Sheet forming die

Abstract

To provide a mouthpiece for sheet molding capable of preventing leakage of a sheet material.SOLUTION: A mouthpiece for sheet molding comprises: a die hopper that supplies a sheet material; a pair of opposing lips installed on a bottom surface of the die hopper; and a side plate installed fixed on respective both end portions of the pair of lips and on the bottom surface of the die hopper. On a bottom surface of the side plate, a groove extending in a sheet thickness direction is shaped. Of the two portions of the side plate divided by the groove in a sheet width direction, one on an outer side in the sheet width direction is a pressing portion, and the other is a to-be-pressed portion. The pressing portion is provided with a pressing mechanism that presses the to-be-pressed portion onto the pair of lips by pushing a wall surface on the to-be-pressed portion among wall surfaces that shape the groove.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sheet forming die. [Background technology]

[0002] A sheet forming die forms a sheet by discharging molten sheet material (typically molten resin, etc.) from a discharge port in an extruder, etc. Because the sheet forming die forms a flow path for the sheet material using multiple parts, there is a problem that the sheet material leaks from the joint surfaces between the parts and adheres to the sheet, causing tears and defects.

[0003] While sheet forming die components vary widely, we will explain the structure of a typical sheet forming die with excellent operability. Figure 4 shows the front and bottom views of a typical sheet forming die. A typical sheet forming die consists of a die hopper 3 that supplies sheet material from a supply port 17, a pair of opposing lips 1 installed on the underside of the die hopper 3, and side plates 2 fixed to both ends of each lip 1 and the underside of the die hopper 3. The pair of lips 1 form the discharge port 4 through which the sheet material is discharged. Damage to the lips 1 can cause uneven thickness in the sheet, requiring frequent repair or replacement. The lip 1 of this sheet forming die is compact, allowing for inexpensive repair or replacement in a short time, resulting in excellent operability. Furthermore, the side plates 2 apply surface pressure to the joint surface 7 with the lips 1 via fastening bolts 5 and to the joint surface 8 with the die hopper 3 via fastening bolts 6, preventing leakage of the sheet material. However, the fastening bolts 5 cannot be placed near the discharge port 4 on the joining surface 7 due to the obstruction of the flow path, and the surface pressure is weak, which can lead to leakage of the sheet material.

[0004] One technique for preventing leakage of sheet material from near the discharge port is to press a block placed between the lip and side plate with a pressure bolt. Patent Document 1 describes an example of this method. Figure 5 shows a front view and a bottom view of the sheet forming die described in Patent Document 1. Patent Document 1 shows a sheet forming die in which a block 9 and a side plate 2 are installed on joint surfaces 7 and 8 that are formed by matching the sheet width dimension of the die hopper 3 to the lip 1. By pressing the block 9 against the lip 1 with pressure bolts 10 installed on the side plate 2, it is possible to increase the surface pressure near the discharge port 4, where fastening bolts cannot be installed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-187189 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technology of Patent Document 1 has the risk of creating a step between the joining surfaces 7 and 8 due to the difference in thermal expansion in the sheet width direction caused by the temperature difference between the lip and the die hopper, weakening the surface pressure and causing the sheet material to leak.

[0007] Therefore, the present invention provides a sheet forming die that can apply sufficient surface pressure to the joining surfaces of the lip, side plate, and die hopper to prevent leakage of the sheet material. [Means for solving the problem]

[0008] [1] A first sheet forming die of the present invention that solves the above-mentioned problems is a sheet forming die including a die hopper for supplying a sheet material, a pair of opposing lips installed on the lower surface of the die hopper, and side plates fixed to both ends of the pair of lips and the lower surface of the die hopper, A groove extending in the sheet thickness direction is formed on the lower surface of the side plate, Of the two portions of the side plate divided in the seat width direction by the groove, one on the outer side in the seat width direction is a pressing portion and the other is a pressed portion, The pressing portion is provided with a pressing mechanism that presses the pressed portion against the pair of lips by pressing the wall surfaces that form the groove and are located on the pressed portion.

