Method for forming arc surface and inclined surface of crankpin neck

Abstract

The present application relates to a method for forming the arc surface and inclined surface of a crank, which comprises the following steps: placing a six-prism blank into a U-shaped anvil, pressing the six-prism blank with a flat anvil when the press is descending, and forming the six-prism blank into a U-shaped blank in the U-shaped anvil; after the U-shaped blank is formed, replacing the U-shaped anvil with a V-shaped convex anvil, contacting the arc surface of the U-shaped blank with the trapezoidal boss of the V-shaped convex anvil, and forming the inclined surface on both sides of the crank by pressing the flat surface of the U-shaped blank with the flat anvil; after the inclined surface on both sides of the crank is pressed, replacing the V-shaped convex anvil with a flat anvil, and pressing the crank arms on both sides with the flat anvil to form the crank blank with crank arms on both sides. The method ensures the formation of the end shape of the crank for the crankshaft of a high-power low-speed diesel engine, makes the end shape of the crank closer to the finish shape, greatly improves the quality of the end and crank neck of the crank, and greatly reduces the raw material cost of the crank. In addition, different specifications of crank blanks only need to replace different U-shaped anvils, and the V-shaped convex anvils can be shared, thereby reducing the mold cost.

Description

Technical Field

[0001] This invention belongs to the field of crank forming technology for marine low-speed diesel engines, specifically relating to a method for forming the arc surface and inclined surface of the crank neck. Background Technology

[0002] Marine low-speed diesel engine crankshafts are typically semi-assembled, consisting of a crankshaft, a central main journal, and output and free ends heat-shrinkable components. Among the components of a marine low-speed diesel engine crankshaft, the crankshaft is the most numerous, heaviest, most structurally complex, and requires the strictest forming precision, making it the most difficult to manufacture. The quality of its forming directly affects the overall mechanical properties of the crankshaft, determines the manufacturing cost, and consequently impacts the survival of the manufacturing company. Therefore, the manufacturing level of the crankshaft determines the manufacturing level of the low-speed engine crankshaft.

[0003] Cranks are usually formed by bending forging, which involves forging a blank with a boss in the middle and then bending it into shape on a mold. The shape of the blank determines the shape of the crank after bending, so the blank making process is the most critical link in the crank forging process.

[0004] The crankshaft's bend consists of an arc on one side and a bevel on the other. Forming the arc and bevel is quite difficult. The original billet-making process involved forging the entire crankshaft bend end into a large block, with the crankshaft blank having a large square boss in the middle and wing-like shapes on both sides. This forging method is the simplest, but forging a large block results in significant waste of raw materials. Furthermore, the arc and bevel at the bend end rely on subsequent machining, resulting in a lower quality compared to integrally formed bends. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings and to provide a method for forming the arc surface and bevel of the crank neck, so that the forming of the crank neck end is closer to the finished dimensions of the product.

[0006] To achieve the above objectives, the present invention provides a method for forming the arc surface and inclined surface of a crankshaft neck, the forming method being as follows:

[0007] The hexagonal prism blank is placed in the U-shaped anvil, and the press moves downwards to press the hexagonal prism blank with a flat anvil. The hexagonal prism blank is formed into a U-shaped blank in the U-shaped anvil, and the arc surface of the U-shaped blank is the arc surface of the neck end.

[0008] After the U-shaped billet is formed, the U-shaped anvil is replaced with a V-shaped convex anvil. The arc surface of the U-shaped billet contacts the trapezoidal boss of the V-shaped convex anvil, and the flat anvil presses the flat surface of the U-shaped billet to form the inclined surfaces on both sides of the crank forging.

[0009] After pressing the beveled surfaces on both sides of the crank forging, replace the V-shaped anvil with a flat anvil, and then use the flat anvil to press out the crank arms on both sides to form a crank blank with crank arms on both sides.

[0010] Furthermore, the crank blank with crank arms is reheated in the furnace. After exiting the furnace, the crank blank is placed on a bending support, and a punch plate with an inner concave arc cavity punches down from the crotch opening of the crank blank to form the crank neck arc surface on the inner side of the crotch opening. When the arc punch plate continues to descend to the process dimension, the crank neck is formed, and the crank arms on both sides of the crank blank are V-shaped. Finally, an arc tongue plate is inserted into the opening, and the crank arms on both sides are flattened on the press to form the crank forging.

[0011] Furthermore, the hexagonal prism blank is an irregular hexagonal prism, the width W of any set of parallel faces of the hexagonal prism is equal to the width of the crank forging, the height H of the two vertices facing each other of the set of parallel faces is equal to the crank forging neck length + 550-650mm, and any one of these two vertices is used to insert into the U-shaped anvil 5.

[0012] Furthermore, the inner cavity of the U-shaped anvil includes a bottom arc surface, inclined surfaces at both ends of the bottom arc surface that slope outwards, and a guide arc surface connected to the inclined surfaces. The diameter of the arc surface is equal to the width of the crank forging. The maximum height of the inner cavity of the U-shaped anvil is greater than or equal to the length of the crank forging's neck, and the thickness of the U-shaped anvil is the same as the width of the flat anvil.

