Die structure for preventing cracking of thermal forming part

Abstract

The invention is applicable to the technical field of thermal forming dies, and provides a thermal forming part anti-cracking die structure which comprises a base box, the top of the base box is connected with a top plate through a supporting plate, the top of the top plate is provided with a lifting assembly, the lifting end of the lifting assembly is connected with a mounting plate, and the bottom of the mounting plate is connected with an upper die through an upper heating assembly. A force application assembly is installed between the flanging position of the upper die and the installation plate, and buffering assemblies are installed on the left side and the right side of the upper die and located at the lifting end of the lifting assembly. An installation groove is formed in the position, under the upper mold, of the top of the base box, a lower heating assembly is installed in the installation groove, a lower mold is installed on the lower heating assembly, and a forming cavity is reserved above the lower mold; the force application end of the force application assembly applies pressure to the flanging of the upper side of the upper die, so that the pressure applied to the material at the plane and the cambered surface of the lower side of the upper die is consistent when the material is stamped, and the problem that the flanging of the material is broken due to uneven stress in the stamping process is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of thermoforming molds, and in particular relates to a mold structure for preventing thermoforming parts from cracking. Background Art

[0002] Thermoforming refers to a production process in which plastic or other materials are heated to a softened or fluid state under high temperature conditions and then shaped or formed through a mold. During the thermoforming process, the molded parts often have cracking problems due to material, process or equipment reasons. Material problems such as inclusions, pores, foreign matter and other defects will cause stress concentration at the flange, causing cracking; process problems such as inappropriate flanging angles and uneven flanging pressure will also cause cracking; equipment problems such as untimely braking during flanging machine processing and frame vibration will also affect the quality of the flanging.

[0003] The Chinese utility model patent with application number 201821841415.1 discloses a stamping and cracking prevention die, including an upper die seat and a lower die seat, wherein an upper forming male is provided at the bottom of the upper die seat, and guide sleeve seats are provided at the four corners of the bottom of the upper die seat; a fixed seat is provided at the top of the lower die seat, and a flanging male is provided on the fixed seat, and a material pressing core is provided in the middle of the flanging male, and guide pillars cooperating with the guide sleeve seat are provided at the four corners of the top of the lower die seat, and an electric heating rod is provided in the milling cavity on the side of the fixed seat, and the electric heating rod is provided on a heating rod fixing plate, and the heating rod fixing plate is provided on the lower die seat, and the electric heating rod is connected to a control switch. This utility model patent heats the flanging male by a heating rod to avoid the problem of flanging cracking of parts during stamping and forming.

[0004] However, the above utility model patent still has some shortcomings:

[0005] During use, the above utility model patent utilizes the thermal conductivity of aluminum to heat the flange pin through a heating rod to ensure that the parts are heated evenly during the stamping process. However, for materials with poor thermal conductivity, heating only the flange pin cannot transfer heat to the entire material well, resulting in temperature differences in the material during the stamping process, and its practicality is low.

[0006] In addition, a very important factor in preventing flange cracking is to ensure balanced pressure when stamping parts. If the upper die seat does not provide buffering when moving downward and directly applies pressure to the lower die seat, it is easy for the parts to be stamped too quickly, resulting in uneven force and thus flange cracking. Summary of the invention

[0007] The present invention provides a mold structure for preventing cracking of thermoformed parts, aiming to solve the problems mentioned in the above background technology.

