An injection molding die for an automobile injection molding part and a manufacturing method thereof

Abstract

This invention discloses an automotive injection molding die and its manufacturing method, comprising a fixed mold base fixedly mounted on an injection platform and an upper mold base fixedly connected to an injection lifting mechanism; a support mold base is fixedly mounted on the upper end of the fixed mold base, and a fixed mold core is detachably mounted on the support mold base; an injection base is fixedly connected to the lower end of the upper mold base, and a movable mold base is fixedly connected to the lower end of the injection base, with a movable mold core that mates with the fixed mold core detachably mounted on the lower end of the movable mold base; an injection hole and an adjustment hole are provided on the injection base, and the injection hole and the adjustment hole are connected; an injection adjustment component for adjusting the opening and closing of the injection hole is provided on the upper mold base; multiple sets of locking components for locking the fixed mold core are provided on the support mold base; this invention can achieve heating and cooling of the mold through an upper temperature control tube and a lower temperature control tube, thereby ensuring the molding quality of the automotive injection molded parts.

Description

Technical Field

[0001] This invention relates to the field of injection mold technology, specifically to an automotive injection mold and its manufacturing method. Background Technology

[0002] Injection molding, also known as injection molding, is a molding method that combines injection and molding. Its advantages include high production speed, high efficiency, automated operation, the ability to produce shapes ranging from simple to complex, and sizes from large to small. It also produces precise dimensions, facilitates product updates, and can create complex parts. Injection molding is suitable for mass production and molding of complex-shaped products, especially in the automotive industry, where plastics are an essential component, primarily used for injection molding automotive parts. In developed countries, the amount of plastic used in automobiles has even become an important indicator of automotive design and manufacturing standards.

[0003] Existing injection molds cannot adjust the injection hole. When the raw material enters the injection hole, the solidification of the raw material in the injection hole can cause voids in the injection molded part. Summary of the Invention

[0004] The purpose of this invention is to provide an automotive injection molding die and its manufacturing method, which solves the technical problem that the solidification of injection molding raw materials in the injection hole can lead to voids in the injection molded parts.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] An automotive injection mold includes a fixed mold base fixedly mounted on an injection platform and an upper mold base fixedly connected to an injection lifting mechanism;

[0007] A support mold base is fixedly provided on the upper end of the fixed mold base, and a fixed mold core is detachably installed on the support mold base;

[0008] The lower end of the upper mold base is fixedly connected to an injection molding base, and the lower end of the injection molding base is fixedly connected to a moving mold base. The lower end of the moving mold base is detachably installed with a moving mold core that cooperates with the fixed mold core. The injection molding base is provided with an injection hole and an adjustment hole, which are connected to each other. The upper mold base is provided with an injection adjustment component for adjusting the opening and closing of the injection hole.

[0009] The support mold base is provided with multiple sets of locking components for locking the fixed mold core.

[0010] As a further embodiment of the present invention: guide posts are fixedly provided at the four corners of the upper end of the fixed mold base, and guide holes that slide with the guide posts are provided on the supporting mold base, the upper mold base, the injection mold base and the moving mold base.

[0011] As a further aspect of the present invention: the lower end of the injection molding base is provided with a central injection molding tube and an edge injection molding tube, both of which are connected to the injection hole.

[0012] As a further aspect of the present invention: the injection molding adjustment component includes an adjustment cylinder fixedly installed on the upper mold base, and an adjustment column is fixedly connected to the end of the telescopic rod of the adjustment cylinder, and the adjustment column is slidably disposed in the adjustment hole.

[0013] As a further aspect of the present invention: the adjusting column is provided with a straight through hole and a right-angle through hole, the straight through hole being located above the right-angle through hole, and the right-angle through hole connecting the injection hole and the edge injection tube.

[0014] As a further aspect of the present invention: an upper temperature control tube is provided on the moving mold base, and a lower temperature control tube is provided on the supporting mold base.

[0015] As a further embodiment of the present invention: the locking component includes an adjusting seat and a guide seat fixedly installed on the support mold base, and a locking slide plate is slidably disposed on the guide seat; an adjusting screw is threadedly connected to the adjusting seat, the threaded end of the adjusting screw is rotatably connected to the locking slide plate, and a support rod is connected to the locking slide plate, and the support rod is rotatably connected to the support mold base.

