A pressure-resistant easy-open lid basic cover stamping die

Abstract

A pressure-resistant, easy-open lid basic cover stamping die, wherein the lower die is primarily composed of a lower die base, a lower die core ring, a lower die core, a lower pressure ring, and a lower blade; and the upper die is primarily composed of an upper die base, an upper die core, an upper inner forming ring, an upper outer forming ring, and an upper blade. The die is characterized in that, for the new basic cover shape, the top of the lower die core ring of the lower die is designed to have a profile that matches the new cover shape, while the upper outer forming ring and the upper inner forming ring of the upper die are designed to have a profile and a suspended section that match the lower die core ring of the lower die above and below. The second blocking limit surface in Comparative Patent 2 is eliminated, and the avoidance space in Comparative Patent 2 is improved to include a profile on the top edge of the lower die core that matches the seventh arc segment, fourth straight segment, eighth arc segment, and fifth straight segment of the new cover shape. This solution, while adapting to the new cover shape, solves the reliability and service life issues of the original easy-open lid basic cover stamping die during use.

Description

Technical Field

[0001] The present invention relates to a stamping die for cans, and more specifically, to a stamping die for a basic open lid used on a punch press. A basic lid, commonly known as a "blank lid," is a lid that has been formed but has not yet been scored or fitted with a pull ring. Background Art

[0002] As people's living standards improve, cans are increasingly used in the food and beverage industry, particularly in beer and beverage packaging. A can consists of a can body and a lid. The lid is typically first stamped from sheet metal through a die into a base lid (plain lid). The base lid is then scored and fitted with a pull ring to create the finished product. Forming and fabricating the base lid is the core of lid production, so for lid manufacturers, choosing the right stamping die is crucial for ensuring both production output and quality.

[0003] For positive pressure cans (with positive gas pressure inside), the basic cover of the easy-open lid is just a cover body, but in order to improve its pressure bearing capacity (pressure resistance), its cross-sectional shape and structure need to be complex and specially designed. Figure 1 As shown in the figure, the cross-section of the basic lid, from the periphery to the center, comprises the can sealing area, the countersunk section, the arc section of the insert ring, the upward extension section of the insert ring, and the central cover surface. An annular groove is formed between the countersunk section and the upward extension section of the insert ring. To stamp out the basic lid of the easy-open lid, a matching stamping die must be designed.

[0004] Chinese Patent CN102176989B (hereinafter referred to as "Comparative Patent 1"), issued on April 29, 2015, granted an invention patent entitled "Method and Apparatus for Forming a Can Shell," with patent number 200980140308.3. This patent discloses a stamping die for producing a basic cover for a can lid. However, overall, the following issues arise: first, the die's structural design is complex, particularly the design of the gas path within the die, making it difficult and costly to manufacture; and second, the basic covers produced by the stamping die vary in shape.

[0005] Chinese Patent CN202239263U (hereinafter referred to as "Comparative Patent 1"), issued on May 30, 2012, granted a utility model patent entitled "Pressure-Resistant Easy-Open Lid Basic Cover Stamping Die," with patent number 201120355905.2. This patent is the closest prior art in this case and also represents the applicant's own prior patented technology. Due to changes in the shape of easy-open lid basic covers, previous easy-open lid basic cover stamping dies have also exposed certain deficiencies in practical applications, such as the susceptibility of the upper press ring's active surface to wear, the tendency of the upper press ring's corresponding basic cover portion to become thinner during stretch forming, and the tendency of the upper die core flange to crack. These factors negatively impact the reliability and service life of these easy-open lid basic cover stamping dies during use.

[0006] In view of this, on the basis of adapting to the new easy-open lid basic cover type, how to improve the original easy-open lid basic cover stamping die to overcome the above-mentioned shortcomings is the subject of the present invention. Summary of the Invention

[0007] The invention provides a pressure-resistant easy-open lid basic cover stamping die, which aims to solve the problems of reliability and service life of the original easy-open lid basic cover stamping die during use on the basis of adapting to new cover types.

[0008] To achieve the above object, the technical solution adopted by the present invention is: a pressure-resistant easy-open lid basic cover stamping die, which consists of a lower die and an upper die.

[0009] The lower die is mainly composed of a lower die base, a lower die core ring, a lower die core, a lower press ring and a lower knife, wherein:

[0010] The lower die base is a cylinder with an open top.

[0011] The lower die core ring is an annular body, which is fixed in the lower die base and is concentric with the lower die base;

[0012] The active part of the lower mold core is a columnar body, which is embedded in the lower mold core ring and slides with the lower mold core ring in the upper and lower directions; the lower mold core ring is sealed below the lower mold core to form a first air chamber, and the air pressure of the first air chamber is used to support the lower mold core.

[0013] The lower pressing ring is an annular body, which is embedded between the lower die base and the lower die core ring, and a second air chamber is formed between the lower die base and the lower die core ring below the lower pressing ring. The air pressure of the second air chamber is used to support the lower pressing ring.

[0014] The lower knife is an annular body, which is fixed on the upper open edge of the lower die base, and the lower blade is arranged on the inner edge of the top of the annular body.

[0015] The upper die is mainly composed of an upper die base, an upper die core, an upper inner forming ring, an upper outer forming ring and an upper cutter, wherein:

[0016] The upper die base is a cylinder with an open bottom.

[0017] The active portion of the upper mold core is a columnar body, located concentrically within the upper mold base. The upper mold core slides vertically relative to the upper mold base. A third air chamber is formed within the upper mold base above the upper mold core, and the air pressure in this third air chamber is used to press against the upper mold core.

[0018] The upper inner molding ring is an annular body, which is embedded between the upper mold core and the upper mold base. A fourth air chamber is formed between the upper mold core and the upper mold base above the upper inner molding ring. The air pressure of the fourth air chamber is used to press the upper inner molding ring.

[0019] The upper outer molding ring is an annular body, which is embedded between the upper mold base and the upper inner molding ring. A fifth air chamber is formed between the upper mold base and the upper inner molding ring above the upper outer molding ring. The air pressure of the fifth air chamber is used to press the upper outer molding ring.