[0008] The present invention is implemented as follows: a mold structure for preventing cracking of hot-formed parts comprises a base box, the top of the base box is relatively fixedly connected to a support plate, the top of the support plate is commonly fixedly connected to a top plate, a lifting assembly is installed on the top of the top plate, the lifting end of the lifting assembly is connected to a mounting plate, the bottom of the mounting plate is connected to an upper mold through an upper heating assembly, a force-applying assembly is installed between the flange of the upper mold and the mounting plate, and a buffer assembly is installed on the left and right sides of the upper mold and at the lifting end of the lifting assembly; the force-applying assembly comprises a hydraulic rod, the fixed end of the hydraulic rod is installed on the upper mold through a mounting block At the bottom of the mounting plate, the telescopic end of the hydraulic rod is fixedly connected with a force arc block, the force arc block is opposite to the inner side of the flange of the upper mold, and the curvature of the force arc block is consistent with the curvature of the inner side of the flange of the upper mold; a mounting groove is opened directly below the upper mold and at the top of the base box, a lower heating component is installed in the mounting groove, a lower mold is installed on the lower heating component, and a molding cavity is reserved above the lower mold; in this scheme, the force component applies additional pressure to the inner flange of the upper mold, so that the upper mold can apply force evenly when stamping the material, and cooperates with the buffer component to enable the upper mold to move smoothly downward for stamping.

[0009] Preferably, the lifting assembly includes a hydraulic cylinder, which is installed on the top of the top plate, and the telescopic end of the hydraulic cylinder penetrates downward through the top plate and is connected to a lifting plate, and lifting grooves are opened on the side walls opposite to the support plate, and the side end surface of the lifting plate is arranged in the lifting groove; in this scheme, the telescopic end of the hydraulic cylinder controls the lifting plate to drive the mounting plate and the components below to move in the vertical direction.

[0010] Preferably, the upper heating assembly includes a control box, which is connected to the bottom of the lifting plate through the mounting plate, and the bottom of the control box is fixedly connected to the top of the upper mold through a plurality of connecting columns, and an electric heating plate is laid on the top of the upper mold, and the electric heating plate is connected to the control box through a line; in this scheme, the control box controls the electric heating plate through the line to heat the upper mold.

[0011] Preferably, the lower heating assembly includes a heating arc block, which is laid in the mounting groove, and the lower mold is attached to the top of the heating arc block. A flow cavity is opened in the heating arc block, and a heating liquid is injected into the flow cavity. In this solution, the heating arc block is heated by the heating liquid to transfer heat to the lower mold.

[0012] Preferably, the heating arc block is connected to a heating circulation mechanism through a connecting pipe, and the heating circulation mechanism is installed at the front wall of the base box. A liquid outlet pipe is installed on the front wall of the base box, and the liquid outlet pipe is connected to the flow chamber, and a control valve is installed on the side wall of the liquid outlet pipe. In this scheme, the heating circulation mechanism is used to ensure that the heating liquid in the flow chamber always maintains a high temperature to heat the lower mold.

[0013] Preferably, the buffer assembly includes a telescopic cylinder, the thick end of the telescopic cylinder is fixedly connected to the bottom of the lifting plate through a connecting plate, the thin end of the telescopic cylinder is fixedly connected to a lower pressing plate, and a spring is sleeved between the connecting plate and the lower pressing plate and on the outer wall of the telescopic cylinder; in this scheme, the elastic force generated by the compression of the spring is used to slow down the speed of the hydraulic cylinder driving the lower mold to move downward.

[0014] Preferably, a protective tube is fixedly connected to the top of the lower pressure plate, and the protective tube arranges the spring cover that is sleeved outside the thin tube end of the telescopic tube inside.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The telescopic end of the hydraulic rod controls the force arc block to move toward the upper flange of the upper mold, so that the arc surface of the force arc block is close to the arc surface of the upper flange of the upper mold, so as to apply pressure to the upper flange of the upper mold, so that the pressure applied to the material by the plane and flange of the lower side of the upper mold is consistent when stamping, ensuring that the material will not break due to uneven force during the stamping process.

[0017] 2. During the stamping process of the material in the molding cavity, the heating circulation mechanism starts to circulate and heat the liquid in the flow cavity through the connecting pipe, so that the heating arc block continuously heats the lower mold. At the same time, the control box drives the electric heating plate to heat the upper mold, so that the temperature of the upper mold and the lower mold is consistent, avoiding the problem of flange breakage due to uneven heating during the stamping process.

