A method for spinning a flat bottom plug cover with a weakened groove and a forming die

Abstract

A method for spinning a flat bottom plug cover with weakened grooves. The outer shape of the plug cover is processed by spinning, and the weakened grooves are processed by milling, which meets the requirements of product indicators and overcomes the disadvantages of the method of forming the outer shape of the original spinning plug cover and then processing the weakened grooves by stamping. By adding a taper angle and a platform design to the end face of the spinning die, for the semi-finished plug cover after spinning and before processing the weakened grooves, the deformation amount generated on its bottom surface due to the spinning process is compensated. Further combined with the special clamping method during milling and the optimized pressing plate design, high-precision weakened grooves are realized through milling; the bottom surface of the plug cover is fixed by the taper angle of the tooling and presents a slightly concave shape, and the pressing points of the pressing plate are located at 1 / 2 to 4 / 5 of the radius of the plug cover, avoiding warping of the bottom surface. The present invention does not require processing adjustment gaskets of different thicknesses, and also avoids the disadvantage of having to determine the depth through experiments when stamping and producing weakened grooves. Multiple plug covers with different weakened groove sizes can be produced at one time, greatly reducing the production cycle and processing costs.

Description

Technical Field

[0001] The present invention relates to the technical field of solid rocket engine nozzles, and specifically to a forming die and method for a thin-walled flat-bottomed plug cover with weakening grooves. Background Technique

[0002] The thin-walled flat-bottomed plug cover with weakening grooves is a new structure designed under the concept of no-throw object for the engine nozzle. In a thin-walled flat-bottomed plug cover with weakening grooves and its forming die and method (CN112024683), a plug cover structure with a thin middle and a thickened bonding section is introduced, and a process method of forming the outer shape of the plug cover by spinning and then machining the weakening grooves by stamping is proposed.

[0003] In recent years, with the increasing application of no-throw object plug covers, the research on related principles has been more in-depth. At present, there have been certain changes in the design and technical requirements of the plug cover compared with those described in the above document, mainly in the following three aspects. First, in terms of the outer shape, the shape accuracy requirements of the bonding section of the plug cover have been improved; second, the dimensional tolerance of the weakening grooves has been increased (from 0.05 mm to 0.02 mm); finally, the opening pressure of the plug cover is changed to be measured by tests. When developing, at least 10 different plug covers with different weakening groove depths need to be provided at one time, and the final dimensions are determined according to the test results.

[0004] Due to the changes in design technical requirements and production rhythm, the existing method of forming the outer shape of the plug cover by spinning and then machining the weakening grooves by stamping begins to show some disadvantages, mainly including:

[0005] 1. It is difficult to produce a plug cover with a "thickened bonding section" by spinning, and it is difficult to accurately control the wall thickness reduction, resulting in "errors and offsets" between the bonding section and the outer shape of the spinning die. Therefore, it is impossible to ensure the high-precision bonding surface shape.

[0006] 2. For the existing plug cover, the outer shape of the plug cover is formed by spinning and then the weakening grooves are machined by stamping. Due to the accuracy limitation of the stamping process, the dimensional accuracy of the weakening grooves produced by it cannot meet the existing design requirements.

[0007] 3. When machining the weakening grooves by stamping, since different weakening groove depths need to be matched with different thickness gaskets, under the current accuracy requirements, the gaskets must be produced by grinding processes. And because the thickness of the gaskets required for each weakening groove depth cannot be accurately calculated, it must be determined through inspection after processing tests. In actual production, it is necessary to repeatedly test and adjust, resulting in a long overall cycle and high production costs.

[0008] 4. Machining the weakening grooves by stamping causes the plug cover to be affected by cold work hardening, and the mechanical properties of local products change greatly. The change between different weakening groove sizes and the bursting pressure during the plug cover test is not linear, increasing the difficulty of testing and simulation.