[0013] Furthermore, the maximum opening width of the U-shaped anvil is 180-220 mm larger than the width of the crank forging.

[0014] Furthermore, the height of the U-shaped billet is equal to the length of the crank forging neck + 300-350 mm.

[0015] Furthermore, the V-shaped anvil includes a cuboid base and a trapezoidal boss. The slope of the trapezoidal boss is equal to the slope of the bevel end of the crank forging, and the height of the trapezoidal boss is equal to the height of the bevel end of the crank forging. The width of the cuboid base is the same as the width of the flat anvil.

[0016] Furthermore, the specific process of forming the inclined surfaces on both sides of the crank forging by pressing the flat surface of the U-shaped billet with the flat anvil is as follows: the flat surface of the U-shaped billet is pressed until the inclined surface formed by the U-shaped billet is flush with the inclined surface of the trapezoidal boss; and in this way, one side of the inclined surface is formed first, and then the other side of the inclined surface of the crank forging is formed by pressing.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention adopts a two-step forming method to ensure the forming of the crank neck end shape of the crankshaft for high-horsepower low-speed diesel engines, making the shape of the crank neck end closer to the precision-machined shape, greatly improving the quality of the crank end and the crank neck, and at the same time greatly reducing the raw material cost of the crank; in addition, different specifications of crank blanks only need to be replaced with different U-shaped anvils, and the V-shaped convex anvil can be shared, reducing the mold cost. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the hexagonal prism blank structure of the present invention;

[0019] Figure 2 This is a schematic diagram of the hexagonal prism blank being placed into a U-shaped anvil according to the present invention;

[0020] Figure 3 This is a schematic diagram of the U-shaped billet forming process of the present invention;

[0021] Figure 4 This is a schematic diagram of the V-shaped anvil pressing U-shaped billet according to the present invention;

[0022] Figure 5 This is a schematic diagram of the crank blank with a crank arm according to the present invention;

[0023] Figure 6 This is a schematic diagram of the crank blank bending forming process of the present invention;

[0024] Figure 7 This is a schematic diagram of the crank forging formed by bending according to the present invention. Detailed Implementation

[0025] This invention employs two tooling methods to form the arc surface 1 and the inclined surface 2 at the end of the crank forging. After forming the crank forging, the formed crank forging is then bent into shape. Details are as follows:

[0026] The billet can be either a hexagonal prism billet or an elliptical cylinder billet, both obtained from a fully heated steel ingot through a single upsetting and drawing process. For example... Figure 1 The image shows a hexagonal prism blank. The blank is an irregular hexagonal prism. The width W of any set of parallel faces of the hexagonal prism is equal to the width of the crank forging. The height H of the two vertices facing each other on this set of parallel faces is equal to the crank forging's neck length + 550-650 mm. Either of these two vertices can be used to insert into the U-shaped anvil 5. This hexagonal prism blank can be easily inserted into the U-shaped anvil 5 without getting stuck.

[0027] like Figure 2 As shown, the inner cavity of the U-shaped anvil includes a bottom arc surface, outwardly inclined slopes at both ends of the bottom arc surface, and a guide arc surface connected to the slopes. The diameter of the arc surface is equal to the width of the crank forging. The width of the maximum opening of the U-shaped anvil is 180-220 mm larger than the width of the crank forging, which facilitates demolding. The maximum height of the inner cavity of the U-shaped anvil 5 is greater than or equal to the length of the crank forging's neck. The thickness of the U-shaped anvil 5 is the same as the width of the flat anvil 4.

[0028] The hexagonal prism blank is placed in the U-shaped anvil 5, and the press moves downwards using the flat anvil 4 to press the hexagonal prism blank. The hexagonal prism blank is gradually shaped into a U-shaped blank in the U-shaped anvil 5. The arc surface of the U-shaped blank is the arc surface 1 at the end of the bend, as shown below. Figure 3As shown; the height of the U-shaped billet is equal to the length of the crank forging neck + 300~350mm. After the U-shaped billet is formed, the lower U-shaped anvil 5 is replaced with a V-shaped convex anvil 3.

[0029] Combination Figure 4 As shown, the V-shaped anvil 3 is a tooling for forming the beveled surface of the crank forging. The V-shaped anvil 3 includes a cuboid base and a trapezoidal boss. The slope of the trapezoidal boss is equal to the slope of the beveled surface at the end of the crank forging, and the height of the trapezoidal boss is equal to the height of the beveled surface at the end of the crank forging. The width of the cuboid base is the same as the width of the flat anvil 4.

[0030] When pressing the beveled surface of the crank neck, the arc surface of the U-shaped billet contacts the trapezoidal boss of the V-shaped anvil 3, and the flat anvil 4 presses the flat surface of the U-shaped billet. When the beveled surface 2 formed by the U-shaped billet is flush with the beveled surface of the trapezoidal boss, the press moves upward. In this way, one side of the beveled surface 2 is gradually formed, and then the other side of the beveled surface 2 of the crank neck end of the billet is formed.