[0018] 3. When the lifting plate moves downward, the buffer assembly moves downward synchronously. When the lower pressure plate moves downward and contacts the top of the base box, the thick end of the telescopic cylinder continues to move downward to compress the spring. The elastic force generated by the contraction of the spring is used to slow down the speed at which the thick end of the telescopic cylinder moves downward, thereby reducing the speed at which the telescopic end of the hydraulic cylinder drives the lifting plate and the upper mold to move downward, allowing the upper mold to enter the forming cavity more smoothly to stamp the material, thereby avoiding cracking of the flange when the material is formed during the stamping process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a front view schematic diagram of the present invention;

[0020] Figure 2 It is a front cross-sectional schematic diagram of the present invention;

[0021] Figure 3 For the present invention Figure 2 A magnified schematic diagram of point A;

[0022] Figure 4 For the present invention Figure 2 An enlarged schematic diagram of point B;

[0023] Figure 5 It is a front cross-sectional schematic diagram of the protective tube in the present invention;

[0024] In the figure:

[0025] 1. Base box; 2. Support plate; 3. Top plate; 4. Lifting assembly; 41. Hydraulic cylinder; 42. Lifting plate; 43. Lifting slot; 5. Mounting plate; 6. Upper heating assembly; 61. Control box; 62. Connecting column; 63. Electric heating plate; 7. Force-applying assembly; 71. Hydraulic rod; 72. Mounting block; 73. Force-applying arc block; 8. Upper mold; 9. Mold block; 10. Mounting slot; 11. Lower heating assembly; 111. Heating arc block; 112. Flow cavity; 113. Connecting pipe; 114. Heating circulation mechanism; 115. Liquid outlet pipe; 116. Control valve; 12. Lower mold; 13. Molding cavity; 14. Buffer assembly; 141. Telescopic cylinder; 142. Connecting plate; 143. Lower pressure plate; 144. Spring; 145. Protective cylinder. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0027] The components of the embodiments of the present invention generally described and shown in the drawings herein may be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention.

[0028] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] See also Figure 1-5 The present invention provides a technical solution: a mold structure for preventing cracking of thermoformed parts, comprising a base box 1, a support plate 2 is relatively fixedly connected to the top of the base box 1, a top plate 3 is commonly fixedly connected to the top of the support plate 2, a lifting assembly 4 is installed on the top of the top plate 3, a mounting plate 5 is connected to the lifting end of the lifting assembly 4, an upper mold 8 is connected to the bottom of the mounting plate 5 through an upper heating assembly 6, a force-applying assembly 7 is installed between the flange of the upper mold 8 and the mounting plate 5, and a buffer assembly 14 is installed on the left and right sides of the upper mold 8 and at the lifting end of the lifting assembly 4;

[0032] The force-applying assembly 7 includes a hydraulic rod 71, the fixed end of which is mounted on the bottom of the mounting plate 5 via a mounting block 72, and a force-applying arc block 73 is fixedly connected to the telescopic end of the hydraulic rod 71, the force-applying arc block 73 is directly opposite to the inner side of the flange of the upper mold 8, and the curvature of the force-applying arc block 73 is consistent with the curvature of the inner side of the flange of the upper mold 8;

[0033] A mounting groove 10 is provided directly below the upper mold 8 and on the top of the base box 1 . A lower heating assembly 11 is installed in the mounting groove 10 . A lower mold 12 is installed on the lower heating assembly 11 . A molding cavity 13 is reserved above the lower mold 12 .

[0034] Specifically, the lifting end of the lifting assembly 4 controls the mounting plate 5 to drive the upper heating assembly 6 and the upper mold 8 to move in the vertical direction, and cooperate with the lower mold 12 to press down the material to be stamped in the molding cavity 13. The mold block 9 is fixedly connected to the highest point of the lower arc surface of the upper mold 8 to prevent the material from leaking from the molding cavity 13 during the molding process.

[0035] During the above-mentioned stamping process, when the upper mold 8 moves downward, the force-applying end of the force-applying component 7 applies pressure to the upper flange of the upper mold 8, so that the pressure applied to the material at the flat surface and the curved surface on the lower side of the upper mold 8 is consistent, ensuring that the material will not break due to uneven force during the stamping process.

