An internal and external shearing spin forming process for a thin-walled conical part with high internal ribs

Abstract

A process for internal and external shearing and spinning forming of a thin-walled conical part with high internal ribs includes: selecting an external shearing and spinning mandrel with a gradually thickening groove on the conical surface; feeding the mandrel along the outer conical surface contour line of the mandrel using a shearing and spinning wheel, and shearing and spinning a circular blank according to a preset negative deviation rate, so that the circular blank forms a conical part with a gradually thickening inner boss; selecting an internal shearing forming mold with a cavity consistent with the shape of the conical part and fixing the conical part in place; using the shoulder of the inner boss as the starting point of the shearing wheel, selecting an acute angle, and controlling the shearing wheel to shear and feed along the generatrix direction of the shearing forming mold according to a set shearing amount, forming a thin-walled conical part with an inner ring rib. This invention achieves the forming of a thin-walled conical part with an inner ring rib through external shearing and spinning and internal shearing forming, while improving the forming height and thickness uniformity of the inner rib.

Description

Technical Field

[0001] This invention relates to the field of metal plastic forming technology, specifically to an internal and external shearing and spinning forming process for a thin-walled conical part with high internal ribs. Background Technology

[0002] Lightweight and efficient tapered components with internal ribs have wide applications in the aerospace field. However, they also have the complex characteristics of large size, thin walls and local internal ribs. Using traditional subtractive manufacturing-split assembly methods to form such components has many disadvantages, such as long processing cycles, low material utilization and high costs, which cannot meet the requirements of high-performance and efficient integral forming manufacturing.

[0003] Spin forming technology is an effective solution for the integrated forming of thin-walled curved components with internal ribs. It has the advantages of simple tooling and equipment, high forming accuracy, low forming load and high material utilization, and is suitable for the integral forming of thin-walled curved components with ribs.

[0004] Chinese patent application CN202111514553.5 discloses a shearing and forming method for annular external ribbed cylindrical parts. By axially loading a shearing wheel, the surface of the material is sheared and deformed, separating it from the material below and transferring it radially to form ribs. This method enables large-scale, large-volume, and long-distance radial flow and transfer of metal materials, achieving precise forming of annular external ribbed cylindrical parts and solving the problem of difficult external rib structure forming in traditional processes.

[0005] However, while shear forming can produce ribbed components with large aspect ratios, it is currently only used for forming cylindrical parts with outwardly ribbed rings, and it suffers from significant thickening at the bottom of the ribs and uneven thickness distribution in the rib area. Therefore, further research is needed to achieve the forming of thin-walled conical parts with internal ribs while improving the uniformity of internal rib thickness and forming height. Summary of the Invention

[0006] To achieve integrated forming of thin-walled conical parts with inner ring ribs, and to improve the uniformity of the inner rib thickness and the forming height, this invention provides an internal and external shear spinning forming process for thin-walled conical parts with high inner ribs, which includes the following steps:

[0007] S1. Select an external rotary shearing and spinning core mold with a half-cone angle of θ and a frustum structure. Coaxially fix the large end plane of the core mold to the spinneret. The conical surface of the external rotary shearing and spinning core mold is provided with a recessed groove ring with a certain angle α with the half-cone angle θ, a width of l, and a maximum depth of h at the tail end. Coaxially fix the circular slab on the small end plane of the external rotary shearing and spinning core mold.

[0008] The included angle α satisfies the following formula:

[0009]

[0010] S2. Install the shearing and spinning roller on the outer spinning roller frame, start the spinning machine to drive the outer spinning shearing and spinning mandrel to rotate, and control the shearing and spinning roller to feed along the outer conical surface contour line of the outer spinning shearing and spinning mandrel according to the preset negative deviation rate Δt', and perform the first pass shearing and spinning to form a conical part with a gradually thickened inner boss on a circular blank with a plate thickness of t;

[0011] The preset negative deviation rate Δt' satisfies the following formula:

[0012] t0=t*sinθ (2)

[0013]

[0014] Δt'∈[-15%, -2%](4)

