A non-constant cross-section elongated workpiece forming tool and method

Abstract

The application discloses a non-equal-section elongated workpiece forming tool and method, and the tool comprises a lower core die mounted on a lower die and an upper core die detachably connected to an upper die, a forming opening is arranged at the top end of the cavity of the lower core die, the size of the forming opening far from the cavity is larger than the size of the forming opening close to the cavity; a plurality of demolding blocks are arranged between the lower die and the lower core die, and the length direction of the demolding blocks is perpendicular to the length direction of the lower core die; the male die of the upper core die is matched with the cavity of the lower core die; the upper die is provided with demolding buckles which are detachably connected with the two end portions of the demolding blocks. The linear degree of the workpiece obtained by the forming tool can meet the requirements, the lower core die can be quickly and conveniently detached, the demolding of the workpiece is facilitated, and the workpiece efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of composite material processing technology, specifically to a tooling and method for forming slender parts with non-uniform cross-sections. Background Technology

[0002] Currently, slender composite parts with an axial to radial ratio of 1:100 or higher are mainly formed by pultrusion. However, the material of pultruded parts is unidirectional carbon fiber filament, which can only be used to make products with a constant cross-section and has low transverse strength.

[0003] When making something similar Figure 1 For slender composite parts with transverse strength requirements, made of fabric, and with fiber direction requirements, such as a large profile at one end and a small profile at the other, pultrusion cannot be used. They can only be formed by other processes such as RTM or compression molding.

[0004] For slender composite parts with an axial-to-radial ratio greater than 1:100, requiring the axial direction to withstand a certain force, and having a non-uniform cross-section, there are two problems with using molding processes to manufacture slender composite parts with non-uniform cross-sections: (1) The tooling cavity is too small, and the woven prepreg cannot be laid in place and fit perfectly with the cavity. The fibers are easily twisted during molding, resulting in the part being twisted after molding and lacking straightness.

[0005] (2) The efficiency of molding is low, the tooling takes a long time to heat up and cool down, the temperature of the hot demolding press is too high, and it is inconvenient for employees to operate. Summary of the Invention

[0006] The purpose of this invention is to provide a tooling and method for forming slender parts with non-uniform cross-sections, so as to solve the problems of difficult forming and low efficiency in the prior art.

[0007] To achieve the above objectives, the present invention is implemented using the following technical solution: In a first aspect, this application discloses a tooling for forming slender parts with non-uniform cross-sections, comprising: A lower core mold is installed on the lower mold. The top of the cavity of the lower core mold is provided with a forming opening. The size of the forming opening at the end away from the cavity is larger than the size at the end closer to the cavity. Multiple ejector modules are provided between the lower mold and the lower core mold, and the length direction of the ejector modules is perpendicular to the length direction of the lower core mold. The upper core mold is detachably connected to the upper mold, and the male mold of the upper core mold is adapted to the cavity of the lower core mold; the upper mold is provided with demolding buckles that are detachably connected to both ends of the demolding module.

[0008] Furthermore, the size of the molding opening gradually decreases towards the end closer to the cavity.

[0009] Furthermore, the lower mold is provided with a lower core mold connecting groove, and the lower core mold is engaged in the lower core mold connecting groove; The lower core mold includes a first lower core mold and a second lower core mold with identical structures, and the first lower core mold and the second lower core mold are positioned by at least two locating pins.

[0010] Furthermore, the lower mold is provided with multiple parallel lower core mold connecting grooves so that the lower mold can connect multiple lower core molds.

[0011] Furthermore, the lower mold is provided with a clearance groove perpendicular to the lower core mold connecting groove.

[0012] Furthermore, one end of the release buckle is rotatably connected to the upper mold via a connecting bolt, the middle part is connected with a ball bolt, and the other end is provided with a slot; The upper mold is provided with a connecting groove, and the ball bolt is connected to the connecting groove so that the demolding buckle is in the unlocked state; The demolding module is provided with a connecting protrusion. The ball bolt is disconnected from the groove, and the slot and the connecting protrusion are engaged to lock the demolding buckle.

[0013] Furthermore, the upper core mold is connected to the upper mold by bolts.