[0009] The first sheet molding die of the present invention preferably has any one of the following aspects [2] to [4]. [2] The sheet forming die of [1], wherein, when the length of the pressed portion in the sheet width direction is L1 [mm] and the distance in the sheet flow direction from the bottom of the joint surface between the pair of lips and the pressed portion to the pressing mechanism is H1 [mm], 0.2≦H1 / L1≦1.0. [3] A sheet forming die according to [1] or [2], in which a notch is formed on the outer side of the side plate in the sheet width direction, extending from the side to the bottom of the groove. [4] The sheet forming die according to any one of [1] to [3] above, wherein the minimum contact surface pressure between the side plate and the lip is 20 MPa or more.

[0010] [5] A second sheet forming die of the present invention that solves the above-mentioned problems is a sheet forming die including a die hopper for supplying a sheet material, a pair of opposing lips installed on the lower surface of the die hopper, and side plates fixed to and installed on both ends of each of the pair of lips and the lower surface of the die hopper, A pressing member is installed on the outer side of the side plate in the sheet width direction, and is fixed to the side plate or is fixed to the pair of lips via the side plate, The pressing member is provided with a pressing mechanism that presses the outer side surfaces of the side plates in the sheet width direction to press the side plates against the pair of lips.

[0011] The second sheet forming die of the present invention is preferably either of the following embodiments [6] or [7]. [6] A sheet forming die according to [5] above, wherein the distance in the sheet width direction from the joint surface between the side plate and the lip to the outer side surface of the side plate in the sheet width direction is L2 [mm], and the distance in the sheet flow direction from the bottom of the joint surface between the pair of lips and the side plate to the pressing mechanism is H2 [mm], such that 0.2≦H2 / L2≦1.0. [7] The sheet forming die of [5] or [6] above, wherein the minimum contact pressure between the side plate and the lip is 20 MPa or more.

[0012] [Terminology] Next, the meaning of each term in the present invention will be explained. "Sheet material" refers to the material that constitutes the sheet. Examples of sheet materials include polyolefin resins such as polyethylene, polypropylene, polystyrene, and polymethylpentene; alicyclic polyolefin resins; polyamide resins such as nylon 6 and nylon 66; aramid resins; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, polybutyl succinate, and polyethylene-2,6-naphthalate; polycarbonate resins; polyarylate resins; polyacetal resins; polyphenylene sulfide resins; fluororesins such as tetrafluoroethylene resin, trifluoroethylene resin, trifluorochloroethylene resin, tetrafluoroethylene-hexafluoropropylene copolymer, and vinylidene fluoride resin; acrylic resins; methacrylic resins; polyacetal resins; polyglycolic acid resins; and polylactic acid resins, which are fluidized by dissolving or melting them in a solvent. These thermoplastic resins may be homopolymers, copolymers, or blends of two or more types. Furthermore, various additives such as antioxidants, antistatic agents, crystal nucleating agents, inorganic particles, organic particles, viscosity reducers, heat stabilizers, lubricants, infrared absorbers, ultraviolet absorbers, and dopants for adjusting the refractive index may be added to each thermoplastic resin.

[0013] The term "sheet forming die" refers to a device that discharges a sheet material from a discharge port to form a sheet. The term "sheet thickness direction" refers to the direction that coincides with the thickness direction of the sheet material when it is formed into a sheet. The "sheet width direction" refers to the direction that coincides with the width direction of the sheet material when it is formed into a sheet. The "sheet flow direction" refers to the direction that coincides with the direction in which the sheet material flows through the sheet forming die, and may be expressed as "down" in the present invention.

[0014] "Die hopper" refers to a part of a sheet forming die that supplies sheet material to the sheet forming die. The term "lip" refers to a pair of opposing sheet forming die members that are installed on the lower surface of the die hopper. The "side plate" refers to a part of the sheet forming die that is fixed to both ends of the pair of lips and the lower surface of the die hopper. The term "discharge port" refers to the portion formed by a pair of lips from which the sheet material is discharged. The "groove" refers to a recess formed on the lower surface of the side plate and extending in the thickness direction of the sheet. The "pressing portion" refers to the outer portion of the two portions of the side plate divided in the seat width direction by the groove. The "pressed portion" refers to the inner portion of the two portions of the side plate divided in the seat width direction by the groove. The "pressing mechanism" refers to a mechanism that is provided in the pressing portion and presses the wall surfaces of the pressed portion among the wall surfaces forming the groove, thereby pressing the pressed portion against the pair of lips. Alternatively, it refers to a mechanism that is provided in the pressing member and presses the outer side surfaces of the side plates in the sheet width direction, thereby pressing the side plates against the pair of lips. "Joint surface" means the surface where two members come into contact. The "notch" refers to a recess formed on the outer side surface of the side plate in the sheet width direction, and reaching the bottom surface of the groove. The "pressing member" refers to a member that is installed on the outer side of the side plate in the sheet width direction and is fixed to the side plate or to a pair of lips via the side plate. "Feed opening" refers to the portion formed at the top of the die hopper through which the sheet material is fed. [Effects of the Invention]