[0009] 5. After the existing spinning die finishes machining the outer shape of the plug cover, that is, before machining the weakening grooves, due to its forming mechanism, the bottom surface of the plug cover will present a slightly convex shape. Therefore, in subsequent processes, it is necessary to ensure the flatness of the bottom surface of the final product through strong forming methods such as stamping, which limits the possibility of using milling to machine the weakening grooves in the original invention. Summary of the Invention

[0010] To overcome the deficiencies in the prior art, such as the machining accuracy not meeting the design requirements and the long production cycle and high cost, the present invention proposes a method for spinning a flat-bottom plug cover with weakening grooves.

[0011] The flat-bottom plug cover with weakening grooves processed by the present invention has a wall thickness of 2.5 mm and a bottom surface structure that is flat; six weakening grooves are machined on the bottom surface along the radial direction; the circumferential wall surface is an adhesive section, and the thickness of this adhesive section is equal to or slightly less than the thickness of the bottom plane. Its characteristics are: the dimensional tolerance requirements for the width and depth of the weakening grooves are less than 0.02 mm, and the surface contour tolerance requirements for the circumferential wall surface are less than 0.05 mm.

[0012] It is characterized in that the specific process is as follows:

[0013] Step 1, blanking:

[0014] Obtain a blank of the flat-bottom plug cover.

[0015] Step 2, install the die:

[0016] The die includes a male die and a ejector.

[0017] Step 3: Place the blank of the flat-bottom plug cover:

[0018] Place the blank of the flat-bottom plug cover on the end face of the male die; adjust the tailstock to press the blank of the flat-bottom plug cover tightly through the ejector.

[0019] Step 4: Spin:

[0020] Calculate the movement trajectory of the spinning wheel according to equal wall thickness, and set the feed rate to 80% at the fillet where the adhesive section of the plug cover meets the bottom surface of the plug cover. Spin and form the plug cover by the method of die-attached spinning; the die-attached gap is 0.02 mm.

[0021] When spinning, the operating parameters of the machine tool are as follows: the spindle speed is 180 ± 20 r / min, and the feed ratio is 1 ± 0.1 mm / r.

[0022] Trim the obtained blank; obtain a semi-finished product of the flat-bottom plug cover.

[0023] Step 5: Mill the grooves:

[0024] Install the fixing tooling of the semi-finished product of the flat-bottom plug cover on the machine tool workbench through a milling fixing tooling, and press and align it. Mill and machine the weakening grooves. The specific process is as follows:

[0025] Fix the fixture at the center of the workbench and align the flatness of the upper end face of the fixture to be ≤ 0.02 mm.

[0026] Invert the semi-finished plug cover after spinning on the base of the fixture, so that the center of the semi-finished plug cover coincides with the center of the base; press four pressing plates respectively at 1 / 2 to 4 / 5 of the radius of the plug cover. The flatness of the bottom surface of the plug cover needs to be ≤ 0.02 mm.

[0027] Machine the weakening groove according to the design requirements. When machining the weakening groove, select an R2 ball-end milling cutter for machining. The machining process includes rough machining and finish machining.

[0028] There are multiple weakening grooves. When machining, machine a pair of the weakening grooves located on the same diameter in sequence. After the first pair of weakening grooves are machined, the spindle of the machine tool rotates clockwise to machine the next pair of two grooves on the same diameter. Until all the weakening grooves are machined.

[0029] Thus, the spinning process of the flat-bottom plug cover with weakening grooves is completed.

[0030] The cutting parameters for the rough machining are: the cutting depth is 0.3 mm, the feed of the ball-end milling cutter is 800 mm / r, and the spindle speed is 2800 r / min; reserve 0.2 mm of the weakening groove depth as the cutting allowance for the finish machining.

[0031] The cutting parameters for the finish machining are: the cutting depth is 0.05 mm, the feed of the ball-end milling cutter is 600 mm / r, and the spindle speed is 2000 r / min.

[0032] The fixture proposed in the present invention includes a base and four pressing plates, and the pressing plates are used in cooperation with the base. Place the semi-finished flat-bottom plug cover on the base, and make the inner end face of the flat-bottom plug cover fit with the upper end face of the base; install the four pressing plates on the periphery of the base respectively, and make the lower surface of each pressing plate fit with the upper surface of the semi-finished flat-bottom plug cover; tighten with a pressing bolt.