[0036] That is, the curvature of the force arc block 73 is consistent with the curvature of the inner side of the flange of the upper mold 8, ensuring that the force arc block 73 can fit the upper flange of the upper mold 8 to apply pressure. The telescopic end of the hydraulic rod 71 controls the force arc block 73 to move toward the upper flange of the upper mold 8, so that the arc surface of the force arc block 73 is closely attached to the arc surface of the upper flange of the upper mold 8, so as to apply pressure to the upper flange of the upper mold 8, so that the pressure applied to the material by the plane and flange of the lower side of the upper mold 8 is consistent.

[0037] In addition, when the upper mold 8 moves downward, the upper heating component 6 heats the upper mold 8, and the lower heating component 11 heats the lower mold 12, ensuring that the material is heated evenly as a whole during the stamping process, and ensuring that the material will not break due to uneven heating during the stamping process.

[0038] In addition, when the lifting end of the lifting component 4 drives the upper mold 8 downward, the buffer component 14 moves downward synchronously. When the upper mold 8 enters the molding cavity 13, the buffer component 14 contacts the top of the base box 1 and contracts under pressure. The elastic reaction force of the buffer component 14 is used to slow down the downward speed of the upper mold 8, so that the upper mold 8 can punch the material inside the molding cavity 13 at a slower speed, further ensuring that the material can be evenly stressed during the punching process.

[0039] Furthermore, the lifting assembly 4 includes a hydraulic cylinder 41, which is installed on the top of the top plate 3, and the telescopic end of the hydraulic cylinder 41 penetrates downward through the top plate 3 and is connected to a lifting plate 42. A lifting groove 43 is opened on the side wall opposite to the support plate 2, and the side end surface of the lifting plate 42 is arranged in the lifting groove 43.

[0040] Specifically, the telescopic end of the hydraulic cylinder 41 drives the lifting plate 42 to move in the vertical direction. Compared with other components such as a cylinder, the hydraulic cylinder 41 is more stable in controlling the lifting of the lifting plate 42. In addition, the left and right sides of the lifting plate 42 are respectively clamped in two lifting grooves 43, ensuring that the lifting plate 42 is more stable and will not be offset in the process of moving in the vertical direction.

[0041] Furthermore, the upper heating assembly 6 includes a control box 61, which is connected to the bottom of the lifting plate 42 through the mounting plate 5. The bottom of the control box 61 is fixedly connected to the top of the upper mold 8 through a plurality of connecting columns 62. The top of the upper mold 8 is provided with an electric heating plate 63, which is connected to the control box 61 through lines.

[0042] Specifically, the control box 61 is fixedly connected to the bottom of the mounting plate 5, and the two ends of the connecting column 62 are respectively fixedly connected to the bottom of the control box 61 and the top of the upper mold 8. The operator controls the electric heating plate 63 through the control box 61 to heat the upper mold 8 to ensure that the material in the molding cavity 13 can be heated evenly during the stamping process. In addition, the upper mold 8 should be made of a material with good thermal conductivity.

[0043] Furthermore, the lower heating assembly 11 includes a heating arc block 111, which is laid in the mounting groove 10, and the lower mold 12 is attached to the top of the heating arc block 111. A flow cavity 112 is opened in the heating arc block 111, and a heating liquid is injected into the flow cavity 112.

[0044] Furthermore, the heating arc block 111 is connected to a heating circulation mechanism 114 through a connecting pipe 113. The heating circulation mechanism 114 is installed on the front wall of the base box 1. A liquid outlet pipe 115 is installed on the front wall of the base box 1. The liquid outlet pipe 115 is connected to the flow chamber 112, and a control valve 116 is installed on the side wall of the liquid outlet pipe 115.

[0045] Specifically, a liquid with good thermal conductivity is injected into the flow cavity 112 to heat the heating arc block 111. In addition, a thermal insulation material can be bonded to the bottom of the heating arc block 111 to reduce the heat loss of the heating arc block 111. The heating arc block 111 and the lower mold 12 are both made of materials with good thermal conductivity, so that the lower mold 12 can heat up quickly.