[0016] As a further aspect of the present invention: a forming cavity is provided on the fixed mold core, and a demolding top plate is provided at the bottom of the forming cavity.

[0017] As a further embodiment of the present invention: the demolding top plate includes an intermediate top plate disposed at the center of the molding cavity and an outer top plate disposed at the edge of the molding cavity, and both the outer top plate and the intermediate top plate are provided with a top plate connecting rod at their lower ends;

[0018] The fixed mold base is equipped with a demolding cylinder for driving the outer top plate and the intermediate top plate to rise and fall.

[0019] As a further aspect of the present invention: a method for manufacturing an automotive injection molding die, the method comprising the following steps:

[0020] Step 1: Install the demolding cylinder onto the fixed mold base, and then fix the fixed mold base onto the injection molding platform;

[0021] Step 2: Fix the support mold base onto the fixed mold base, install the temperature control tube and locking components on the support mold base, then install the fixed mold core onto the support mold base and lock and fix the fixed mold core using the locking components;

[0022] Step 3: The demolding cylinder extends upward, connecting the outer top plate and the middle top plate to their respective demolding cylinders. Then, the demolding cylinder retracts and resets, allowing the outer top plate and the middle top plate to retract into the molding cavity.

[0023] Step 4: Install the injection adjustment component onto the upper mold base, fix the upper mold base onto the injection lifting mechanism, and then fix the upper injection base onto the lower end of the upper mold base;

[0024] Step 5: Install the upper temperature control tube onto the moving mold base, then fix the moving mold base to the lower end of the injection mold base. At the same time, fix the moving mold core that mates with the fixed mold core to the lower end of the moving mold base, thus completing the assembly and manufacturing of the injection mold.

[0025] The beneficial effects of this invention are:

[0026] Heating the mold is necessary to ensure the fluidity of the injection molding material and prevent the material from solidifying, which could lead to hollow areas in the injection molded parts. When the mold cavity is filled with injection molding material, the mold needs to be cooled so that the injection molded parts can cool and solidify quickly. The upper and lower temperature control pipes can achieve the heating and cooling of the mold, thereby ensuring the molding quality of automotive injection molded parts.

[0027] Locking components are installed to lock the fixed mold core. Two sets of locking components are usually arranged symmetrically, and multiple sets can be installed as needed. Multiple locking components are distributed in a ring array to ensure the stability of the fixed mold core installation.

[0028] The injection molded part is assisted in demolding by the middle top plate and multiple outer top plates, making it easy to completely remove the injection molded part from the molding cavity.

[0029] When the injection molded part is small, only the center injection tube is needed to complete the injection molding. When the injection molded part is large, both the center injection tube and the edge injection tube can be used to inject the part at the same time, thereby ensuring the quality of the finished product and preventing the injection molding effect from being affected by the solidification of the injection molding material. Attached Figure Description

[0030] The present invention will now be further described with reference to the accompanying drawings.

[0031] Figure 1 This is a three-dimensional structural diagram of the entire invention;

[0032] Figure 2 This is an exploded structural diagram of the entire invention;

[0033] Figure 3 This is a front view schematic diagram of the overall exploded structure of the present invention;

[0034] Figure 4 This is a schematic diagram of the installation structure of the fixed mold core of the present invention;

[0035] Figure 5 This is the present invention. Figure 4 Enlarged structural diagram at point A;

[0036] Figure 6 This is a three-dimensional structural schematic diagram of the locking component of the present invention;

[0037] Figure 7 This is a cross-sectional structural schematic diagram of the locking component of the present invention;

[0038] Figure 8 This is a schematic diagram of the installation structure of the injection molding adjustment component of the present invention;

[0039] Figure 9 This is a three-dimensional structural schematic diagram of the adjusting column of the present invention;

[0040] Figure 10 This is a cross-sectional structural schematic diagram of the adjusting column of the present invention.