[0015] According to the present invention, leakage of the sheet material can be prevented. [Brief explanation of the drawings]

[0016] [Figure 1] 1A and 1B are front and bottom views of a first sheet forming die of the present invention; [Figure 2] 1A and 1B are front and bottom views of a first sheet forming die of the present invention, in which notches are formed in the side plates; [Figure 3] 1 is a front view and a bottom view of a second sheet forming die of the present invention. [Figure 4] Front and bottom views of a typical sheet molding die [Figure 5] Front and bottom views of a sheet molding die described in Patent Document 1 DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described in detail below, but is not limited to the following embodiments including the following examples. Figures 1 to 3 are diagrams showing a sheet molding die according to the present invention. Note that components having the same uses and functions as those in the prior art may be designated by the same reference numerals.

[0018] [First sheet forming die] A first sheet forming die of the present invention will be described with reference to FIG. 1. FIG. 1 shows a front view and a bottom view of the first sheet forming die of the present invention. As shown in FIG. 1, the first sheet forming die of the present invention includes a die hopper 3 that supplies sheet material from a supply port 17, a pair of opposing lips 1 installed on the underside of the die hopper 3, and side plates 2 that are fixed to both ends of the pair of lips 1 and the underside of the die hopper 3. A groove 11 extending in the sheet thickness direction is formed on the underside of the side plate 2. The groove 11 divides the side plate 2 in the sheet width direction into two parts. One of the two parts, located on the outer side in the sheet width direction, is a pressing portion 12, and the other is a pressed portion 13. A pressing mechanism 14 provided in the pressing portion 12 can press the pressed portion 13 against the pair of lips 1 by pressing the wall surface that forms the groove 11, which is located at the pressed portion 13.

[0019] Here, the surface pressure of each joining surface will be explained. As with the prior art, the first sheet forming die of the present invention applies surface pressure to each of the joining surfaces 7 and 8 using the fastening bolts 5 and 6. However, the surface pressure near the discharge port 4 of the joining surface 7 is weak when using the fastening bolts 5 alone. Therefore, in the first sheet forming die of the present invention, by using the pressing mechanism 14 to press the pressed portion 13 against the pair of lips 1, it is possible to apply strong surface pressure to the joining surface 7 near the discharge port 4 without reducing the surface pressure of the other joining surfaces. Therefore, the first sheet forming die of the present invention can apply sufficient surface pressure to the entire joining surfaces 7 and 8, preventing leakage of the sheet material.

[0020] 1 , in the first sheet forming die of the present invention, where L1 [mm] is the length of the pressed portion 13 in the sheet width direction and H1 [mm] is the distance in the sheet flow direction from the bottom of the joining surface 7 to the pressing mechanism 14, it is preferable that 0.2≦H1 / L1≦1.0 be satisfied. Here, "up to the pressing mechanism 14" means up to the center position of the range in which the pressing mechanism 14 presses the wall surface of the groove 11 when viewed from the front of the sheet forming die. If the lower surfaces of the pair of lips 1 protrude further in the sheet conveyance direction than the lower surfaces of the pressed portion 13, H1 is the distance in the sheet flow direction from the lower surface of the pressed portion 13 to the pressing mechanism 14. If the lower surface of the pressed portion 13 protrudes further in the sheet conveyance direction than the lower surfaces of the pair of lips 1, H1 is the distance in the sheet flow direction from the lower surface of the pair of lips 1 to the pressing mechanism 14.

