. It has the advantages of simple process and high material utilization. The effects of extrusion speed and die corner on forming force and contact stress between billet and die were analyzed. According to the simulation results under different conditions, the reasonable process parameters are selected to obtain the products with full shape and without obvious defects. It can provide an effective reference for the parameter design in the cold extrusion process of this kind of multi-ribs parts.

Abstract: Joining of steel and aluminum is a commonly applied manufacturing process to obtain lightweight components. Cold pressure welding by means of direct extrusion allows gaining high bond strengths between these two materials. The contacting surfaces are usually prepared by using scratch brushing to enhance the bond strength. Most studies have shown the benefit of the brushing whereas the resulting bond strength scatters. Variations in the parameters of the brush treatment are presumed to be a major cause for the variations in strength. Within the presented work, scratch brushing parameters are adjusted to further improve the resulting bond strength. Cracking of the surfaces at low strains is a beneficial effect to enhance the bond strength. Therefore, the crack formation of the surfaces brushed under different conditions is analyzed in tensile tests. Roughness, residual stresses and microstructural changes of the aluminum surfaces resulting from brushing processes are evaluated to enhance the understanding of the cracking mechanism. Concluding, the brushing parameters are adjusted to improve bond strengths up to the material strength of the used aluminum.

Abstract: This paper established the model base, knowledge base, application base and test base for the cold extrusion process of internal thread and developed decision support system which realized the centralized management of related information for cold extrusion process of internal thread, maintained the consistency of data in real time and enforced the degree of information sharing. By using of the decision support system, expert system, intelligent inference technology and depending on the application requirements of the system, the overall structure of the decision support system for cold extrusion process of internal thread was established based on J2EE technology. Two accessorial decision-making methods of hybrid forecasting and application modification facilitated modeling the system business. Three-dimensional frame structure was used to represent the application example of the internal thread by cold extrusion process and to achieve the application type, information scalability of internal thread by cold extrusion process. Hybrid fast predicting mechanism which was the dynamic integration of internal thread by cold extrusion process knowledge and instance inference was applied to seek the optimal degree of internal thread by cold extrusion process.

Abstract: The existing process of 2A12 aluminium alloy piston is cutting completed by hot- drawing pole , as a material utilization rate less than 40%. In order to improve material utilization, cold-extrusion process is the reasonable choice, but only if solve the annealing before cold-extrusion, surface lubricated, the Parameter optimization of cold-extrusion and quenching process after extrusion. This research uses the DEFORM finite element analysis and a good effect in practical application is obtained to enhance the rate of more than 80% material utilization, scrap rate is less than 0.5%.

Abstract: The near-net forging processes for the body of overrunning clutch was studied by adopting the warm upsetting,warm no-flash die forging,cold extrusion and cold coining process。The arrangement of the near-net forging processes,the procedure of the near-net forging process,the choice of forging press,the structures of the punch and the lower die,and the key problem of die design were introduced in detail。The chief advantages of this process include the high surface quality,closer tolerances and qualified inner avity for the body of overrunning clutch without subsequent machining;so it is significantly energy-saving,material-saving,and the economic benefit is remarkable。

Abstract: These days, the call for more efficient cars, e.g. EURO 6, to reduce substantial the emissions of carbon dioxide and nitrous oxide raises the demand and development for Battery Electric Vehicles (BEV) or Plug-in Hybrid Electric Vehicles (PHEV). Thus, the German Government in cooperation with the industry has the goal to get at least 6 million electric vehicles on German streets by the year 2030. Until today battery systems increase the cars weight significantly, therefore weight reduction and utilization of the required space are two of the most important strategies. Because of its low density and high formability aluminum is preferred as cell housing material. Besides a light material it is necessary to use the required space of the battery pack in the car as efficient as possible. Thus a prismatic shape is favored compared to a cylindrical one. Unfortunately a prismatic cell causes an asymmetric material flow and an asymmetric tool loading during the production via bulk metal forming as the material tends to flow into the direction of the larger edges of the housing walls. That is why new forming tools for bulk forming have to be developed. To do this economically the development will be done by using design of experiments (DoE) and the finite element method (FEM). On the one hand DoE shortens time-consuming FE-simulations by stating exactly which simulations need to be done to identify main determining factors for the personal command variable(s) e.g. tool lifetime. On the other hand FEM can be used to achieve simulation results, e.g. tool loading, which are comparable to real life experiments. By using DoE, 2D FE-simulations show that the geometry of the punchs extrusion shoulder can decrease the required forming force precisely. In addition the geometry of so called deceleration seams can affect the forming force in minor degree. In combination of all significant geometric parameters and the number and position of deceleration seams the tool loading of a cold extrusion punch could be reduced significantly.

Abstract: The analysis of the composition of cold extrusion die, extrusion die working part, backward extrusion die parts design, at the same time the plunger design, analyzed the packed dimension and tolerances of convex die and concave die manufacturing.

Abstract: The quality of the honeycomb radiator structure has a great impact on thermal performance of the LED lamp. In order to make honeycomb radiators structure more uniform and materials fluidity much better; we firstly take use of cold extrusion to form the honeycomb radiator, then it will be machined. In the honeycomb radiator deformation than the larger places where prone to stress concentration, that has a seriously affect on the effect of the radiator forming. Therefore, we optimized the extrusion die, including upper and lower mold prone to stress concentration places create fillet. The results show that an appropriate fillet of the mold can greatly improve the forming uniformity and reduce the force on the die.

Abstract: The relationships between microsturcture and cold forming property of 38CrMoAl steel have been studied by experimental analysis investigation. The heat treatment p rocess of guenching cyclic sphereidized annealing for obtaining sturcture with optimum cold forming property was suggested. Through this process the characters with lowerhardness, lower plastic deformation resistance and better processing plastic of the steel can get. the properties of this steel can meet the requirement of cold forming process for materials.