[0041] In the diagram: 1. Fixed mold base; 2. Support mold base; 3. Upper mold base; 4. Injection base; 41. Injection hole; 42. Center injection tube; 43. Edge injection tube; 44. Adjustment hole; 5. Moving mold base; 6. Upper temperature control tube; 7. Locking component; 71. Adjustment seat; 72. Adjustment screw; 73. Adjustment spring; 74. Guide seat; 75. Locking slide plate; 76. Support rod; 77. Guide plate; 78. Guide connecting rod; 79. 8. Support slider; 9. Lower temperature control tube; 10. Injection molding adjustment component; 11. Adjustment cylinder; 12. Telescopic rod; 13. Adjustment column; 14. Straight through hole; 15. Right angle through hole; 16. Guide column; 17. Moving mold core; 18. Fixed mold core; 19. Molding cavity; 10. Outer top plate; 11. Intermediate top plate; 12. Top plate connecting rod; 13. Upper connecting plate; 14. Demolding cylinder; 15. Demolding connecting rod; 16. Connecting pin. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Please see Figures 1-10As shown, a first aspect of the present invention provides an automotive injection molding die, including a fixed mold base 1 fixedly mounted on an injection platform and an upper mold base 3 fixedly connected to an injection lifting mechanism; a support mold base 2 is fixedly mounted on the upper end of the fixed mold base 1, and a fixed mold core 12 is detachably mounted on the support mold base 2; an injection base 4 is fixedly connected to the lower end of the upper mold base 3, and a movable mold base 5 is fixedly connected to the lower end of the injection base 4, and a movable mold core 11 that cooperates with the fixed mold core 12 is detachably mounted on the lower end of the movable mold base 5; an injection hole 41 and an adjustment hole 44 are provided on the injection base 4, and the injection hole 41 and the adjustment hole 44 are connected; an injection adjustment component 9 for adjusting the opening and closing of the injection hole 41 is provided on the upper mold base 3; and multiple sets of locking components 7 for locking the fixed mold core 12 are provided on the support mold base 2.

[0044] The upper mold base 3 is fixedly provided with an upper connecting plate 13. The upper mold base 3 can be fixedly installed on the injection molding lifting mechanism through the upper connecting plate 13. The injection molding lifting mechanism drives the upper mold base 3 and the moving mold core 11 to move downward, so that the moving mold core 11 and the fixed mold core 12 are closed together. Then, the injection base 4 injects raw materials into the fixed mold core 12, thereby completing the processing of automotive injection molded parts.

[0045] Since the fixed mold core 12 and the moving mold core 11 need to continuously close and separate the mold, the upper mold base 3 needs to continuously rise and fall. It is also necessary to ensure the accuracy of the mold core 12 and the moving mold core 11 when closing the mold. The guide posts 10 are fixedly set at the four corners of the upper end of the fixed mold base 1 to position the rise and fall of the upper mold base 3. The support mold base 2, the upper mold base 3, the injection mold base 4 and the moving mold base 5 are all provided with guide holes that slide with the guide posts 10.

[0046] Please see Figures 8-10 As shown, the lower end of the injection molding base 4 is provided with a central injection tube 42 and an edge injection tube 43. Both the central injection tube 42 and the edge injection tube 43 are connected to the injection hole 41. The central injection tube 42 is located at the center of the lower end of the injection molding base 4, and the edge injection tubes 43 are symmetrically distributed with the central injection tube 42 as the center. When the size of the injection molded part is small, only the central injection tube 42 is used to complete the injection molding of the part. When the size of the injection molded part is large, both the central injection tube 42 and the edge injection tube 43 can be used to inject the part at the same time, thereby ensuring the quality of the finished product of the injection molded part and preventing the effect of the injection molded part from being affected by the solidification of the injection molding material.

[0047] Since the center injection tube 42 and the edge injection tube 43 do not need to be used simultaneously, an injection adjustment component 9 is provided to adjust the opening and closing of the injection hole 41. The injection adjustment component 9 includes an adjustment cylinder 91 fixedly installed on the upper mold base 3. An adjustment column 93 is fixedly connected to the end of the telescopic rod 92 of the adjustment cylinder 91. The adjustment column 93 is slidably disposed in the adjustment hole 44. The adjustment column 93 is provided with a straight through hole 94 and a right-angle through hole 95. The straight through hole 94 is located above the right-angle through hole 95, and the right-angle through hole 95 connects the injection hole 41 and the edge injection tube 43.