[0020] The upper knife is an annular body fixed on the lower open edge of the upper die seat, and an upper blade that cooperates with the lower blade is provided on the outer edge of the bottom end of the upper knife.

[0021] Its innovation lies in: for the basic cover, the basic cover is formed by the tangential connection of the sealing area, the countersunk section, the embedded ring arc section, the embedded ring upward extension section and the center cover surface in sequence from the periphery to the center in cross section, wherein an annular groove is formed between the countersunk section, the embedded ring arc section and the embedded ring upward extension section; the sealing area is composed of the tangential connection of the first straight line segment, the first circular arc segment, the second circular arc segment and the third circular arc segment; the countersunk section is composed of the tangential connection of the second straight line segment, the fourth circular arc segment, the fifth circular arc segment, the sixth circular arc segment and the third straight line segment; the embedded ring arc segment is composed of the seventh circular arc segment; the embedded ring upward extension section is composed of the tangential connection of the fourth straight line segment and the eighth circular arc segment; and the center cover surface is composed of the fifth straight line segment.

[0022] The upper outer molding ring and the upper inner molding ring of the upper mold are arranged in vertical relation to the lower mold core ring of the lower mold, wherein the top of the lower mold core ring is provided with a contour corresponding to and matching the first straight line segment, the first arc segment, the second arc segment, the third arc segment, the second straight line segment, the fourth arc segment, the fifth arc segment, the sixth arc segment, and the third straight line segment of the basic cover. The bottom of the upper outer molding ring is provided with a contour corresponding to and matching the second arc segment of the basic cover, and the portion of the bottom of the upper outer molding ring corresponding to the first and third arc segments of the basic cover is suspended relative to the top of the lower mold core ring when the mold is closed. The bottom of the upper inner molding ring is provided with a contour corresponding to and matching the fourth and fifth arc segments of the basic cover, and the portion of the bottom of the upper inner molding ring corresponding to the second straight line segment, the sixth arc segment, and the third straight line segment of the basic cover is suspended relative to the top of the lower mold core ring when the mold is closed.

[0023] The upper mold core of the upper mold and the lower mold core of the lower mold are arranged in a vertically opposed relationship. The top of the lower mold core is provided with a contour corresponding to and matching the seventh arc segment, the fourth straight segment, the eighth arc segment, and the fifth straight segment of the basic cover. The bottom of the upper mold core is provided with a contour corresponding to and matching the fifth straight segment of the basic cover.

[0024] The relevant contents of the above technical solution are explained as follows:

[0025] 1. In the above solution, the bottom of the upper mold core corresponds to the seventh arc segment, the fourth straight line segment and the eighth arc segment of the basic cover and is suspended relative to the top of the lower mold core in the mold closing state, thereby forming a stamping mold without pre-forming.

[0026] 2. In the above solution, the bottom of the upper mold core is provided with a contour corresponding to the eighth arc segment of the basic cover, and the bottom of the upper mold core (13) corresponding to the seventh arc segment and the fourth straight line segment of the basic cover is suspended relative to the top of the lower mold core in the mold closing state, thereby forming a pre-formed stamping die.

[0027] The design principle and concept of the present invention are: in order to solve the reliability and service life problems of the original easy-open lid basic lid stamping die during use on the basis of adapting to the new lid shape, the present invention mainly adopts the following improvement measures: first, the top of the lower die core ring of the lower die is designed to have a contour corresponding to the new lid shape, and at the same time, the upper outer forming ring and the upper inner forming ring of the upper die are designed to have a contour and a suspended section that match the lower die core ring of the lower die; second, the second blocking limit surface in the comparative patent 2 (i.e., the second blocking limit surface in the comparative patent 2) is cancelled. Figure 2 Third, the avoidance space between the lower mold core and the top of the lower mold core ring in the comparative patent 2 (i.e., the "avoidance space 11" recorded in the last line of paragraph

[0020] of the specification of the comparative patent 2) is improved as follows: the top edge of the lower mold core is provided with contours corresponding to the seventh arc segment, the fourth straight segment, the eighth arc segment and the fifth straight segment of the new cover shape.

[0028] Due to the application of the above technical solution, the present invention has the following advantages and effects compared with the prior art:

[0029] 1. Compared with Comparative Patent 2, the present invention offers significant advantages in the mold structure design for the easy-open lid basic cover. In Comparative Patent 2 (see the description and accompanying drawings of Comparative Patent 2), the can sealing area 41, upper transition arc 46, and upper countersunk section 47 of the easy-open lid basic cover are formed by the combined action of the annular bevel at the bottom end face of the upper forming ring 32 and the bottom end face of the upper press ring 14. During molding, a downward-facing second blocking surface 34 is provided on the outer periphery of the upper forming ring 32, which mates with the top of the upper press ring 14, ensuring that the annular bevel at the bottom end face of the upper forming ring 32 and the bottom end face of the upper press ring 14 maintain a precisely fixed height difference. At this fixed drop, the annular inclined surface of the bottom end face of the upper forming ring 32 and the outer contour of the bottom end face of the upper pressing ring 14 correspond to the outer contours of the sealing area 41, the upper transition arc 46 and the upper countersunk section 47 of the basic cover of the easy-open lid, thereby ensuring the stability of the outer contours of the sealing area 41, the upper transition arc 46 and the upper countersunk section 47 of the basic cover of the easy-open lid. The upper forming ring 32 and the upper pressing ring 14 of this structure must not only ensure the accuracy of the annular inclined surface of the bottom end face of the upper forming ring 32 and the bottom end face of the upper pressing ring 14, but also ensure the relative accuracy between the annular inclined surface of the bottom end face of the upper forming ring 32 and the bottom end face of the upper pressing ring 14, which increases the difficulty of processing and manufacturing. Moreover, after the easy-open lid basic cover stamping die has been running for a period of time, the annular inclined surface of the bottom end face of the upper forming ring 32 and the bottom end face of the upper pressing ring 14 will produce different degrees of surface wear. At this time, it is impossible to ensure that the annular inclined surface of the bottom end face of the upper forming ring 32 and the bottom end face of the upper pressing ring 14 maintain the initially set drop. At the same time, the air spring force acting on the upper forming ring 32 is transmitted to the upper pressing ring 14 via a second blocking surface 34 provided on the outer periphery of the upper forming ring 32, which faces downward and engages with the top of the upper pressing ring 14. This causes excessive force on the upper pressing ring 14, thereby causing increased surface wear on the bottom end surface of the upper pressing ring 14. The structure of the easy-open lid basic lid stamping die design of the present invention effectively solves this problem.

