Flange-free cross shaft forging die and forging die pressing method

Abstract

The invention relates to the field of forging die pressing, in particular to a flash-free cross shaft forging die and a forging die pressing method. Comprising an upper die part composed of an upper die and an upper die base and a lower die part composed of a lower die and a lower die base, an upper cross shaft cavity is formed in the bottom face of the upper die, a corresponding lower cross shaft cavity is formed in the bottom face of the lower die, and flow dividing columns are arranged at the connecting positions of shaft necks of the lower cross shaft cavity and adjacent middle bosses. And a shunting column hole corresponding to the shunting column is formed in the joint of the shaft neck of the upper cross shaft cavity and the adjacent middle boss. The invention further provides a forging die pressing method using the forging die. The die is extremely simple in structure, easy to transform, high in material utilization rate, good in metal streamline, short in machining period and low in production cost, and the problem of flash in the die pressing process is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of forging and molding, specifically to a flashless cross shaft forging die and a forging and molding method. Background Technology

[0002] The cross shaft is a key component in the cross shaft connector system. With the widespread application of cross shaft connector transmission systems in various industries such as metallurgy, its usage is gradually increasing. In recent years, forging plants have been committed to researching forging methods for cross shafts. Through several years of unremitting efforts, the production method of cross shafts has evolved from directly forging steel ingots in the initial hammer forging plant to now using a hydraulic press for billet preparation and then blanking. Although the external dimensions can barely meet customer requirements, the utilization rate of steel ingots is low, production costs are high, and delivery cycles are long. Currently, the main production methods for large cross shafts in China are free forging or die forging. However, traditional flat die forging of large cross shafts has many shortcomings in both forging and subsequent machining: First, during forging, it is difficult to forge a cylindrical cross shaft with four sides using flat die forging, resulting in low material utilization and a long processing cycle. Second, when using die forging, due to the special shape of the cross shaft, if the amount of blank used is equal to the design amount, it is difficult to evenly distribute the blank into the cavities of the two journals and two intermediate bosses during pressing. Therefore, to ensure forming accuracy, the amount of blank used is slightly greater than the design amount. This excess blank will overflow outside the cross cavity under pressure (or overflow into the trimming groove outside the cross cavity), inevitably leading to flash. Therefore, the existing die forging process for cross shafts requires pre-forming, final forging, and trimming. Although the material utilization rate is slightly higher than that of free forging, the proportion of flash is still relatively high, and a trimming process is also required. The production cost is high, the process is complex, and a lot of equipment is needed, resulting in a large production investment.

[0003] Publication No. 210231396U discloses a cross-shaft forging die for use on a friction press. The die's side is sloped, giving it a shape similar to a frustum of a cone. The inner diameter of the clamping ring is larger than the minimum diameter of the die but smaller than its maximum diameter. When the clamping ring is fitted onto and tightened on the die, the die's position is fixed, thus solving the problems of misalignment and displacement caused by locking and dovetail locking methods. The design also includes guide pillars and corresponding guide sleeves, but these are only for guiding the die's movement and increasing accuracy; they do not solve the aforementioned flash problem during the molding process. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned technical problems and provide a flash-free cross shaft forging die with an extremely simple structure, easy modification, effective solution to the flash problem in the molding process, high material utilization, good metal flow, short machining cycle, and low production cost.

[0005] The present invention also provides a flashless cross shaft forging die and a forging die pressing method using the above-mentioned shaft forging die, which can eliminate the pre-forming and trimming processes, and the cross shaft can be molded in one step.

[0006] The present invention relates to a flashless cross shaft forging die, comprising an upper die portion consisting of an upper die and an upper die base, and a lower die portion consisting of a lower die and a lower die base. The bottom surface of the upper die is provided with an upper cross shaft cavity, and the bottom surface of the lower die is provided with a corresponding lower cross shaft cavity. The journal of the lower cross shaft cavity is provided with a flow divider at the connection between it and the adjacent intermediate boss, and the journal of the upper cross shaft cavity is provided with a flow divider hole corresponding to the flow divider at the connection between it and the adjacent intermediate boss.

[0007] The inner arc surface of the diverter column is consistent with the inner arc surface of the journal and the connection between the middle boss of the lower cross shaft cavity.

[0008] The flow divider column is interference-fitted with the flow divider column hole.