[0014] Secondly, this application discloses a forming method for forming a non-uniform cross-section elongated part according to any one of the first aspects, comprising: Connect the upper die to the upper plate of the press, and connect the lower die to the lower plate of the press; Fill the two corners of the cavity of the lower core mold with yarn, and place the preform onto the forming opening of the lower core mold; Start the press to close the upper and lower molds, and heat and pressurize to solidify and shape the part. Connect the release clip and the release module; The press opens the mold, and the ejector module and lower core mold follow the upper mold to detach from the lower mold. The ejector buckle and ejector module are released, and the lower core mold and ejector module detach from the upper mold under the action of gravity. Remove the part from the lower core mold.

[0015] Furthermore, the method for obtaining the preform includes: The composite material is laid in the V-shaped cavity of the serrated laying fixture; Vacuum bag making involves heating and pre-pressing to obtain a V-shaped preform with a certain hardness.

[0016] Furthermore, the step of removing the part from the lower core mold includes: Separate the lower core mold and the demolding module; Separate the first and second lower core molds.

[0017] According to the above technical solution, the beneficial effects of the present invention are as follows: The molding tooling of this application has a molding opening at the top of the cavity of the lower core mold. When in use, the pre-made preform can be placed on the molding opening first. When the mold is closed, the male mold protruding from the upper core mold can be smoothly embedded in the middle of the preform without bending the prepreg to the bottom, and without causing the bottom thickness of the part to be too thick, which would prevent the tooling from closing the mold properly. The straightness of the part obtained by using this tooling can meet the requirements. The molding fixture of this application has a demolding module between the lower mold and the lower core mold, and a demolding buckle that can be detachably connected to both ends of the demolding module on the upper mold. When demolding, the demolding buckle is connected to the demolding module first, and the upper mold can drive the lower core mold to follow the demolding module and detach from the lower mold. The lower core mold can be removed quickly and easily, which facilitates the demolding of the part and improves the part manufacturing efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a non-uniform cross-section component in the background art; Figure 2 A schematic diagram showing the cross-section of the part and the prepreg installed on it; Figure 3 This is a cross-sectional schematic diagram of the lower core mold in this invention; Figure 4 This is a schematic diagram of the sawtooth-shaped paving fixture in this invention; Figure 5 This is a schematic diagram showing the connection arrangement of the V-shaped preform and the core mold in this invention; Figure 6 This is a schematic diagram of the molding tooling of the present invention; Figure 7 This is a partial cross-sectional view of the molding tooling of the present invention; Figure 8 A schematic diagram showing different tooling states for the demolding clip; Figure 9 This is a schematic diagram of the ball bolt structure.

[0019] Among them: 1. Upper mold; 2. Upper core mold; 3. Lower core mold; 31. First lower core mold; 32. Second lower core mold; 33. Cavity; 34. Forming opening; 4. Demolding module; 5. Lower mold; 51. Clearance groove; 6. Demolding buckle; 61. Connecting bolt; 62. Ball bolt; 63. Connecting protrusion; 64. Slot; 65. Connecting groove; 7. Serrated laying fixture; 00. V-shaped preform; 01. Partial yarn filling. Detailed Implementation

[0020] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0021] It should be noted that in the description of this invention, the terms "front," "rear," "left," "right," "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "front," "rear," "left," "right," "upper," and "lower" used in the description of this invention refer to the directions shown in the accompanying drawings, while the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0022] To address the problems of the molding process mentioned in the background art, this application provides technical optimizations for such parts in the following ways: After use, the following problems were found that would occur with this process before optimization: Question 1: The prepreg is thicker before curing than after curing. Figure 2 As shown, the opening space at the top of the part is only 4.5mm. When the fluffy prepreg is laid, the actual opening space is only 2-3mm. Moreover, the edge of the material droops towards the middle. When the mold is closed, the male mold protruding from the upper mold cannot fully open the prepreg from the middle, which easily bends the material and presses it to the bottom, resulting in the bottom part being too thick and the tooling not being able to close the mold in place.

[0023] The optimization measures in this application are as follows: Figure 3 As shown, allowances are left on both sides of the lower core mold 3 to form a V-shape, making the V-shaped opening of the lower core mold 3 larger. When the mold is pressed and closed, the protruding male mold of the upper mold can be smoothly embedded in the middle of the material.

