Cold forging of a hollow flanged part by an unconventional extrusion method

This paper presents a numerical analysis of a new cold forming process for a hollow part with an external flange. The following techniques were used: forward extrusion, an unconventional method of extrusion with a moving sleeve, and upsetting in a tapered die cavity. The billet (42CrMo4 steel tube) was formed at ambient temperature. The study aimed to investigate the proposed method in terms of forged part accuracy. The following are examined and discussed: material flow, process force parameters in relation to tool strength, energy consumption of individual operations, as well as the distributions of strains, stresses, temperature and Cockcroft-Latham integrals in the produced part. The study has confirmed that hollow forged parts with external flanges of relatively large diameters and heights can be cold formed in several operations using different techniques.

Elimination of Non-stick on Leads Defect through Re-designed WCTP

This paper presents the reformation and fabrication resolved on the wire clamp and top plate (WCTP) design to eliminate the presence of lead finger bouncing resulting to high rejection of non-stick on leads (NSOL). Problem experienced was that the hollow or half-etched portion of the leadframe at the top and bottom units caused its bouncing effect. With the aim to improve localized massive NSOL defect, WCTP has been modified to provide positive bias to support its hollow part or the half-etched part of the leadframe at the top and bottom of the units. The re-designed WCTP was fabricated, extending its clamping with enhanced vacuum on top and bottom rows. The implementation of the improved WCTP design reduced the defect with 88 % improvement with the defect reduction during the lot runs.

Boat-shaped enkolpiobracelets: the areal peculiarities

Boat-shaped bracelets with a bulging middle hollow part are represented by two types: those with free ends and examples with hinged terminals. The first type is known in the monuments of the Karelian Istmus and northern coast of Lake Ladoga, the second type is represented at barrows on the Oyat’ river.They are complicated in manufacture and because of the use of expensive non-ferrous metal and are made most probably at the order of elite jewellery workshops.

Influence of Material and Arrangement Mold on the Foaming Behavior of Extruded Precursor

In this paper, the extruded precursors were prepared by Powder compact method (PCM),with two different powder AlSi10 or pure Al mixed foaming agent ZrH2 or TiH2, then they were foamed to fill the hollow part. L9 (33) orthogonal test was planned, including three factors, furnace temperature; foaming time; and arrangement mode. The results indicated that the pore structure were effectively improved through adjusting the arrangement mode of precursors. The specimens have been obtained the homogeneous foam expansion when the AlSi10-TiH2 agent were arranged on the top while AlSi10-ZrH2 agent precursors at the bottom in the hollow, and foamed 14 min~16 min at 800 °C

Lubrication in Hot Forging with Pulsed Ram Motion

The effect of pulsed (oscillating) ram motion control on lubrication was investigated in hot forging of stainless steel workpiece with oxide glass lubricant. During the retreat in the pulsed ram motion, the workpiece was re-lubricated by flow of lubricant through the gap between the workpiece and the die. A hot spike-type forging test on a servo press with pulsed ram motions was carried out to investigate the lubrication performance of the oxide glass. In the test, the workpiece with a temperature of 1223 K was extruded into the hollow part of the upper die together with oxide glass in a manner that combined pulsed and stepwise ram operations. The re-lubrication of the workpiece with oxide glass was confirmed by the test results showing 5–10% reduction in the forging load and 5% longer length of the backward extruded part of the workpiece under an appropriate pulsed ram motion.

Research on Single Pass Deep Drawing Spinning Formability of Cup-Shaped Parts

The deep drawing spinning (DDS) formability of metal material refers to the ability to produce an opened hollow part with a circular blank through DDS without fracture or wrinkling defect. The cup-shaped parts of DP600 were selected as the research object, the coefficient m=d/D0 was put forward as the evaluation index of DDS formability, and the minimum coefficient without the occurrences of wrinkle and fracture is defined as the limit DDS coefficient mlim. The single pass DDS formability of cup-shaped parts was investigated experimentally and the influences of blank thickness, roller feed rate and roller fillet radius on the DDS formability were discussed in detail. The results show that the DDS coefficient decreases with the increasing of blank thickness; fracture or wrinkling occurs easily when the roller feed rate is excessively large or excessively small; the large roller fillet radius is helpful to improve the DDS formability of metal material.