[0048] When the edge injection tube 43 is needed to feed material into the injection molded part, the adjusting cylinder 91 drives the adjusting column 93 to move upward, so that one end of the right angle through hole 95 is connected to the injection hole 41, and the other end of the right angle through hole 95 is connected to the edge injection tube 43. When the raw material enters the injection hole 41, it flows into the edge injection tube 43 through the guide of the right angle through hole 95, and then flows into the molding cavity 121 of the fixed mold core 12 through the edge injection tube 43, thus completing the injection molding process of the part.

[0049] When the central injection tube 42 is needed, the adjusting cylinder 91 drives the adjusting column 93 to move downward, so that the through hole 94 is connected to the injection hole 41, thereby connecting the injection hole 41 to the central injection tube 42. When the raw material enters the injection hole 41, it flows into the central injection tube 42 through the guide of the through hole 94, and then flows into the molding cavity 121 of the fixed mold core 12 through the central injection tube 42, completing the injection molding process of the processed part.

[0050] During injection molding, the mold needs to be heated to ensure the fluidity of the injection material and prevent the material from solidifying, which could lead to hollow parts. When the molding cavity 121 is filled with injection material, the mold needs to be cooled to allow the injection part to cool and solidify quickly. The moving mold base 5 is equipped with an upper temperature control pipe 6, and the supporting mold base 2 is equipped with a lower temperature control pipe 8. The upper temperature control pipe 6 and the lower temperature control pipe 8 can heat and cool the mold, thereby ensuring the molding quality of automotive injection molded parts.

[0051] Please see Figure 6 and Figure 7 As shown, since the fixed mold core 12 and the moving mold core 11 are replaced according to the different parts to be processed, in order to facilitate the disassembly and assembly of the fixed mold core 12 and ensure that the fixed mold core 12 remains stable after installation, a locking component 7 is set to lock the fixed mold core 12. The locking components 7 are usually arranged in two sets symmetrically, and multiple sets can be set as needed. The multiple locking components 7 are distributed in a ring array to ensure the stability of the fixed mold core 12 during installation.

[0052] The locking component 7 includes an adjusting seat 71 and a guide seat 74 fixedly installed on the support mold base 2. A locking slide plate 75 is slidably disposed on the guide seat 74. An adjusting screw 72 is threadedly connected to the adjusting seat 71. An adjusting spring 73 is sleeved on the outer periphery of the adjusting screw 72. The threaded end of the adjusting screw 72 is rotatably connected to the locking slide plate 75. A support rod 76 is connected to the locking slide plate 75. The support rod 76 is rotatably connected to the support mold base 2.

[0053] The locking component 7 also includes a guide plate 77, which is fixedly installed on the support mold base 2. At the same time, multiple guide rods 78 are slidably arranged through the guide plate 77. A support slider 79 is fixedly connected to the guide rods 78. The support slider 79 is slidably arranged on the support mold base 2, and the locking slide plate 75 is fixedly arranged on the support slider 79.

[0054] When it is necessary to lock the fixed mold core 12, rotate the adjusting screw 72. Through the threaded connection between the adjusting screw 72 and the adjusting seat 71, the locking slide plate 75 moves along the guide seat 74 toward the fixed mold core 12. The locking slide plate 75 clamps the fixed mold core 12, ensuring that the fixed mold core 12 remains stable during injection molding, thereby ensuring the accurate mold closing of the fixed mold core 12 and the moving mold core 11.

[0055] Please see Figure 4 and Figure 5 As shown, a molding cavity 121 is provided on the fixed mold core 12, and a demolding top plate is provided at the bottom of the molding cavity 121. The demolding top plate includes an intermediate top plate 123 located at the center of the molding cavity 121 and an outer top plate 122 located at the edge of the molding cavity 121. Both the outer top plate 122 and the intermediate top plate 123 are provided with top plate connecting rods 124 at their lower ends.

[0056] The intermediate top plate 123 is located at the center of the molding cavity 121, and multiple outer top plates 122 are provided and evenly distributed near the edge of the molding cavity 121. The intermediate top plate 123 and multiple outer top plates 122 assist in demolding the injection molded part, making it easy to completely remove the injection molded part from the molding cavity 121.

