Thermoforming machine

Abstract

The present invention is a thermoforming machine (3) for simultaneously forming two or more rows of containers (C11) in the feeding direction of a continuously supplied resin sheet (S1) by thermoforming the resin sheet (S1), the thermoforming machine (3) having convex linear portions (42a, 43a) of a front clamp plate (40) and convex linear portions (25a, 26a) of an upper mold (20), the convex linear parts (42a, 43a) of the front clamping plate (40) and the convex linear parts (25a, 26a) of the upper mold (20) form thin-walled parts (S11, S12) in the direction orthogonal to the feeding direction between more than two rows of containers (C11), the convex linear parts (42a, 43a) are provided with cooling mechanisms, and the thin-walled parts (S11, S12) are not raised to the crystallization temperature during heat setting and heat forming.

Description

Technical Field

[0001] The present invention relates to a thermoforming machine which thermoforms continuously supplied resin sheets and simultaneously forms two or more rows of containers in a feeding direction of the resin sheets. Background Art

[0002] Conventionally, thermoforming machines have been used that continuously supply foamed resin (e.g., foamed PET, foamed PLA) in sheet form to form containers (see Patent Document 1). The heat resistance temperature of ordinary PET is about 60°C, and there is a problem that it deforms when heated in a heater such as an oven and cannot maintain its function as a container. C-PET is made by mixing a nucleating agent into PET, and PET can be crystallized by heating it to a temperature above the crystallization temperature (130°C for PET). The heat resistance of crystallized PET exceeds 200°C, so it will not deform even when heated in a heater such as an oven. This type of thermoforming is called heat-setting thermoforming.

[0003] In a thermoforming machine that simultaneously forms, for example, three rows of containers in the feeding direction of the resin sheet by thermoforming a continuously supplied C-PET sheet, the C-PET sheet is heated to 190° C. during thermoforming and the containers are crystallized by heat setting molding.

[0004] The forming unit containing three rows of containers in the thermoforming machine is transported to the trimming device of the next process and trimmed to the size of the container. The trimming device has a higher speed than the thermoforming machine, so it does not punch out three rows at the same time but punches out one row at a time. In this case, a bend is formed between the thermoforming machine and the trimming device in the form of a buffer to adjust the working state of the thermoforming machine and the trimming device. Prior art literature Patent Literature

[0005] Patent Document 1: Japanese Utility Model Registration No. 3221505 Summary of the invention Problem that the invention aims to solve

[0006] However, problems arise due to the bend (buffer) of the PET sheet formed between the thermoforming machine and the trimming device, and the bend of the PET sheet formed between containers arranged in the conveying direction (between rows of containers) when the PET sheet enters the trimming device. Crystallized PET has high rigidity and reduced toughness, and is easily cracked. Therefore, when the waste portion between rows of containers is greatly deformed, especially due to the bend formed between rows of containers when the PET sheet enters the trimming device, there is a risk of cracks forming in the portion where the large deformation has occurred. As a result, there is a problem that the conveyance to the trimming process becomes difficult due to the generation of cracks, and even if the conveyance is completed, the generation of cracks causes the distance between rows of containers to change, so the trimming position of the container is wrong and the container cannot be punched out with high precision.

[0007] Therefore, the purpose of the thermoforming machine of the present invention is to solve the above-mentioned problems and provide a thermoforming machine in which the crystallized PET sheet will not crack even if the waste part between the rows of containers is greatly deformed just before entering the trimming device. Technical means of solving problems

[0008] A thermoforming machine in one aspect of the present invention is a thermoforming machine that simultaneously forms two or more rows of containers in the feeding direction of the resin sheet by thermoforming a continuously supplied resin sheet, and is characterized in that it has a thin-walled portion forming mechanism that forms a thin-walled portion between the two or more rows of containers in a direction orthogonal to the feeding direction, and the thin-walled portion forming mechanism has a cooling mechanism that prevents the thin-walled portion from rising to a crystallization temperature during heat setting thermoforming. Here, heat setting thermoforming refers to thermoforming that causes the container to crystallize.

[0009] In the above-mentioned thermoforming machine, it is preferable that the thin-walled portion is formed continuously from one end surface to the other end surface of the resin sheet.

