Link mold production technology and research

Taking a car engine connecting rod example, the technical requirements are: ( 1 ) quenching , HB220 ¯ 270. ( 2 ) did not note the draft angle 3 ° ~ 5 °, did not note fillet R2 ~ R5; (3) the direction of the metal structure of the fiber longitudinal section along the centerline and should match the rod shape , not a disorder and intermittent , allowed to have pores, cracks , folds , bubbles , delamination , inclusion , and other  plastic injection mould non-metallic inclusions and other defects. ( 4 ) does not machined surfaces should be smooth, not allowed to have cracks , folds , scars , and metal oxide is not full and other defects. Residual fly 5 ) parting edge ≤ 0.8mm, allowing total ≤ 3, the width of ≤ 5mm, ≤ pit depth or ground traces 1mm defect repair , but not in the position of the same cross section . ( 6 ) shall be subject to inspection rod . ( 7 ) does not allow forging defects repaired by welding . ( 8 ) the difference in weight of each batch of forging ≤ 3%.
Car engine connecting rod materials are: ( 1 ) quenched and tempered steel , such as 42CrMo, 35CrMo, 45 , etc. ; ( 2 ) non- quenched and tempered steel , such as C70S6 ( one kind of cracking material ) , etc., the surface after the procedure is no longer machining , the surface quality requirements , and this requires a further increase trend. Further, in order to enable smooth operation of the engine to reduce engine noise and power consumption , high tolerance requirements rod weight , generally less than 5% , this requirement also tends to be improved further . These requirements are very high for forging process for manufacturers of production technology is a challenge , not the conventional production process in general forging , otherwise there will be a lot of substandard goods . Car engine connecting rod and die forging process heating equipment: medium frequency induction furnace, oil furnace . Forging equipment: hot forging press , friction press , high-energy screw press , electro-hydraulic forging hammer .
Mold insert commonly used type and is a two- cavity mold that has a beginning and end forging forging two pairs on a mold cavity , generally  2 inch pvc coupling mould use the open slot with a flash form guide for the locking type or guide pins and bushings mold material class H13 tool steel , using conventional heat treatment , hardness HRC40 ~ 47, die life of about 3000 . The above process and die type commonly used in the current general manufacturers , production technology is more mature and stable, but the rod forging quality in general, it is necessary to be improved. Improve the technical requirements of the production of raw materials found in some raw material manufacturers rod car engine does not fully understand the material requirements , treat it as a general view of the thermal processing of steel , there are many problems caused by raw bar, resulting in the bulk of the waste generated .
Therefore, the proposed increase in raw materials inclusions grade requirements in the standard , the inclusion level not higher than 2 , in order to effectively improve the surface and internal quality.
Car engine connecting rod is generally little change in cross-sectional area , can employ cross wedge rolling billet , while the use of roll forging billet billet system will increase the time and the need to increase the mechanical hand and roll forging machine, so that the operation becomes complicated , reduces productivity improved rejection rate. Forging preform rod car engine uses a rotating outer wedge rolling , cross rolling process this principle is to heat billets placed two co-rotating rolls , making the rough turning and molding surface along the corresponding the reduced diameter and extension. Cross wedge rolling billet with high efficiency , saving raw materials and equipment manufacturing and easy . Meanwhile, the rolling line inside the contour line and the part of the flow , thereby improving the mechanical properties of the product . Currently cross wedge rolling billet technology is a mature technology , such as the Beijing Institute of Electrical and other domestic units can be supplied from process analysis, design and manufacture  tapping tee electrofusion mould of equipment to mold a set of technical services to meet the requirements of manufacturers of forging . Many forging equipment available for car engine connecting rod , how to choose depends on the equipment cost and the amount of investment , hot forging press is generally used in more imports expensive, but its movement works slider crank linkage structure principle , a fixed bottom dead center position , while forging forming, mold drop height is fixed, thus forging a high degree of tolerance, so forgings weight tolerance , good product quality. If large choice of investment . The basic choice of domestic friction press , low prices, its motion principle of rotary motion of the flywheel is converted to screw by screw nut up and down movement , the drop height is not fixed mold and blow energy is not accurate and well -oriented performance , resulting in forging height tolerance big , wrong move , so forging weight tolerance , poor product quality, and therefore , should not be optional .