Material conveying device for coating film detection

Abstract

The invention discloses a material conveying device for coating film detection. A first vacuum carrier, a second vacuum carrier and a connection carrier of the material conveying device each comprise a base provided with a vacuum channel, a base plate installed on the base and an elastic carrier plate arranged on the side, opposite to the base, of the base plate. At least two adsorption hole sets are formed in the upper surface of the elastic carrier plate used for being in adsorption contact with a to-be-carried product, the first vacuum carrier and the second vacuum carrier are oppositely arranged, and the elastic carrier plates of the first vacuum carrier and the second vacuum carrier are far away from each other. Each adsorption hole group corresponding to the to-be-carried product is formed by arranging a plurality of adsorption holes at intervals, and each adsorption hole group is formed by arranging two adsorption holes which are distributed in the length direction of the to-be-carried product at intervals; the shape of the adsorption holes is the same as that of a product to be carried, and the area ratio of each adsorption hole to the product to be carried is 1: 2.5-4. According to the invention, the functional surface of the product can be detected and processed conveniently, and the functional surface can be shielded and protected to avoid damage when not necessary.

Description

Technical Field

[0001] The invention relates to the technical field of coating detection, and in particular to a material conveying device for coating detection. Background Art

[0002] With the popularity of mobile phones, tablet computers and various smart wearable devices, in order to meet the diverse needs of users, it is usually necessary to use laminated glass cover plates to increase the aesthetics and quality of electronic devices. In the production process of glass cover plates, in order to meet functional requirements such as anti-scratch, anti-fingerprint, and anti-blue light, a coating will be applied on the outside. In actual industrial production, the coating process cannot achieve uniform coverage, and often leads to poor coating due to many limitations. Therefore, the coated surface needs to be inspected after the coating is completed. The glass cover plate itself is small, fragile and easily damaged, and the coated surface on the glass cover plate is more susceptible to damage. Therefore, how to avoid damage to the coated surface while realizing the detection of the coated surface has become a problem that needs to be solved in the coating detection process. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a material transport device for coating detection, which is convenient for detecting and processing the functional surface of the product and can shield and protect the functional surface from damage when not necessary.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a material transport device for coating inspection, comprising: a first vacuum carrier, a second vacuum carrier and a docking carrier, the docking carrier corresponding to the first vacuum carrier and the second vacuum carrier is installed on the piston rod of a docking cylinder, the docking cylinder is installed on a driving module, the first vacuum carrier and the second vacuum carrier are respectively installed on both ends of a rotating plate, the rotating plate rotatably installed on a bracket is connected to the output shaft of a rotating motor installed on the bracket; The first vacuum carrier, the second vacuum carrier, and the docking carrier further include: a base with a vacuum channel, a substrate mounted on the base, and an elastic carrier disposed on the substrate opposite to the base, the upper surface of the elastic carrier for adsorbing and contacting the product to be transported is provided with at least two adsorption hole groups, and the first vacuum carrier and the second vacuum carrier are disposed opposite to each other so that their respective elastic carriers are away from each other; Each of the adsorption hole groups corresponding to the product to be carried is composed of a plurality of adsorption holes arranged at intervals, and the other end of the adsorption hole in contact with the product to be carried is connected to the vacuum channel on the base through a through hole opened on the substrate, and each of the adsorption hole groups is composed of 2 adsorption holes distributed at intervals along the length direction of the product to be carried, the shape of the adsorption hole is the same as the shape of the product to be carried, and the area ratio between each adsorption hole and the product to be carried is 1:2.5~4.

[0005] The further improved scheme in the above technical scheme is as follows: 1. In the above scheme, each of the first vacuum carrier and the second vacuum carrier is installed on the side of the rotating plate opposite to the rotating motor through at least one set of mutually cooperating slide rails and sliders, and each of the first vacuum carrier and the second vacuum carrier is provided with a stopper on the side opposite to the adsorption hole, and a spring extending along the moving direction of the first vacuum carrier and the second vacuum carrier is provided between the stopper installed on the rotating plate and the corresponding first vacuum carrier and the second vacuum carrier.

[0006] 2. In the above solution, a support block is installed on the surface of each of the first vacuum carrier and the second vacuum carrier facing the stopper, and the support block is connected to the rotating plate through a slide rail and a slider.