[0010] In addition, another form of the present invention is a thermoforming machine, which simultaneously forms more than two rows of containers in the feeding direction of the resin sheet by thermoforming a continuously supplied resin sheet, and is characterized in that it has a thin-walled portion forming mechanism, which forms a thin-walled portion between the more than two rows of containers in a direction orthogonal to the feeding direction, and the thin-walled portion has recessed portions formed facing each other on both sides.

[0011] In addition, another form of the present invention is a thermoforming machine, which simultaneously forms more than two rows of containers in the feeding direction of the resin sheet by thermoforming a continuously supplied resin sheet, and is characterized in that it has a thin-walled portion forming mechanism, which forms a thin-walled portion between the more than two rows of containers in a direction orthogonal to the feeding direction, and the thin-walled portion is formed at the top end of the convex protrusion.

[0012] In addition, another form of the present invention is a thermoforming machine, which simultaneously forms more than two rows of containers in the feeding direction of the resin sheet by thermoforming a continuously supplied resin sheet, and is characterized in that it has a thin-walled portion forming mechanism, which forms a thin-walled portion between the more than two rows of containers in a direction orthogonal to the feeding direction, and has a front clamp, and the thin-walled portion forming mechanism of the front clamp is equipped with a cooling mechanism. Effects of the Invention

[0013] According to the thermoforming machine having the above configuration, since thin-walled portions are formed between rows of containers, the thin-walled portions in the waste portions between rows of containers can be greatly deformed due to the bending formed between rows of containers when the crystallized PET sheet enters the trimming device, so cracks are not generated. Furthermore, since cracks are not generated, the conveyance to the trimming process does not become difficult. In addition, the distance between the rows of containers supplied to the trimming device does not change, the trimming position of the containers does not make a mistake, and the containers can be punched out with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a diagram showing the configuration of an entire system using a thermoforming machine. Figure 2 A cross-sectional view of the main parts of a thermoforming machine. Figure 3 is with Figure 2 The cross-sectional view also shows the state of the clamping process. Figure 4 is with Figure 2 The cross-sectional view also shows the state of the hot forming process. Figure 5 for Figure 4 Enlarged view of part A. Figure 6 For the second embodiment Figure 4 The corresponding figure. Figure 7 It is a figure which shows the state of the resin sheet after molding. Figure 8 It is a perspective view showing the structure of the front splint. Fig. 9 This is an exploded perspective view showing the structure of the upper mold, the front clamping plate, and the lower mold. DETAILED DESCRIPTION

[0015] A first embodiment of a thermoforming machine according to the present invention will be described in detail with reference to the drawings.

[0016] Figure 1The structure of the overall system using the thermoforming machine 3 is shown. The resin sheet S1 is supplied from the supply roller 1. A radiation-type heating device 2 is arranged above and below the supply roller 1 in such a manner as to clamp the resin sheet S1, and a thermoforming machine 3 for heat setting thermoforming is arranged immediately downstream of the heating device 2. A trimming device 4 is arranged at a certain distance from the thermoforming machine 3, and a winding roller 5 for winding up the waste sheet S3 is arranged downstream of the trimming device 4. The container C11 trimmed by the trimming device 4 is carried out to the outside of the trimming device 4 by the conveyor 7 and manually gathered.

[0017] The thermoforming machine 3 is a thermoforming machine that thermoforms 9 containers C11, 3 rows in the width direction (direction perpendicular to the conveying direction) of the resin sheet S1 and 3 columns in the conveying direction at the same time. The trimming device 4 is a trimming device for punching out 3 containers C11, 3 rows in the width direction and 1 column in the conveying direction (that is, punching out 3 containers C11 at the same time). The tact time of the trimming device 4 is more than 3 times faster than the tact time of the thermoforming machine 3, so the trimming device 4 is on and off controlled, and a buffer 6 is arranged between the thermoforming machine 3 and the trimming device 4 to bend and hold the formed resin sheet S2.

[0018] The resin sheet S1 is foamed C-PET (PET containing a crystallization-promoting additive, i.e., a nucleating agent). The foaming ratio is 4 to 5 times, and the thickness is 2 to 3 mm. The upper and lower surfaces of the resin sheet S1 are heated simultaneously by the upper and lower radiation heating devices 2. The heating temperature varies depending on the material of the resin sheet S1. The resin sheet S1 in this embodiment is heated in a manner to reach about 100°C, which is higher than the glass transition temperature of PET, 71.1°C.

