Inverted compression molding die for special-shaped heat insulation coating sleeve and production process

Abstract

The invention relates to the technical field of molds, in particular to an inverted compression molding mold for a special-shaped heat insulation coating sleeve and a production process, the inverted compression molding mold comprises an upper mold, a middle mold and a lower mold which are arranged from top to bottom, a feeding cavity is formed below the upper mold and the inner side of the middle mold and used for placing main materials, and the lower mold is used for molding an inner molded surface part of a product; the middle mold comprises a middle mold cavity and a middle mold outer frame. The middle mold cavity is divided into a front half shell and a rear half shell. According to the inverted compression molding die for the special-shaped heat insulation coating sleeve and the production process, a traditional convex-concave die structure is changed, an inverted upper, middle and lower die structure is adopted, a part of material sheets consistent with the thickness of a product are laid on the side walls of the middle die and the lower die in advance, and the remaining material sheets are extruded and filled from a feeding cavity; non-uniform flowing of materials in the mold pressing process is prevented to a great extent, deviation of the upper portion of the middle mold cavity is avoided, the wall thickness of a product can completely meet the design requirement, and the problem that the wall thickness of a special-shaped heat insulation coating sleeve is difficult to control is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of molds, in particular to an inverted compression molding mold and a production process for a special-shaped thermal insulation covering sleeve. Background Art

[0002] In the development process of a certain type of engine, the special-shaped insulation cover plays an indispensable role as a key component. Its typical structure presents unique design features, with a right-side fan-shaped cross-section, two straight sides with a thickness of 6mm, and a circular arc side with a thickness of only 3mm. The significant wall thickness difference puts strict requirements on the molding process; at the same time, the size of the opening end is 2.5mm smaller than the rear end, forming an inverted structure, which further increases the difficulty of manufacturing.

[0003] At present, the traditional male and female mold structures have exposed many drawbacks when dealing with the production of such special-shaped insulation covering sleeves. On the one hand, in the material laying process, if the material is laid on the side wall, it is very easy to wrinkle and entrap air during the pressure process, so the material can only be laid on the bottom of the die. However, due to the large depth of the cavity, it is difficult for the material to flow evenly during the molding process, resulting in the offset of the bottom of the punch, and ultimately causing the thickness of the outer arc edge to be insufficient and unable to meet the design requirements. Even if a guide plate or guide column and guide sleeve structure is set at the position of the mating surface in the traditional male and female mold structure, it is difficult to effectively control the offset problem of the bottom of the punch. On the other hand, the traditional mold structure is prone to generate negative pressure during the molding process, making the demolding process difficult. In addition, the product opening size is smaller than the middle section size, which not only makes compression molding difficult, but demolding becomes a major obstacle to production.

[0004] To solve the above problems, the existing process divides the product into two sections, pre-pressing them separately, and then bonding them through secondary vulcanization of the airbag. However, this process still has obvious defects. The product design thickness is difficult to accurately guarantee, and quality problems such as air inclusion and debonding are prone to occur during the molding process. At the same time, the production process is cumbersome, resulting in low production efficiency and unable to meet the growing production needs and quality standards.

[0005] Taking the patent with application number CN202011469396.6 (application publication number: CN112677391A) as an example, it involves a rapid pre-molding device for the thermal insulation layer of the head, which is mainly aimed at the pre-molding process of the thermal insulation layer of the head of the solid rocket engine. The device realizes the direct entry of the circulating medium inside the mold by setting water holes and series-parallel channels in the male mold and the female mold, thereby improving the heating and cooling rates of the mold and reducing energy consumption. However, the application scenario of this patent is limited to the thermal insulation layer of the head, and its mold structure and process cannot solve the molding and demolding problems faced by the present invention due to the large difference in wall thickness of the special-shaped thermal insulation covering sleeve and the smaller size of the opening end than the rear end size. The male mold and female mold positioning method adopted by it cannot avoid the uneven flow of materials and the offset of the bottom of the punch during the molding process when facing the complex special-shaped structure in the present invention, and it is also difficult to overcome the negative pressure and demolding difficulties caused by the depth of the cavity and the special structure of the product. Summary of the invention

[0006] The purpose of the present invention is to provide an inverted compression molding die and production process for a special-shaped insulating covering sleeve, so as to solve the problems raised in the above-mentioned background technology that when faced with the complex special-shaped structure in the present invention, it is impossible to avoid the uneven flow of materials and the deviation of the bottom of the punch during the molding process, and it is also difficult to overcome the negative pressure and demolding difficulties caused by the cavity depth and the special structure of the product.

