A forming process for automotive crankshaft pulleys with unequal wall thickness

Abstract

This invention discloses a forming process for automotive crankshaft pulleys with unequal wall thickness, comprising the following steps: (1) stretching: stretching the raw steel plate into a trapezoidal cross-section through multiple stretching processes; (2) stretching and punching: stretching the semi-finished product from step (1) and punching holes at the top of the trapezoid; (3) stretching: stretching the semi-finished product from step (2) further; (4) first shaping: rough shaping the semi-finished product from step (3) and increasing the thickness at the hole position; (5) second shaping: fine shaping the semi-finished product from step (4) to achieve a smooth hole position; (6) chamfering: stamping a groove around the outside of the hole position and achieving a smooth chamfer transition at each location; (7) embossing: embossing at the hole position. The processing and forming process provided by this invention uses a thinner steel plate to process pulleys with unequal wall thickness, with the thickness of the embossed part reaching 1.5 times the material thickness, reducing production costs and ensuring stable quality.

Description

Technical Field

[0001] This invention belongs to the technical field of engine transmission components, and more specifically, relates to a forming process for automotive crankshaft pulleys with unequal wall thickness. Background Technology

[0002] A type of automotive crankshaft pulley with unequal wall thickness, due to its connection to the crankshaft and the use of a grooved design to transmit torque, requires a thicker wall in the grooved area, while other parts have relatively thinner walls to achieve weight reduction. There are currently two manufacturing processes:

[0003] 1. Using thicker steel plates to spin patterns on flat surfaces, followed by stamping and spinning to form the final product, consumes a lot of materials, has low efficiency, and results in high manufacturing costs.

[0004] 2. Using thicker steel plates to stamp patterns results in high material consumption, low efficiency, and high manufacturing costs.

[0005] Chinese patent CN1843650A discloses a method for processing sheet metal into a thickened cylindrical workpiece using a stamping process. The method involves pre-forming the sheet metal into a raised shape through stamping, ensuring the differential volume equals the raised portion. Then, using concave and convex dies, the raised portion is stamped to reduce its diameter, maintaining the workpiece height consistent with the pre-formed height. A set of concave dies arranged sequentially with a fixed diameter further stamps the outer diameter of the raised portion, reducing its diameter until it reaches the diameter of the raised cylindrical column in the finished part. Finally, a composite die for expanding the diameter and pressing is used to expand the diameter to the inner diameter of the cylindrical column, pressing it to the height of the finished part, thus producing the finished part. This invention overcomes the shortcomings of other processes used to process the same parts, allowing the sheet metal base and the thickened cylindrical column to be integrally formed, ensuring the strength requirements of the workpiece and improving its service life. However, this patent can only achieve cylindrical thickening, not planar or arc-shaped thickening.

[0006] For example, Chinese patent CN106583545A discloses a method for forming a multi-wedge wheel hub with thickened crankshaft for automobiles. The process involves sequentially drawing the wheel into a cup shape, reverse-stretching the boss, reverse-stretching the spherical boss again, shaping the rounded corners, thickening the wheel, punching the center hole, spinning the outer multi-wedge grooves, and embossing to complete the entire process. Its advantages are that the wheel hub pattern processing method provided by this invention is faster and more efficient than traditional spinning patterns, eliminating the need for specialized spinning equipment, reducing unnecessary costs, and improving product quality, making it suitable for mass production. However, this patent can only achieve planar thickening; it cannot thicken the curved areas, which are prone to delamination defects and cannot meet strength requirements. Summary of the Invention

[0007] Purpose of the invention: The purpose of this invention is to overcome the shortcomings of the prior art and provide a forming process for automotive crankshaft pulleys with unequal wall thickness. This process uses thinner steel plates to form pulleys with unequal wall thickness, with the thickness of the patterned part reaching 1.5 times the material thickness. This reduces production costs, consumes less material, increases efficiency, and ensures stable quality.

[0008] Technical solution: The present invention provides a forming process for automotive crankshaft pulleys with unequal wall thickness, comprising the following steps:

[0009] (1) Stretching: The raw steel plate is stretched into a trapezoidal cross-section through multiple stretching processes;

[0010] (2) Stretching and punching: Stretch the semi-finished product from step (1) and punch a hole at the top of the trapezoid;

[0011] (3) Stretching: Continue to stretch the semi-finished product from step (2);

[0012] (4) First shaping: The semi-finished product from step (3) is roughly shaped and the thickness at the hole position is increased;

[0013] (5) Second shaping: The semi-finished product from step (4) is finely shaped to achieve a smooth surface at the hole position;

[0014] (6) Chamfering: A groove is punched around the outside of the hole to achieve a smooth chamfer transition at each location;

[0015] (7) Embossing: Embossing is performed at the hole positions;

[0016] (8) Spin forming.