[0019] The main part of the thermoforming machine 3 is shown in cross section. Figure 2 Furthermore, Figure 2 The left-right direction is the conveying direction of the resin sheet S1. The resin sheet S1 is held between the upper mold 20 as a concave mold and the lower mold 30 as a convex mold. A front clamp 40 is arranged between the resin sheet S1 and the lower mold 30.

[0020] The upper mold 20 is formed with three rows of concave mold recesses 21, 22, and 23 along the conveying direction of the resin sheet S1. Figure 2 The die recesses 21A, 21B, and 21C are arranged in a row in the depth direction (hereinafter referred to as the width direction) (refer to Fig. 9 ), the row of the concave mold portions 22 along the width direction ( Figure 2 The die recesses 22A, 22B, and 22C are arranged in a row (in the depth direction of the Fig. 9 ), the row of the concave mold portions 23 along the width direction ( Figure 2 The die recesses 23A, 23B, and 23C are arranged in a row (in the depth direction of the Fig. 9 ), a total of 9 die recesses are formed. In addition, a clamp 24 is formed on the left end side of the lower surface of the upper mold 20 (the side facing the resin sheet S1), a clamp 25 is formed between the die recess 21 and the die recess 22 on the lower surface of the upper mold 20, a clamp 26 is formed between the die recess 22 and the die recess 23 on the lower surface of the upper mold 20, and a clamp 27 is formed on the right end side of the lower surface of the upper mold 20.

[0021] The lower mold 30 is formed with three rows of convex mold protrusions 31, 32, and 33 along the conveying direction of the resin sheet S1. Figure 2 The convex mold portions 31A, 31B, and 31C are arranged in a row (in the depth direction of the Fig. 9 ), the row of the convex mold convex parts 32 along the width direction ( Figure 2 The convex mold portions 32A, 32B, and 32C are arranged in a row (in the depth direction of the Fig. 9 ), the row of the convex mold convex parts 33 along the width direction ( Figure 2 The convex mold portions 33A, 33B, and 33C are arranged in a row (in the depth direction of the Fig. 9 ), forming a total of 9 convex mold parts.

[0022] The structure of the front clamping plate 40 is shown in a three-dimensional diagram. Figure 8 . Fig. 9 2 shows the structure of the upper mold 20, the front clamping plate 40 and the lower mold 30 in an exploded perspective view. A water cooling flow path (not shown) is formed inside the front clamping plate 40, and a cooling water inlet 48 for cooling water to flow into the water cooling flow path and a cooling water outlet 49 for cooling water to be discharged from the water cooling flow path are formed on the front clamping plate 40. The front clamping plate 40 is provided with openings 45A, 45B, and 45C at positions corresponding to the convex convex parts 31A, 31B, and 31C of the lower mold 30 so as to penetrate the front clamping plate 40, openings 46A, 46B, and 46C are provided at positions corresponding to the convex convex parts 32A, 32B, and 32C of the lower mold 30 so as to penetrate the front clamping plate 40, and openings 47A, 47B, and 47C are provided at positions corresponding to the convex convex parts 33A, 33B, and 33C of the lower mold 30 so as to penetrate the front clamping plate 40. Furthermore, Figure 2-4 The symbols of the openings 45A, 45B, 45C and the openings 46A, 46B, 46C are abbreviated as 45 and 46 respectively for simplicity.

[0023] The front clamping plate 40 is provided with convex straight portions 42a and 43a as thin-walled portion forming means. The convex straight portion 42a is formed in a straight line along the width direction at the center of the intermediate portion 42 between the openings 45A, 45B, 45C and the openings 46A, 46B, 46C. In addition, the convex straight portion 43a is formed in a straight line along the width direction at the center of the intermediate portion 43 between the openings 46A, 46B, 46C and the openings 47A, 47B, 47C.

[0024] The center of the clamping part 25 and the clamping part 26 of the upper mold 20 are respectively formed with convex straight line parts 25a and 26a in a straight line shape along the width direction. Figure 2-3 As shown, the convex straight portion 42a is located opposite to the convex straight portion 25a, and the convex straight portion 43a is located opposite to the convex straight portion 26a. In this embodiment, the convex straight portion is not provided at the left end portion 41 (end portion on the rear side of the conveying direction) and the right end portion 44 (end portion on the front side of the conveying direction) of the front clamping plate 40 in the figure, but it may be provided.