[0015] Among them, t f The thickness of the tapered part is preset, t0 is the thickness of the tapered part that satisfies the sinusoidal law, t is the initial wall thickness of the circular slab, and θ is the half-cone angle of the shearing and spinning mandrel; and the maximum depth of the recessed groove ring of the external shearing and spinning mandrel satisfies: 0.5mm. <h≤t f / 2;

[0016] S3. Using the recessed portion of the outer conical surface of the tapered part with the gradually thickened inner boss formed by the first pass of shearing and spinning as a reference, the outer conical surface of the tapered part is machined flat along the half-cone angle θ.

[0017] S4. Select an internal rotary shearing forming die with a cavity that matches the shape of the machined tapered part, fix it coaxially on the spindle of the spinning machine, and then fix the machined tapered part in the cavity of the internal rotary shearing forming die so that the outer cone surface of the tapered part fits against the cone surface of the cavity of the internal rotary shearing forming die.

[0018] S5. Select a single-cone rotating wheel as the shearing rotating wheel. The shearing rotating wheel includes an upper shearing working surface and a lower shearing working surface. The upper shearing working surface and the lower shearing working surface are connected by an outwardly convex arc shearing angle, and the included angle between the upper shearing working surface and the lower shearing working surface (i.e., the rotating wheel shearing angle) is 60° to 90°. Install the shearing rotating wheel on the inner rotating wheel frame, and make its arc shearing angle abut against the shoulder of the inner boss. The lower shearing working surface is in contact with the inner conical surface of the conical part.

[0019] S6. Starting the shearing wheel at the shoulder of the inner boss of the conical part, select the sum of the height h of the boss's tail end and the wall thickness of the conical part's tail end as the initial shearing wall thickness t. h Let the cutoff amount be t1, where t1 ∈ [20%t]. h 50% t hStart the spinning machine to drive the inner spinning shearing forming die to rotate, and control the shearing wheel to feed along the generatrix of the cone surface inside the cavity of the inner spinning shearing forming die, and form the inner ring rib through the second shearing;

[0020] The above shearing wheel and the included angle α satisfy the following formula:

[0021] 0 <R<h-tanα*S (5)

[0022] Where R is the radius of the shearing wheel arc shearing angle, S is the feed distance of the shearing wheel, h is the maximum depth of the end of the recessed groove ring (referring to the end near the large end face of the external shearing and spinning mandrel), and the radius of the shearing wheel R is less than the shearing amount t1.

[0023] As a further preferred embodiment of the present invention, the cone wall thickness t of the formed cone-shaped component is... f No more than 5mm.

[0024] As a further preferred embodiment of the present invention, the conical surface on the small end plane side of the external rotary shearing and spinning mandrel is smoothly transitioned to the recessed groove ring via a beveled surface to facilitate demolding of the conical part with a boss. The tail end of the recessed groove ring on the large end plane side is designed with a shoulder to facilitate rotary shearing. More preferably, the included angle α is set to 0.5-0.7 degrees to reduce the problem of uneven inner rib thickness caused by the increased shearing depth during the feeding process.

[0025] As a further preferred embodiment of the present invention, the shearing and spinning wheel is a single-conical wheel with an exit angle of 35 to 45 degrees.

[0026] As a further preferred technical solution of the present invention, the angle between the exit surface of the second-pass shearing wheel and the lower shearing working surface is 3 to 30 degrees, and the radius of the arc shearing angle is 0.1 to 1.5 mm.

[0027] As a further preferred technical solution of the present invention, in step S6, the rotational speed ω of the internal rotation shearing forming die is 60r / min to 200r / min, and the feed ratio of the shearing wheel is 0.1 to 2mm / r.

