In this paper, we described deep drawing that entailed ultrasonic vibration. The deep drawing method described uses with a punch, a die and a tool of blank holder. In this study, a metal mold through which a die exhibited longitudinal vibration was produced experimentally. A bolt-clamped Langevin-type transducer vibrator was used as the source of vibration. Using this manufactured metal mold, the decrease in the largest deep-drawing load and the improvement in the limiting drawing ratio were compared and examined with usual restrictions. It was also used for general purposes and restrictions and for deep-drawing cold-rolled steel sheets as processed materials. The result showed that the maximum load decreased, but no improvement in the limiting drawing ratio could be observed.
The flow of a billet surface inserted into the profile during the extrusion of Cu alloy has been investigated by the finite element method under several extrusion conditions. The billet surface material is inserted into the profile in two ways. We have defined the forward flow into the profile surface as Flow type 1, and the flow into the inner parts of the profile as Flow type 2. These lengths of insertion into the profile have been estimated. In the initial billet temperature range of 500-800℃, the higher the temperature, the larger is the insertion length of Flow type 1, and the shorter that of Flow type 2. The insertion length of Flow type 1 increases because the deformation resistance of the billet surface increases when the initial billet temperature is higher than the container temperature. For extrusion ratios of 11-42, the higher the extrusion ratio, the larger is the insertion length of Flow type 1, and the shorter that of Flow type 2. The insertion length of Flow type 1 decreases because the length between the billet surface and the profile is large when the extrusion ratio is high.
A servo-controlled multiaxial tube expansion testing machine was developed to measure the plastic deformation behavior of sheet metals under biaxial stress condition in a large strain range. The test material was an interstitial free steel sheet. The test specimen was fabricated by bending and laser-welding the sheet into a tube specimen with an inner diameter of 44.6 mm and a wall thickness of 0.7 mm. Many linear stress paths in the first quadrant of stress space were applied to the tubular specimens using the servo-controlled multiaxial tube expansion testing machine. Moreover, biaxial tensile tests using a cruciform specimen were also performed to precisely measure the deformation behavior in a small strain range following the initial yielding. True stress-true plastic strain curves, the contours of plastic work in stress space up to an equivalent plastic strain of 0.15, and the directions of plastic strain rates were successfully measured. The test material exhibited differential hardening. Moreover, forming limit strains and stresses were determined.
In a previous paper, we proposed a two-step cold extrusion method of shaping external spur gears and helical gears. In the present paper, we describe how this filling method is applied to the shaping of internal helical gears. A specially designed mandrel for an internal helical gear utilizing the two-step filling method was used to expand and the inner diameter of the cylindrical workpiece. The specifications of these gears are as follows: module m=1.0, 1.25 and 1.5 mm; helix angle ß=20 deg; number of teeth Z=12-15 and whole depth h=2.00 module. The materials used were aluminum A1200 and low carbon steel S15C. The criterion for shaping complete teeth is discussed primarily in terms of punch pressure and the reduction in the area and the expansion ratio of the inner diameter of the workpiece. The approach that we described here successfully produced a filled up internal helical gear with only a few percent reduction in area. The punch pressure was very low, far below the strength of the punch material.
The shaping conditions for a spur gear with an inner spline by cold extrusion are examined experimentally. The specifications of the spur gear examined are as follows: module m=1.25-2.0, number of teeth Z=18-13, pressure angle α=20°, and tooth depth h=2.25m; those of the inner spline are as follows: module ms=1.0, number of teeth Z=8-18, pressure angle α=20°, and tooth depth hs=1.25m. The tested material is low-carbon steel, S15C. The inner diameter of the workpiece, inner spline tooth depth, addendum modification coefficient, and module are varied to examine the effect of the reduction in area. It is found that well-shaped spur gears and inner splines can be produced. The shaping conditions are closely connected with the reduction in area. The accuracy of the shaped spur gear was about 7 Grade in the old JIS. The punch pressure needed for the shaping is much lower than the strength of the punch material.