[0025] Next, the operation of the thermoforming machine 3 will be described with reference to the drawings. Figure 2 This is the state before thermoforming. The resin sheet S1 is heated by the heating device 2 to a temperature higher than the glass transition temperature, that is, to about 100°C.

[0026] The following clamping process is shown in Figure 3 The next process after the clamping process is the hot forming process shown in Figure 4 .and then, Figure 4 The enlarged view of part A is shown in Figure 5 The upper mold 20 descends toward the heated resin sheet S1 and the front clamp 40 ascends, whereby the left end portion (clamp 24) of the upper mold 20 and the left end portion 41 of the front clamp 40 clamp and press the resin sheet S1, so that the thickness of the resin sheet S1 becomes, for example, 1.5 mm. Similarly, the right end portion (clamp 27) of the upper mold 20 and the right end portion 44 of the front clamp 40 clamp and press the resin sheet S1, so that the thickness of the resin sheet S1 becomes, for example, 1.5 mm.

[0027] The clamping portion 25 of the upper mold 20 and the middle portion 42 of the front clamping plate 40 clamp the resin sheet S1 and press it. Figure 5As shown, the resin sheet S1 is changed to a thickness of, for example, W1 = 1.5 mm. At the same time, a thin-walled portion S11 having a thickness of, for example, W2 = 0.7 mm is formed in the portion of the resin sheet S1 sandwiched by the convex straight portion 42a of the middle portion 42 and the convex straight portion 25a of the clip portion 25 (resin sheet portion). Similarly, a thin-walled portion S12 having a thickness of, for example, W2 = 0.7 mm is formed in the portion of the resin sheet S1 sandwiched by the convex straight portion 43a of the middle portion 43 and the convex straight portion 26a of the clip portion 26 (resin sheet portion) (refer to Figure 7 ). The positions of the thin-walled parts S11 and S12 are shown in Figure 7 .

[0028] Next, the thermoforming process is described. The lower mold 30 rises toward the resin sheet S1 clamped by the upper mold 20 and the front clamp 40, and heat-sets and thermoforms the nine containers C11 at the same time. Figure 4 The temperature of the upper mold 20 and the lower mold 30 is raised to 190° C. and maintained for 10 seconds without changing the state. By maintaining the temperature at 190° C. for 10 seconds, the nine container C11 parts that are formed by being sandwiched by the concave mold concave parts 21A, 21B, 21C, 22A, 22B, 22C, 23A, 23B, 23C of the upper mold 20 and the convex mold convex parts 31A, 31B, 31C, 32A, 32B, 32C, 33A, 33B, 33C of the lower mold 30 are heated to 190° C. and crystallized.

[0029] Here, since the front clamp 40 is cooled by cooling water at 20°C, even if the upper mold 20 is heated to 190°C, the resin sheet portion clamped by the convex straight portion 42a of the middle portion 42 and the convex straight portion 25a of the clamp 25 and the vicinity of the thin-walled portions S11 and S12 clamped by the convex straight portion 43a of the middle portion 43 and the convex straight portion 26a of the clamp 26 are heated to approximately 30 to 50°C, and therefore will not crystallize, thereby maintaining a low rigidity state.

[0030] Next, the trimming step of punching out one row of containers C11 at a time and the buffering step at the buffer section 6 between the thermoforming machine 3 and the trimming device 4 will be described. Figure 7 The resin sheet S2 after the forming process is shown. Furthermore, the thermoforming machine 3 forms 9 containers C11 in 3 rows and 3 columns through a single thermoforming process. Figure 7 The groups G1 and G2 in the figure represent groups of containers obtained by two consecutive thermoforming steps.

[0031] There is a portion where the upper mold 20 and the lower mold 30 are not in contact between the group G1 and the group G2 in which 9 containers C11 are formed. This portion will not be heated to 190°C by the thermoforming machine 3, so it will not crystallize. It has low rigidity and is therefore flexible. When the resin sheet S2 is bent during the buffering process, it will deform naturally, so there is no risk of cracking.