[0057] The fixed mold base 1 is equipped with a demolding cylinder 14 for driving the outer top plate 122 and the intermediate top plate 123 to rise and fall. A demolding connecting rod 15 is fixedly connected to the output end of the demolding cylinder 14, and the demolding connecting rod 15 is fixedly connected to the top plate connecting rod 124 through the connecting pin 16. The demolding cylinder 14 can drive the demolding top plate to rise and fall, thereby realizing the demolding of the injection molded part.

[0058] Furthermore, both the intermediate top plate 123 and the outer top plate 122 are driven independently. When demolding is required, the demolding cylinder 14 first drives the intermediate top plate 123 and the outer top plate 122 to move upward simultaneously, ejecting the injection molded part from the molding cavity 121. Then, the outer top plates 122 are lowered one by one to separate them from the injection molded part, and after separation, they rise again to press the injection molded part. When all the outer top plates 122 are separated from the injection molded part, the intermediate top plate 123 is moved downward to separate from the injection molded part, ensuring that the injection molded part is not damaged during demolding.

[0059] A second aspect of the present invention provides a method for manufacturing an injection mold for automotive parts, the method comprising the following steps:

[0060] Step 1: Install the demolding cylinder 14 onto the fixed mold base 1, and then fix the fixed mold base 1 onto the injection molding platform;

[0061] Step 2: Fix the support mold base 2 onto the fixed mold base 1, install the temperature control tube 8 and the locking component 7 on the support mold base 2, and then install the fixed mold core 12 onto the support mold base 2 and lock and fix the fixed mold core 12 by the locking component 7;

[0062] Step 3: The demolding cylinder 14 extends upward, connecting the outer top plate 122 and the middle top plate 123 to the corresponding demolding cylinder 14 respectively. Then the demolding cylinder 14 retracts and resets, so that the outer top plate 122 and the middle top plate 123 are retracted into the molding cavity 121.

[0063] Step 4: Install the injection adjustment component 9 onto the upper mold base 3, fix the upper mold base 3 onto the injection lifting mechanism, and then fix the upper injection base 4 onto the lower end of the upper mold base 3.

[0064] Step 5: Install the upper temperature control tube 6 onto the moving mold base 5, then fix the moving mold base 5 onto the lower end of the injection mold base 4, and fix the moving mold core 11, which cooperates with the fixed mold core 12, onto the lower end of the moving mold base 5 to complete the assembly and manufacturing of the injection mold.