[0030] 2. Compared with Comparative Patent 2, the present invention utilizes a more advanced mold forming principle for the easy-open lid basic cover. In Comparative Patent 2 (see the description and accompanying drawings of the comparative patent), the insert ring arc segment 42 and the insert ring upward extension segment 43 of the easy-open lid basic cover are formed by the flange 16 on the upper mold core 13 and the avoidance space 11 for insert ring forming on the lower mold 2. During the entire insert ring forming process, the blank is limited by the flange 16 on the upper mold core 13, resulting in the blank of the insert ring arc segment 42 and the insert ring upward extension segment 43 becoming thinner, affecting the performance of the easy-open lid basic cover. In addition, the rounded corner radius of the flange 16 on the upper mold core 13 must be greater than or equal to 0.4 mm, that is, the rounded corner radius of the basic cover insert ring arc segment 42 must be greater than or equal to 0.4 mm. If it is less than 0.4 mm, the blank will directly crack during the insert ring forming process. At the same time, the flange 16 on the upper mold core 13 is very thin, making it prone to breakage during operation of the easy-open lid basic cover mold. Consequently, the service life of the upper mold core 20 is reduced. In contrast, in the present invention (see the accompanying drawings), the seventh arc segment R7 (the embedded ring arc segment) and the fourth straight line segment L4 of the easy-open lid basic cover are formed by natural bending. During the molding process, the annular groove 11 on the outer side of the top end surface of the lower mold core 5 serves as a support and limiter. The blanks of the seventh arc segment R7 (the embedded ring arc segment) and the fourth straight line segment L4 of the basic cover produced using the mold of the present invention do not become thinner. Therefore, the easy-open lid basic cover mold of the present invention produces basic covers with improved performance, namely, higher pressure resistance. Furthermore, the easy-open lid basic cover mold of the present invention can form seventh arc segments R7 (the embedded ring arc segment) with smaller corner radiuses, with the smallest corner radius capable of forming seventh arc segments R7 (the embedded ring arc segment) being 0.25 mm. The smaller the radius of the seventh arc segment R7 (the ring-embedded arc segment), the higher the pressure resistance of the basic lid. Therefore, the basic lid produced by the easy-open lid basic lid mold of the present invention has a higher pressure resistance. Furthermore, the upper mold core 20 of the upper mold core 13 of the present invention lacks a thin-walled flange structure on its bottom end surface, thus extending the service life of the upper mold core 20 of the present invention.

[0031] 3. Compared with the comparative patent 1, the air chamber structure of the present invention is simpler. Figure 1In the patent specification and accompanying drawings (see the comparative patent description), the air pressure of the annular outer pressure sleeve 55 enters through port 92, passes through the annular chamber 91 and the annular air pressure chamber 89, and ultimately acts on the annular outer pressure sleeve 55. The air pressure of the annular inner pressure sleeve 80 enters through port 74, passes through channel 76, reaches the air storage chamber 70, and then passes through the second air channel 88 to reach the second air piston chamber 84, ultimately acting on the annular inner pressure sleeve 80. This air chamber structure makes the air passage of the annular inner pressure sleeve 80 very complex, increasing the processing cost of the parts. At the same time, the air pressure inlet port 92 of the annular outer pressure sleeve 55 and the air pressure inlet port 74 of the annular inner pressure sleeve 80 are distributed at the left and right ends of the processing assembly 35. This distribution of the air inlet ports results in very limited operating space for the air inlet ports 92 and 74 when producing multiple processing assemblies 35 in two rows, making them impossible to operate and install.

[0032] 4. In the appendix of comparative patent 1 Figure 2 In the embodiment (see the comparative patent specification and drawings), the air pressure of the annular outer pressure sleeve 55 enters through port 92, passes through the annular chamber 91 and the annular air pressure chamber 89, and ultimately acts on the annular outer pressure sleeve 55. The air pressure of the annular inner pressure sleeve 80 enters through port 92, passes through the annular chamber 91 and the third channel 135, reaches the air storage chamber 70, and then passes through the second air channel 88 to the second air piston chamber 84, ultimately acting on the annular inner pressure sleeve 80. This air chamber structure complicates the air passages of the annular inner pressure sleeve 80, increasing the processing cost of the parts. Furthermore, the air pressure acting on the annular outer pressure sleeve 55 and the annular inner pressure sleeve 80 is the same. When setting the air pressure of the annular outer pressure sleeve 55 and the annular inner pressure sleeve 80, the larger of the air pressures required by the annular outer pressure sleeve 55 and the annular inner pressure sleeve 80 must be used. This results in a higher set pressure for one of the pressure sleeves. The higher the air pressure, the more severe the surface wear of the parts, the shorter the part life, and the more severe the thinning of the blank. In the present invention (see the accompanying drawings of the present invention), the air pressure of the upper inner molding ring 32 enters from the upper molding ring air inlet port 40, passes through the fourth air chamber 28, and finally acts on the upper inner molding ring 32. The air pressure of the upper outer molding ring 14 enters from the upper pressing ring air inlet port 41, passes through the fifth air chamber 33, and finally acts on the upper outer molding ring 14. Therefore, the air chamber structure of the present invention is simple, and the air pressure of the upper inner molding ring 32 and the upper outer molding ring 14 can be set independently, which can make the air pressure setting of the upper inner molding ring 32 and the upper outer molding ring 14 more reasonable. In addition, the upper molding ring air inlet port 40 and the upper pressing ring air inlet port 41 are distributed on the same side of the easy-open lid basic cover mold. When producing double-row multiple easy-open lid basic cover molds, the upper molding ring air inlet port 40 and the upper pressing ring air inlet port 41 are more convenient to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Attachment Figure 1 A partial cross-sectional view of the basic easy-open lid (new lid type) manufactured by the present invention;

