Swaging and split forging process for a knuckle with arm

Abstract

The present application relates to the technical field of die forging process, and particularly relates to a closed-extrusion split forging process of a knuckle with arms, which steps are as follows: step one, heating an alloy steel round steel section to 1170-1230 DEG C; step two, placing the heated round steel section on a lower die, and pressing the bar flat through a lower movement of an upper die; step three, placing the pressed bar on a pre-forging die, and moving the upper die downward, splitting the bar with a splitting knife from the middle, and continuing the downward movement of the upper die to make the upper and lower dies close to form a closed cavity, thereby extruding the bar and forming two knuckles with arms in the closed cavity; and step four, transferring the formed blank of step three to a finish forging die, and completely splitting the blank from the middle after the upper and lower dies are closed, and obtaining two knuckle forgings with arms after finishing. The present application can better split the material by setting a UV cavity in the pre-forging die, and supplement the material for the subsequent finish forging. Through the two processes of pre-forging and finish forging, one-die two-piece forging of the knuckle with arms with short ear parts and shaft parts can be realized, and the production efficiency is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of die forging process, in particular to a closed extrusion split forging process for a knuckle with arms. BACKGROUND

[0002] The existing knuckles with arms are usually produced by fine rod material vertical forging process, which is sequentially shaped through local upsetting, oblique laying and extruding the upsetting part, pre-forging and final forging steps; because the knuckle itself has a complex shape and structure, and the plastic strain ratio is large during forging, generally only one piece can be completed at a time, the efficiency is low, and even if the performance of the equipment is increased to produce multiple pieces at a time, it is not cost-effective considering the consumption and energy consumption.

[0003] In order to improve the production efficiency of knuckles with arms, numerous thoughts and attempts have been made in technology and production, and various means have been used to improve production efficiency. For example, the patent 2019112266422 hot forging forming process method of knuckle arm first forges a forging piece including two workpieces, and then cuts the forging piece into two workpieces from the middle, which is essentially still one piece per mold; the patent CN201120278945 automobile accessory forging die discloses a one-mold two-piece mold, but the product structure is relatively simple, the mold cavity is shallow, and the plastic strain ratio of the forging piece during forging is not large.

[0004] The existing knuckle with arms (such as Figure 1 ), the height of the ear part and the length of the shaft part are both smaller than those of the conventional knuckle, and the production efficiency of the forging piece is improved by using one mold for two pieces, so a new forging process is needed to prevent defects such as tearing and folding during the forming of the forging piece, and to make the mold cavity full of plastic during forging to obtain qualified and high-quality forging pieces. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art and provide a closed extrusion split forging process for a knuckle with arms, which places a steel bar horizontally in a mold with two cavities, and simultaneously forms two forging pieces after forging.

[0006] The technical scheme adopted by the present application to solve its technical problems is: the closed-extrusion split forging process of the arm steering knuckle, which is formed in accordance with the following characteristics: the ratio of the ear height to the width is less than 2, the ratio of the shaft length to the diameter is less than 2.1, and the ratio of the ear height to the shaft length is 0.9-1.1; the steps of forging the steering knuckle are as follows: Step one, cutting the alloy steel round bar into a round steel segment by using a high-speed disc saw and heating it to 1170-1230 DEG C; Step two, placing the heated round steel segment on the lower die and flattening the bar by lowering the upper die; Step three, placing the flattened bar on the pre-forging die, at this time the bar crosses the two cavities of the lower die, and the upper die is lowered, the split knife arranged in the two cavities of the upper and lower dies first contacts the bar and starts to split the bar from the middle, the upper die continues to be lowered and extrudes the bar, until the upper and lower dies are closed to form a closed cavity, thereby forming two arm steering knuckle blanks in the closed cavity; Step four, transferring the blank formed in Step three to the finish forging die, after the upper and lower dies are closed, the blank can be completely split from the middle, and two arm steering knuckle forgings are obtained after finishing; in addition, the cavities of the upper and lower dies of the pre-forging die are UV conical structures, that is, the cavity is first "U"-shaped from the parting surface of the upper and lower dies, and then it is connected to a "V"-shaped structure. In Step three, after the upper and lower dies are closed, there is no gap between the parting surfaces of the upper and lower dies, and the upper die cavity and the lower die cavity form a complete closed cavity, which includes two cavities for forming arm steering knuckle blanks and a cavity for accommodating unsplit bars and flash. The flash is mainly the metal oxide skin and a small amount of excess metal, so the cavity for accommodating the flash has a small volume to save materials. The V-shaped cavity refers to the cavity wall being provided with a draft angle, and the U-shaped cavity refers to the cavity wall being perpendicular to the die parting surface without a draft angle.