[0007] To achieve the above object, the present invention provides an inverted compression molding die for a special-shaped thermal insulation covering sleeve, comprising an upper die, a middle die and a lower die arranged from top to bottom, wherein a feeding cavity is formed below the upper die and inside the middle die for placing the main material, and the lower die is used for molding the inner surface part of the product;

[0008] The middle mold includes a middle mold cavity and a middle mold outer frame. The middle mold cavity is divided into a front half shell and a rear half shell. After the front half shell and the rear half shell are spliced, the inner wall is consistent with the outer shape of the product. The outer wall of the middle mold cavity and the inner wall of the middle mold outer frame are precisely positioned by a cone. The middle mold outer frame and the lower mold are precisely positioned by a positioning component.

[0009] This setting ensures that the mold gap meets the design thickness requirements of the product, effectively solves the problem of difficult wall thickness control of special-shaped insulation covering sleeves, and lays the foundation for smooth demoulding.

[0010] As a preferred solution of the present invention, ejection holes are provided at the four corners of the upper mold, and a guide port is installed at the top of the middle mold outer frame near the ejection holes.

[0011] This setting effectively avoids mold damage or product deformation due to uneven force during the demoulding process, making the demoulding process smoother and more efficient, and improving the stability and reliability of demoulding.

[0012] As a preferred solution of the present invention, a mold base is installed at the bottom of the lower mold, and an annular overflow groove is opened on the top of the mold base. The annular overflow groove is located at the bottom of the inner wall of the middle mold cavity.

[0013] The annular overflow groove can timely accommodate and discharge excess material during the molding process, avoid material accumulation in the mold, and ensure the dimensional accuracy of the product molding.

[0014] As a preferred solution of the present invention, hanging ring openings are provided at the four corners of the mold base.

[0015] This setting facilitates the hoisting and handling of the mold, reduces the difficulty of operating the mold during transportation, installation and disassembly, improves work efficiency, and at the same time ensures the safety of operators and molds, and reduces the risk of mold damage caused by improper handling.

[0016] As a preferred solution of the present invention, the positioning assembly includes a guide column and a guide sleeve, the bottom end of the guide column is connected and fixed to the mold base, the top of the guide sleeve is connected and fixed to the middle mold outer frame, and the guide column and guide sleeve are slidably matched.

[0017] This setting ensures that all parts of the mold are accurately aligned during the mold closing process, effectively preventing the mold from shifting during the molding process, thereby ensuring the accuracy of the product molding size and the uniformity of the wall thickness, and improving product quality.

[0018] As a preferred solution of the present invention, an ejection plate is horizontally welded to the outer wall of the middle mold outer frame.

[0019] This setting reduces the local stress concentration on the outer frame of the center mold during the ejection process, prevents mold damage, and further improves demoulding efficiency and mold service life.

[0020] As a preferred solution of the present invention, the cross-section of the product is a fan-shaped structure, the front half shell is an arc portion, the rear half shell is a V-shaped straight edge, and the middle mold cavity is adapted to the shape of the lower mold.

[0021] The present invention also provides a production process of an inverted compression molding die for a special-shaped thermal insulation covering sleeve, which is used for the inverted compression molding die for the special-shaped thermal insulation covering sleeve, and comprises the following steps:

[0022] S1. Place and fix the lower mold;

[0023] S2, place a sheet with a thickness of 3 mm and a width of half the size on one side of the arc edge of the lower mold, and then place the back half shell of the middle mold cavity closely, and place a sheet with a width of half the size on the two straight sides of the lower mold from top to bottom, and then place the front half shell of the middle mold cavity closely, and roughly position it with a hexagonal screw;

[0024] S3, put the middle mold outer frame into it, and use the positioning component to accurately position the middle mold;

[0025] S4, put the remaining tablets into the feeding cavity between the middle mold and the upper mold, close the upper mold and start preheating molding;

[0026] S5. After the product is vulcanized and cooled, open the upper mold and clean up the overflow;

[0027] S6. Lift up the outer frame of the middle mold and remove it, disassemble and remove the front half shell and the back half shell of the middle mold cavity respectively, and blow out the product.