[0021] When L1 is large, the surface pressure applied by the pressing mechanism 14 to the joining surface 7 is applied over a wide range, but the surface pressure itself is weak. Furthermore, the range over which the surface pressure needs to be applied to prevent leakage of the sheet material is the distance from the pressing mechanism 14 to the bottom of the joining surface 7, i.e., H1. By setting H1 / L1 to 0.2 or more, a strong surface pressure can be applied. Furthermore, by setting H1 / L1 to 1.0 or less, the surface pressure can be applied all the way to the bottom of the joining surface 7. Therefore, by setting the ratio 0.2≦H1 / L1≦1.0, a strong surface pressure can be applied all the way to the bottom of the joining surface 7, further preventing leakage of the sheet material. More preferably, 0.2≦H1 / L1≦0.5.

[0022] Another embodiment of the first sheet forming die of the present invention will be described with reference to Figure 2. In the first sheet forming die of the present invention, it is preferable that a notch 15 is formed in the outer side surface 18 of the side plate 2 in the sheet width direction, extending from the side surface 18 to the bottom surface of the groove 11. Figure 2 shows a front view and a bottom view of the first sheet forming die of the present invention, in which the notch 15 is formed in the side plate 2. The formation of the notch 15 suppresses the reaction force of the pressing mechanism 14 from the pressing portion 12 to the side plate 2, making it easier to uniform the surface pressure on the joining surface 7 and improving the effect of preventing leakage of the sheet material.

[0023] In the first sheet forming die of the present invention, the minimum contact pressure between the side plate 2 and the lip 1 is preferably 20 MPa or more. By setting the minimum contact pressure to 20 MPa, leakage of the sheet material can be further prevented regardless of the temperature, the state of the sheet material, etc. More preferably, the minimum contact pressure is 30 MPa or more.

[0024] [Second sheet forming die] A second sheet forming die of the present invention will be described with reference to Figure 3. Figure 3 is a front view and a bottom view of the second sheet forming die of the present invention. As shown in Figure 3, the second sheet forming die of the present invention, like the first sheet forming die of the present invention, includes a die hopper 3, a pair of lips 1, and a side plate 2. A pressing member 16 is installed on the outer side of the side plate 2 in the sheet width direction and is fixed to the side plate 2 by a bolt 19. A pressing mechanism 14 provided on the pressing member 16 can press the side plate 2 against the pair of lips 1 by pressing a side surface 18 on the outer side of the side plate 2 in the sheet width direction. The bolt 19 may be fixed to the pair of lips 1 via the side plate 2.

[0025] Here, the surface pressure of each joining surface will be explained. Like the prior art and the first sheet forming die of the present invention, the second sheet forming die of the present invention applies surface pressure to each of the joining surfaces 7 and 8 using the fastening bolts 5 and 6. However, the surface pressure near the discharge port 4 of the joining surface 7 is weak with the fastening bolts 5 alone. Therefore, in the second sheet forming die of the present invention, by pressing the side plate 2 against the pair of lips 1 using the pressing mechanism 14, it is possible to apply strong surface pressure to the joining surface 7 near the discharge port 4 without reducing the surface pressure of the other joining surfaces. Therefore, the second sheet forming die of the present invention can apply sufficient surface pressure to the entire joining surfaces 7 and 8, preventing leakage of the sheet material.

[0026] 3 , in the second sheet forming die of the present invention, where L2 [mm] is the distance in the sheet width direction from the joining surface 7 between the side plate 2 and the lip 1 to the outer side surface 18 of the side plate 2 in the sheet width direction, and H2 [mm] is the distance in the sheet flow direction from the bottom of the joining surface 7 to the pressing mechanism 14, it is preferable that 0.2≦H2 / L2≦1.0 be satisfied. Here, "up to the pressing mechanism 14" means up to the center position of the area where the pressing mechanism 14 presses the side surface 18 of the side plate 2 when viewed from the front of the sheet forming die. If the lower surfaces of the pair of lips 1 protrude further in the sheet conveyance direction than the lower surfaces of the side plate 2, H2 is the distance in the sheet flow direction from the lower surfaces of the side plate 2 to the pressing mechanism 14. Alternatively, if the lower surface of the side plate 2 protrudes further in the sheet conveyance direction than the lower surfaces of the pair of lips 1, H2 is the distance in the sheet flow direction from the lower surfaces of the pair of lips 1 to the pressing mechanism 14.