[0046] The heating circulation mechanism 114 is composed of a heater and a circulation pump, so that the liquid injected into the heating arc block 111 is always in a circulating heating state to ensure that the lower mold 12 is in a continuous heating state. The heating temperature of the lower mold 12 is regulated by the heater to ensure that it is consistent with the heating temperature of the electric heating plate 63 for the upper mold 8, ensuring that the material in the molding cavity 13 is heated evenly during the stamping process.

[0047] The arrangement of the liquid outlet pipe 115 and the control valve 116 can supplement or replace the heating liquid in the flow chamber 112 .

[0048] Furthermore, the buffer assembly 14 includes a telescopic cylinder 141, the thick end of the telescopic cylinder 141 is fixedly connected to the bottom of the lifting plate 42 through a connecting plate 142, the thin end of the telescopic cylinder 141 is fixedly connected to a lower pressure plate 143, and a spring 144 is sleeved between the connecting plate 142 and the lower pressure plate 143 and on the outer wall of the telescopic cylinder 141.

[0049] Furthermore, a protective tube 145 is fixedly connected to the top of the lower pressing plate 143 , and the protective tube 145 covers the spring 144 which is sleeved on the thin tube end of the telescopic tube 141 inside.

[0050] Specifically, the connecting plate 142 is fixedly connected to the bottom of the lifting plate 42, and the thick end of the telescopic cylinder 141 is fixedly installed at the bottom of the connecting plate 142. When the lower pressing plate 143 moves downward to contact the top of the base box 1, the thick end of the telescopic cylinder 141 continues to move downward to compress the spring 144. The elastic force generated by the contraction of the spring 144 is used to slow down the speed at which the thick end of the telescopic cylinder 141 moves downward, thereby reducing the speed at which the telescopic end of the hydraulic cylinder 41 drives the lifting plate 42 and the upper mold 8 to move downward, so that the upper mold 8 can enter the molding cavity 13 more smoothly to stamp the material, thereby avoiding the occurrence of cracking of the flange when the material is formed during the stamping process.

[0051] In addition, the height of the protective tube 145 is consistent with the thin tube end of the telescopic tube 141, so as to protect the part of the spring 144 outside the thin tube end of the telescopic tube 141, so as to prevent part of the fluid material to be stamped from splashing onto the spring 144 when pouring into the molding cavity 13, causing damage to the spring 144 and affecting the buffering effect.

[0052] The working principle and use process of the present invention: After the present invention is installed, the fluid material to be stamped is poured into the molding cavity 13, and the heating circulation mechanism 114 is started to circulate and heat the liquid in the flow cavity 112 through the connecting pipe 113, so that the heating arc block 111 continuously heats the lower mold 12.

[0053] The telescopic end of the hydraulic cylinder 41 drives the lifting plate 42 to move downward along the lifting groove 43 and the mounting plate 5, and the control box 61 drives the upper mold 8 to move downward synchronously through the connecting column 62. During this process, the control box 61 drives the electric heating plate 63 to heat the upper mold 8, so that the temperature of the upper mold 8 and the lower mold 12 are consistent.

[0054] At the same time, the telescopic end of the hydraulic rod 71 controls the force arc block 73 to move toward the upper flange of the upper mold 8, so that the arc surface of the force arc block 73 is tightly attached to the arc surface of the upper flange of the upper mold 8, so as to apply pressure to the upper flange of the upper mold 8, so that the pressure applied to the material at the plane and flange of the lower side of the upper mold 8 is consistent.