[0034] Attachment Figure 2 This is a cross-sectional view of a stamping die without a preform in Example 1 of the present invention, showing a state where the upper die and the lower die are separated;

[0035] Attachment Figure 3 This is a cross-sectional view of the stamping die without preforming in Example 1 of the present invention, which shows the state of the upper die and the lower die at the bottom dead center of the punch press, that is, the state when the basic cover of the easy-open lid is formed in the forward direction;

[0036] Attachment Figure 4 This is a cross-sectional view of the stamping die without preforming in Example 1 of the present invention, which shows the state of the upper die and the lower die when the basic cover of the easy-open lid is completely formed;

[0037] Attachment Figure 5 This is a partial enlarged view of the stamping process of Example 1 of the present invention;

[0038] Attachment Figure 6 This is a partial enlarged view of the second stamping process of Example 1 of the present invention;

[0039] Attachment Figure 7 This is a partial enlarged view of the stamping process of Example 1 of the present invention;

[0040] Attachment Figure 8 This is a partial enlarged view of the stamping process of Example 1 of the present invention;

[0041] Attachment Figure 9 This is a partial enlarged view of the fifth stamping process of Example 1 of the present invention;

[0042] Attachment Figure 10 This is a partial enlarged view of the sixth stamping process of Example 1 of the present invention;

[0043] Attachment Figure 11 This is a partial enlarged view of the stamping process of Example 1 of the present invention;

[0044] Attachment Figure 12 This is an enlarged view of a part of the stamping process of Example 1 of the present invention;

[0045] Attachment Figure 13 This is a partial enlarged view of the ninth stamping process of Example 1 of the present invention;

[0046] Attachment Figure 14 This is a partial enlarged view of the stamping process of Example 1 of the present invention;

[0047] Attachment Figure 15 This is a partial enlarged view of the stamping process of Example 1 of the present invention;

[0048] Attachment Figure 16 A cross-sectional view of a preforming stamping die according to embodiment 2 of the present invention is shown, showing a state where the upper die and the lower die are separated;

[0049] Attachment Figure 17 This is a partial enlarged view of the stamping process of Example 2 of the present invention;

[0050] Attachment Figure 18 This is a partial enlarged view of the second stamping process of Example 2 of the present invention;

[0051] Attachment Figure 19 This is a partial enlarged view of the stamping process of Example 2 of the present invention;

[0052] Attachment Figure 20 This is a partial enlarged view of the stamping process of Example 2 of the present invention;

[0053] Attachment Figure 21 This is a partial enlarged view of the fifth stamping process of Example 2 of the present invention;

[0054] Attachment Figure 22 This is a partial enlarged view of the sixth stamping process of Example 2 of the present invention;

[0055] Attachment Figure 23 This is a partial enlarged view of the seventh part of the stamping process of Example 2 of the present invention;

[0056] Attachment Figure 24 This is an enlarged view of a part of the stamping process of Example 2 of the present invention;

[0057] Attachment Figure 25 This is a partial enlarged view of the ninth stamping process of Example 2 of the present invention;

[0058] Attachment Figure 26 This is a partial enlarged view of the stamping process of Example 2 of the present invention;

[0059] Attachment Figure 27 This is a partial enlarged view of the stamping process of Example 2 of the present invention.

[0060] In the figure above: 1. Upper mold; 2. Lower mold; 3. Lower mold base; 4. Lower mold core ring; 5. Lower mold core; 6. Lower pressure ring; 7. Lower knife; 8. First air chamber; 9. Second air chamber; 10. Lower blade; 11. Annular groove for supporting and limiting the insert ring molding; 12. Upper mold base; 13. Upper mold core; 14. Upper outer molding ring; 15. Upper knife; 16. R angle of upper mold core; 17. Third air chamber; 18. Upper blade; 19. Upper mold core base; 20. Upper mold core body; 21. Lower mold core base; 22. Lower mold core body; 23. Exhaust hole 1; 24. Exhaust hole 2; 25. Exhaust hole; 26. Basic cover when forward molding is completed; 27. Basic cover after complete forming; 28. Fourth air chamber; 29. ​​First blocking limit surface; 30. Basic cover blank; 31. Annular depression; 32. Upper inner molding ring; 33. Fifth air chamber; 40. Air inlet port of upper inner molding ring; 41. Air inlet port of upper inner molding ring; R1. First arc segment; R2. Second arc segment; R3. Third arc segment; R4. Fourth arc segment; R5. Fifth arc segment; R6. Sixth arc segment; R7. Seventh arc segment; R8. Eighth arc segment; L1. First straight line segment; L2. Second straight line segment; L3. Third straight line segment; L4. Fourth straight line segment; L5. Fifth straight line segment. DETAILED DESCRIPTION

[0061] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0062] The embodiment of the present invention is directed to the basic cover structure of the pressure-resistant easy-open cover (new cover type), see Figure 1 As shown: the cross section of the basic cover is composed of the can sealing area, the countersunk section, the embedded ring arc section, the embedded ring upward extension section and the central cover surface from the periphery to the center, and an annular groove is formed between the countersunk section, the embedded ring arc section and the embedded ring upward extension section (see Figure 1 ).

[0063] The can sealing area is composed of a first straight line segment L1, a first arc segment R1, a second arc segment R2 and a third arc segment R3, wherein:

[0064] One end of the first straight line segment L1 is connected to the first end of the first arc segment R1, and the first straight line segment L1 is tangent to the first arc segment R1, the second end of the first arc segment R1 is connected to the first end of the second arc segment R2, and the first arc segment R1 is tangent to the second arc segment R2, the second end of the second arc segment R2 is connected to the first end of the third arc segment R3, and the second arc segment R2 is tangent to the third arc segment R3.