[0032] The trimming device 4 punches out one row of containers C11 at a time, so when the resin sheet S2 enters the trimming device 4 from the buffer 6, a large bend may occur between rows of containers. Figure 4 There may be a large deflection between the row of containers C11 formed by the concave mold portion 23 and the convex mold portion 33 and the row of containers C11 formed by the concave mold portion 22 and the convex mold portion 32. In this case, the thin-walled portions S11 and S12 are also easily deformed due to the combination of the factors that they are thin and easy to deform and the factors that they are not crystallized and easy to deform. Therefore, there is no risk of cracking.

[0033] The thermoforming machine 3 of the present embodiment achieves the following operations and effects. (1) A thermoforming machine 3, which thermoforms a continuously supplied resin sheet S1 to simultaneously form two or more rows of containers C11 in a feeding direction of the resin sheet S1, characterized in that the machine has convex straight portions 42a, 43a of a front clamping plate 40 and convex straight portions 25a, 26a of an upper mold 20, wherein the convex straight portions 42a, 43a of the front clamping plate 40 and the convex straight portions 25a, 26a of the upper mold 20 form thin-walled portions S11, S12 in a direction orthogonal to the feeding direction between the two or more rows of containers C11, so that thin-walled portions S11, S12 are formed between the rows of containers C11, and therefore, the thin-walled portions S11, S12 in the waste portions between the rows of containers C11 can be greatly deformed due to the bending formed between the rows of containers C11 when the crystallized PET sheet enters the trimming device 4, so that cracks are not generated. In addition, since cracks are not generated, the conveyance to the trimming process does not become difficult. Furthermore, the distance between the rows of the containers C11 does not change, and the trimming position of the containers C11 does not go wrong, so that the containers C11 can be punched out with high accuracy.

[0034] (2) The thermoforming machine 3 according to (1) is characterized in that the convex straight portions 42a and 43a of the front clamp 40 have a cooling mechanism (for example, a cooling water inlet 48 and a cooling water outlet 49), which prevents the thin-walled portions S11 and S12 from rising to the crystallization temperature during heat setting and thermoforming. Therefore, the container C11 is partially crystallized and has high rigidity, but the thin-walled portions S11 and S12 are not crystallized, have low rigidity and can be easily deformed, so there is no risk of cracking in the deformed portion.

[0035] (3) The thermoforming machine 3 according to (1) or (2) is characterized in that the thin-walled portions S11 and S12 are continuously formed from one end surface of the resin sheet S2 to the other end surface, so that the crystallized resin sheet S2 spans the entire length in the width direction and deforms at the thin-walled portions S11 and S12, so that the thin-walled portions can be deformed reliably and uniformly.

[0036] (4) The thermoforming machine 3 according to any one of (1) to (3) is characterized in that the thin-walled portions S11 and S12 have recessed portions formed facing each other on both sides. Therefore, when deformation occurs at the recessed portions of the thin-walled portions S11 and S12, no surface will hinder the deformation of the resin sheet S2 on either side, thereby enabling the thin-walled portions to deform stably and uniformly.

[0037] (5) The thermoforming machine 3 according to any one of (1) to (4) is characterized in that it has a front clamp 40, and the convex straight line portions 42a and 43a of the front clamp 40 are provided with a cooling mechanism (for example, a cooling water inlet 48 and a cooling water outlet 49). Therefore, the waste portion between the containers C11 is clamped by the front clamp 40 and the upper mold 20 before thermoforming, and the resin sheet S1 abutted by the front clamp 40 is cooled. Therefore, the waste portion between the containers C11 does not reach the crystallization temperature, and this portion does not crystallize, so the rigidity can be reduced.

[0038] Next, a second embodiment of the present invention will be described. The second embodiment has substantially the same configuration and function as the first embodiment, so only the differences will be described, and description of the same parts will be omitted.

[0039] The shapes of the thin-walled portions S11 and S12 and the convex straight line portions in the second embodiment are shown in FIG. Figure 6 A concave straight portion 25b is formed in the clamping portion 25 of the upper mold 20 instead of a convex straight portion. The depth W5 of the concave portion of the concave straight portion 25b is, for example, W5=4 to 5 mm. In addition, a convex straight portion 42b is formed in the middle portion 42 of the front clamping plate 40, and the convex straight portion 42b has a height higher than the convex straight portion 42a of the first embodiment.