[0009] The top surface of the upper mold is provided with a dovetail, and the bottom surface of the upper mold base is provided with a corresponding dovetail groove.

[0010] A conical iron wedge is also inserted between the dovetail and one side of the dovetail groove.

[0011] The top edge of the upper mold has a keyway, and the bottom edge of the upper mold base has a corresponding keyway. A flat key is inserted into the corresponding keyway of the upper mold and the keyway of the upper mold base.

[0012] The lower mold base is provided with a lower mold base groove, the lower end of the lower mold is inserted into the lower mold base, the outer circular surface of the lower mold is provided with an axial narrow edge, the inner circular surface of the lower mold base groove is correspondingly provided with an axial keyway, and the narrow edge is correspondingly inserted into the keyway.

[0013] A forging die pressing method for a flashless cross shaft, using the aforementioned flashless cross shaft forging die, involves the following steps: Step 1: Operate the press to align the upper surface of the upper die with the lower surface of the lower die; Step 2: Use the clamps to hold the blank and place it into the center of the lower cross shaft cavity of the lower mold. Operate the press to move the upper mold towards the lower mold. During the pressing process, under the guidance and diversion of the flow column, the blank is evenly pressed into each journal and the middle boss until the upper mold and the lower mold are closed, forming the cross shaft in one step.

[0014] Beneficial effects: This application, through in-depth analysis of the cross shaft structure, cleverly sets a flow divider at the connection between the journal and the adjacent intermediate boss in the lower cross shaft cavity, and a flow divider hole at the corresponding position in the upper cross shaft cavity. The flow divider and the flow divider hole are interference-fitted, which, in addition to providing conventional guiding functions, also forms a closed flow channel during the molding process. When the blank is under pressure, excess blank is evenly and precisely guided into the journal and intermediate boss, rather than overflowing out of the cavity and forming flash. This design allows the blank usage to precisely match the design requirements of the cross shaft, eliminating the need for additional flash allowance. Aside from normal heat loss, material utilization directly reaches 100%, significantly reducing raw material waste and production costs. Due to the special shape, using flow dividers and flow divider holes to solve the flash problem is only applicable to the forging and molding process of cross shafts and not to other shaped molded workpieces.

[0015] (2) This invention achieves one-time molding of the cross shaft by optimizing the mold structure, directly eliminating the pre-forming and trimming processes. The production process only requires two steps: blank placement and mold closing. The production cycle of a single cross shaft is shortened from 40-60 minutes in the traditional process to 15-20 minutes, and the production efficiency is more than doubled. At the same time, it reduces equipment investment, production site occupation and equipment maintenance costs, and is more suitable for large-scale mass production. (3) The inner arc surface of the flow divider column is consistent with the inner arc surface of the journal and the middle boss of the lower cross shaft cavity, ensuring that the metal flow path is continuous and smooth during the molding process, avoiding the problems of metal flow line breakage and disorder caused by flash formation or uneven blank flow in traditional processes. The metal flow line of the formed cross shaft is complete and consistent with the force direction of the part. It has good tensile strength, impact toughness and other mechanical properties, and the service life of the product is significantly extended, which can better meet the high strength and high reliability requirements of cross shafts in metallurgy, machinery and other industries.

[0016] (4) The upper mold is secured by a dovetail joint with the dovetail groove of the upper mold base, and further secured by a tapered iron wedge and a flat key, thus achieving double fixation of the upper mold and the upper mold base and effectively preventing mold misalignment or displacement during the molding process. The lower mold is secured by an axial keyway in the groove of the lower mold base through the axial narrow edge of its outer circular surface, ensuring the circumferential positioning accuracy of the lower mold during the molding process. The positioning structure of each component of the mold is reasonably designed, which greatly reduces the subsequent machining allowance, shortens the machining cycle, and further reduces the overall production cost.

[0017] In summary, the forging die of this invention, based on the traditional cross-shaft forging die, only requires the addition of a flow divider and flow divider hole at a specific location, without the need for complex modifications to the die body. This results in low modification difficulty and low cost. The other components of the die have simple structures and are easy to assemble and disassemble, facilitating daily inspection and maintenance and extending the die's service life. Attached Figure Description

[0018] Figure 1 This is a front view of the upper mold structure of the present invention; Figure 2 This is a left view of the upper mold structure of the present invention; Figure 3 This is a front view of the lower mold structure of the present invention; Figure 4 This is a left view of the lower mold structure of the present invention. Figure 5 This is a schematic diagram of the upper mold portion of the present invention; Figure 6 This is a schematic diagram of the lower mold portion of the present invention; Figure 7 This is a diagram showing the usage state of the present invention; Figure 8 This is a schematic diagram of a cross shaft forged using the present invention.