[0065] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for manufacturing an injection mold for automotive parts, characterized in that, The molding die includes a fixed mold base (1) and an upper mold base (3) fixedly connected to the injection molding lifting mechanism; The fixed mold base (1) is fixedly provided with a support mold base (2) at the upper end, and the fixed mold core (12) is detachably installed on the support mold base (2). The lower end of the upper mold base (3) is fixedly connected to an injection base (4), and the lower end of the injection base (4) is fixedly connected to a moving mold base (5). The lower end of the moving mold base (5) is detachably installed with a moving mold core (11) that cooperates with the fixed mold core (12). The injection base (4) is provided with an injection hole (41) and an adjustment hole (44). The injection hole (41) and the adjustment hole (44) are connected. The upper mold base (3) is provided with an injection adjustment component (9) for adjusting the opening and closing of the injection hole (41). The support mold base (2) is provided with multiple sets of locking components (7) for locking the fixed mold core (12); The fixed mold base (1) is fixedly provided with guide posts (10) at the four corners of the upper end. The support mold base (2), upper mold base (3), injection mold base (4) and moving mold base (5) are all provided with guide holes that slide with the guide posts (10). The injection molding adjustment component (9) includes an adjustment cylinder (91) fixedly installed on the upper mold base (3). An adjustment column (93) is fixedly connected to the end of the telescopic rod (92) of the adjustment cylinder (91). The adjustment column (93) is slidably disposed in the adjustment hole (44). The adjusting column (93) is provided with a straight through hole (94) and a right angle through hole (95). The straight through hole (94) is located above the right angle through hole (95). The right angle through hole (95) connects the injection hole (41) and the edge injection tube (43). The production method includes the following steps: Step 1: Install the demolding cylinder (14) onto the fixed mold base (1), and then fix the fixed mold base (1) onto the injection molding platform; Step 2: Fix the support mold base (2) onto the fixed mold base (1), install the temperature control tube (8) and locking component (7) on the support mold base (2), and then install the fixed mold core (12) onto the support mold base (2) and lock the fixed mold core (12) with the locking component (7); Step 3: The demolding cylinder (14) extends upward, connecting the outer top plate (122) and the middle top plate (123) to the corresponding demolding cylinder (14) respectively. Then the demolding cylinder (14) retracts and resets, so that the outer top plate (122) and the middle top plate (123) are retracted into the molding cavity (121). Step 4: Install the injection adjustment component (9) onto the upper mold base (3), fix the upper mold base (3) onto the injection lifting mechanism, and then fix the upper injection base (4) at the lower end of the upper mold base (3). Step 5: Install the upper temperature control tube (6) onto the moving mold base (5), then fix the moving mold base (5) onto the lower end of the injection mold base (4), and fix the moving mold core (11) that cooperates with the fixed mold core (12) onto the lower end of the moving mold base (5) to complete the assembly and production of the injection mold; The lower end of the injection molding base (4) is provided with a central injection molding tube (42) and an edge injection molding tube (43), both of which are connected to the injection hole (41). When the edge injection tube (43) is needed to feed the injection molded part, the adjusting cylinder (91) drives the adjusting column (93) to move upward, so that one end of the right angle through hole (95) is connected to the injection hole (41) and the other end of the right angle through hole (95) is connected to the edge injection tube (43). When the raw material enters the injection hole (41), it enters the edge injection tube (43) through the guide of the right angle through hole (95), and flows into the molding cavity (121) of the fixed mold core (12) through the edge injection tube (43) to complete the injection molding process of the processed part. When the central injection tube (42) is needed, the adjusting cylinder (91) drives the adjusting column (93) to move downward, so that the through hole (94) is connected to the injection hole (41), thereby connecting the injection hole (41) with the central injection tube (42). When the raw material enters the injection hole (41), it enters the central injection tube (42) through the guide of the through hole (94), and flows into the molding cavity (121) of the fixed mold core (12) through the central injection tube (42), thus completing the injection molding process of the processed part. The middle top plate (123) and the outer top plate (122) are driven independently. When demolding is required, the demolding cylinder (14) first drives the middle top plate (123) and the outer top plate (122) to move upward at the same time, pushing the injection molded part out of the molding cavity (121). Then, the outer top plate (122) is lowered one by one to separate it from the injection molded part. After separation, it rises again to press the injection molded part. When all the outer top plates (122) are separated from the injection molded part, the middle top plate (123) is moved downward to separate it from the injection molded part, ensuring that the injection molded part will not be damaged when demolding.

2. The method for manufacturing an automotive injection mold according to claim 1, characterized in that, The moving mold base (5) is provided with an upper temperature control tube (6), and the supporting mold base (2) is provided with a lower temperature control tube (8).

3. The method for manufacturing an automotive injection mold according to claim 1, characterized in that, The locking component (7) includes an adjusting seat (71) and a guide seat (74) fixedly installed on the support mold base (2). A locking slide plate (75) is slidably provided on the guide seat (74). An adjusting screw (72) is threadedly connected to the adjusting seat (71). The threaded end of the adjusting screw (72) is rotatably connected to the locking slide plate (75). A support rod (76) is connected to the locking slide plate (75). The support rod (76) is rotatably connected to the support mold base (2).

4. The method for manufacturing an automotive injection mold according to claim 1, characterized in that, The fixed mold core (12) is provided with a forming mold cavity (121), and the bottom of the forming mold cavity (121) is provided with a demolding top plate.

5. The method for manufacturing an automotive injection mold according to claim 4, characterized in that, The demolding top plate includes an intermediate top plate (123) located at the center of the molding cavity (121) and an outer top plate (122) located at the edge of the molding cavity (121). The lower ends of the outer top plate (122) and the intermediate top plate (123) are both provided with top plate connecting rods (124). The mold base (1) is equipped with a demolding cylinder (14) for driving the outer top plate (122) and the middle top plate (123) to rise and fall.

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