[0065] The countersunk segment is composed of a second straight segment L2, a fourth arc segment R4, a fifth arc segment R5, a sixth arc segment R6 and a third straight segment L3, wherein:

[0066] The second end of the third arc segment R3 is connected to the first end of the second straight line segment L2, and the third arc segment R3 is tangent to the second straight line segment L2. The second end of the second straight line segment L2 is connected to the first end of the fourth arc segment R4, and the second straight line segment L2 is tangent to the fourth arc segment R4. The second end of the fourth arc segment R4 is connected to the first end of the fifth arc segment R5, and the fourth arc segment R4 is circumscribed to the fifth arc segment R5. The second end of the fifth arc segment R5 is connected to the first end of the sixth arc segment R6, and the fifth arc segment R5 is inscribed to the sixth arc segment R6. The second end of the sixth arc segment R6 is connected to the first end of the third straight line segment L3, and the sixth arc segment R6 is tangent to the third straight line segment L3.

[0067] The embedded circular arc segment is composed of the seventh circular arc segment R7, wherein:

[0068] The second end of the third straight line segment L3 is connected to the first end of the seventh arc segment R7, and the third straight line segment L3 is tangent to the seventh arc segment R7.

[0069] The upward extension section of the embedded ring is composed of a fourth straight line segment L4 and an eighth arc segment R8, wherein:

[0070] The second end of the seventh arc segment R7 is connected to the first end of the fourth straight line segment L4, and the fourth straight line segment L4 is tangent to the seventh arc segment R7. The second end of the fourth straight line segment L4 is connected to the first end of the eighth arc segment R8, and the fourth straight line segment L4 is tangent to the eighth arc segment R8.

[0071] The central cover surface is composed of a fifth straight line segment L5, wherein:

[0072] The second end of the eighth arc segment R8 is connected to one end of the fifth straight line segment L5, and the eighth arc segment R8 is tangent to the fifth straight line segment L5.

[0073] Example 1: A pressure-resistant easy-open lid basic cover stamping die (stamping die without preforms)

[0074] like Figure 1-3 As shown, the stamping die consists of two parts: the lower die 2 and the upper die 1 (see Figure 2 ).

[0075] The lower die 2 is mainly composed of a lower die base 3, a lower die core ring 4, a lower die core 5, a lower pressure ring 6 and a lower knife 7 (see Figure 2 ), wherein: the lower die base 3 is a cylinder with an open top (see Figure 2 The lower die core ring 4 is an annular body, which is fixed in the opening of the lower die base 3 by positioning pins and bolts, and is concentric with the lower die base 3 (see Figure 2 The lower mold core 5 is composed of a lower mold core seat 21 and a lower mold core body 22 (see Figure 2), the lower mold core seat 21 is fixedly connected to the lower mold core body 22, the working part of the lower mold core 5 is the lower mold core body 22, the lower mold core body 22 is a columnar body, the columnar body is embedded in the lower mold core ring 4 and slides with the lower mold core ring 4 in the up and down directions (see Figure 2 The lower mold core ring 4 is sealed below the lower mold core 5 to form a first air chamber 8 (see Figure 2 ), the air pressure of the first air chamber 8 is used to support the lower mold core 5. The lower mold core body 22 is provided with an exhaust hole 1 23 and an exhaust hole 24 (see Figure 2 ), used for exhaust when stamping the basic cover. The lower pressing ring 6 is an annular body, which is embedded between the lower die base 3 and the lower die core ring 4 (see Figure 2 ), and a second air chamber 9 is formed between the lower die base 3 and the lower die core ring 4 below the lower press ring 6. The air pressure of the second air chamber 9 is used to support the lower press ring 6 (see Figure 2 The lower knife 7 is an annular body, which is fixed on the upper open edge of the lower die base 3, and a lower blade 10 is provided on the inner edge of the top of the annular body (see Figure 2 ).

[0076] The upper die 1 is mainly composed of an upper die base 12, an upper die core 13, an upper inner forming ring 32, an upper outer forming ring 14 and an upper knife 15 (see Figure 2 ), wherein: the upper mold base 12 is a cylindrical body with an open bottom. The upper mold core 13 is composed of an upper mold core base 19 and an upper mold core body 20 (see Figure 2 ), the upper die core seat 19 is fixedly connected to the upper die core body 20 by bolts and pads (see Figure 2 ), the action part of the upper mold core 13 is the upper mold core body 20, which is a columnar body. The columnar body is arranged in the upper mold base 12 and is concentric with the upper mold base 12 (see Figure 2 The upper mold core 13 slides in the vertical direction relative to the upper mold base 12, and the upper mold core body 20 is provided with an exhaust hole 25 (see Figure 2 ), used for exhaust when stamping the basic cover. The bottom corner of the upper mold core body 20 is provided with an upper mold core R angle 16 (see Figure 2 The upper mold base 12 is sealed to form a third air chamber 17 above the upper mold core 13. The air pressure of the third air chamber 17 is used to press the upper mold core 13. The upper inner molding ring 32 is an annular body, which is embedded between the upper mold core 13 and the upper mold base 12 (see Figure 2 ), a fourth air chamber 28 is formed between the upper mold core 13 and the upper mold base 12 above the upper inner molding ring 32 (see Figure 2 ), the air pressure of the fourth air chamber 28 is used to press the upper inner molding ring 32, and the fourth air chamber 28 is provided with an upper inner molding ring air inlet port 40 on the upper mold base 12 (see Figure 2 The upper outer molding ring 14 is an annular body, which is embedded between the upper mold base 12 and the upper inner molding ring 32 (see Figure 2 ), a fifth air chamber 33 is formed between the upper die seat 12 and the upper inner molding ring 32 above the upper outer molding ring 14 (see Figure 2 The air pressure of the fifth air chamber 33 is used to press the upper outer mold ring 14. The fifth air chamber 33 is provided with an upper inner mold ring air inlet port 41 on the upper mold base 12. The upper blade 15 is an annular body fixed to the lower open edge of the upper mold base 12. The upper blade 15 has an upper blade 18 on its bottom outer edge that cooperates with the lower blade 10.