[0028] This setting realizes the orderly operation of each mold component and the reasonable laying of materials through clear process steps, ensuring the standardization and stability of the product molding process.

[0029] As a preferred solution of the present invention, a portion of the sheet having the same thickness as the product is first laid on the side walls of the middle mold and the lower mold, and the remaining sheet is squeezed and filled from the feeding cavity to prevent uneven flow of the material from causing the upper part of the middle mold cavity to shift.

[0030] This setting avoids the upper part of the middle model cavity from shifting due to uneven material flow, ensuring uniform wall thickness of the product and fully meeting the design requirements.

[0031] As a preferred solution of the present invention, before positioning the middle mold outer frame, lubricant is first applied to the matching surfaces of the guide pins and guide sleeves to reduce frictional resistance during positioning.

[0032] Applying lubricant in this setting can reduce the friction coefficient between the guide pin and the guide sleeve, making the positioning process of the middle mold frame smoother, reducing positioning time and improving production efficiency.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. In the inverted compression molding die and production process of the special-shaped thermal insulation covering sleeve, the traditional convex and concave mold structure is changed, and an inverted upper, middle and lower mold structure is adopted. Some sheets with the same thickness as the product are pre-laid on the side walls of the middle mold and the lower mold, and the remaining sheets are squeezed and filled from the feeding cavity. This greatly prevents the uneven flow of materials during the molding process and avoids the upper deviation of the middle mold cavity, so that the wall thickness of the product can fully meet the design requirements, effectively solving the problem of difficult control of the wall thickness of the special-shaped thermal insulation covering sleeve.

[0035] 2. In the inverted compression molding mold and production process of the special-shaped insulation covering sleeve, the upper mold is opened first during demoulding, and then the middle mold frame is lifted up, which solves the negative pressure problem caused by the excessive depth of the cavity and is conducive to demoulding; after the middle mold frame is removed, the middle mold cavity is divided into front and rear halves for disassembly, which effectively solves the problem of inverted demoulding caused by the smaller size of the opening end of the product than the rear end, making the demoulding process smoother and more efficient.

[0036] 3. In the inverted compression molding die and production process of the special-shaped insulation covering sleeve, compared with the traditional process of pre-compression molding the product in sections and then vulcanizing and bonding it, the present invention can mold a product that meets the design requirements in one time, avoiding quality problems such as air entrapment and debonding, reducing production processes, significantly improving production efficiency, reducing production costs, and fully meeting the production needs of this type of special-shaped insulation sleeve.

[0037] 4. In the inverted compression molding mold and production process of the special-shaped insulation covering sleeve, guide pins and guide sleeves are used for precise positioning between the middle mold frame and the lower mold, and the middle mold frame and the cavity part are positioned in a conical shape. The double positioning method ensures the precise positioning of the middle mold cavity part and the lower mold, thereby ensuring that the mold gap (product thickness) meets the design requirements and improves the molding accuracy of the mold and the stability of product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0039] Figure 2 It is a cross-sectional schematic diagram of the mold outer frame in the present invention;

[0040] Figure 3 It is a top view schematic diagram of the mold outer frame in the present invention;

[0041] Figure 4 is a cross-sectional schematic diagram of the model cavity in the present invention;

[0042] Figure 5 It is a top view schematic diagram of the model cavity in the present invention;

[0043] Figure 6 It is a top view schematic diagram of the mold base of the present invention;

[0044] Figure 7 It is a structural schematic diagram of the positioning assembly of the present invention;

[0045] Figure 8 It is a structural schematic diagram of the product to be processed of the present invention;

[0046] The meaning of each number in the figure is:

[0047] 1. Upper mold; 11. Ejector hole; 2. Middle mold outer frame; 21. Guide port; 3. Middle mold cavity; 31. Rear half shell; 32. Front half shell; 4. Lower mold; 5. Positioning assembly; 51. Guide post; 52. Guide sleeve; 6. Mold base; 61. Annular overflow groove; 62. Lifting ring port; 7. Ejector plate; 8. Feeding cavity; 9. Product. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] The present invention provides a special-shaped heat-insulating covering sleeve inverted molding die and production process, such as Figure 1 , Figure 5 As shown, it includes an upper mold 1, a middle mold and a lower mold 4 arranged from top to bottom, the lower part of the upper mold 1 and the inner side of the middle mold form a feeding cavity 8 for placing the main material, and the lower mold 4 is used to form the inner surface part of the product;

[0050] The middle mold includes a middle mold cavity 3 and a middle mold outer frame 2. The middle mold cavity 3 is divided into a front half shell 32 and a rear half shell 31. After the front half shell 32 and the rear half shell 31 are spliced, the inner wall is consistent with the outer shape of the product 9. The outer wall of the middle mold cavity 3 and the inner wall of the middle mold outer frame 2 are precisely positioned in a conical shape. The middle mold outer frame 2 and the lower mold 4 are precisely positioned by a positioning component 5.

[0051] Through the inverted mold structure, the traditional mold forming method is changed, and the setting of the feeding cavity 8 is convenient for material filling; the middle model cavity 3 is divided into a front half shell 32 and a rear half shell 31, and cooperates with the conical positioning and positioning component 5. On the one hand, it is convenient to deal with the problem of falling off caused by the small opening end of the product, and on the other hand, it ensures the accurate positioning of each mold component, thereby ensuring that the mold gap meets the design thickness requirements of the product, effectively solving the problem of difficult control of the wall thickness of the special-shaped insulation coating sleeve, and at the same time laying the foundation for smooth demoulding.

[0052] In this embodiment, Figure 1 , Figure 3 As shown, ejection holes 11 are opened at the four corners of the upper mold 1, and a guide port 21 is installed at the top of the middle mold outer frame 2 near the ejection holes 11.

[0053] The arrangement of the ejection hole 11 and the guide opening 21 provides a guide and a fulcrum for the ejection device during the demolding process, facilitating the ejection of the middle mold outer frame 2, and effectively avoiding mold damage or product deformation due to uneven force during the demolding process, making the demolding process smoother and more efficient, and improving the stability and reliability of demolding.

[0054] Specifically, Figure 1 As shown, a mold base 6 is installed at the bottom of the lower mold 4 , and an annular overflow groove 61 is opened on the top of the mold base 6 . The annular overflow groove 61 is located at the bottom of the inner wall of the middle mold cavity 3 .

[0055] The annular overflow groove 61 can timely accommodate and discharge excess material during the molding process, avoiding material accumulation in the mold and ensuring the dimensional accuracy of the product molding; at the same time, it prevents overflow from damaging the mold, extending the service life of the mold and ensuring the normal operation of the mold and the stability of product quality.

[0056] Further, such as Figure 1 As shown, the four corners of the mold base 6 are provided with hanging ring openings 62 .

[0057] The setting of the lifting ring 62 facilitates the lifting and transportation of the mold, reduces the operating difficulty of the mold during transportation, installation and disassembly, improves work efficiency, and at the same time ensures the safety of operators and molds, and reduces the risk of mold damage caused by improper transportation.

[0058] In addition, if Figure 1 , Figure 6 , Figure 7 As shown, the positioning assembly 5 includes a guide column 51 and a guide sleeve 52. The bottom end of the guide column 51 is connected and fixed to the mold base 6, and the top of the guide sleeve 52 is connected and fixed to the middle mold outer frame 2. The guide column 51 and the guide sleeve 52 are slidably matched.

[0059] The sliding fit between the guide pin 51 and the guide sleeve 52 provides precise positioning and guiding for the middle mold frame 2 and the lower mold 4, ensuring accurate alignment of the various components of the mold during the mold closing process, and effectively preventing the mold from shifting during the molding process, thereby ensuring the accuracy of the product molding size and the uniformity of the wall thickness, and improving product quality.

[0060] In addition, Figure 1 , Figure 2 , Figure 3 As described above, an ejector plate 7 is horizontally welded to the outer wall of the middle mold outer frame 2 .