[0019] Among them, the upper mold 1, upper mold base 2, lower mold 3, lower mold base 4, press connecting plate 5, conical iron wedge 6, flat key 7, dovetail 8, dovetail groove 9, upper mold keyway 10, upper mold base keyway 11, narrow side 12, upper cross shaft cavity 13, journal 13.1, middle boss 13.2, lower cross shaft cavity 14, journal 14.1, middle boss 14.2, inner arc surface 14.3, flow divider 15, inner arc surface 15.1, flow divider hole 16, lower mold base groove 17, keyway 18, blank 19. Detailed Implementation

[0020] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. The invention is described more specifically in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of the invention will become clearer from the following description and claims. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] Mold Example: The flashless cross shaft forging die includes an upper die portion consisting of an upper die 1 and an upper die base 2, and a lower die portion consisting of a lower die 3 and a lower die base 4. See [reference needed]. Figure 1 and Figure 2The bottom surface of the upper mold 2 is provided with an upper cross shaft cavity 13, and the bottom surface of the lower mold 3 is provided with a corresponding lower cross shaft cavity 14. The cavity surfaces are polished to a roughness Ra≤0.8μm to ensure the surface quality of the cross shaft after forming. See also Figure 3 and Figure 4 The lower cross shaft cavity 14 has four flow dividers 15 at the connection between the journal 14.1 and the adjacent intermediate boss 14.2. The upper cross shaft cavity 13 has four flow divider holes 16 corresponding to the flow dividers 15 at the connection between the journal 13.1 and the adjacent intermediate boss 13.2, forming a closed flow divider channel during the molding process. When the blank is under pressure, excess blank is precisely guided by the four flow dividers into the journal 14.1 and the intermediate boss 14.2, instead of overflowing out of the cavity and forming flash. The inner arc surface 15.1 of the flow divider 15 is consistent with the inner arc surface 14.3 at the connection between the journal 14.1 and the intermediate boss 14.2 of the lower cross shaft cavity 14, ensuring a continuous and smooth flow path for the metal during the molding process, resulting in a complete flow line on the metal surface of the molded cross shaft and a good surface quality of the molded product. The flow divider 15 and the flow divider hole 16 are interference-fitted to ensure guiding accuracy and prevent material from overflowing into the flow divider hole 16 under pressure during the pressing process.

[0023] As another example: see Figure 5 The upper mold 1 has a dovetail 8 on its top surface, and the bottom surface of the upper mold base 2 has a dovetail groove 9 that matches the dovetail 8. A conical iron wedge 6 is also inserted between the dovetail 8 and the dovetail groove 9 on one side. The inserted conical iron wedge 6 is used to axially lock the upper mold 1 and the upper mold base 2 to prevent the upper mold from moving during molding. The top edge of the upper mold 1 has an upper mold keyway 10, and the bottom edge of the upper mold base 2 has a corresponding upper mold base keyway 11. A flat key 7 is inserted into the keyway of the rectangular structure formed by the upper mold keyway 10 and the upper mold base keyway 11 to achieve circumferential positioning of the upper mold and the upper mold base and avoid relative rotation.

[0024] As another embodiment, see Figure 6 The lower mold base 3 is provided with a lower mold base groove 17. The lower end of the lower mold 3 is inserted into the lower mold base 3. The outer circle of the lower mold 3 is symmetrically provided with two axial narrow edges 12. The inner circle of the lower mold base groove 17 is correspondingly provided with symmetrical axial keyways 18. The narrow edges 12 are correspondingly inserted into the keyways 18. The fitting clearance is 0.01-0.02mm, which realizes the circumferential positioning of the lower mold 3 and the lower mold base 4 and prevents the lower mold 3 from rotating during molding.

[0025] A forging die pressing method for a flashless cross shaft, using the aforementioned flashless cross shaft forging die, involves the following steps: Put the upper mold 1 ( Figure 2The dovetail 8 is inserted into the dovetail groove 9 of the upper mold base 2, and the two are fixed together by the inserted conical iron wedge 6 and the flat key 7 inserted into the keyway 10 of the upper mold and the keyway 11 of the upper mold base; then the upper mold base 2 is connected to the press connecting plate 5 by bolts.