[0024] During installation, reuse materials such as... Figure 4 The serrated laying fixture 7 shown directly lays the preform into a V-shape, and the vacuum bagging and heating pre-pressing can keep the fibers of the preform smooth, straight and not twisted, and present a relatively hard V-shape.

[0025] like Figure 5 As shown, the bottom is partially filled with yarn (the part is not uniformly thick and conforms to the shape; it has an internal shaped surface, and there is more material at the two corners. A small amount of yarn is filled first to avoid the two sharp corners of the shape not being able to be pressed out). Then, the V-shaped preform 00 is placed in the cavity 33 of the lower core mold of the molding fixture. The pressure is slowly and evenly applied by the male mold protruding from the upper core mold 2, so that the fibers are evenly stressed and kept smooth and straight without twisting. In this way, the part will not be twisted and deformed due to the internal stress generated by the twisting of the fibers, resulting in poor straightness.

[0026] This process also has a second problem: because the tooling needs to be heated, the curing time is relatively long, and the parts also need to be disassembled and demolded after the tooling cools down. The efficiency is far inferior to that of the pultrusion production line. The curing time is determined by the properties of the material itself and cannot be changed. The only solution is to optimize the design of the tooling structure to achieve rapid demolding and rapid material loading, thereby reducing the manufacturing cycle.

[0027] To address the two issues mentioned above, this application designs a non-uniform cross-section slender part forming fixture, including a lower core mold 3 mounted on a lower mold 5 and an upper core mold 2 detachably connected to an upper mold 1. The top of the cavity 33 of the lower core mold 3 is provided with a forming opening 34, the size of the end of the forming opening 34 away from the cavity 33 is larger than the size of the end closer to the cavity 33; a plurality of ejector modules 4 are provided between the lower mold 5 and the lower core mold 3, and the length direction of the ejector modules 4 is perpendicular to the length direction of the lower core mold 3; the male mold of the upper core mold 2 is adapted to the cavity 33 of the lower core mold 3; the upper mold 1 is provided with ejector buckles 6 detachably connected to both ends of the ejector modules 4.

[0028] The molding fixture of this application has a molding opening 34 at the top of the cavity of the lower core mold. During use, the pre-made part can be placed on the molding opening 34. When the mold is closed, the protruding male mold of the upper core mold 2 can smoothly embed into the middle of the pre-made part, preventing the prepreg from being bent or pressed to the bottom, thus avoiding the problem of the bottom thickness of the part being too thick and the fixture failing to close properly. The straightness of the part obtained using this fixture meets the requirements. A release module 4 is provided between the lower mold 5 and the lower core mold 3. The length direction of the release module 4 is perpendicular to the length direction of the lower core mold 3, facilitating the detachment of the lower core mold from the lower mold 5. The upper mold has release buckles that are detachably connected to both ends of the release module. During demolding, the release buckles are connected to the release module, and the upper mold can drive the lower core mold to follow the release module and detach from the lower mold, allowing for quick and convenient removal of the lower core mold, facilitating demolding of the part and improving manufacturing efficiency.

[0029] The molding tooling of this application will be described below through a specific embodiment.

[0030] Forming tooling structure such as Figure 6 As shown, it mainly consists of an upper mold 1, an upper core mold 2, a lower mold 5, a lower core mold 3, a demolding module 4, a demolding clip 6, and several standard parts. The tooling of this application has four cavities, allowing for the molding of four parts at once. In other embodiments, the number of cavities in the tooling can be appropriately increased or decreased.

[0031] like Figure 7As shown, the upper core mold 2 is positioned on the upper mold 1 by its own shape and is locked at the back by bolts. Two sets of upper core molds are made at a time, totaling eight pieces, of which four pieces are used as interchangeable spare parts. This structure allows the upper core mold to be replaced with a spare when it suffers wear or damage after multiple uses, saving time on tooling mold repair. This application uses bolts to connect the upper core mold 2 and the upper mold 1, facilitating the replacement of the upper core mold 2.