[0028] This invention, based on shear spinning to form conical parts and shear forming to form cylindrical parts with outer ring ribs, effectively combines the external and internal shear deformation processes of shear spinning and shear forming. Through the interaction of these two shear deformation modes, the performance of the component is greatly improved, ultimately achieving the integrated forming of thin-walled conical parts with high internal ribs. Compared with existing technologies, the beneficial effects achieved by this invention through the adoption of the above technical solution are:

[0029] 1. The forming of a thin-walled conical part with inner ring ribs is achieved by the first pass of external shearing and the second pass of internal shearing. At the same time, the presence of the gradually thickened inner boss reduces the material accumulation process under the pressure of the spinning wheel and avoids the phenomenon of the shearing amount gradually increasing with the feed of the spinning wheel, thus improving the uniformity of the thickness of the formed inner rib.

[0030] 2. The angle between the upper and lower shearing working surfaces of the shearing wheel (i.e., the wheel shearing angle) is reduced, which reduces the squeezing and friction of the shearing wheel working surface on the metal material during the forming process, promotes the radial elongation of the material, and reduces the relative increase in thickness in the thickness direction, thereby improving the forming height and uniformity of the inner rib. Attached Figure Description

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0032] Figure 1 This is a schematic diagram of the processing state of a circular slab undergoing the first pass of shearing and spinning.

[0033] Figure 2 This is the front view and the corresponding AA sectional view of the first pass shearing and spinning mandrel.

[0034] Figure 3 This is a magnified view of a portion of the shearing and spinning mandrel;

[0035] Figure 4 A tapered part with an inner boss of gradually varying thickness, formed by the first pass of shearing and spinning.

[0036] Figure 5 This is a schematic diagram of the processing state of a tapered part with an inner boss of gradually varying thickness undergoing a second-pass shearing process.

[0037] Figure 6 This is a thin-walled conical part with inner ring ribs formed by the second shearing process.

[0038] Figure 7 This is a schematic diagram of the shearing wheel structure;

[0039] Figure 8 This is a magnified view of a portion of the shearing wheel.

[0040] In the diagram: 1. Mandrel, 2. External spinning shearing and spinning mandrel, 21. Groove, 22. Smooth inclined surface, 3. Circular blank, 31. Gradual thickness inner boss, 4. Shearing and spinning wheel, 5. Tail top mechanism, 6. Internal spinning shearing forming mold, 7. Thin-walled conical part, 71. Inner ring rib, 8. Inner spinning wheel frame, 9. Shearing wheel, 91. Upper shearing working surface, 92. Arc shearing angle, 93. Lower shearing working surface, 94. Exit surface.

[0041] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Terms such as "upper," "lower," "left," "right," "middle," and "one" used in the preferred embodiments are merely for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0043] Example 1

[0044] like Figure 1-8 As shown, an internal and external shearing spin forming process for a thin-walled conical part with high internal ribs is provided, including the following steps:

[0045] Step S1, Assembly of circular slabs:

[0046] A frustum-shaped external shear spinning mandrel 2 (hereinafter referred to as shear spinning mandrel 2) with a half-cone angle θ = 35 degrees is selected and coaxially fixed to the mandrel 1 of the spinning machine through its large end plane. The conical surface of the mandrel 2 has a groove with a maximum depth h = 2 mm and a width l = 100 mm (the opening distance along the generatrix direction, excluding the width of the smooth inclined surface 22 used for transition) near its large end plane (referring to the bottom plane of the conical surface). The groove has a recessed groove ring 21 with an angle α of 0.7° between the conical surface and the half-cone angle of the shear spinning mandrel 2 (see reference). Figure 2 and 3 The circular slab 3 with a thickness of t = 8 mm is fixed on the small end plane (referring to the conical top plane) of the shearing and spinning mandrel 2 by the tail-top mechanism 5, and the axis of the shearing and spinning mandrel 2, the axis of the circular slab 3, and the axis of the tail-top mechanism 5 are aligned. See the installation structure for details. Figure 1 As shown.

[0047] Step S2, First pass of external shear spinning:

[0048] like Figure 1 As shown, the single-cone shearing and spinning roller 4 is installed on the outer spinning roller frame. The spinning machine is started to drive the shearing and spinning mandrel 2 to rotate. The shearing and spinning roller 4 is fed along the outer conical contour line of the shearing and spinning mandrel 2 according to the preset negative deviation Δt' = -14.7%. Through the first pass of external shearing and spinning, the circular blank 3 is formed into a conical part with a gradually thickened inner boss 31 (e.g., Figure 4 As shown, the inner boss fills and fits into the groove 21 of the shearing and spinning mandrel.