[0033] The pressing plate is divided into a working section and a fixed section according to its function. There is a strip-shaped adjustment hole in the fixed section of the pressing plate for adjusting the position of the pressing plate; the center line in the width direction of the adjustment hole coincides with the center line in the width direction of the pressing plate. The outer shape of the fixed section of the pressing plate is trapezoidal, and the included angle β between the two side edges of the trapezoid is 60°. The lower surface of the fixed section is a working surface that fits with the upper surface of the semi-finished plug cover; the working surface protrudes 10 mm from the lower surface of the fixed section.

[0034] The diameter D3 of the base is more than 10 mm smaller than the diameter at the tangent point of the bonding section and the bottom surface of the plug cover; the flatness of the upper end face of the base plate must be ≤ 0.02 mm.

[0035] In the present invention, in the said mold, the male mold is divided into a clamping section and a forming section according to its functions, and its outer shape is in a T shape. The circumferential surface is an inclined surface, and the surface of the upper surface of the forming section is the same as the inner surface of the flat bottom plug cover. At the center of the upper surface of the forming section of the male mold, there is a conical groove, and the groove depth is The wall surface of the groove is an inclined surface with an angle of about 0.2° - 0.35°, the diameter of the groove opening of the said groove is Φ110mm, and the diameter of the groove bottom is Φ20.5mm.

[0036] The ejector is divided into a clamping section and a forming section according to its functions, and its outer shape is in a convex shape. The large diameter end of the ejector is the forming section, and the lower end surface of the forming section is the forming surface of the flat bottom plug cover. At the center of the forming surface, there is a conical boss, and the height of the boss is The taper of the circumferential surface of the conical boss is 0.3° - 0.45°; the diameter of the bottom end of the conical boss is Φ20mm, and the diameter of the top end is Φ109.5mm. Through this conical boss, the deformation generated during the spinning process of the bottom surface of the plug cover is compensated.

[0037] The method for spinning and forming a thin - walled plug cover with a weakening groove proposed by the present invention is to process the outer shape of the plug cover by spinning and process the weakening groove by milling, which meets the product index requirements and overcomes the drawbacks of the method of forming the outer shape of the original spinning - formed plug cover and then processing the weakening groove by stamping.

[0038] In the present invention, due to the taper design of the spinning tooling, the bottom surface of the fixed tooling plug cover presents a slightly concave shape. The pressing point of the pressing plate must be located at the position of 1 / 2 - 4 / 5 of the radius of the plug cover. If the pressing plate is too close to the center of the bottom surface or too close to the edge of the bottom surface, it will cause warping of the bottom surface. At the same time, the shape of the pressing plate should be customized according to the size of the plug cover to ensure that the contact area of the pressing plate is as large as possible without interfering with the processing of the weakening groove.

[0039] The said fixed tooling has a taper and a small platform. After spinning and forming, the plug cover, through the optimized clamping method and combined with the specially made pressing plate tooling, has a good flatness of the bottom surface after being clamped and fixed.

[0040] The bases of the contact planes of the male mold and the ejector are fixed on the working table of the machine tool by pressing plates, and the spun - formed plug cover is fixed on the base by the reformed pressing plate.

[0041] The technical key points of the present invention lie in the optimized spinning - forming mold, the fixed tooling for plug cover milling, and the selection of process parameters. Compared with the prior art, the beneficial effects obtained by the present invention are:

[0042] 1. The present invention designs a conical angle and a platform on the end face of the spinning die. For the semi-finished plug cover before machining the weakening groove after spinning, it compensates for the deformation of its bottom surface caused by the spinning process. Further combined with a special clamping method during milling and an optimized pressing plate design, a method for machining a high-precision weakening groove by milling is achieved;