[0032] The lower core mold 3 is a modular design, consisting of two parts: a first lower core mold 31 and a second lower core mold 32. The first and second lower core molds 31 and 32 are positioned by two locating pins. Specifically, the first and second lower core molds 31 and 32 have pin holes in their width direction to facilitate the connection of the locating pins. After connection, the left and right ends and the bottom of the first and second lower core molds 31 and 32 are flush, and the top surface forms a cavity 33. The lower core mold 3 uses the overall shape of the two parts for positioning on the lower mold 5. The segmented structure makes it easier to clean the corners of the tooling cavity, and the workpiece can be easily removed from the lower core mold 3.

[0033] The lower core mold 3 has a molding opening 34 at the top of its cavity 33. The size of the molding opening 34 at the end furthest from the cavity 33 is larger than the size at the end closest to the cavity 33. Furthermore, the shape of the molding opening 34 can be an inverted figure-eight, an arc, a V-shape, etc. The molding opening 34 is used to place the V-shaped preform 00. Therefore, the shape of the V-shaped preform 00 is adapted to the shape of the molding opening 34.

[0034] Furthermore, such as Figure 3-5 As shown, the molding opening 34 is preferably V-shaped. With this design, on the one hand, during the molding process, the V-shaped preform 00 is more easily pressed into the cavity 33 along the inclined surface of the molding opening 34; on the other hand, the V-shaped preform 00 is easier to produce than preforms of other shapes.

[0035] like Figure 4 As shown, this application provides a serrated laying fixture for forming V-shaped preforms 00, which has multiple V-forming cavities on a main body plate. Each V-forming cavity includes two symmetrical inclined surfaces, and the bottom ends of the two inclined surfaces are connected by an arc groove. The serrated laying fixture 7 designed in this application can form multiple V-shaped preforms 00 at one time.

[0036] The molding fixture of this application has a molding opening at the top of the cavity of the lower core mold. When in use, the pre-made V-shaped preform 00 can be placed on the molding opening first. When the mold is closed, the male mold protruding from the upper core mold can be smoothly embedded in the middle of the V-shaped preform 00. It will not bend the prepreg material to the bottom, and will not cause the bottom thickness of the part to be too thick, so that the fixture cannot be closed in place. The straightness of the part obtained by using this fixture can meet the requirements. The molding fixture of this application has a demolding module between the lower mold and the lower core mold, and a demolding buckle that can be detachably connected to both ends of the demolding module on the upper mold. When demolding, the demolding buckle is connected to the demolding module first, and the upper mold can drive the lower core mold to follow the demolding module and detach from the lower mold. The lower core mold can be removed quickly and easily, which facilitates the demolding of the part and improves the part manufacturing efficiency.

[0037] The demolding module 4 and the lower mold 5 are assembled as a whole. A set of tooling contains four demolding modules, each with bolt mounting holes at both ends for matching demolding clips 6. The installation position of the demolding clips 6 on the tooling is as follows: Figure 8 As shown, the demolding buckle 6 is connected to the upper mold 1 by a connecting bolt 61 of equal height, and the demolding buckle 6 can rotate around the connecting bolt 61 of equal height.

[0038] The upper mold 1 has a spherical connecting groove 65 near the mounting holes of the connecting bolts 61 at the same height. Under the action of force, the ball of the spherical ball bolt 62 will be pressed into the connecting groove 65. Therefore, the demolding buckle 6 will be held in place by the connecting groove 65 with the help of the ball bolt 62. When the demolding buckle 6 is in the horizontally open position, the spherical connecting groove 65 will hold the ball of the ball bolt 62, preventing the demolding buckle from rotating and sliding down due to its own weight. When demolding is required, a little force can be applied to put it in a vertical working state. In this state, the slot 64 on the demolding buckle 6 and the connecting protrusion 63 on the demolding module engage. If the press is opened at this time, since the upper mold is fixed to the upper pressure plate of the press with bolts / pressure plates, the four sets of lower core molds 3 will be pulled by the demolding module 4 and the demolding buckle 6 and will follow the upper mold 1 to separate from the lower mold 5. When the bottom of the demolding module is at a predetermined distance from the mold closing surface of the lower mold, a heat-insulating fiberglass plate can be inserted, and the demolding buckle 6 can be released so that the demolding module 4 and the lower core mold 3 fall on the fiberglass plate and can be lifted out as a whole.