[0049] S3. External conical surface turning and shaping:

[0050] In step S2, since the outer conical surface of the shearing and spinning mandrel 2 has a recessed groove ring 21, the conical part will form a gradually thickened inner boss 31 in the recessed groove ring 21 during the first shearing and spinning process. Correspondingly, a depression is formed on the outer conical surface of the conical part. In order to ensure the flatness of the outer conical surface to facilitate subsequent processing, the outer conical surface of the conical part needs to be shaped. Specifically, taking the depression on the outer conical surface of the conical part as a reference, the outer conical surface of the conical part is machined flat along a half-cone angle θ = 35 degrees; the first shearing and spinning mandrel 2 is removed from the mandrel 1, and the conical part with the gradually thickened inner boss is removed from the mandrel 2.

[0051] S4. The tapered part is clamped into the internal rotation shearing forming die:

[0052] Select an internal spinning shearing forming die 6 (hereinafter referred to as shearing forming die 6) with a cavity that matches the shape of the tapered part after turning. Coaxially fix the shearing forming die 6 on the spindle 1 of the spinning machine. Then use the tail-end mechanism 5 to fix the tapered part in the cavity of the shearing forming die 6 so that the outer cone surface of the tapered part fits with the inner cone surface of the shearing spinning die 6.

[0053] Step S5: Selection and assembly of the shearing wheel:

[0054] A single-cone rotating wheel is selected as the shearing wheel 9. The shearing wheel 9 includes an upper shearing working surface 91 and a lower shearing working surface 93. The upper shearing working surface 91 and the lower shearing working surface 93 are connected by a convex arc shearing angle 92. The radius of the arc shearing angle 92 is 0.5 mm, and the included angle between the upper shearing working surface 91 and the lower shearing working surface 93 (i.e., the wheel shearing angle) is 80 degrees. The shearing wheel 9 also has an exit surface 94 connected to the lower shearing working surface 93. The included angle between the exit surface 94 and the lower shearing working surface 93 is 7 degrees (e.g., ...). Figure 7 and 8 (As shown); Install the shearing wheel 9 on the inner wheel frame 8, and make its arc shearing angle abut against the shoulder of the inner boss 31, with the lower shearing working surface in contact with the inner conical surface of the conical part (as shown). Figure 5 (As shown).

[0055] Step S6, Second pass of inward rotation shearing shaping:

[0056] like Figure 5 As shown, the shearing wheel 9 starts rotating from the shoulder at the tail end of the inner boss 31, and the shearing depth is set to t1 = 30%t. h The spinning machine is started, driving the shearing and spinning die 6 to rotate. The shearing roller 9 is controlled to feed along the generatrix of the shearing and spinning die 6. The spinning machine drives the shearing and spinning die 6 to rotate at a speed ω of 70 r / min, the feed speed of the shearing roller 9 is 0.3 mm / s, and the feed distance is 30 mm. This ultimately forms a thin-walled conical part 7 with inner ring ribs 71 (e.g., ...). Figure 6 (As shown).

[0057] Step S7: Unloading of the thin-walled conical part with inner ring ribs:

[0058] The shearing wheel 9 is withdrawn in the opposite direction of the shearing feed. The end face of the shearing and spinning die 6 is provided with an air blowing hole that communicates with the cavity. By blowing air into the air blowing hole, the thin-walled conical part 7 with inner ring rib 71 is unloaded from the shearing and spinning die 6.

[0059] Examples 2 and 3

[0060] The difference from Example 1 is that only in step S5 is the shearing amount t1 increased to 40% t. h and 50% t h The remaining processes are the same as in Example 1. It should be noted that when the shear depth t1 is greater than the height of the boss of the tapered part with the gradually thickened inner boss, the shearing wheel needs to be radially pre-pressed to the set shear depth for shearing feed.