[0007] 3. In the above solution, the spring is connected between the support block and the stop block.

[0008] 4. In the above scheme, the through holes on the substrate are arranged in one-to-one correspondence with the adsorption holes directly above them.

[0009] 5. In the above scheme, the through hole having the same shape as the adsorption hole has a smaller area than the adsorption hole.

[0010] 6. In the above scheme, the number of the vacuum channels is the same as the number of the adsorption hole groups, and the two adsorption holes in the same adsorption hole group are connected to the same vacuum channel.

[0011] 7. In the above scheme, the vacuum channel further includes: a vacuum groove portion opened on the upper surface of the base, a vertical connecting portion whose upper end is connected to the vacuum groove portion, and a horizontal connecting portion connected to the lower end of the vertical connecting portion, and the end of the horizontal connecting portion opposite to the vertical connecting portion is connected to the air pipe joint installed on the side surface of the base.

[0012] 8. In the above scheme, the adsorption hole that passes through from top to bottom is connected to the vacuum groove of the vacuum channel through a corresponding through hole, the shape of the vacuum groove is the same as that of the adsorption hole and the edge of the vacuum groove is located outside the adsorption hole.

[0013] 9. In the above solution, the substrate is mounted on the base through a cover plate, and the cover plate, whose upper surface is flush with the elastic carrier plate, is provided with a through hole for the elastic carrier plate to pass through.

[0014] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: 1. The material transport device for coating inspection of the present invention comprises: a first vacuum carrier, a second vacuum carrier and a docking carrier, the docking carrier corresponding to the first vacuum carrier and the second vacuum carrier is installed on the piston rod of a docking cylinder, the docking cylinder is installed on a driving module, the first vacuum carrier and the second vacuum carrier are respectively installed at both ends of a rotating plate, the rotating plate rotatably installed on a bracket is connected to the output shaft of a rotating motor installed on the bracket, so as to realize efficient flipping, docking and transportation of products and ensure the stability of product position before and after flipping and during flipping, so as to facilitate the inspection and processing of product functional surfaces and shield and protect the functional surfaces from damage when not necessary; further, the first vacuum carrier, the second vacuum carrier and the docking carrier further comprise: a base with a vacuum channel, a substrate installed on the base and an elastic carrier plate arranged on the side of the substrate opposite to the base, the upper surface of the elastic carrier plate for adsorption contact with the product to be transported is provided with to There are at least two adsorption hole groups, the first vacuum carrier and the second vacuum carrier are arranged opposite to each other and their respective elastic carrier plates are far away from each other, each adsorption hole group corresponding to the product to be carried is composed of a plurality of adsorption holes arranged at intervals, the other end of the adsorption hole in contact with the product to be carried is connected with the vacuum channel on the base through a through hole opened on the substrate, each adsorption hole group is composed of two adsorption holes distributed at intervals along the length direction of the product to be carried, the shape of the adsorption hole is the same as the shape of the product to be carried and the area ratio between each adsorption hole and the product to be carried is 1:2.5~4, while realizing the adsorption positioning of the product, it is beneficial to form an adsorption force matching the product size in the area where the adsorption hole contacts the product, avoiding the situation where the product is deflected by force due to insufficient adsorption force or the product is damaged by excessive adsorption force in the subsequent processing process, and can improve the uniformity of the product force, and can avoid the formation of adsorption marks and dirt on the surface of the product in contact with the adsorption hole to affect the product quality.

[0015] 2. In the material transport device for coating inspection of the present invention, the first vacuum carrier and the second vacuum carrier are each installed on the side of the rotating plate opposite to the rotating motor through at least one set of mutually cooperating slide rails and sliders, and the first vacuum carrier and the second vacuum carrier are each provided with a stopper on the side opposite to the adsorption hole, and a spring extending along the moving direction of the first vacuum carrier and the second vacuum carrier is provided between the stopper installed on the rotating plate and the corresponding first vacuum carrier and the second vacuum carrier, so that when placing products on the carrier and connecting and picking up products on the carrier, the force acting on the products can be buffered and balanced to avoid damage to the products caused by excessive local force. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Attached Figure 1 It is a schematic diagram of the overall structure of the material transport device for coating detection of the present invention; Attached Figure 2 for Figure 1 Local structure magnification in Figure 1 ; Attached Figure 3 for Figure 1 Local structure magnification in Figure 2 ; Attached Figure 4 It is a partial structural schematic diagram of the material conveying device for coating detection of the present invention; Attached Figure 5 A cross-sectional view of a carrier in a material transport device for coating inspection of the present invention in one direction; Attached Figure 6 It is a cross-sectional view of a carrier in a material transport device for coating inspection of the present invention in another direction.