[0039] In some further embodiments, the lower mold 5 is provided with multiple parallel lower core mold connecting grooves, and the lower core mold and the lower core mold connecting grooves can adopt a transition fit connection. For example... Figure 6 As shown, the lower mold 5 is provided with a relief groove 51, which is set along the width direction of the lower mold and perpendicular to the lower core mold connecting groove, so that there is a gripping point for the hand when each set of core molds is removed. The demolding module designed in this application can remove multiple sets of lower core molds 3 at the same time, and the design of the relief groove 51 facilitates the removal of a single set of lower core molds.

[0040] Furthermore, lifting rings are provided at both ends of the top surface of the demolding module 4, which facilitates the application of pulling force to the demolding module and makes demolding easier.

[0041] Based on the molding tooling of this application, this application also discloses a molding method, which includes the following steps: Step 1: Connect the upper mold 1 to the upper plate of the press, and the lower mold 5 to the lower plate of the press. This process involves connecting the upper mold 1 and the lower mold 5. A guide device is installed during installation to ensure accurate positioning when the film is closed. In this step, the upper core mold 2 is already connected to the upper mold, and the lower core mold 3 is already connected to the lower mold 5.

[0042] Step 2: Fill the two corners of the cavity of the lower core mold 3 with yarn, place the preform onto the forming opening 34 of the lower core mold 3, and partially fill with yarn as shown in step 01. Figure 5 As shown.

[0043] Step 3: Start the press to close the upper mold 1 and lower mold 5, and heat and pressurize to solidify and form the part.

[0044] Step 4: Connect the demolding clip 6 and the demolding module 4. This step is achieved by operating the ball bolt 62 and engaging the slot 64 on the demolding clip 6 with the connecting protrusion 63 on the demolding module.

[0045] Step 5: The press opens the mold, the ejector module 4 and the lower core mold 3 move with the upper mold 1 to separate from the lower mold 5, the ejector buckle 6 and the ejector module 4 are released, and the lower core mold 3 and the ejector module 4 separate from the upper mold 1 under the action of gravity.

[0046] Step 6: Remove the part from the lower core mold.

[0047] In step 2, the preform is a V-shaped preform 00. The method for obtaining the V-shaped preform 00 includes: laying the composite material in the V-forming cavity of the serrated laying fixture 7; vacuum bagging, heating and pre-pressing to obtain a V-shaped preform with a certain hardness.

[0048] In step 6, removing the part from the lower core mold includes: separating the lower core mold 3 and the demolding module 4; separating the first lower core mold 31 and the second lower core mold 32 of the lower core mold 3, and the part automatically detaches from the lower core mold 3.

[0049] The above steps can be as follows: Fix the upper mold to the upper platen of the press using bolts / pressure plates, and the lower mold to the lower platen of the press. Open the demolding clips and open the press. Remove the V-shaped preform from the serrated laying mold. Fill the two corners of the core mold cavity with yarn, and then press the V-shaped preform... Figure 5The design is placed on the lower core mold. The mold is closed, and the V-shaped preform is pressed into the cavity of the lower core mold by the protruding surface of the upper mold. It is then heated and pressurized to solidify. After the part has solidified, the demolding clips are removed (out of 8, only 4 symmetrically distributed clips need to be removed, meaning only 2 clips are needed for demolding), hooking them onto the connecting protrusions on the demolding clips. The press opens the mold, the lower core mold detaches from the lower mold, a fiberglass insulation board is placed inside, the demolding clips are released, and the lower core mold detaches from the upper mold under gravity, landing on the fiberglass board. The entire piece is then pulled out. The lower core mold is then pried open, the part is removed, and the core mold is quickly cleaned before being used for the next round of part solidification. Alternatively, two sets of lower core molds can be made. One set is removed from the press and cooled to room temperature, while the other set is placed directly on top with the part. After cooling, the removed core mold is pried open for demolding, cleaned, and ready for the next batch of replacements.

[0050] In summary, this application has the following advantages: (1) The above process methods and tooling help solve the problems of difficult laying, pressing, fiber twisting and operation difficulties that occur in the molding process of slender composite material parts.