[0061] Comparing the thin-walled conical parts with inner ring ribs formed in Examples 1-3, all yielded inner ring ribs with uniform aspect ratios, and no wrinkling was observed at the tail end of the components. As the shearing depth increased, the width of the inner rib gradually increased, while the aspect ratio decreased to some extent. However, with increasing shearing depth, the stiffness of the formed inner rib improved, reducing the tendency for instability, wrinkling, and inward curling, increasing the feed distance, and resulting in a higher formed rib height.

[0062] Extensive experiments were conducted on tapered parts with the same wall thickness using different shear penetration amounts. When the shear penetration was too small, the material was prone to shear fracture along the bottom of the forming inner rib as the shearing wheel fed; while when the shear penetration was too large, the wall stiffness gradually became insufficient, especially when the shear penetration exceeded 50% of the shear penetration. h Subsequently, excessive thinning of the web can easily lead to fracture. Therefore, the optimal shearing depth t1 ∈ [20%t] was ultimately determined. h 50% t h ];

[0063] Comparative Example 1

[0064] As a comparative experiment of Example 1, a thin-walled conical part with high internal ribs was formed based on the forming process of Example 1. The specific process is as follows:

[0065] Step S1 is basically the same as step S1 in Example 1, except that the cone surface of the selected shearing and spinning mandrel has no groove.

[0066] Step S2 is basically the same as step S2 in Example 1, except that the circular blank is sheared and spun into a conical part without an inner boss after the first pass.

[0067] Step S3: Since the conical surface of the shearing and spinning mandrel has no groove, the conical part does not need to be turned;

[0068] Step S4 is the same as step S3 in Example 1;

[0069] Step S5 is basically the same as step S4 in Example 1, except that: since the conical part obtained in step S2 does not have an inner boss, the arc shearing angle of the shearing wheel abuts against the same diameter as in Example 1.

[0070] Step S6 is basically the same as step S4 in Example 1, except that the shearing wheel is first pressed down radially and then fed along the generatrix direction to keep the shearing amount the same as in Example 1.

[0071] Step S7 is the same as step S6 in Example 1.

[0072] Comparing Example 1 with Comparative Example 1, in the initial shearing stage of Example 1, the presence of the gradually thickened inner boss reduces the material accumulation process, accelerates the forming process of the inner rib, and avoids the problem of significant thickening at the bottom of the rib and uneven wall thickness caused by the gradual increase in shear depth. This indicates that setting the structure with the gradually thickened inner boss significantly improves the uniformity of the formed inner rib and the component's wall thickness.

[0073] Comparative Example 2

[0074] As a comparative experiment of Example 1, a thin-walled conical part with high internal ribs was formed based on the forming process of Example 1. The difference from Example 1 is that the included angle between the shearing working surface 91 and the shearing working surface 93 of the shearing wheel in step S5 is 90 degrees, and the rest of the process is the same as Comparative Example 1.

[0075] Compared with Example 1, the increase in the shear angle in Comparative Example 2 increases the extrusion friction of the shearing wheel on the metal material, increases the radial flow resistance of the material, makes it easier to thicken in the thickness direction, significantly reduces the height-to-width ratio of the inner rib, and worsens the uniformity of the inner rib wall thickness.

[0076] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.