[0007] Preferably, it further includes cutting off the flash after finish forging.

[0008] Preferably, the material of the alloy steel round bar in Step one is 42CrMo or 40Cr.

[0009] Preferably, the cross-sectional area A of the bar in Step one is equal to the area S of the cross-sectional plane containing the ear axis and the shaft axis multiplied by a parameter K, that is, A=K*S, wherein 0.9≤K≤1.2; the length of the bar is required to be 1-2 cm longer than the two cavities of the lower die.

[0010] Preferably, the thickness of the flattened bar in Step two is 0.9-0.95 times the diameter of the original bar.

[0011] Preferably, one of the two cavities of the pre-forging die in Step three and the finish forging die in Step four is obtained by rotating the other cavity by 180 DEG around the center of the two cavities, the steering knuckle arms are located in the middle of the two cavities, and the hammer heads of the two steering knuckle arms coincide when viewed from the side.

[0012] Preferably, the step three extrusion forming arm knuckle blank, the two ear parts of the shaft part position is provided with the storage package for the step four material supplement.

[0013] Preferably, the step three shaft cavity depth is greater than the step four shaft cavity, and the step three shaft cavity has a smaller cross-sectional dimension than the step four.

[0014] Preferably, the die cavity used in steps two to four can be arranged in the same die, and the forging equipment used is an electric screw press.

[0015] Preferably, the depth of the V-shaped cavity of the pre-forging die accounts for 35% to 40% of the overall cavity depth.

[0016] The beneficial effects of the present application are as follows: the closed extrusion split forging process for the arm knuckle includes the following steps: step one, cutting an alloy steel round bar into a round steel segment using a high-speed circular saw and heating the round steel segment to 1170-1230 DEG C; step two, placing the heated round steel segment on a lower die and flattening the bar by lowering an upper die; step three, placing the flattened bar on a pre-forging die, at which time the bar spans two cavities of the lower die, and the upper die is lowered, the wedge-shaped knives arranged in the upper die and the lower die first contact the bar and start to split the bar from the middle, the upper die continues to be lowered and extrudes the bar, until the upper and lower dies are closed to form a closed cavity, thereby forming two arm knuckle blanks in the closed cavity; step four, transferring the blanks formed in step three to a finish forging die, after the upper and lower dies are closed, the blanks can be completely split from the middle, and two arm knuckle forgings are obtained after finishing. The UV cavity arranged in the pre-forging die can better split the material and supplement the material for subsequent finish forging. Through the pre-forging and finish forging processes, one-die two-piece forging can be realized for the arm knuckle with short ear parts and shaft parts, and the production efficiency is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a perspective view of the arm knuckle to be forged by the present application;

[0018] Figure 2 is a perspective view of the arm knuckle blank formed by the pre-forging die of the present application;

[0019] Figure 3 is a front view of the arm knuckle blank formed by the pre-forging die of the present application;

[0020] Figure 4 is a top view of Figure 3 ;

[0021] Figure 5 is a perspective view of the arm knuckle forging formed by the finish forging die of the present application;

[0022] Figure 6 is a front view of the arm knuckle forging formed by the finish forging die of the present application;

[0023] Figure 7 is Figure 6 a top view;

[0024] Figure 8 is a structural diagram of a UV conical cavity. DETAILED DESCRIPTION

[0025] The application will be further described in detail below with reference to the accompanying drawings and specific embodiments, which are not intended to limit the scope of the application.