[0017] In the above drawings: 100, product to be transported; 1, bracket; 2, rotating motor; 3, rotating plate; 41, first vacuum carrier; 42, second vacuum carrier; 5, docking carrier; 6, docking cylinder; 7, driving module; 81, slide rail; 82, slider; 9, stopper; 10, spring; 11, support block; 21, base; 22, substrate; 23, adsorption hole; 24, vacuum channel; 241, vacuum groove; 242, vertical connecting part; 243, horizontal connecting part; 25, air pipe joint; 26, sealing ring; 27, elastic carrier plate; 28, through hole; 29, cover plate; 291, avoidance through hole. DETAILED DESCRIPTION

[0018] The present invention can be further understood through the specific embodiments given below, but they are not intended to limit the present invention.

[0019] Embodiment 1: A material transport device for coating inspection, comprising: a first vacuum carrier 41, a second vacuum carrier 42 and a docking carrier 5, wherein the docking carrier 5 corresponding to the first vacuum carrier 41 and the second vacuum carrier 42 is mounted on a piston rod of a docking cylinder 6, and the docking cylinder 6 is mounted on a driving module 7, wherein the first vacuum carrier 41 and the second vacuum carrier 42 are respectively mounted on both ends of a rotating plate 3, and the rotating plate 3 rotatably mounted on a bracket 1 is connected to the output shaft of a rotating motor 2 mounted on the bracket 1; The first vacuum carrier 41, the second vacuum carrier 42, and the docking carrier 5 further include: a base 21 with a vacuum channel 24, a substrate 22 mounted on the base 21, and an elastic carrier 27 disposed on the substrate 22 opposite to the base 21, wherein at least two adsorption hole groups are disposed on the upper surface of the elastic carrier 27 for adsorption contact with the product 100 to be transported, and the first vacuum carrier 41 and the second vacuum carrier 42 are disposed opposite to each other and their respective elastic carriers 27 are separated from each other; Each of the adsorption hole groups corresponding to the product 100 to be transported is composed of a plurality of adsorption holes 23 arranged at intervals. The other end of the adsorption hole 23 in contact with the product 100 to be transported is connected to the vacuum channel 24 on the base 21 via a through hole 28 provided on the substrate 22. Each of the adsorption hole groups is composed of two adsorption holes 23 arranged at intervals along the length direction of the product 100 to be transported. The shape of the adsorption hole 23 is the same as that of the product 100 to be transported, and the area ratio between each adsorption hole 23 and the product 100 to be transported is 1:3.

[0020] The first vacuum carrier 41 and the second vacuum carrier 42 are each mounted on the side of the rotating plate 3 opposite to the rotating motor 2 through at least one set of mutually cooperating slide rails 81 and sliders 82. The first vacuum carrier 41 and the second vacuum carrier 42 are each provided with a stopper 9 on the side opposite to the adsorption hole 5. A spring 10 extending along the moving direction of the first vacuum carrier 41 and the second vacuum carrier 42 is provided between the stopper 9 mounted on the rotating plate 3 and the corresponding first vacuum carrier 41 and the second vacuum carrier 42. A support block 11 is installed on the surface of each of the first vacuum carrier 41 and the second vacuum carrier 42 facing the stopper 9. The support block 11 is connected to the rotating plate 3 via a slide rail 81 and a slide block 82. The spring 10 is connected between the support block 11 and the stopper 9. The first vacuum carrier 41 and the second vacuum carrier 42 are respectively arranged on the outer sides of the two ends of the rotating plate 3; the rotating motor 2 and the rotating plate 3 are respectively located on both sides of the bracket 1; the output shaft of the rotating motor 2 and the rotating plate 3 are connected to each other through a reducer installed on the bracket 1; The elastic carrier plate 27 is a PEEK carrier plate. There are six adsorption hole groups, which are spaced apart in a direction perpendicular to the length of the product 100 to be transported.