[0055] When the lifting plate 42 moves downward, the buffer assembly 14 moves downward synchronously. After the lower pressure plate 143 moves downward and contacts the top of the base box 1, the thick end of the telescopic cylinder 141 continues to move downward to compress the spring 144. The elastic force generated by the contraction of the spring 144 is used to slow down the speed at which the thick end of the telescopic cylinder 141 moves downward, thereby reducing the speed at which the telescopic end of the hydraulic cylinder 41 drives the lifting plate 42 and the upper mold 8 to move downward, so that the upper mold 8 can enter the molding cavity 13 more smoothly to punch the material.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A mold structure for preventing cracking of thermoformed parts, characterized in that: The invention comprises a base box (1), the top of the base box (1) is relatively fixedly connected to a support plate (2), the top of the support plate (2) is commonly fixedly connected to a top plate (3), a lifting assembly (4) is installed on the top of the top plate (3), the lifting end of the lifting assembly (4) is connected to a mounting plate (5), the bottom of the mounting plate (5) is connected to an upper mold (8) through an upper heating assembly (6), a force-applying assembly (7) is installed between the flange of the upper mold (8) and the mounting plate (5), and a buffer assembly (14) is installed on the left and right sides of the upper mold (8) and at the lifting end of the lifting assembly (4); The force-applying assembly (7) comprises a hydraulic rod (71), the fixed end of the hydraulic rod (71) is mounted on the bottom of the mounting plate (5) via a mounting block (72), the telescopic end of the hydraulic rod (71) is fixedly connected with a force-applying arc block (73), the force-applying arc block (73) is directly opposite to the inner side of the flange of the upper mold (8), and the curvature of the force-applying arc block (73) is consistent with the curvature of the inner side of the flange of the upper mold (8); A mounting groove (10) is provided directly below the upper mold (8) and at the top of the base box (1), a lower heating component (11) is installed in the mounting groove (10), a lower mold (12) is installed on the lower heating component (11), and a molding cavity (13) is reserved above the lower mold (12).

2. A mold structure for preventing cracking of thermoformed parts according to claim 1, characterized in that: The lifting assembly (4) comprises a hydraulic cylinder (41), the hydraulic cylinder (41) is installed on the top of the top plate (3), and the telescopic end of the hydraulic cylinder (41) penetrates downward through the top plate (3) and is connected to a lifting plate (42), a lifting groove (43) is provided on the side wall opposite to the support plate (2), and the side end surface of the lifting plate (42) is arranged in the lifting groove (43).

3. A mold structure for preventing cracking of thermoformed parts according to claim 2, characterized in that: The upper heating assembly (6) comprises a control box (61), the control box (61) is connected to the bottom of the lifting plate (42) via the mounting plate (5), the bottom of the control box (61) is fixedly connected to the top of the upper mold (8) via a plurality of connecting columns (62), the top of the upper mold (8) is provided with an electric heating plate (63), and the electric heating plate (63) is connected to the control box (61) via a line.

4. A mold structure for preventing cracking of thermoformed parts according to claim 1, characterized in that: The lower heating component (11) comprises a heating arc block (111), the heating arc block (111) is laid in the installation groove (10), the lower mold (12) is attached to the top of the heating arc block (111), a flow cavity (112) is opened in the heating arc block (111), and a heating liquid is injected into the flow cavity (112).

5. A mold structure for preventing cracking of thermoformed parts according to claim 4, characterized in that: The heating arc block (111) is connected to a heating circulation mechanism (114) via a connecting pipe (113); the heating circulation mechanism (114) is installed on the front wall of the base box (1); a liquid outlet pipe (115) is installed on the front wall of the base box (1); the liquid outlet pipe (115) is connected to the flow chamber (112); and a control valve (116) is installed on the side wall of the liquid outlet pipe (115).

6. A mold structure for preventing cracking of thermoformed parts according to claim 2, characterized in that: The buffer assembly (14) comprises a telescopic cylinder (141), the thick end of the telescopic cylinder (141) is fixedly connected to the bottom of the lifting plate (42) through a connecting plate (142), the thin end of the telescopic cylinder (141) is fixedly connected to a lower pressure plate (143), and a spring (144) is sleeved between the connecting plate (142) and the lower pressure plate (143) and on the outer wall of the telescopic cylinder (141).

7. A mold structure for preventing cracking of thermoformed parts according to claim 6, characterized in that: A protective tube (145) is fixedly connected to the top of the lower pressure plate (143), and the protective tube (145) covers the spring (144) sleeved on the thin tube end of the telescopic tube (141) inside.

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