[0040] The plane part of the clamping part 25 and the middle part 42 forms the resin sheet S1 with a thickness of, for example, W6 = 1.5 mm. The convex straight line part 42b enters the concave straight line part 25b to form a convex protrusion S23 on the resin sheet S1. At the same time, a thin-walled part S13 is formed at the top of the convex protrusion S23. The thin-walled part S13 has a thickness of, for example, W4 = 1 mm. The clamping part 26 and the middle part 43 are also formed with a convex protrusion, and a thin-walled part S14 is formed at the top of the convex protrusion (see Figure 7 ).

[0041] According to the second embodiment of the thermoforming machine 3, it is characterized in that the thin-walled portions S13 and S14 are formed at the top end portions of the convex protrusions S23 and S24, so the top end angle formed at the top end portion of the convex protrusion S23 makes it easy for the convex protrusions S23 and S24 to become wider through the deformation of the thin-walled portions S13 and S14, and the inclined surfaces on both sides of the convex protrusion are deformed uniformly, so that the inclined surfaces can be included and the thin-walled portion can be deformed stably and uniformly.

[0042] The above is a description of the thermoforming machine 100 of the present invention, but the present invention is not limited thereto, and various changes can be made within the scope of the purpose. For example, in the first embodiment, the thickness of the resin sheet S1 is set to W1 = 1.5 mm, and the thickness of the thin-walled parts S11 and S12 is set to W2 = 0.7 mm. In the second embodiment, the thickness of the resin sheet S1 is set to W5 = 1.5 mm, and the thickness of the thin-walled parts S13 and S14 is set to W2 = 1.0 mm, but the ratio is preferably changed arbitrarily according to the type of material. In addition, in this embodiment, the thin-walled parts S11 and S12 are continuously formed in the width direction of the resin sheet, but the thin-walled parts S11 and S12 can also be intermittently formed in the width direction of the resin sheet. Explanation of symbols

[0043] 2…Heating device 3…Thermoforming machine 4…Trimming device 6…Buffer 20…upper mold 25, 26…Clamp 25a, 26a ... convex straight line portion 25b, 26b...concave straight line portion 30…Lower die 40…Front splint 42, 43…Middle 42a, 43a ... convex straight line portion 42b, 43b ... convex straight line portion S1…Resin sheet before thermoforming S2…Thermoformed resin sheet S3…Trimmed resin sheet (waste) S11, S12…Thin-walled part S13, S14…Thin-walled part S23…convex protrusion.

Claims

1. A thermoforming machine, which thermoforms continuously supplied resin sheets to simultaneously form two or more rows of containers in a feeding direction of the resin sheets, characterized in that: A thin-walled portion forming mechanism is provided, wherein the thin-walled portion is formed between the two or more rows of containers in a direction perpendicular to the feeding direction, The thin-walled portion forming mechanism has a cooling mechanism to prevent the thin-walled portion from rising to a crystallization temperature during heat setting and thermoforming.

2. The thermoforming machine according to claim 1, characterized in that The thin-walled portion is formed continuously from one end surface to the other end surface of the resin sheet.

3. A thermoforming machine, which thermoforms continuously supplied resin sheets to simultaneously form two or more rows of containers in the feeding direction of the resin sheets, characterized in that: A thin-walled portion forming mechanism is provided, wherein the thin-walled portion is formed between the two or more rows of containers in a direction perpendicular to the feeding direction, The thin-walled portion has concave portions formed on both surfaces so as to face each other.

4. A thermoforming machine, which thermoforms continuously supplied resin sheets to simultaneously form two or more rows of containers in a feeding direction of the resin sheets, characterized in that: A thin-walled portion forming mechanism is provided, wherein the thin-walled portion is formed between the two or more rows of containers in a direction perpendicular to the feeding direction, The thin-walled portion is formed at a tip end portion of the convex protrusion.

5. A thermoforming machine, which thermoforms continuously supplied resin sheets to simultaneously form two or more rows of containers in a feeding direction of the resin sheets, characterized in that: A thin-walled portion forming mechanism is provided, wherein the thin-walled portion is formed between the two or more rows of containers in a direction perpendicular to the feeding direction, The invention also includes a front clamping plate, wherein the thin-walled portion forming mechanism of the front clamping plate includes a cooling mechanism.

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