Wire drawing die "linear" and "arc"
With the increase of drawing speed, the service life of drawing die become a prominent problem. Americans T Maxwall and E G Kennth proposed to adapt to the high speed wire drawing new wire-drawing die pass theory, namely "linear" theory. According to the theory of production of wire drawing die has the following features:
(1) the entrance area, lubrication area close 2 for one, has the lubrication Angle decreases, the lubricant does not enter the workspace under certain pressure, thereby better lubricating effect.
(2) the entrance area and the workspace extended to build better lubricating pressure, its Angle according to the drawing material and each time compression rate optimization, respectively.
(3) sizing area must be flat and reasonable length.
(4) all parts of the vertical line must be straight.
In recent years, domestic wire drawing industry to "linear" and "arc" type drawing die widely discussed, are controversial among them is the workspace shape and the shape of the workspace and sizing border. Many people have held a positive attitude to "linear" mode. But the author thinks that there are two types of wire drawing die all have their own characteristics and the applicable occasions, indiscriminately concluded that at the end of the free of bias.
"Arc" on the mold core workspace, will make the flow of metal in the deformation zone is more twists and turns, lead to the increase of additional shear deformation and excessive deformation work, and make the drawing stress increases (usually a "linear" modulus increased 10-30%). And "linear" model workspace contour line of the same slope, so that when we determine the best working area half cone Angle alpha, can under the stress state of minimum drawing metal; And "arc" die due to the different contour line curvature of each point, so can't make the entire workspace there exists a best workspace half cone Angle alpha. From is advantageous to the metal flow and reduce the perspective of the drawing stress, at present abroad in the compression ratio is 10 ~ 35% (most of the deformation of the wire are in this range) and drawing, rough specifications of the wire, generally adopt the "linear" workspace.
And use "arcs" workspace, the deformation of metal, holes can be decreased gradually with the increase of the degree of strain hardening, the inner hole wall pressure distribution and wear are homogeneous, so "arc" workspace wearability. Especially during the time compression ratio is small (less than 10%), and USES the "arc" workspace, can be in the workspace half cone Angle alpha for long enough under the condition of rather smaller deformation zone. Combined with the "arc" workspace has the characteristics of strong ability to adapt, so in a way times larger compression ratio (> 35%) or small (less than 10%) and the drawing wire, should adopt the "arc" mode.