[0061] The ejector plate 7 provides a larger force-bearing area for the ejection device, which facilitates the ejection of the middle mold outer frame 2 during demolding, making the ejection process smoother, reducing local stress concentration on the middle mold outer frame 2 during the ejection process, preventing mold damage, and further improving demolding efficiency and mold service life.

[0062] Further, such as Figure 5 , Figure 6 , Figure 8 The cross-section of the product 9 is a fan-shaped structure, the front half shell 32 is an arc portion, the rear half shell 31 is a V-shaped straight edge, and the middle mold cavity 3 is adapted to the shape of the lower mold 4.

[0063] The middle mold cavity 3 and the lower mold 4 are designed to match the shape of the product, which can better fit the appearance of the product 9 and ensure the quality of product molding. At the same time, the design of dividing the middle mold cavity 3 into the front half shell 32 and the rear half shell 31 matches the special structure of the product 9, effectively solving the problem of falling off caused by the opening end of the product being smaller than the rear end, ensuring that the product can be demoulded smoothly and meeting the special structural molding requirements of the special-shaped insulation covering sleeve.

[0064] The present invention also provides a production process of an inverted compression molding die for a special-shaped thermal insulation covering sleeve, which is used for the inverted compression molding die for the special-shaped thermal insulation covering sleeve, and comprises the following steps:

[0065] S1, placing and fixing the lower mold 4;

[0066] S2, place a sheet with a thickness of 3 mm and a width of half the size on one side of the arc edge of the lower mold 4, and then place the rear half shell 31 of the middle mold cavity 3 closely, and place sheets with a width of half the size on the two straight sides of the lower mold 4 from top to bottom, and then place the front half shell 32 of the middle mold cavity 3 closely, and roughly position it with a hexagonal screw;

[0067] S3, insert the middle mold outer frame 2, and accurately position the middle mold by relying on the positioning component 6;

[0068] S4, put the remaining tablets into the feeding cavity 8 between the middle mold and the upper mold 1, close the upper mold 1 and start preheating molding;

[0069] S5. After the product is vulcanized and cooled, open the upper mold 1 and clean up the overflow;

[0070] S6, lift up the middle mold outer frame 2 and remove it, disassemble and remove the front half shell 32 and the rear half shell 31 of the middle mold cavity 3 respectively, and blow out the product 9.

[0071] Through clear process steps, orderly operation of various mold components and reasonable laying of materials are achieved, ensuring the standardization and stability of the product molding process; first, part of the sheet is laid on the side wall of the mold, and the remaining sheet is squeezed and filled from the feeding cavity 8, which effectively prevents uneven flow of materials from causing the upper part of the middle model cavity 3 to shift, ensuring that the product wall thickness meets the design requirements; the step-by-step demoulding method solves the problems of too deep cavity and product inversion, making the demoulding process smoother and improving production efficiency and product quality.

[0072] Furthermore, by first laying a portion of the sheet having the same thickness as the product on the side walls of the middle mold and the lower mold 4, the remaining sheet is squeezed and filled from the feeding cavity 8 to prevent uneven flow of the material from causing the upper part of the middle mold cavity 3 to deviate.

[0073] This material laying method effectively controls the material flow, avoids the upper displacement of the middle model cavity 3 due to uneven material flow, ensures the uniform wall thickness of the product, can fully meet the design requirements, fundamentally solves the problem of difficult control of the wall thickness of the special-shaped insulation covering sleeve, and improves product quality and production stability.

[0074] Furthermore, before positioning the middle mold outer frame 2, lubricant is applied to the mating surfaces of the guide pillar 51 and the guide sleeve 52 to reduce friction resistance during positioning.

[0075] Applying lubricant can reduce the friction coefficient between the guide pin 51 and the guide sleeve 52, making the positioning of the middle mold frame 2 smoother, reducing positioning time and improving production efficiency; at the same time, reducing friction resistance can reduce the wear of mold components, extend the service life of the mold, and ensure the positioning accuracy of the mold and the stability of product quality.

