Showing papers on "Hydroforming published in 1994"

Controlled time-overlapped hydroforming

Abstract: Apparatus and method for hydroforming a dual wall conduit having a controlled size gap between the walls, a frame having an upper crown and a lower bed defining a hydroforming space therebetween, the bed having a slideway extending from the space to a load-unload-preform position out of the space. A mold assembly on the slideway has a lower platen and an upper platen defining at least two hydroforming cavities, one cavity being an elongated preform and semi-finish cavity, and the other cavity being an elongated finish cavity. Mold shifting means is positioned for shifting the mold assembly on the slideway from the position in the space between the crown and bed, to and from the forward load-unload-preform position. Mold closing and preforming hydraulic cylinders are operably connected to the upper mold platen for closing the upper platen onto the lower platen and creating mechanical preforming on dual wall tubular stock in the preform and semi-finish form cavity. The upper crown has a peripherally retained bladder over the mold assembly for applying a closure clamping force on the mold assembly by the bladder. A first pair of double acting, tube sealing, hydroforming elements are at the ends of the preform, semi-finish cavity, and a second pair of tube sealing hydroforming elements are at the ends of the finish cavity.

Process for hydroforming a vehicle manifold

Abstract: A hydroforming process and apparatus for manufacturing components of a vehicle exhaust or intake manifold. The hydroforming process is utilized to form a tubular member to the desired configuration for use in a manifold. The tubular member is loaded into a hydroform press and filled with a suitable liquid. The liquid within the tube is pressurized in order to maintain a predetermined internal fluid pressure which prevents collapse and crimping of the tube during forming. The hydroform press includes two sets of dies to form a compound bend in the pressurized tube. Upper and lower dies close on the tube first to bend the tube in a vertical plane. Horizontal dies are wedged inwardly spreading the first die set and bending the tube in a horizontal plane. As a result, a compound configuration may be placed on the tube making it suitable for use in a vehicle manifold.

Hydroforming platen and seal

Abstract: A platen for applying pressure during hydroforming of polycarbonate and similar sheet material includes a flexible diaphragm for applying pressure in response to hydraulic fluid under pressure within a platen cavity and a diaphragm circumscribing sealing member for inhibiting seepage of hydraulic fluid and for preventing outward migration of the material of the diaphragm during a hydroforming operation. The junction between the sealing member and the diaphragm is conforming and void free to prevent hydraulic fluid flow therebetween. To help contain the hydraulic fluid within the platen cavity, a circumscribing inwardly extending foot of the diaphragm provides a mechanical and dynamic seal against an adjacent surface of the platen cavity.

A method of forming a tubular structural member

Abstract: A method of forming a tubular structural member (10) which can longitudinally vary in wall thickness and/or perimeter, and possibly material, using the hydroforming process. This is accomplished by first fabricating a tube blank of the desired longitudinal combination of wall thickness, perimeter and material by welding together portions of tubing (18,20) having the desired characteristics and then hydroforming the resultant blank. The hydroformed part will have nearly the same thickness, perimeter and material characteristics as the blank in the corresponding longitudinal location.

Prediction of Forming Pressure Curve for Hydroforming Processes Using Artificial Neural Network

Abstract: In a hydroforming process, forming pressure versus punch stroke is critical to product quality, and thus the operating pressure curve is strictly controlled according to a preplanned control method. The conventional method of determining such a curve is trial and error, which demands tremendous effort and high cost. In this paper, a neural network approach is proposed to replace the conventional method. It automatically generates the appropriate operating curve whenever any changes in part material properties and forming geometries occur. The network maps non-linear relationships between part geometric variables and forming pressure throughout the punch stroke. The performance of the trained network was tested for various drawing ratios and punch shapes which had not been used for training. The results show that the proposed neural network approach yields products of uniform thickness, thus exhibiting the ability to design an operating pressure curve necessary for guaranteeing good product quality.

Forming of seamless high beta accelerating cavities by the spinning technique

Abstract: High beta superconducting accelerating resonators of both bulk niobium and niobium sputtered onto copper types are commonly manufactured by spinning two half-cells, which are then electron-beam welded together from the inside. Welding is a complicated and costly operation that places severe limitations on the fabrication of high frequency cavities due to the narrow size of the bore. We have built a very particular die and adapted the well-known spinning technique to form a fully spun resonator without electron beam welding. In this way, starting from a disk, we have been able to build seamless cavities with only one intermediate annealing, more rapidly, simply, and with more uniform thickness than through hydroforming.

Plastic strain determination using peak speckle pattern intensity

Abstract: This paper presents an integrated peak spectral intensity method for the measurement of plastic deformation in metallic materials. The method employs a laser speckle technique and a computer based image processing system. Test results on aluminium, brass and copper sheets subjected to bi-axial stretching using the hydroforming process shows a correlation between the integrated peak spectral intensity coefficient Hi and the equivalent strain. In addition, the use of the parameter Hi requires less computation and enables measurement of plastic strains of up to 30%.

Hydroformen von Aluminiumrohr

Abstract: Hydroforming is a novel metal forming technique. The paper presented, deals with hydroforming of tubes under the action of axial forces, internal or external pressure and a torque, regarding both work-hardening of the tube material and thickness changing in tube wall. In case of cylindrical expansion at constant rate of a thick-walled aluminium tube the time-depending state of stresses in the tube wall is computed and the corresponding pressure and force funtions are determined