[0043] 2. Since the improved method of the present invention does not require adjusting the adjustment structure on the tooling, does not require machining adjustment gaskets of different thicknesses, and also avoids the disadvantage of needing to determine the depth through experiments when stamping and producing the weakening groove, multiple plug covers with different weakening groove sizes can be produced at one time. Therefore, when continuously producing plug covers with the same appearance but having multiple (more than 5 kinds) weakening groove sizes, the production cycle can be significantly reduced;

[0044] 3. The present invention realizes the machining of the weakening groove by milling, avoiding the disadvantage of large wall thickness change in the stamping process, with less deformation, and can produce the plug cover with the structure of "the thickness of the bonding section becomes equal to or slightly less than that of the middle section" as described above. When producing such a plug cover by spinning, since the wall thickness does not change, the shape of the bonding surface can be accurately obtained through the profile shape of the spinning die, so the accurate forming of the bonding surface can be realized.

[0045] 4. Finally, the weakening groove of the present invention is machined by milling with a small cutting amount, avoiding the influence of cold work hardening on the mechanical properties of the plug cover when stamping and forming the weakening groove. The ratio of different weakening groove sizes to the burst pressure is more linear during the plug cover test process, which is beneficial to the accumulation of test data and the determination of the final size, and can speed up the development progress of the entire product;

[0046] The forming solution provided by the present invention has high machining accuracy, and can ensure that the profile tolerance of the bonding section surface is less than 0.05 mm, the product bonding gap is less than 0.1 mm, the size tolerance of the weakening groove is less than 0.02 mm, etc.; it has high processing efficiency. This method can process products with different weakening groove depths, reducing the cycle of replacing tooling and repairing gaskets. The continuous spinning processing time of the plug cover is basically equal to that of stamping processing, but the production cycle of the spinning die is short, and the die installation and debugging time can be saved by 30% compared with the stamping die. Therefore, the overall production cycle of the plug cover is reduced and the processing cost is low. Specifically, the production cost of the specified spinning die and milling fixture is about 1 / 3 of that of a set of stamping dies. Description of the Drawings

[0047] Figure 1 is a structural schematic diagram of a flat-bottom plug cover with a weakening groove.

[0048] Figure 2 is a schematic diagram of a spinning forming die; among them, Figure 2 a is the front view, Figure 2 b is Figure 2 a partial enlarged view of part Ⅰ in

[0049] Figure 3 It is a schematic diagram of a male mold; among them, Figure 3 a is the front view, Figure 3 b is Figure 3 the partial enlarged view of part Ⅰ in a.

[0050] Figure 4 It is a schematic diagram of a top tool; among them, Figure 4 a is the front view, Figure 4 b is Figure 4 the top view of a.

[0051] Figure 5 It is a schematic diagram of a spinning wheel; among them, Figure 5 a is the front view, Figure 5 b is Figure 5 the top view of a.

[0052] Figure 6 It is a schematic diagram of a milling fixture.

[0053] Figure 7 It is the flow chart of spin - forming a flat bottom plug with weakened grooves according to the present invention.

[0054] In the figure: 1. Top tool; 2. Semi - finished product plug; 3. Spinning wheel; 4. Male mold; 5. Base; 6. Pressure plate; 7. Compression bolt Specific implementation method

[0055] This embodiment is a method for spin - forming a flat bottom plug with weakened grooves.

[0056] The wall thickness of the flat bottom plug with weakened grooves is 2.5 mm, and the bottom is a flat structure; six weakened grooves are machined on this bottom surface along the radial direction; the circumferential wall surface is an adhesive section, and the thickness of this adhesive section is equal to or slightly less than the thickness of the bottom plane. Its characteristics are: the dimensional tolerance requirements for the width and depth of the weakened grooves are less than 0.02 mm, and the surface contour tolerance requirement for the circumferential wall surface is less than 0.05 mm.

[0057] The aluminum plate material of the flat bottom plug with weakened grooves is in the 1060 - O state, and the plate thickness is 2.5 mm.

[0058] The specific process of this embodiment is as follows:

[0059] Step 1, blanking:

[0060] Mark lines on the aluminum plate surface and cut out a circle with a diameter of 210 ± 1, and grind the periphery and surface. Obtain the blank of the flat bottom plug.