[0027] The surface pressure applied to the joining surface 7 by the pressing mechanism 14 is applied over a wide range when L2 is large, but the surface pressure itself is weak. Furthermore, the range over which the surface pressure needs to be applied to prevent leakage of the sheet material is the distance from the pressing mechanism 14 to the bottom of the joining surface 7, i.e., H2. By setting H2 / L2 to 0.2 or less, a strong surface pressure can be applied. Furthermore, by setting H2 / L2 to 1.0 or more, the surface pressure can be applied all the way to the bottom of the joining surface 7. Therefore, by setting 0.2≦H2 / L2≦1.0, a strong surface pressure can be applied all the way to the bottom of the joining surface 7, further preventing leakage of the sheet material. More preferably, 0.2≦H2 / L2≦0.5.

[0028] In the second sheet forming die of the present invention, the minimum contact pressure between the side plate 2 and the lip 1 is preferably 20 MPa or more. By setting the minimum contact pressure to 20 MPa, leakage of the sheet material can be further prevented regardless of the temperature, the state of the sheet material, etc. More preferably, the minimum contact pressure is 30 MPa or more. [Example]

[0029] [Example 1] The following describes the results of actually forming a sheet using the sheet forming die shown in Figure 1 and evaluating leakage of the sheet material from the lip edge. The specific specifications of the sheet forming die, the sheet manufacturing method, and the leakage evaluation method in this embodiment are as follows. (1) Sheet material: Polypropylene. (2) Extrusion: The sheet material was fed into an extruder set at 190°C, passed through a gear pump and a filter, and then fed into a sheet forming die while increasing the flow rate from 100 to 500 kg / h. (3) Sheet forming die: The discharge width was 900 mm. The groove formed in the side plate had a dimension in the sheet thickness direction of 100 mm and a depth of 50 mm. The pressing mechanism was equipped with an M12 set screw in the pressing part. The length L1 of the pressed part in the sheet width direction was 25 mm. The distance H1 in the sheet flow direction from the bottom of the joint surface between the pair of lips and the pressed part to the pressing mechanism was 30 mm (H1 / L1 = 1.2). The minimum contact pressure between the side plate and lip was 10 MPa. (4) Molding: After extruding into a sheet from a sheet molding die, the material was cooled and solidified in a casting drum and molded. (5) Leakage evaluation: The maximum discharge amount at which no visible leakage of the sheet material occurred (hereinafter referred to as the limit discharge amount) was confirmed.

[0030] [Example 2] A sheet was formed in the same manner as in Example 1, except that H1 was changed to 10 mm (H1 / L1=0.4).

[0031] [Example 3] A sheet was formed in the same manner as in Example 1, except that a notch was formed on the outer side surface of the side plate in the sheet width direction, extending from the side surface to the bottom surface of the groove. The dimension of the notch in the sheet thickness direction was 100 mm, and the dimension in the sheet flow direction was 3 mm.

[0032] [Example 4] A sheet was formed in the same manner as in Example 1, except that the minimum contact pressure between the side plate and the lip was set to 35 MPa.

[0033] [Example 5] A sheet was formed in the same manner as in Example 1, except that the sheet forming die shown in Figure 3 was used. A pressing member was fixed to the outside of the side plate in the sheet width direction, and an M12 set screw was provided on the pressing member as a pressing mechanism. The distance L2 in the sheet width direction from the joint surface between the side plate and the lip to the outer side surface of the side plate in the sheet width direction was 25 mm, the distance H2 in the sheet flow direction from the lowest part of the joint surface between the pair of lips and the side plate to the pressing mechanism was 30 mm (H2 / L2 = 1.2), and the minimum contact surface pressure between the side plate and the lip was 10 MPa.

[0034] [Example 6] A sheet was formed in the same manner as in Example 5, except that H2 was changed to 10 mm (H2 / L2=0.4).

[0035] [Example 7] A sheet was formed in the same manner as in Example 5, except that the minimum contact surface pressure between the side plate and the lip was set to 35 MPa.

[0036] [Comparative Example 1] A sheet was formed in the same manner as in Example 1, except that no grooves or pressing mechanisms were formed in the side plates.

[0037] [Evaluation of results of Examples and Comparative Examples] The leakage prevention effect of the sheet material of each example was evaluated based on how much the limit discharge rate could be increased compared to 100 kg / h in Comparative Example 1.