[0051] (2) The press opens automatically to demold, and the hot demolding module and core module are pulled out by the glass fiber heat insulation board, avoiding the danger of employees being burned by the high temperature when taking the core mold. The operation is more convenient and safer.

[0052] (3) After removing the core mold from the demolding module with heat-resistant gloves, the part can be easily demolded by gently prying it off. The lower core mold can be quickly cleaned and used for the next round of part curing and molding. Alternatively, two sets of lower core molds can be made. After removing one set from the press, the other set can be placed directly on the part. The removed set can be cooled to room temperature. After cooling, the part can be demolded and cleaned before the next batch of replacements. This method is efficient, saves the time of the press constantly heating and cooling, and also improves the power consumption. (4) The V-shaped preform and core mold structure make feeding more convenient and faster.

[0053] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or equivalent to the scope of this invention are included in this invention.

Claims

1. A forming tooling for slender parts with non-uniform cross-sections, characterized in that, include: A lower core mold is installed on the lower mold. The top of the cavity of the lower core mold is provided with a forming opening. The size of the forming opening at the end away from the cavity is larger than the size at the end closer to the cavity, and it is V-shaped. Multiple ejector modules are provided between the lower mold and the lower core mold, and the length direction of the ejector modules is perpendicular to the length direction of the lower core mold. A detachable upper core mold is attached to the upper mold, the male part of the upper core mold being compatible with the cavity of the lower core mold; the upper mold is provided with demolding buckles that are detachably connected to both ends of the demolding module; The lower core mold includes a first lower core mold and a second lower core mold with the same structure; One end of the demolding buckle is rotatably connected to the upper mold via a connecting bolt, the middle part is connected with a ball bolt, and the other end is provided with a slot. The upper mold is provided with a connecting groove, and the ball bolt is connected to the connecting groove so that the demolding buckle is in the unlocked state; The demolding module is provided with a connecting protrusion. The ball bolt is disconnected from the groove, and the slot and the connecting protrusion are engaged to lock the demolding buckle.

2. The forming tooling for slender parts with non-uniform cross-sections according to claim 1, characterized in that, The size of the molding opening gradually decreases towards the end closer to the cavity.

3. The forming tooling for slender parts with non-uniform cross-sections according to claim 1, characterized in that, The lower mold is provided with a lower core mold connecting groove, and the lower core mold is engaged in the lower core mold connecting groove; The first lower core mold and the second lower core mold are positioned by at least two locating pins.

4. The forming tooling for slender parts with non-uniform cross-sections according to claim 1, characterized in that, The lower mold is provided with multiple parallel lower core mold connecting grooves so that the lower mold can connect multiple lower core molds.

5. The forming tooling for slender parts with non-uniform cross-sections according to claim 4, characterized in that, The lower mold is provided with a clearance groove that is perpendicular to the lower core mold connecting groove.

6. The forming tooling for slender parts with non-uniform cross-sections according to claim 1, characterized in that, The upper core mold is connected to the upper mold by bolts.

7. A forming method for forming a non-uniform cross-section slender part according to any one of claims 1-6, characterized in that, include: Connect the upper die to the upper plate of the press, and connect the lower die to the lower plate of the press; Fill the two corners of the cavity of the lower core mold with yarn, and place the preform onto the forming opening of the lower core mold; Start the press to close the upper and lower molds, and heat and pressurize to solidify and shape the part. Connect the release clip and the release module; The press opens the mold, and the ejector module and lower core mold follow the upper mold to detach from the lower mold. The ejector buckle and ejector module are released, and the lower core mold and ejector module detach from the upper mold under the action of gravity. Remove the part from the lower core mold.

8. The method for forming slender parts with non-uniform cross-sections according to claim 7, characterized in that, The method for obtaining the preform includes: The composite material is laid in the V-shaped cavity of the sawtooth laying fixture (7); Vacuum bag making involves heating and pre-pressing to obtain a V-shaped preform with a certain hardness.

9. The method for forming slender parts with non-uniform cross-sections according to claim 7, characterized in that, The process of removing the part from the lower core mold includes: Separate the lower core mold and the demolding module; Separate the first and second lower core molds.

Images