[0026] As Figures 1-8 shown, the embodiment uses 42CrMo or 40Cr round steel as the material to forge the knuckle with arms, the ear height and shaft length of the knuckle are less than those of the conventional knuckle, such as the ratio of ear height to width is less than 2, the ratio of shaft length to diameter is less than 2.1, and the ratio of ear height to shaft length is 0.9-1.1. The steps to forge the knuckle are as follows: Step one, cut the alloy steel round bar into round steel segments by using high-speed disc saw and heat to 1200℃±30℃; Step two, place the heated round steel segment horizontally on the lower die, and press the bar flat by the descending upper die; Step three, place the flattened bar horizontally on the pre-forging die, at this time the bar spans the two cavities of the lower die, and the descending upper die first contacts the bar with the wedge knives arranged in the two cavities of the upper and lower dies to split the bar from the middle, and the upper die continues to descend and extrudes the bar until the upper and lower dies are closed to form a closed cavity, thereby forming two knuckles with arms in the closed cavity; Step four, transfer the formed billet of Step three to the finish forging die, and after the upper and lower dies are closed, the billet can be completely split from the middle, and two knuckles with arms are obtained by finishing; Step five, cut off the flash.

[0027] Step two is to press the round steel segment flat, which is to facilitate the placement in Step three, because the bar is placed horizontally in the pre-forging die, in order to prevent it from rolling, and the bar will not move to affect positioning when the upper and lower dies are closed. The two cavities of the pre-forging die of Step three and the finish forging die of Step four are obtained by rotating one cavity 180° around the center of the two cavities, the knuckle arms are located in the middle of the two cavities, and the hammer heads of the two knuckle arms coincide when viewed from the side. The flattened round steel segment is placed horizontally on the lower die of the pre-forging die, directly above the two cavities, and the ends of the flattened round steel segment exceed the two cavities by 1-2 cm, so that the flattened round steel segment can fully cover the two cavities when extruded in the pre-forging die. In addition, in order for the material to fill the cavity fully without causing excessive waste during extrusion, the cross-sectional area A of the bar of Step one is equal to the area S of the cross-sectional plane containing the ear axis and the shaft axis multiplied by a parameter K, that is, A=K*S, where 0.9≤K≤1.2.

[0028] The step three does not cut off the bar completely, so the two arm knuckle blanks formed by the preforming die are connected by the middle part of the excess material and the flash, and thus the blanks can be transferred integrally when they are transferred from the preforming die to the finish forming die. Therefore, the preforming die and the finish forming die are arranged on one die, so that the preforming and the finish forming can be performed simultaneously when the forging press is pressed each time.