Claims

1. A process for internal and external shearing and spinning forming of a thin-walled conical part with high internal ribs, characterized in that: The process includes the following steps: S1. Select an external rotary shearing and spinning core mold with a half-cone angle of θ and a frustum structure. Coaxially fix its large end plane to the spinneret core shaft. The conical surface of the external rotary shearing and spinning core mold is provided with a recessed groove ring that forms an angle α with its half-cone angle θ. Coaxially fix the circular slab on the small end plane of the external rotary shearing and spinning core mold. The included angle α satisfies the following formula: （1） in, h is the opening width of the recessed groove ring along the generatrix direction of the external shearing and spinning mandrel, and h is the maximum depth of the tail end of the recessed groove ring; S2. Install the shearing and spinning roller on the outer spinning roller frame, start the spinning machine to drive the outer spinning shearing and spinning mandrel to rotate, control the shearing and spinning roller to feed along the outer conical surface contour line of the outer spinning shearing and spinning mandrel according to the preset negative deviation rate Δt', and perform the first pass of shearing and spinning to form a conical part with a gradually thickened inner boss on a circular blank with a plate thickness of t. The preset negative deviation rate Δt' satisfies the following formula: （2） （3） （4） Among them, t f The thickness of the tapered part is preset, t0 is the thickness of the tapered part that satisfies the sinusoidal law, t is the initial wall thickness of the circular slab, θ is the half-cone angle of the shearing and spinning mandrel, and the maximum depth of the recessed groove ring of the external shearing and spinning mandrel satisfies: 0.5mm < h ≤ t f / 2; S3. Using the recessed portion of the outer conical surface of the tapered part with the gradually thickened inner boss formed by the first pass of shearing and spinning as a reference, the outer conical surface of the tapered part is machined flat along the half-cone angle θ. S4. Select an internal rotary shearing forming die with a cavity that matches the shape of the machined tapered part, fix it coaxially on the spindle of the spinning machine, and then fix the machined tapered part in the cavity of the internal rotary shearing forming die so that the outer tapered surface of the tapered part fits against the tapered surface of the cavity of the internal rotary shearing forming die. S5. Select a single-cone rotating wheel as the shearing wheel. The shearing wheel includes an upper shearing working surface and a lower shearing working surface. The upper shearing working surface and the lower shearing working surface are connected by an outwardly convex arc shearing angle, and the included angle between the upper shearing working surface and the lower shearing working surface is 60°~90°. Install the shearing wheel on the inner rotating wheel frame, and make its arc shearing angle abut against the shoulder of the inner boss. The lower shearing working surface is in contact with the inner conical surface of the conical part. S6. Starting the shearing wheel at the shoulder of the inner boss of the conical part, select the sum of the height h of the boss's tail end and the wall thickness of the conical part's tail end as the initial shearing wall thickness t. h Set the cut-in amount to t1, the cut-in amount Start the spinning machine to drive the inner spinning shearing forming die to rotate, and control the shearing wheel to feed along the generatrix direction of the cone surface inside the cavity of the inner spinning shearing forming die, so as to form the inner ring rib through the second shearing. The fillet radius R of the shearing wheel and the included angle α satisfy the following formula: （5） Where R is the radius of the shearing wheel arc shearing angle, S is the feed distance of the shearing wheel, h is the maximum depth of the sinking groove ring tail end, and the radius of the shearing wheel R is less than the shearing depth t1.

2. The internal and external shearing and spinning forming process for a thin-walled conical part with high internal ribs according to claim 1, characterized in that, In step S2, the thickness t of the pre-set tapered component is... f No more than 5mm.

3. The internal and external shearing and spinning forming process for a thin-walled conical part with high internal ribs according to claim 1, characterized in that, The conical surface on the small end plane side of the external spin shearing and spinning mandrel transitions with the sunken groove ring through a smooth inclined surface, and the tail end of the sunken groove ring on the large end plane side is designed with a shoulder.

4. The internal and external shearing and spinning forming process for a thin-walled conical part with high internal ribs according to claim 1, characterized in that, The shearing and spinning wheel is a single-conical wheel with an exit angle of 35 to 45 degrees.

5. The internal and external shearing and spinning forming process for a thin-walled conical part with high internal ribs according to claim 1, characterized in that, The angle between the shearing wheel exit surface and the lower shearing working surface is 3 to 30 degrees, and the radius of the arc shearing angle is 0.1 to 1.5 mm.

6. The internal and external shearing and spinning forming process for a thin-walled conical part with high internal ribs according to claim 1, characterized in that, In step S6, the rotational speed ω of the internal rotary shearing forming die is 60 ~ 200 r / min, and the feed ratio of the shearing wheel is 0.1 ~ 2 mm / r.

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