GCr15 bearing steel extrusion deformation resistance of a larger, resulting in mold wear, use the drop in life expectancy, blank annealing softening light, rolling, pickling, phosphating, washing soap, and then squeeze.
1. Stock preparation
Cold extrusion of material there so kinds of forms: wire, Rod, tube, sheet metal.
Is also very important for selection of cold extrusion of material forms, which directly affect the rationality of design and use of mould, parts production quality, and ease of processing. So first of all to understand certain forms of various materials.
Wire fasteners mainly for upsetting-extruding bolts or spark plug shell of automobile, motorcycle, as well as large quantities of small extrusion. General wire diameter 3-25mm, case 35mm. Special wire rod surface and lubrication on the surface, for multi-station cold heading machine automatically forming, high material utilization, productivity is very high.
Cold extrusion billet rods are more generally used for extrusion equipment for the operation. Lower productivity compared with wire, but its surface and lubrication all surfaces can be processed, if you need multiple extrusion, sometimes for the intermediate annealing. Bar high material utilization, cutting stock up to 70% per cent, the use of press cutting stock up almost 100%. Stock length to diameter ratio is greater than 1, such as less than 1 o'clock, with pressure machine material more difficult. When the stock while also upsetting slab, l/d ratio of upsetting loss of temperature caused by the General Assembly, had better control at below 2 per cent. Steel hot-rolled bar round and Leng Jingla rods. The latter diameter size more accurate, the use of press cutting preparation time, blank volume error can be controlled on a smaller scale.
Tube of seamless steel tubes or heat-extruded aluminum, copper tubes, can be used as direct extrusion of hollow workpiece or backward extrusion billets. Cold extrusion of shape and size, the use of tube extrusion billets economy than with solid bar while squeezing pressure also has a larger reduction.
(4) sheet metal
When the ratio of length to diameter of the blank hour in extruding nonferrous metal parts or appearance is not a circle, sheet metal can be used as billets, sheet metal blanking punch.
Parts to be designed and produced according to the shape and size of precision, that bearing steel swing Rod body parts by cold extrusion billet rods are more reasonable, highly utilized. So, decided to adopt the bar.
2. Stock preparation
Stock preparation cutting blanking cutting, cutting, cutting with cutting, sawing and other methods, on-demand selection.  in the characteristics of each method.
(1) bar or tube cutting feed
On a mechanical press with a special cutting die-cutting the bar or tube feeding is the most widely used method. Preparation of cutting die stock, high efficiency, high material utilization, but truncates the blank face of a rough, face the central axis is not perpendicular, a certain degree of slope, especially in semi-enclosed cutting die, the situation is particularly serious. Therefore stock after the cutting, heading for general use flat die off after blank face flattening in squeeze.
(2) blanking of sheet metal cutting
Plate blanking material is typically used under stock length to diameter ratio is under the cylinder blank or non-circular non-ferrous metal flat stock. The main advantage of this method is high production efficiency, billet high dimensional accuracy, end surface is flat. Its disadvantage is that the low utilization of materials, usually only about 60%. For ferrous metal cold extrusions, Blanking with normal clearance on stocks in General. For non-ferrous metal cold extrusions, especially of pure aluminium or copper cold extrusions of the thin-walled parts, if blank face does not clean, squeezing in the squeeze when cracks appear on the surface, usually cutting with fine punching method. In practice, often using small clearance or negative clearance, rounded concave die die punching.
(3) bar cutting feed
Transverse cutting could cut larger billets, section formation, higher dimensional accuracy, but saw larger incision material loss. Cutting using a reciprocating saw or circular saw cutting, production efficiency is low; if a high speed band saw cutting, high production efficiency, and blank shape rules, blanking is an advanced cutting methods. At present, large diameter bar using high speed band saw cutting.
(4) lathe cutting feed
Blank face has special requirements or long, thin stock, lathe cutting can be used. This method of cutting stock higher dimensional accuracy, regular shape, but lower production efficiency, and material utilization is not high.
Above, the higher the dimensional precision of bearing steel billet material, to ensure that the blank section of the formation should be used in lathe cutting.