[0061] Step 2, install the mold:

[0062] The mold includes a male mold 3 and a top tool 1.

[0063] Install the male mold 3 on the spinning machine tool and align it with the center of the machine tool spindle. It is required that the total runout of the working section of the male mold is less than 0.03 mm. Install the top tool 1 on the tailstock.

[0064] Adopt an R8 spinning wheel.

[0065] Step 3: Place the flat-bottom plug blank:

[0066] Place the flat-bottom plug blank on the end face of the male mold 3; adjust the tailstock to press the flat-bottom plug blank tightly through the top tool 1.

[0067] Step 4: Spinning:

[0068] Calculate the movement trajectory of the spinning wheel according to equal wall thickness, and set the feed rate to 80% at the fillet where the bonding section of the plug meets the bottom surface of the plug. Adopt the method of die-sinking spinning to spin and form the plug; the die-sinking gap is 0.02 mm.

[0069] During spinning, the operating parameters of the machine tool are as follows: the spindle speed is 180 ± 20 r / min, and the feed ratio is 1 ± 0.1 mm / r.

[0070] Repair the shape of the obtained blank; obtain a semi-finished product of a flat-bottom plug with a height of 24 mm.

[0071] Step 5: Milling the groove:

[0072] Fix the semi-finished flat-bottom plug on the machine tool workbench through the milling fixture for fixing and press it tightly and align it. Milling the weakening groove. The specific process is as follows:

[0073] Clean the workbench, fix the base on the center of the workbench through the pressing plate, press it tightly, and align the flatness of its upper end face ≤ 0.02 mm.

[0074] Invert the semi-finished plug after spinning on the base, ensure that the center of the plug coincides with the center of the base, and press 4 pressing plates respectively at 1 / 2 to 4 / 5 of the radius of the plug through the four pressing plates around the base. After pressing and aligning, measure the bottom surface along the direction of the scratch, and require that the flatness of the bottom surface of the plug needs to be ≤ 0.02 mm, otherwise it should be re-clamped and aligned or corrected through the spinning fixture.

[0075] Machine the weakening groove according to the design requirements. When machining the weakening groove, select an R2 ball-end milling cutter for machining. The machining process includes rough machining and finish machining.

[0076] The cutting parameters for rough machining are: the cutting depth is 0.3 mm, the feed of the ball-end milling cutter is 800 mm / r, and the spindle speed is 2800 r / min; reserve 0.2 mm of the weakening groove depth as the cutting allowance for finish machining.

[0077] The cutting parameters for finish machining are as follows: the depth of cut is 0.05 mm, the feed of the ball end mill is 600 mm / r, and the spindle speed is 2000 r / min.

[0078] There are multiple weakening grooves. During machining, a pair of the weakening grooves located on the same diameter are machined in sequence. After the first pair of weakening grooves are machined, the machine tool spindle rotates clockwise to machine the next pair of two grooves on the same diameter. This process continues until all the weakening grooves are machined. In this embodiment, there are six weakening grooves.

[0079] Thus, the spinning process of the flat bottom plug cover with weakening grooves is completed.

[0080] In this embodiment, the milling fixture includes a base 5 and four pressing plates 6. The pressing plates are used in cooperation with the base. The semi-finished flat bottom plug cover is placed on the base, and the inner end surface of the flat bottom plug cover is fitted to the upper end surface of the base. The four pressing plates are respectively installed around the base, and the lower surfaces of the pressing plates are fitted to the upper surface of the semi-finished flat bottom plug cover. Then, it is tightened by a pressing bolt 7.

[0081] The pressing plate is divided into a working section and a fixing section according to its function. There is a strip-shaped adjustment hole in the fixing section of the pressing plate for adjusting the position of the pressing plate. The length A of the adjustment hole is 50 mm, and the width B is 12 mm. The center line in the width direction of the adjustment hole coincides with the center line in the width direction of the pressing plate. The outer shape of the fixing section of the pressing plate is trapezoidal, and the included angle β between the two side edges of the trapezoid is 60°. The lower surface of the fixing section is a working surface that fits the upper surface of the semi-finished plug cover. The working surface protrudes 10 mm from the lower surface of the fixing section.