[0076] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An inverted compression molding die for a special-shaped thermal insulation covering sleeve, characterized in that: It comprises an upper die (1), a middle die and a lower die (4) arranged from top to bottom, wherein a feeding cavity (8) is formed below the upper die (1) and inside the middle die for placing main materials, and the lower die (4) is used for forming the inner surface of the product; The middle mold comprises a middle mold cavity (3) and a middle mold outer frame (2); the middle mold cavity (3) is divided into a front half shell (32) and a rear half shell (31); the inner wall of the front half shell (32) and the rear half shell (31) after being spliced ​​is consistent with the outer shape of the product (9); the outer wall of the middle mold cavity (3) and the inner wall of the middle mold outer frame (2) are precisely positioned by a conical shape; and the middle mold outer frame (2) and the lower mold (4) are precisely positioned by a positioning component (5).

2. The inverted compression molding die for the special-shaped thermal insulation covering sleeve according to claim 1, characterized in that: The four corners of the upper mold (1) are provided with ejection holes (11), and the top of the middle mold outer frame (2) is provided with a guide opening (21) near the ejection holes (11).

3. The inverted compression molding die for the special-shaped thermal insulation covering sleeve according to claim 1, characterized in that: A die base (6) is installed at the bottom of the lower die (4), and an annular overflow groove (61) is provided at the top of the die base (6). The annular overflow groove (61) is located at the bottom of the inner wall of the middle mold cavity (3).

4. The inverted compression molding die for the special-shaped thermal insulation covering sleeve according to claim 3, characterized in that: The four corners of the mold base (6) are provided with hanging ring openings (62).

5. The inverted compression molding die for the special-shaped thermal insulation covering sleeve according to claim 1, characterized in that: The positioning assembly (5) comprises a guide column (51) and a guide sleeve (52); the bottom end of the guide column (51) is connected and fixed to the mold base (6); the top end of the guide sleeve (52) is connected and fixed to the middle mold outer frame (2); and the guide column (51) and the guide sleeve (52) are slidably matched.

6. The inverted compression molding die for the special-shaped thermal insulation covering sleeve according to claim 1, characterized in that: An ejection plate (7) is horizontally welded to the outer wall of the middle mold outer frame (2).

7. The inverted compression molding die for the special-shaped thermal insulation covering sleeve according to claim 1, characterized in that: The cross-section of the product (9) is a fan-shaped structure, the front half shell (32) is a circular arc portion, the rear half shell (31) is a V-shaped straight edge, and the middle mold cavity (3) is compatible with the shape of the lower mold (4).

8. A production process for an inverted compression molding die for a special-shaped thermal insulation covering sleeve, used for the inverted compression molding die for a special-shaped thermal insulation covering sleeve as claimed in any one of claims 1 to 7, characterized in that: The steps include: S1, placing and fixing the lower mold (4); S2, a sheet with a thickness of 3 mm and a width of half the size is placed on one side of the arc edge of the lower mold (4), and then the rear half shell (31) of the middle mold cavity (3) is placed closely thereon; sheets with a width of half the size are placed on the two straight sides of the lower mold (4) from top to bottom, and then the front half shell (32) of the middle mold cavity (3) is placed closely thereon, and roughly positioned with a hexagonal screw; S3, insert the middle mold outer frame (2), and use the positioning component (6) to accurately position the middle mold; S4, placing the remaining tablets into the feeding cavity (8) between the middle mold and the upper mold (1), closing the upper mold (1) and starting preheating molding; S5. After the product is vulcanized and cooled, the upper mold (1) is opened to clean the overflow; S6, lift up the middle mold outer frame (2) and remove it, disassemble and remove the front half shell (32) and the rear half shell (31) of the middle mold cavity (3), and blow out the product (9).

9. The production process of the inverted compression molding die for the special-shaped thermal insulation covering sleeve according to claim 8, characterized in that: By first placing a portion of the sheet having the same thickness as the product on the side walls of the middle mold and the lower mold (4), and then squeezing and filling the remaining sheet from the feeding cavity (8), it is prevented that uneven flow of the material causes the upper part of the middle mold cavity (3) to deviate.

10. The production process of the inverted compression molding die for the special-shaped thermal insulation covering sleeve according to claim 8, characterized in that: Before the middle mold outer frame (2) is positioned, lubricant is first applied to the matching surfaces of the guide pillar (51) and the guide sleeve (52) to reduce friction resistance during the positioning process.

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