[0031] After pressing the inclined surfaces 2 on both sides of the crank forging, replace the V-shaped anvil 3 with a flat anvil 4, and then use the flat anvil 4 to press out the crank arms on both sides, forming a crank blank with crank arms on both sides, such as... Figure 5 As shown.

[0032] Combination Figure 6 As shown, the crank blank with crank arms is fully heated in the furnace. After exiting the furnace, the crank blank is placed on the bending support 8. A punch plate 7 with a concave arc cavity punches down from the crotch opening of the crank blank, i.e., the axis of symmetry, forming the crank neck arc surface 6 on the inner side of the crotch opening. The crank neck arc surface 6 on the inner side of the crotch opening and the arc surface 1 at the end of the crank neck together form the entire arc of the crank neck. The arc punch plate continues to descend to the process dimension to form the crank neck. The crank arms on both sides of the crank blank are V-shaped, with a V-angle close to 60°. Finally, an arc tongue plate is inserted into the opening, and the crank arms on both sides are flattened on the press. The crank forging is finally formed, as shown. Figure 7 As shown.

[0033] This invention employs a two-step molding method to ensure the quality of the crankshaft end and crank neck for high-horsepower low-speed diesel engines, while significantly reducing the raw material cost of the crankshaft. In addition, the molding of different specifications of crank neck end shapes makes the shape of the crank neck end closer to the precision-machined shape, greatly improving the efficiency of crank blanks. Only different U-shaped anvils need to be changed, while V-shaped convex anvils can be shared, reducing mold costs.

Claims

1. A method for forming the arc surface and inclined surface of a crankshaft neck, characterized in that: The method is as follows: Place the hexagonal prism blank into the U-shaped anvil (5), and press the hexagonal prism blank with the flat anvil (4) as it moves down. The hexagonal prism blank is formed into a U-shaped blank in the U-shaped anvil (5). The arc surface of the U-shaped blank is the arc surface (1) at the end of the neck. After the U-shaped billet is formed, the U-shaped anvil (5) is replaced with a V-shaped convex anvil (3). The arc surface of the U-shaped billet contacts the trapezoidal boss of the V-shaped convex anvil (3), and the flat anvil (4) presses the flat surface of the U-shaped billet to form the inclined surfaces (2) on both sides of the crank forging. After pressing the inclined surfaces (2) on both sides of the crank forging, replace the V-shaped anvil (3) with a flat anvil (4), and then use the flat anvil (4) to press out the crank arms on both sides to form a crank blank with crank arms on both sides. The V-shaped anvil (3) includes a cuboid base and a trapezoidal boss. The slope of the trapezoidal boss is equal to the slope of the crank forging's neck end slope. The height of the trapezoidal boss is equal to the height of the crank forging's neck end slope. The width of the cuboid base is the same as the width of the flat anvil (4). The flat anvil (4) presses the U-shaped blank to form the inclined surfaces (2) on both sides of the crank forging. The specific process is as follows: the flat anvil (4) presses the U-shaped blank until the inclined surface (2) formed by the U-shaped blank is flush with the inclined surface of the trapezoidal boss. And in this way, one side of the inclined surface (2) is formed first, and then the other side of the U-shaped blank's neck end is formed.

2. The method for forming the arc surface and inclined surface of the crankshaft neck according to claim 1, characterized in that: The crank blank with the crank arm is reheated in the furnace. After it is taken out of the furnace, the crank blank is placed on the bending support (8). The punch plate (7) with the concave arc cavity is used to punch down from the crotch of the crank blank to form the crank neck arc surface (6) on the inner side of the crotch. The punch plate continues to go down to the process dimension to form the crank neck. The crank arms on both sides of the crank blank are V-shaped. Finally, the arc tongue plate is inserted into the crotch and the crank arms on both sides are flattened on the press to form the crank forging.

3. The method for forming the arc surface and inclined surface of the crankshaft neck according to claim 1, characterized in that: The hexagonal prism blank is an irregular hexagonal prism. The width W of one set of parallel faces of the hexagonal prism is equal to the width of the crank forging. The height H of the two vertices between the set of parallel faces is equal to the crank forging neck length + 550~650mm. Either of these two vertices is used to insert into the U-shaped anvil (5).

4. The method for forming the arc surface and inclined surface of the crankshaft neck according to claim 1, characterized in that: The inner cavity of the U-shaped anvil includes a bottom arc surface, inclined surfaces at both ends of the bottom arc surface that are inclined outward, and a guide arc surface connected to the inclined surface. The diameter of the arc surface is equal to the width of the crank forging. The maximum height of the inner cavity of the U-shaped anvil (5) is greater than or equal to the length of the crank forging neck. The thickness of the U-shaped anvil (5) is the same as the width of the flat anvil (4).

5. The method for forming the arc surface and inclined surface of the crankshaft neck according to claim 4, characterized in that: The width of the maximum opening of the U-shaped anvil is 180-220 mm larger than the width of the crank forging.

6. The method for forming the arc surface and inclined surface of the crankshaft neck according to claim 1, characterized in that: The height of the U-shaped billet is equal to the length of the crank forging neck + 300~350mm.

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