[0017] In some embodiments, in step (1), the width of the trapezoidal structure of the steel plate cross-section is gradually reduced and the height is gradually increased through the multi-stage stretching process. The stretching process is achieved using a die structure that combines a concave die and a convex die, thereby stretching the steel plate into a trapezoidal cross-section.

[0018] In some implementations, the thickness of the steel plate remains constant throughout step (1).

[0019] In some implementations, the width of the trapezoidal structure of the stretched section in step (2) is smaller than the width after stretching in step (1).

[0020] In some implementations, the width of the trapezoidal structure of the cross section after stretching in step (3) is smaller than the width after stretching in step (2).

[0021] In some implementations, the thickness at the hole after rough shaping in step (4) is 1.5 times the initial thickness of the steel plate, and the height of the trapezoidal structure of the cross section after rough shaping is less than the height after processing in step (3).

[0022] In some embodiments, the rough forming die is set to a tapered shape, with the diameter of the opening end being larger than that of the die in step (3), and the diameter of the other end being larger than that of the die in step (3). The rough forming die is set to a shape with a three-segment arc conical surface at the top, with the gap between the end and the punch being large in the middle and gradually decreasing outward.

[0023] The rough forming punch is set to a tapered shape, with the upper end diameter being smaller than the punch diameter in step (3) and the large end diameter being larger than the punch diameter in step (3). The height of the straight arm of the rough forming punch is 1.5 times smaller than the height of the straight arm of the punch in step (3) than the material thickness.

[0024] In some implementations, the semi-finished product is vertically flipped 180° during step (6) chamfering.

[0025] In some embodiments, step (7) involves vertically flipping the semi-finished product processed in step (6) by 180° and performing an embossing operation at the hole using an embossing mold.

[0026] In some embodiments, the stretching die in steps (1) to (3) includes an upper pressure plate.

[0027] Beneficial effects: The processing and forming process provided by this invention uses thinner steel plates to process belt pulleys with varying wall thicknesses. The thickness of the patterned part reaches 1.5 times the material thickness, which reduces production costs, consumes less material, increases efficiency, and ensures stable quality.

[0028] The upper die of the stretching die of the present invention is provided with an upper pressure plate structure, which has the following advantages: the stretching process generates a thrust on the outer circle of the blank, which causes the blank to flow into the middle concave mold cavity, thus avoiding thinning during stretching; the stretched blank is automatically centered.

[0029] The rough shaping process of this invention utilizes a special shaping mold structure:

[0030] The rough forming die is set to a tapered shape, with the diameter of the opening end being 1.0 mm larger than the diameter of the die of the previous stretching process, and the diameter of the other end being 0.5 mm larger than the diameter of the die of the previous stretching process. The rough forming die 11 is set to a shape with three arc-shaped conical surfaces at the top, with the gap between the end and the punch being larger in the middle and gradually decreasing outward.

[0031] The rough forming punch is set to a tapered shape, with the upper end diameter being 0.1mm smaller than the diameter of the previous stretching process punch, and the large end diameter being 0.6mm larger than the diameter of the previous stretching process punch. The straight arm height of the rough forming punch is 1.5 times smaller than the straight arm height of the previous stretching process punch than the material thickness.

[0032] Ultimately, the process of forming pulleys with unequal wall thickness was realized. Attached Figure Description

[0033] Figure 1 These are a front view and a sectional view of the raw material structure according to an embodiment of the present invention;

[0034] Figure 2 This is a comparison diagram of the first stretching process and the previous process in one embodiment of the present invention;

[0035] Figure 3 This is a comparison diagram of the second stretching process and the previous process in one embodiment of the present invention;

[0036] Figure 4 This is a comparison diagram of the third stretching process and the previous process in one embodiment of the present invention;

[0037] Figure 5 This is a comparison diagram of the fourth stretching process and the previous process in one embodiment of the present invention;

[0038] Figure 6 This is a comparison diagram of the stretching and punching process and the previous process according to one embodiment of the present invention;

[0039] Figure 7 This is a comparison diagram of the stretching process and the previous process according to one embodiment of the present invention;

[0040] Figure 8 This is a comparison diagram of the first shaping process and the previous process in one embodiment of the present invention;

[0041] Figure 9 This is a comparison diagram of the second shaping process and the previous process in one embodiment of the present invention;

[0042] Figure 10 This is a schematic diagram of the chamfering process structure according to an embodiment of the present invention;

[0043] Figure 11 This is a schematic diagram of an embossing process according to an embodiment of the present invention;

[0044] Figure 12 This is a schematic cross-sectional view of a pulley according to an embodiment of the present invention;

[0045] Figure 13 This is a schematic diagram of a stretching process mold structure according to an embodiment of the present invention;

[0046] Figure 14 This is a schematic diagram of the mold structure for the first shaping process according to an embodiment of the present invention. Detailed Implementation