[0077] This embodiment, based on adapting to the new cover type, has made improvements in the following aspects in order to solve the reliability and service life issues of the original easy-open cover basic cover stamping die during use:

[0078] For the basic cover (see Figure 1 ), the basic cover is formed by the tangential connection of the can sealing area, the countersunk section, the embedded ring arc section, the embedded ring upward extension section and the center cover surface in the cross section from the periphery to the center, wherein an annular groove is formed between the countersunk section, the embedded ring arc section and the embedded ring upward extension section; the can sealing area is composed of the tangential connection of the first straight line segment L1, the first circular arc segment R1, the second circular arc segment R2 and the third circular arc segment R3; the countersunk section is composed of the tangential connection of the second straight line segment L2, the fourth circular arc segment R4, the fifth circular arc segment R5, the sixth circular arc segment R6 and the third straight line segment L3; the embedded ring arc segment is composed of the seventh circular arc segment R7; the embedded ring upward extension section is composed of the tangential connection of the fourth straight line segment L4 and the eighth circular arc segment R8; and the center cover surface is composed of the fifth straight line segment L5.

[0079] The upper outer molding ring 14 and the upper inner molding ring 32 of the upper mold 1 are opposite to the lower mold core ring 4 of the lower mold 2, wherein the top of the lower mold core ring 4 is provided with a contour corresponding to the first straight line segment L1, the first arc segment R1, the second arc segment R2, the third arc segment R3, the second straight line segment L2, the fourth arc segment R4, the fifth arc segment R5, the sixth arc segment R6 and the third straight line segment L3 of the basic cover, wherein the top of the lower mold core ring 4 forms an annular recess 31 (see Figure 2 The bottom of the upper outer molding ring 14 is provided with a profile that matches the second arc segment R2 of the basic cover, while the bottom of the upper outer molding ring 14 corresponding to the first arc segment R1 and the third arc segment R3 of the basic cover is suspended relative to the top of the lower mold core ring 4 in the mold closed state. The bottom of the upper inner molding ring 32 is provided with a profile that matches the fourth arc segment R4 and the fifth arc segment R5 of the basic cover, while the bottom of the upper inner molding ring 32 corresponding to the second straight line segment L2, the sixth arc segment R6, and the third straight line segment L3 of the basic cover is suspended relative to the top of the lower mold core ring 4 in the mold closed state.

[0080] The upper mold core 13 of the upper mold 1 is opposite to the lower mold core 5 of the lower mold 2, wherein the top of the lower mold core 5 is provided with a contour corresponding to the seventh arc segment R7, the fourth straight segment L4, the eighth arc segment R8 and the fifth straight segment L5 of the basic cover, wherein the top of the lower mold core 5 corresponds to the seventh arc segment R7, the fourth straight segment L4 and the eighth arc segment R8 of the basic cover to form an annular groove 11 for inserting ring forming support and limiting (see Figure 2 The bottom of the upper mold core 13 is provided with a profile that matches the fifth straight line segment L5 of the basic cover.

[0081] The bottom of the upper mold core 13 corresponding to the seventh arc segment R7, the fourth straight line segment L4 and the eighth arc segment R8 of the basic cover is suspended relative to the top of the lower mold core 5 in the mold closing state.

[0082] The basic cover stamping process of this embodiment 1 is as follows: Figures 5 to 15 As shown, where: Figure 5 Indicates the stamping process, from Figure 5 It can be seen that the upper mold 1 moves downward as a whole, and 30 in the figure represents the basic cover blank. Figure 6 Indicates the second stamping process, from Figure 6 As can be seen in the figure, the upper blade 15 of the upper die 1 and the lower blade 7 of the lower die 2 first shear the basic cover blank 30, and then the upper blade 15 pushes the lower press ring 6 downward through the basic cover blank 30. Because the lower core ring 4 is fixed to the lower die base 3, the upper outer forming ring 14 presses the lower core ring 4 through the basic cover blank 30 and is in a stationary state. Figure 7 Indicates the stamping process three, from Figure 7 It can be seen that the basic cover blank 30 is relatively Figure 6 There is deformation again. Figure 8 Indicates the stamping process four, from Figure 8 It can be seen that the basic cover blank 30 between the upper knife 15 and the lower pressure ring 6 has slipped, the upper knife 15 directly contacts the lower pressure ring 6, and the upper inner molding ring 32 and the upper mold core body 20 have begun to contact the basic cover blank 30. Figure 9 Indicates the stamping process five, from Figure 9 As can be seen in FIG, the upper mold core body 20 pushes the lower mold core body 22 downward through the basic cover blank 30. Figure 10 Indicates the stamping process six, from Figure 10 It can be seen from the figure that the upper die 1 and the lower die 2 are in the state of the bottom dead center of the punch press, that is, the state when the basic cover of the easy-open lid is formed in the forward direction. Figure 10 The basic cover 26 is formed when the forward molding is completed. Figure 11 Indicates the stamping process seven, from Figure 11As can be seen in the figure, the upper mold 1 moves upward, and the lower press ring 6 and the lower mold core body 22 also move upward under the action of the corresponding first air chamber 8 and the second air chamber 9. Figure 12 Indicates the stamping process of eight rounds, from Figure 12 It can be seen from the figure that the lower mold core 22 has moved to the top dead center position and is no longer moving upward. At this time, the upper mold and the lower mold are in the state when the basic cover of the easy-open lid is completely formed. Figure 12 The fully formed rear basic cover 27 in. Figure 13 Indicates the stamping process nine, from Figure 13 As can be seen in FIG, the upper mold core 20 has left the fully formed basic cover 27. Figure 14 Indicates the stamping process, from Figure 14 As can be seen in FIG, the upper inner molded ring 32 has left the fully molded basic cover 27. Figure 15 Indicates the stamping process eleven, from Figure 15 As can be seen in FIG, the basic cover 27 is demoulded after being completely formed.

