A two-heating forming forging process for a large crank throw, involving a forging machine, a plurality of anvil dies, and an operating equipment, the anvil dies comprising an upper anvil, a lower die, core dies, and an upper die, the lower die comprising a small flat anvil, a large flat anvil, a double-ridged groove die, a convex die, a trapezoidal die, and a concave die, the upper die comprising an upsetting plate, a replaceable anvil die, and a reverse-fastening bending die;
- the operating equipment comprising a worktable and a manipulator, the worktable comprising a transverse worktable and a longitudinal worktable, the manipulator comprising a first manipulator and a second manipulator;
- the upper anvil being connected to the forging machine, the convex die and the double-ridged groove die respectively forming a fixed hinge with the large flat anvil, the replaceable anvil die comprising a concave replaceable anvil die and an arc-shaped replaceable anvil die, a plurality of core dies being provided, thickness differences between two ends of different core dies being different, the lower die being placed on the transverse worktable and moving with the transverse worktable, the first manipulator clamping a forged part, the second manipulator clamping the core dies or the upper die,
- the two-heating forming forging process for a large crank throw comprising:
- a first heating:
- forging a prefabricated part of a double-winged body with a boss in a middle part, setting the double-winged body to have a length of L, a width of b, and a height of h1;
- and
- setting the boss to have a height of h2 and a width of b, then the total height of the prefabricated part being h=h1+h2, comprising:
- step I:
- selecting a steel billet according to a weight requirement of the crank throw forged part, and heating the steel billet to a set forging temperature;
- step II:
- placing the steel billet heated in step I between the upper anvil and the small flat anvil, and drawing out the steel billet;
- step III:
- standing a length direction of the forged part drawn out in step II on the longitudinal worktable, clamping and placing the upsetting plate between the forged part and the upper anvil through the second manipulator, and upsetting the forged part to ½ of an original length;
- step IV:
- drawing out the forged part upset in step III to obtain a forged part with a cross section of (3b/4)×(3b/4);
- step V:
- standing a length direction of the forged part drawn out in step IV on the longitudinal worktable, and upsetting the forged part to ½ of the original length;
- step VI:
- drawing out the forged part upset in step V to obtain a forged part with a cross section of b×b;
- step VII:
- placing a middle part of the forged part drawn out in step VI above the double-ridged groove die, and forging parallel left and right grooves below the forged part;
- and
- step VIII:
- vertically flipping the forged part with the left and right grooves obtained in step VII 180°, placing the forged part on the large flat anvil for forging, correspondingly forging a left side of the left groove and a right side of the right groove into a double-winged body with a width of b, a height of h1, and a length of L, and forging a part between the left and right grooves into a boss with a height of h2 and a width of b to obtain the prefabricated part of the double-winged body;
- and
- a second heating:
- forging forming, setting transition shapes and parameters of double wings and a throw journal, and setting bending parameters, comprising:
- step IX:
- heating the prefabricated part obtained in step VIII to a forging temperature;
- step X:
- placing the heated prefabricated part on the large flat anvil, thinning and drawing out the double wings, and performing finishing to a set size;
- step XI:
- clamping the prefabricated part through the first manipulator, placing a middle part of the prefabricated part obtained in step X above the convex die, and performing forging by flipping 180° back and forth, moving laterally and changing positions for a plurality of times to preliminarily forge two side surfaces of the throw journal;
- step XII:
- placing the boss of the prefabricated part obtained in step XI upwards on the trapezoidal die, clamping and sleeving the concave anvil replaceable anvil die on the prefabricated part through the second manipulator, and forging a bottom surface of the double-winged body opposite to the boss to preliminarily forge a lower surface of the throw journal;
- step XIII:
- placing the two side surfaces and the lower surface of the throw journal obtained in step XI and step XII on the convex die, and alternately forging the two side surfaces, the lower surface, and a connecting position of the throw journal by flipping back and forth and moving laterally until a shape is close to the shape of the throw journal;
- step XIV:
- placing the throw journal of the prefabricated part obtained in step XIII on the concave die, changing forging angles by flipping back and forth, and downwards pressing a head of the boss through the upper anvil, so that the head of the boss is forged into a polygonal upper surface of the throw journal, and the two side surfaces and the lower surface of the throw journal are forged into a semi-cylindrical body;
- step XV:
- placing the throw journal forged in step XIV alternately on the convex die and the concave die, and forging the throw journal at a plurality of angles through the upper anvil by respectively adopting a non-flat anvil and the arc-shaped replaceable anvil die to obtain a cylindrical billet of the throw journal;
- step XVI:
- placing a lower surface of the cylindrical throw journal on the concave die, and clamping and reversely fastening the reverse-fastening bending die onto the upper surface of the double wings of the double-winged body through the second manipulator, so that the prefabricated part is bent to a set angle to form a V-shape;
- step XVII:
- placing the V-shaped prefabricated part on the large flat anvil, inserting the core dies with the largest thickness difference between two ends into an opening of the prefabricated part through the second manipulator, press-fitting two sides of the V-shape so that the two sides of the prefabricated part get close to each other, and performing forging again by flipping vertically so that the two sides of the prefabricated part get close to the core dies;
- step XVIII:
- sequentially replacing the core dies with gradually decreasing thickness differences between two ends, repeating step XVII so that the double wings of the double-winged body are in contact with the core dies, flipping the prefabricated part for forging, and finishing an outer side of the double-winged body to obtain a crank of the crank throw;
- step XIX:
- synchronously flipping the core dies and the prefabricated part in a press-fit state, forging the head of the boss, and drawing the head into a quadrangular-frustum-pyramid crank throw head;
- and
- step XX:
- placing the prefabricated part obtained in step XIX on the large flat anvil or the small flat anvil, and finishing the crank throw to a set size.