[0047] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship shown, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0049] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0050] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Example

[0051] A forming process for automotive crankshaft pulleys with unequal wall thickness includes the following steps:

[0052] (1) Stretching: The raw steel plate is stretched into a trapezoidal cross-section through multiple stretching processes;

[0053] (2) Stretching and punching: Stretch the semi-finished product from step (1) and punch a hole at the top of the trapezoid;

[0054] (3) Stretching: Continue to stretch the semi-finished product from step (2);

[0055] (4) First shaping: The semi-finished product from step (3) is roughly shaped and the thickness at the hole position is increased;

[0056] (5) Second shaping: The semi-finished product from step (4) is finely shaped to achieve a smooth surface at the hole position;

[0057] (6) Chamfering: A groove is punched around the outside of the hole to achieve a smooth chamfer transition at each location;

[0058] (7) Embossing: Embossing is performed at the hole positions;

[0059] (8) Spin forming. Example

[0060] A forming process for automotive crankshaft pulleys with unequal wall thickness includes the following steps:

[0061] (1) Stretching: Through multiple stretching processes, Figure 1 The raw steel plate shown is stretched into a trapezoidal cross-section.

[0062] like Figures 2 to 5 As shown, in this embodiment, a steel plate of a certain thickness is stretched into a trapezoidal cross-section through four stretching processes.

[0063] Depend on Figures 2 to 5 It can be seen that through the implementation of the four stretching processes, the width of the trapezoidal structure of the steel plate cross section gradually decreases, while the height gradually increases.

[0064] In this embodiment, it is not limited to using four processes. Other processes such as two, three, or five processes can also be used. The ultimate goal is to achieve a certain width and a certain height of the steel plate cross section.

[0065] In this embodiment, the stretching process is achieved using a die structure that combines a concave die and a convex die, thereby stretching the material into a trapezoidal cross-section.

[0066] Specific stretching process die structure, such as Figure 13 As shown, the mold structure includes an upper mold base 1, an upper backing plate 2, a die cavity 3, an upper pressure plate 4, a punch 5, a lower backing plate 6, a lower mold base 7, a lower pad block 8, a lower support plate 9, and a lower positioning block 10. The upper mold of the stretching die incorporates an upper pressure plate 4, which offers the following advantages:

[0067] 1. The stretching process generates a thrust on the outer circle of the billet, causing the material to flow into the central concave mold cavity, thus preventing it from becoming thinner during stretching;

[0068] 2. Automatic centering of stretched billets.

[0069] In this embodiment, the thickness of the raw steel plate remains unchanged throughout after multiple stretching processes.

[0070] (2) Stretching and punching: Stretch the semi-finished product from step (1) and punch holes at the top of the trapezoid.

[0071] like Figure 6 As shown, this step further stretches the steel plate after multiple stretching steps, and the width of the trapezoidal structure of the cross section after stretching is smaller than the width after stretching in step (1); the height of the trapezoidal structure of the cross section after stretching in step (2) is not much different from the height after stretching in step (1). At the same time, a hole is punched at the top of the trapezoid of the steel plate.

[0072] In this embodiment, the stretching process is achieved using a die structure combining a concave die and a convex die. Punching is performed using a punch and a punching insert.

[0073] (3) Stretching: Continue to stretch the semi-finished product from step (2).

[0074] like Figure 7 As shown, this step further stretches the semi-finished product after stretching and punching to meet the requirements. Among them, the width of the trapezoidal structure of the cross section after stretching in this step is smaller than the width after stretching in step (2); the height of the trapezoidal structure of the cross section after stretching in step (3) is not much different from the height after stretching in step (2).

[0075] (4) First shaping: The semi-finished product from step (3) is roughly shaped and the thickness at the hole position is increased;

[0076] like Figure 8 As shown, this shaping step is the core of the entire process. The shaping process is achieved through a die structure combining a die, a punch, and a plunger, as shown below. Figure 14 As shown. The thickness at the hole position after rough shaping is 1.5 times the initial thickness of the steel plate. The height after shaping is lower than that of the previous process, while the width remains consistent. Since this pulley is connected to the crankshaft and uses the pattern to transmit torque, the patterned area needs to have a thicker wall. Other parts, considering weight reduction, have relatively thinner walls.

[0077] Specifically, such as Figure 14 As shown, the rough forming mold is similar in structure to the aforementioned stretching mold, except that the rough forming mold adopts a structure that combines the rough forming die 11 and the rough forming punch 12.

[0078] Among them, such as Figure 14 As shown, the rough forming die 11 is set in a tapered shape. The diameter of the opening end is 1.0 mm larger than the diameter of the die of the previous stretching process, and the diameter of the other end is 0.5 mm larger than the diameter of the die of the previous stretching process. The rough forming die 11 is set in a shape with three arc-shaped conical surfaces at the top. The gap between the end and the punch is large in the middle and gradually decreases outward.