[0026] Align the protruding narrow edge 12 on the side of the lower mold with the keyway 13 of the lower mold base, and place the lower mold 3 ( Figure 2 Place it into the lower mold base 4, place it on the press platform, assemble the upper and lower molds, and operate the press to align the upper surface of the upper mold 1 with the upper surface of the lower mold 3.

[0027] Reference Figure 7 The blank 19 is held in the jaws of the blank manipulator and placed in the center of the lower cross shaft cavity 14 of the lower die 3. The press is operated to press down, causing the upper die 1 to move towards the lower die 3. During the pressing process, under the guidance and diversion of the flow divider 15, the blank 18 is evenly pressed into each journal and the middle boss until the upper die 1 and the lower die 3 are closed, forming the cross shaft in one step (see...). Figure 8 ).

[0028] The mold and method of this invention are used to produce cross shafts of models F4, F1, and R1 for finishing mill stands. The main parameters are: shaft diameter ≥ 200mm, total width > 1000mm, and total length > 1000mm. The cross shaft material formed by the method of this invention has a material utilization rate of up to 100% except for normal heat loss, and the dimension is 2.5mm on each side from the finishing dimension.

[0029] The above embodiments demonstrate that the flash-free cross shaft forging die and forging method of the present invention can effectively solve the flash problem in traditional processes, improve product quality and production efficiency, reduce production costs, and has significant practical value and promotion prospects.

[0030] This invention eliminates the pre-forming and trimming processes, directly forming the required cross shaft forgings. Furthermore, by changing the cross shaft cavity to different sizes or shapes according to the different dimensions and shapes of the cross shaft, different cross shaft forgings can be forged.

Claims

1. A flashless cross shaft forging die, comprising an upper die portion consisting of an upper die and an upper die base, and a lower die portion consisting of a lower die and a lower die base, characterized in that, The bottom surface of the upper mold is provided with an upper cross shaft cavity, and the bottom surface of the lower mold is provided with a corresponding lower cross shaft cavity. The journal of the lower cross shaft cavity is provided with a flow divider at the connection between it and the adjacent intermediate boss. The journal of the upper cross shaft cavity is provided with a flow divider hole corresponding to the flow divider at the connection between it and the adjacent intermediate boss.

2. The flashless cross shaft forging die as described in claim 1, characterized in that, The inner arc surface of the diverter column is consistent with the inner arc surface of the journal and the connection between the middle boss of the lower cross shaft cavity.

3. The flashless cross shaft forging die as described in claim 1, characterized in that, The flow divider column is interference-fitted with the flow divider column hole.

4. The flashless cross shaft forging die as described in any one of claims 1-3, characterized in that, The top surface of the upper mold is provided with a dovetail, and the bottom surface of the upper mold base is provided with a corresponding dovetail groove.

5. The flashless cross shaft forging die as described in claim 4, characterized in that, A conical iron wedge is also inserted between the dovetail and one side of the dovetail groove.

6. The flashless cross shaft forging die as described in claim 5, characterized in that, The top edge of the upper mold has a keyway, and the bottom edge of the upper mold base has a corresponding keyway. A flat key is inserted into the corresponding keyway of the upper mold and the keyway of the upper mold base.

7. The flashless cross shaft forging die as described in any one of claims 1-3, characterized in that, The lower mold base is provided with a lower mold base groove, the lower end of the lower mold is inserted into the lower mold base, the outer circular surface of the lower mold is provided with an axial narrow edge, the inner circular surface of the lower mold base groove is correspondingly provided with an axial keyway, and the narrow edge is correspondingly inserted into the keyway.

8. A forging die pressing method for a flash-free cross shaft, characterized in that, Using the flashless cross shaft forging die according to any one of claims 1-7, the following steps are performed: Step 1: Operate the press to align the upper surface of the upper die with the lower surface of the lower die; Step 2: Use the clamps to hold the blank and place it into the center of the lower cross shaft cavity of the lower mold. Operate the press to move the upper mold towards the lower mold. During the pressing process, under the guidance and diversion of the flow column, the blank is evenly pressed into each journal and the middle boss until the upper mold and the lower mold are closed, forming the cross shaft in one step.

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