[0083] Example 2: A pressure-resistant easy-open lid basic cover stamping die (with a preformed stamping die)

[0084] like Figure 16 As shown, the stamping die consists of two parts: the lower die 2 and the upper die 1 (see Figure 16 ).

[0085] The difference between Example 2 and Example 1 is that the bottom of the upper mold core 20 is different. The bottom of the upper mold core 20 in Example 1 is flat, that is, the bottom of the upper mold core 20 corresponding to the seventh arc segment R7, the fourth straight line segment L4 and the eighth arc segment R8 of the basic cover is suspended relative to the top of the lower mold core 22 in the mold closing state. In contrast, the bottom of the upper mold core 20 in Example 2 has an R angle with a downward protrusion on the edge (see Figure 17 ), that is, the bottom of the upper mold core body 20 is provided with a contour corresponding to the eighth arc segment R8 of the basic cover, and the bottom of the upper mold core body 20 corresponding to the seventh arc segment R7 and the fourth straight line segment L4 of the basic cover is suspended relative to the top of the lower mold core body 22 in the mold closing state.

[0086] The other structures of Example 2 are the same as those of Example 1 and will not be described again here.

[0087] The basic cover stamping process of this embodiment 2 is as follows: Figures 17 to 27 As shown, the entire stamping process is similar to that of Example 1, but the forming methods differ. Example 1 is a basic cap forming method without a preform, while Example 2 is a basic cap forming method with a preform. More detailed information can be obtained by comparing the stamping process diagrams of the two examples, and will not be described in detail here.

[0088] Compared with the basic cover forming method without preform in Example 1, the basic cover forming method with preform in Example 2 has the following advantages:

[0089] 1. The pressure of the outer molding ring 14 is 30-60psi, and the pressure of the inner molding ring 32 is 100-130psi. Figure 21 Compared with Example 1 Figure 9 The upper outer molding ring 14 and the lower core ring 4 clamp the outer circumference of the basic cover blank. The annular bevel on the bottom end face of the upper inner molding ring 32 contacts the basic cover blank, but does not yet clamp the middle circumference of the basic cover blank with the lower core ring 4. During preforming, only the upper outer molding ring 14 compresses the basic cover blank, while the upper inner molding ring 32 does not. In this state, the basic cover blank has good material fluidity, so the basic cover blank does not become thinner during the stamping process and preforming.

[0090] 2. In the stamping process 6 (Example 2 Figure 22 Compared with Example 1 Figure 10 ), the upper molding ring 14 and the upper inner molding ring 32 both compress the basic cover blank. In this state, the basic cover blank has poor material fluidity, causing slight thinning during the molding process. By adding a preforming process during the fifth stamping step, preforming is performed in advance, thereby reducing the molding process in the sixth stamping step and improving the thinning of the basic cover blank.

[0091] 3. In the stamping process seven (Example 2 Figure 23 Compared with Example 1 Figure 11 ), the basic cover blank begins reverse forming. If a structure without preforming is used, in the initial stage of the reverse forming of the basic cover blank, the basic cover blank will apply a large upward thrust to the upper inner forming ring 32. In order to ensure the stability of the entire forming process, the air pressure acting on the upper inner forming ring 32 must ensure that the upper inner forming ring 32 always presses the basic cover blank, so a large air pressure needs to be applied to the upper inner forming ring 32. If a structure with preforming is used, when the basic cover blank begins reverse forming, part of the insert ring has already been preformed. During the entire reverse forming process, the basic cover blank will not apply a large upward thrust to the upper inner forming ring 32. Therefore, compared with the structure without preforming, the upper inner forming ring 32 of the structure with preforming has a lower working pressure. The lower working pressure can improve the thinning of the basic cover blank and increase the service life of the parts.

[0092] 4. If a structure without preforming is used, a small bend R angle (R angle radius less than 0.25mm) will be formed during the reverse forming of the basic cover blank, ultimately causing slight cracks on the surface around the fourth straight line segment L4 of the easy-open lid, thereby affecting the performance of the easy-open lid. A structure with preforming can control the size of the initial bend R angle during reverse forming of the basic cover blank by adjusting the R angle of the bottom end face of the upper mold core 20. This controls the minimum bend R angle formed during reverse forming of the basic cover blank, ensuring that the minimum bend R angle radius is greater than or equal to 0.25mm, thus resolving the problem of slight cracks around the surface around the fourth straight line segment L4 of the easy-open lid.

[0093] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable people familiar with the technology to understand the contents of the present invention and implement them accordingly, and are not intended to limit the scope of protection of the present invention.