[0038] In Example 1, in which the side plate was provided with a groove and a pressing mechanism, the limit discharge rate increased twofold to 200 kg / h, and the sheet material leakage prevention effect was improved compared to Comparative Example 1. Furthermore, in Example 2, in which H1 / L1 was set to 0.4, the limit discharge rate increased threefold to 300 kg / h, in Example 3, in which a notch was formed, the limit discharge length increased fourfold to 400 kg / h, and in Example 4, in which the minimum contact surface pressure between the side plate and the lip was set to 35 MPa, the limit discharge rate increased fivefold to 500 kg / h. In all cases, the sheet material leakage prevention effect was further improved compared to Example 1.

[0039] On the other hand, Example 5, which was equipped with a pressing member and pressing mechanism, had a limit discharge rate of 300 kg / h, which was three times higher, and was more effective in preventing leakage of the sheet material than Comparative Example 1. Furthermore, Example 6, in which H2 / L2 was set to 0.4, had a limit discharge rate of 400 kg / h, which was four times higher, and Example 7, in which the minimum contact surface pressure between the side plate and the lip was set to 35 MPa, had a limit discharge rate of 500 kg / h, which was five times higher. In both cases, the effectiveness in preventing leakage of the sheet material was further improved compared to Example 1. [Industrial Applicability]

[0040] According to the present invention, in the sheet forming die, the pressure mechanism is used to increase the surface pressure near the discharge port on the joint surface between the side plate and the lip, thereby preventing leakage of the sheet material. [Explanation of symbols]

[0041] 1 pair of lips 2 Side panels 3 Die Hopper 4 outlet 5, 6 Fastening bolts 7, 8 Joint surface 9 blocks 10 Push Bolt 11 Groove 12 Pressing section 13 Pressed part 14 Pressing mechanism 15 Cut 16 Pressing member 17 Supply port 18 Outer side of side panel in the seat width direction 19 volts

Claims

1. A sheet forming die including a die hopper for supplying a sheet material, a pair of opposing lips installed on a lower surface of the die hopper, and side plates fixed to both ends of the pair of lips and the lower surface of the die hopper, A groove extending in the sheet thickness direction is formed on the lower surface of the side plate, The side plate is divided into two parts in the seat width direction by the groove, and one part located on the outer side in the seat width direction is a pressing part, and the other part is a pressed part, The pressing portion is provided with a pressing mechanism that presses a wall surface of the wall surface forming the groove that is located on the pressed portion, thereby pressing the pressed portion against the pair of lips. Sheet forming nozzle.

2. 2. The sheet forming die of claim 1, wherein, when the length of the pressed portion in the sheet width direction is L1 [mm] and the distance in the sheet flow direction from the bottom of the joint surface between the pair of lips and the pressed portion to the pressing mechanism is H1 [mm], 0.2≦H1 / L1≦1.

0.

3. 2. The sheet forming die according to claim 1, wherein a notch is formed on an outer side surface of each of said side plates in the sheet width direction, said notch extending from said side surface to a bottom surface of said groove.

4. 2. The sheet forming die according to claim 1, wherein the minimum contact pressure between the side plate and the lip is 20 MPa or more.

5. A sheet forming die including a die hopper for supplying a sheet material, a pair of opposing lips installed on a lower surface of the die hopper, and side plates fixed to both ends of the pair of lips and the lower surface of the die hopper, A pressing member is installed on the outer side of the side plate in the sheet width direction, and is fixed to the side plate or is fixed to the pair of lips via the side plate, The pressing member is provided with a pressing mechanism that presses outer side surfaces of the side plates in the sheet width direction to press the side plates against the pair of lips. Sheet forming nozzle.

6. A sheet forming die according to claim 5, wherein the distance in the sheet width direction from the joint surface between the side plate and the lip to the outer side surface of the side plate in the sheet width direction is L2 [mm], and the distance in the sheet flow direction from the lowest part of the joint surface between the pair of lips and the side plate to the pressing mechanism is H2 [mm], wherein 0.2≦H2 / L2≦1.

0.

7. 6. The sheet forming die according to claim 5, wherein the minimum contact surface pressure between the side plate and the lip is 20 MPa or more.

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