[0082] In this embodiment, the length L of the pressing plate is 110 mm, the width H is 60 mm, and the thickness S is 15 mm.

[0083] The base 5 is cylindrical and is used to place the semi-finished plug cover after spinning. The diameter D3 of the base is more than 10 mm smaller than the diameter at the tangent point of the bonding section of the plug cover and the bottom surface. Otherwise, interference will occur with the bottom arc of the plug cover after installation, resulting in warping of the bottom surface and affecting machining. The flatness of the upper end surface of the base plate must be ≤0.02 mm.

[0084] The pressing plate is used to press the plug cover onto the base. When designing the pressing plate, it should be ensured that the pressing plate can achieve pressing within the range of 1 / 2 to 4 / 5 of the radius of the plug cover and will not interfere with the machining process.

[0085] In the die, the male die 4 is divided into a clamping section and a forming section according to its function, and its outer shape is T-shaped. The circumferential surface is an inclined surface, and the surface shape on the upper surface of the forming section is the same as the inner surface shape of the flat bottom plug cover. There is a conical groove in the center of the upper surface of the forming section of the male die, and the groove depth is The groove wall surface is an inclined plane with an angle of approximately 0.2° to 0.35°. The diameter of the groove opening is Φ110mm, and the diameter of the groove bottom is Φ20.5mm. The top tool 1 is divided into a clamping section and a forming section according to its function, and its outer shape is convex-shaped. The large-diameter end of the top tool is the forming section, and the lower end surface of the forming section is the forming surface of the flat bottom plug cover. There is a conical boss at the center of the forming surface, and the height of the boss is The taper of the circumferential surface of the conical boss is 0.3° to 0.45°; the bottom diameter of the conical boss is Φ20mm, and the top diameter is Φ109.5mm. The deformation generated during the spinning process of the bottom surface of the plug cover is compensated by this conical boss.

[0086] When processing with a traditional spinning die with a flat end face, due to the spinning and stretching effect, the flatness of the bottom surface of the semi-finished plug cover can only reach 0.05 - 0.1mm during the alignment of the milling weakening groove, which cannot meet the precision requirements of the design for the depth of the weakening groove. When using the improved spinning tooling, after clamping and aligning the semi-finished plug cover on the milling fixture, the flatness of the bottom surface ≤0.02mm, meeting the precision requirements of the weakening groove.