[0029] In order to better distribute the material and supplement the material during the finish forming, the cavities of the upper and lower dies of the preforming die are UV conical structures, that is, the cavities are first "U" shaped and then "V" shaped from the parting surface of the upper and lower dies, and the junction of the U shape and the V shape and the bottom of the V shape are all rounded. In addition, the depth of the V-shaped cavity at the bottom accounts for 35% of the depth of the entire cavity. The U-shaped cavity is arranged at the top of the cavity, which not only can cut the material more easily when the material is extruded in the preforming (the cavity wall is perpendicular to the bar), but also can accommodate more material to supplement the local material of the forged piece during the finish forming to prevent the generation of tearing defects. Here, in order to further supplement the material, the shaft part position between the two ear parts of the arm knuckle blank extruded in step three is provided with a storage bag for supplementing the material in step four; the depth of the shaft part cavity in step three is greater than that in step four, and the cross-sectional size of the shaft part cavity in step three is smaller than that in step four.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and in order to facilitate the description of the technical solutions, the front, back, left, right, up, middle, down and other directions are set based on the drawings, and are not limited to the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A closed-die swage split forging process with an arm knuckle, characterized in that: The arm steering knuckle formed thereby has the following characteristics: the ratio of the ear height to the ear width is less than 2, the ratio of the shaft length to the shaft diameter is less than 2.1, and the ratio of the ear height to the shaft length is 0.9-1.1; the forging process of the steering knuckle is as follows: step one, cutting the alloy steel round bar into round steel segments using a high-speed disc saw and heating to 1170-1230 DEG C; step two, laying the heated round steel segments flat on the lower die and pressing the bar flat by lowering the upper die; step three, laying the pressed bar flat on the pre-forging die, at this time the bar spans the two cavities of the lower die, and the upper die is lowered, the split knives arranged in the two cavities of the upper and lower dies first contact the bar and start to split the bar from the middle, the upper die continues to be lowered and extrudes the bar until the upper and lower dies are closed to form a closed cavity, thereby forming two arm steering knuckle blanks in the closed cavity; step four, transferring the blank formed in step three to the finish forging die, after the upper and lower dies are closed, the blank can be completely split in the middle, and two arm steering knuckle forgings are obtained after finishing; in addition, the cavities of the upper and lower dies of the pre-forging die are UV conical structures, that is, the cavities are first "U" shaped from the parting surface of the upper and lower dies, and then "V" shaped, and the junction of the U-shaped and V-shaped portions and the bottom of the V-shaped portion are all rounded, the V-shaped portion refers to the cavity wall being provided with a draft angle, and the U-shaped portion refers to the cavity wall being perpendicular to the die parting surface and not having a draft angle; in step three, after the upper and lower dies are closed, there is no gap between the parting surfaces of the upper and lower dies, and the upper die cavity and the lower die cavity form a complete closed cavity, and the closed cavity includes two cavities for forming arm steering knuckle blanks and a cavity for accommodating the unsplit bar and flash.

2. The closed-die swage split forging process of a knuckle arm according to claim 1, characterized by: It also includes cutting off the flash after finish forging.

3. The closed-die swage forming process for a knuckle arm knuckle as defined in claim 1 wherein: The material of the round bar in step one is 42CrMo or 40Cr.

4. The closed-die swage split forging process of a knuckle arm according to claim 1, wherein: The cross-sectional area A of the bar in step one is equal to the area S of the cross-section including the ear axis and the shaft axis multiplied by a parameter K, that is, A=K*S, wherein 0.9≤K≤1.2; the length of the bar is required to be 1-2 cm longer than the two cavities of the lower die.

5. The closed-die swage forming process for a knuckle arm knuckle as defined in claim 1 wherein: The thickness of the pressed bar in step two is 0.9-0.95 times the diameter of the original bar.

6. The closed-die swage split forging process of a knuckle arm according to claim 1, wherein: In step three, the pre-forging die and the finish forging die in step four have two die cavities, one of which is obtained by rotating the other die cavity by 180 DEG around the center of the two cavities, the steering knuckle arms are located in the middle of the two die cavities, and from the side, the hammer heads of the two steering knuckle arms coincide.

7. The closed-die swage forming process for a knuckle arm knuckle as defined in claim 1 wherein: The extruded arm steering knuckle blank in step three has a shaft portion located between the two ears, and a storage package for step four is arranged at the shaft portion.

8. The closed-die swage forming process for a knuckle arm knuckle as defined in claim 1 wherein: The shaft portion cavity in step three is deeper than the shaft portion cavity in step four, and the shaft portion cavity in step three has a smaller cross-sectional size than step four.

9. The closed-die swage forming process for a knuckle arm knuckle as defined in claim 1 wherein: The die cavities used in steps two to four are arranged in the same die, and the forging press used is an electric screw press.

10. The closed-die swage forming process for a knuckle arm knuckle as defined in claim 1 wherein: The depth of the V-shaped cavity of the pre-forging die accounts for 35-40% of the overall cavity depth.

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