[0079] The rough forming punch 12 is set in a tapered shape. The diameter of the upper end is 0.1 mm smaller than the diameter of the punch of the previous stretching process, and the diameter of the large end is 0.6 mm larger than the diameter of the punch of the previous stretching process. The height of the straight arm of the rough forming punch is 1.5 times the material thickness smaller than the height of the straight arm of the punch of the previous stretching process.

[0080] Because the punched area needs to be embossed later, the wall thickness at the hole position must be greater than the thickness of other areas to ensure the overall quality requirements of the pulley.

[0081] (5) Second shaping: The semi-finished product from step (4) is finely shaped to achieve a smooth surface at the hole position.

[0082] like Figure 9 As shown, the second shaping, or fine shaping, involves smoothing the entire raised surface based on the first shaping. After fine shaping, the width is the same as the previous process, but the height is reduced.

[0083] (6) Chamfering: A groove is punched around the outside of the hole to achieve a smooth chamfer transition at each location.

[0084] like Figure 10 As shown, after the second shaping, the semi-finished product is vertically flipped 180° for chamfering. Specifically, during chamfering, according to the design requirements of the pulley, a groove is designed on both the inner and outer sides of the trapezoidal structure from the previous step, and an angle transition is achieved at the corner.

[0085] (7) Embossing: Embossing is performed at the hole positions.

[0086] like Figure 11 As shown, this step involves vertically flipping the semi-finished product after step (6) by 180° and performing embossing operation at the hole position using an embossing mold.

[0087] (8) Spin forming: The end of the pulley is spun from the semi-finished steel plate processed in step (7), and the final pulley is as follows: Figure 12 As shown.

[0088] The present invention provides a processing and forming process that uses thin steel plates to process pulleys with unequal wall thicknesses, with the thickness of the patterned part reaching 1.5 times the material thickness. This reduces production costs, consumes less material, increases efficiency, and ensures stable quality.

[0089] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A forming process for automotive crankshaft pulleys with unequal wall thickness, characterized in that: Includes the following steps: (1) Stretching: The raw steel plate is stretched into a trapezoidal structure through multiple stretching processes. The multiple stretching processes gradually reduce the width and increase the height of the trapezoidal structure, while keeping the thickness of the steel plate constant at all points. (2) Stretching and punching: Stretch the semi-finished product from step (1) and punch a hole at the top of the trapezoid; (3) Stretching: Continue to stretch the semi-finished product from step (2); (4) First shaping: The semi-finished product of step (3) is roughly shaped. The cavity of the rough shaping mold is tapered. The diameter of the opening end is 1.0 mm larger than the diameter of the cavity of step (3), and the diameter of the other end is 0.5 mm larger than the diameter of the cavity of step (3). The cavity is set to have a three-section arc cone shape at the top. The gap between the end and the punch is large in the middle and gradually decreases outward. The punch of the rough forming die is tapered, with the upper end diameter being 0.1 mm smaller than the punch diameter in step (3), the large end diameter being 0.6 mm larger than the punch diameter in step (3), and the height of the punch straight arm being 1.5 times the material thickness smaller than the height of the punch straight arm in step (3). Through the rough forming, the thickness at the hole position reaches 1.5 times the initial thickness of the steel plate, and the height of the trapezoidal structure of the cross section after rough forming is less than the height after processing in step (3). (5) Second shaping: The semi-finished product from step (4) is finely shaped to achieve a smooth surface at the hole position; (6) Chamfering: A groove is punched around the outside of the hole to achieve a smooth chamfer transition at each location; (7) Embossing: Embossing is performed at the hole positions; (8) Spin forming; In steps (1) to (3), the stretching die includes an upper pressure plate. During the stretching process, the upper pressure plate exerts a pushing force on the outer circle of the blank to promote the material to flow into the middle concave mold cavity, thus preventing the material from becoming thinner during stretching. The upper pressure plate achieves automatic centering of the stretched blank.

2. The forming process for an automotive crankshaft pulley with unequal wall thickness according to claim 1, characterized in that: In step (2), the width of the trapezoidal structure of the cross section after stretching is smaller than the width after stretching in step (1).

3. The forming process for an automotive crankshaft pulley with unequal wall thickness according to claim 1, characterized in that: In step (3), the width of the trapezoidal structure of the cross section after stretching is smaller than the width after stretching in step (2).

4. The forming process for an automotive crankshaft pulley with unequal wall thickness according to claim 1, characterized in that: In step (6), the semi-finished product is vertically flipped 180° for chamfering.

5. The forming process for an automotive crankshaft pulley with unequal wall thickness according to claim 1, characterized in that: Step (7) involves vertically flipping the semi-finished product processed in step (6) by 180° and performing embossing operations at the hole positions using an embossing mold.

Images