Claims

1. A pressure-resistant easy-open lid basic cover stamping die, consisting of a lower die (2) and an upper die (1); The lower die (2) is mainly composed of a lower die base (3), a lower die core ring (4), a lower die core (5), a lower pressure ring (6) and a lower knife (7), wherein: The lower die base (3) is a cylindrical body with an open top; The lower die core ring (4) is an annular body, which is fixed in the lower die base (3) and is concentric with the lower die base (3); The active part of the lower mold core (5) is a columnar body, which is embedded in the lower mold core ring (4) and slides with the lower mold core ring (4) in the upper and lower directions; the lower mold core ring (4) is sealed to form a first air chamber (8) below the lower mold core (5), and the air pressure of the first air chamber (8) is used to support the lower mold core (5); The lower pressing ring (6) is an annular body, which is embedded between the lower die base (3) and the lower die core ring (4), and a second air chamber (9) is formed between the lower die base (3) and the lower die core ring (4) below the lower pressing ring (6). The air pressure of the second air chamber (9) is used to support the lower pressing ring (6); The lower knife (7) is an annular body, which is fixed on the upper open edge of the lower die base (3), and a lower blade (10) is provided on the inner edge of the top of the annular body; The upper mold (1) is mainly composed of an upper mold base (12), an upper mold core (13), an upper inner molding ring (32), an upper outer molding ring (14) and an upper knife (15), wherein: The upper die seat (12) is a cylindrical body with an open bottom; The action portion of the upper mold core (13) is a columnar body, which is arranged in the upper mold base (12) and is concentric with the upper mold base (12). The upper mold core (13) slides in the upper and lower directions relative to the upper mold base (12); a third air chamber (17) is formed in the upper mold base (12) above the upper mold core (13) in a sealed manner, and the air pressure of the third air chamber (17) is used to press the upper mold core (13); The upper inner molding ring (32) is an annular body, which is embedded between the upper mold core (13) and the upper mold base (12). A fourth air chamber (28) is formed between the upper mold core (13) and the upper mold base (12) above the upper inner molding ring (32). The air pressure of the fourth air chamber (28) is used to press the upper inner molding ring (32). The upper outer molding ring (14) is an annular body, which is embedded between the upper mold base (12) and the upper inner molding ring (32). A fifth air chamber (33) is formed between the upper mold base (12) and the upper inner molding ring (32) above the upper outer molding ring (14). The air pressure of the fifth air chamber (33) is used to press the upper outer molding ring (14). The upper knife (15) is an annular body fixed on the lower open edge of the upper die seat (12), and an upper blade (18) is provided on the outer edge of the bottom end of the upper knife (15) to cooperate with the lower blade (10); The invention is characterized in that: for the basic cover, the basic cover is formed by tangentially connecting a can sealing area, a countersunk section, an embedded ring arc section, an embedded ring upward extension section and a central cover surface in sequence from the periphery to the center in cross section, wherein an annular groove is formed between the countersunk section, the embedded ring arc section and the embedded ring upward extension section; the can sealing area is composed of a first straight line segment (L1), a first arc segment (R1), a second arc segment (R2) and a third arc segment (R3) connected tangentially; the countersunk section is composed of a second straight line segment (L2), a fourth arc segment (R4), a fifth arc segment (R5), a sixth arc segment (R6) and a third straight line segment (L3) connected tangentially; the embedded ring arc segment is composed of a seventh arc segment (R7); the embedded ring upward extension section is composed of a fourth straight line segment (L4) and an eighth arc segment (R8) connected tangentially; and the central cover surface is composed of a fifth straight line segment (L5); The upper outer molding ring (14) and the upper inner molding ring (32) of the upper mold (1) are opposite to the lower mold core ring (4) of the lower mold (2) in upper and lower positions, wherein the top of the lower mold core ring (4) is provided with contours corresponding to the first straight line segment (L1), the first arc segment (R1), the second arc segment (R2), the third arc segment (R3), the second straight line segment (L2), the fourth arc segment (R4), the fifth arc segment (R5), the sixth arc segment (R6) and the third straight line segment (L3) of the basic cover, wherein the top of the lower mold core ring (4) corresponds to the parts of the second straight line segment (L2), the fourth arc segment (R4), the fifth arc segment (R5) and the sixth arc segment (R6) of the basic cover. An annular recess (31) is formed; the bottom of the upper outer molding ring (14) is provided with a profile corresponding to the second arc segment (R2) of the basic cover, and the bottom of the upper outer molding ring (14) corresponding to the first arc segment (R1) and the third arc segment (R3) of the basic cover is suspended relative to the top of the lower mold core ring (4) in the mold closing state; the bottom of the upper inner molding ring (32) is provided with a profile corresponding to the fourth arc segment (R4) and the fifth arc segment (R5) of the basic cover, and the bottom of the upper inner molding ring (32) corresponding to the second straight line segment (L2), the sixth arc segment (R6) and the third straight line segment (L3) of the basic cover is suspended relative to the top of the lower mold core ring (4) in the mold closing state; The upper mold core (13) of the upper mold (1) and the lower mold core (5) of the lower mold (2) are opposite to each other in the upper and lower directions, wherein the top of the lower mold core (5) is provided with a contour corresponding to the seventh arc segment (R7), the fourth straight segment (L4), the eighth arc segment (R8) and the fifth straight segment (L5) of the basic cover, wherein the top of the lower mold core (5) corresponds to the seventh arc segment (R7), the fourth straight segment (L4) and the eighth arc segment (R8) of the basic cover to form an annular groove for supporting and limiting the embedded ring molding; the bottom of the upper mold core (13) is provided with a contour corresponding to the fifth straight segment (L5) of the basic cover; The bottom of the upper mold core (13) is provided with a profile corresponding to the eighth arc segment (R8) of the basic cover, and the portion of the bottom of the upper mold core (13) corresponding to the seventh arc segment (R7) and the fourth straight line segment (L4) of the basic cover is suspended relative to the top of the lower mold core (5) in the mold closing state.

2. The stamping die according to claim 1, characterized in that: The lower mold core (5) is composed of a lower mold core seat (21) and a lower mold core body (22). The lower mold core seat (21) is fixedly connected to the lower mold core body (22). The active part of the lower mold core (5) is the lower mold core body (22), and the lower mold core body (22) is a columnar body.

3. The stamping die according to claim 2, wherein: The lower mold core (22) is provided with a first exhaust hole (23) and a second exhaust hole (24) for exhausting air when the basic cover is stamped and formed.

4. The stamping die according to claim 1, wherein: The upper mold core (13) is composed of an upper mold core seat (19) and an upper mold core body (20). The upper mold core seat (19) and the upper mold core body (20) are fixedly connected by bolts and pads. The active part of the upper mold core (13) is the upper mold core body (20), and the upper mold core body (20) is a columnar body.

5. The stamping die according to claim 4, characterized in that: The upper mold core (20) is provided with an exhaust hole for exhausting air when the basic cover is stamped and formed.

6. The stamping die according to claim 1, wherein: The fourth air chamber (28) is provided with an upper inner molding ring air inlet port on the upper die base (12).

7. The stamping die according to claim 1, characterized in that: The fifth air chamber (33) is provided with an upper inner molding ring air inlet port on the upper die base (12).

Images