Claims

1. A method for spinning a flat bottom plug cover with weakened grooves, the wall thickness of the flat bottom plug cover with weakened grooves is 2.5 mm, and the bottom is a flat structure; six weakened grooves are machined on the bottom along the radial direction; the circumferential wall surface is an adhesive section, and the thickness of the adhesive section is equal to or less than the thickness of the bottom plane; it is characterized in that: The dimensional tolerances of the width and depth of the weakening groove are required to be less than 0.02 mm, and the surface profile tolerance of the circumferential wall surface is required to be less than 0.05 mm; It is characterized in that the specific process is as follows: Step 1, blanking: Obtain a blank of the flat-bottomed plug cover; Step 2, install the mold: The mold includes a male mold and a top tool; In the said mold, the male mold is divided into a clamping section and a forming section according to its functions, and its outer shape is in a T shape; the surface of the upper surface of the forming section is the same as the inner surface of the flat bottom plug cover; at the center of the upper surface of the forming section of the male mold, there is a conical groove with a groove depth of The wall surface of the groove is an inclined surface with an angle of 0.2° to 0.35°, the diameter of the groove opening of the groove is Φ110mm, and the diameter of the groove bottom is Φ20.5mm; The top tool is divided into a clamping section and a forming section according to its functions, and its outer shape is convex-shaped; the large-diameter end of the top tool is the forming section, and the lower end surface of the forming section is the forming surface of the flat bottom plug cover; there is a conical boss at the center of the forming surface, and the height of the boss is The taper of the circumferential surface of the conical boss is 0.3° to 0.45°; the bottom diameter of the conical boss is Φ20mm, and the top diameter is Φ109.5mm; the deformation generated during the spinning process of the bottom surface of the plug cover is compensated by the conical boss; Step 3: Place the flat-bottomed plug cover blank: Place the flat-bottomed plug cover blank on the end face of the male mold; adjust the tailstock to press the flat-bottomed plug cover blank tightly through the top tool; Step 4: Spinning: Calculate the movement trajectory of the spinning wheel according to equal wall thickness, and set the feed rate to 80% at the fillet where the bonding section of the plug cover meets the bottom surface of the plug cover; spin and form the plug cover by the method of die-sinking spinning; the die-sinking gap is 0.02 mm; Trim the obtained blank; obtain a semi-finished product of the flat-bottomed plug cover; Step 5: Milling the groove: Install the fixing tooling of the flat-bottomed plug cover semi-finished product on the machine tool workbench through the milling fixing tooling, and press and align it; mill the weakening groove; The milling fixing tooling includes a base and four pressing plates, and each pressing plate is used in cooperation with the base. Place the flat-bottomed plug cover semi-finished product on the base, and make the inner end face of the flat-bottomed plug cover fit with the upper end face of the base; install the four pressing plates on the periphery of the base respectively, and make the lower surface of each pressing plate fit with the upper surface of the flat-bottomed plug cover semi-finished product; press tightly through the pressing bolts; The pressing plate is divided into a working section and a fixing section according to its function; there is a strip-shaped adjustment hole in the fixing section of the pressing plate for adjusting the position of the pressing plate; the center line in the width direction of the adjustment hole coincides with the center line in the width direction of the pressing plate; the outer shape of the fixing section of the pressing plate is trapezoidal, and the included angle β between the two side edges of the trapezoid is 60°; the lower surface of the fixing section is a working surface that fits with the upper surface of the semi-finished plug cover; the working surface protrudes 10 mm from the lower surface of the fixing section; The specific process is as follows: Fix the fixing tooling at the center of the workbench, and align the flatness of the upper end face of the fixing tooling ≤0.02 mm; Invert the spun plug cover semi-finished product on the base of the fixing tooling, and make the center of the plug cover semi-finished product coincide with the center of the base; press the four pressing plates respectively at 1 / 2 to 4 / 5 of the radius of the plug cover; the flatness of the bottom surface of the plug cover needs to be ≤0.02 mm; Machine the weakening groove according to the design requirements; when machining the weakening groove, select an R2 ball-end milling cutter for machining; the machining process is rough machining and finish machining; There are multiple weakening grooves. During machining, a pair of the weakening grooves located on the same diameter are machined in sequence; when the first pair of weakening grooves are machined, the machine tool spindle rotates clockwise to machine the next pair of two grooves on the same diameter; until all the weakening grooves are machined; So far, the spinning process of the flat-bottomed plug cover with weakening grooves is completed.

2. The method of spin - forming a flat bottom plug cover with weakened grooves as described in claim 1, characterized in that, During spinning, the spindle speed of the machine tool is 180±20 r / min, and the feed ratio is 1±0.1 mm / r.

3. The method for spin-forging a flat bottom plug cover with weakened grooves as claimed in claim 1, characterized in that, The cutting parameters for rough machining are: the cutting depth is 0.3 mm, the feed of the ball-end milling cutter is 800 mm / r, and the spindle speed is 2800 r / min; reserve 0.2 mm for the depth of the weakening groove as the cutting allowance for finish machining; The cutting parameters for finish machining are as follows: the depth of cut is 0.05 mm, the feed of the ball-end mill is 600 mm / r, and the spindle speed is 2000 r / min.

4. The method for spin-forging a flat bottom plug cover with weakened grooves as described in claim 1, characterized in that, The diameter D3 of the base is more than 10 mm smaller than the diameter at the tangent point of the bonding section of the plug cover and the bottom surface; the flatness of the upper end surface of the bottom plate must be ≤ 0.02 mm.

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