[0021] Embodiment 2: A material transport device for coating inspection, comprising: a first vacuum carrier 41, a second vacuum carrier 42 and a docking carrier 5, wherein the docking carrier 5 corresponding to the first vacuum carrier 41 and the second vacuum carrier 42 is mounted on a piston rod of a docking cylinder 6, and the docking cylinder 6 is mounted on a driving module 7, and the first vacuum carrier 41 and the second vacuum carrier 42 are respectively mounted on both ends of a rotating plate 3, and the rotating plate 3 rotatably mounted on a bracket 1 is connected to the output shaft of a rotating motor 2 mounted on the bracket 1; The first vacuum carrier 41, the second vacuum carrier 42, and the docking carrier 5 further include: a base 21 with a vacuum channel 24, a substrate 22 mounted on the base 21, and an elastic carrier 27 disposed on the substrate 22 opposite to the base 21, wherein at least two adsorption hole groups are disposed on the upper surface of the elastic carrier 27 for adsorption contact with the product 100 to be transported, and the first vacuum carrier 41 and the second vacuum carrier 42 are disposed opposite to each other and their respective elastic carriers 27 are separated from each other; Each of the adsorption hole groups corresponding to the product 100 to be transported is composed of a plurality of adsorption holes 23 arranged at intervals. The other end of the adsorption hole 23 in contact with the product 100 to be transported is connected to the vacuum channel 24 on the base 21 through a through hole 28 opened on the substrate 22. Each of the adsorption hole groups is composed of two adsorption holes 23 distributed at intervals along the length direction of the product 100 to be transported. The shape of the adsorption hole 23 is the same as that of the product 100 to be transported, and the area ratio between each adsorption hole 23 and the product 100 to be transported is 1:2.8.

[0022] The through holes 28 on the substrate 22 are arranged in one-to-one correspondence with the adsorption holes 23 directly above them; the through holes 28 having the same shape as the adsorption holes 23 have a smaller area than the adsorption holes 23; the number of the vacuum channels 24 is the same as the number of the adsorption hole groups, and two adsorption holes 23 in the same adsorption hole group are connected to the same vacuum channel 24; The vacuum channel 24 further comprises: a vacuum groove 241 provided on the upper surface of the base 21, a vertical connecting portion 242 whose upper end is connected to the vacuum groove 241, and a horizontal connecting portion 243 connected to the lower end of the vertical connecting portion 242, wherein one end of the horizontal connecting portion 243 opposite to the vertical connecting portion 242 is connected to the air pipe joint 25 installed on the side surface of the base 21; The adsorption holes 23 passing through from top to bottom are connected to the vacuum grooves 241 of the vacuum channel 24 through corresponding through holes 28. The shape of the vacuum grooves 241 is the same as that of the adsorption holes 23, and the edge of the vacuum grooves 241 is located outside the adsorption holes 23. A sealing ring 26 is provided between the base 21 and the substrate 22 and outside each vacuum groove 241. The substrate 22 is mounted on the base 21 through a cover plate 29. The cover plate 29, whose upper surface is flush with the elastic carrier plate 27, is provided with a through hole 291 for the elastic carrier plate 27 to pass through. The inner wall of the through hole 291 is in close contact with the outer surface of the elastic carrier plate 27. The elastic carrier plate 27 is a silica gel carrier plate; the adsorption hole groups are provided in eight numbers and are spaced apart and distributed in a direction perpendicular to the length of the product 100 to be transported.

[0023] Working principle: When in use, the vacuum channel of each carrier is connected to a vacuum generator or a vacuum pump, etc., to form a negative pressure in the vacuum channel; The rotating plate is driven by a rotating motor to rotate to a first vertical position, at which time the surface with the adsorption holes on the first vacuum carrier faces upward, and the surface with the adsorption holes on the second vacuum carrier faces downward; The products to be loaded (such as glass cover plates of mobile phone side keys) that have completed the inspection and processing and have the same number as the adsorption hole groups are transported to the upper surface of the elastic carrier of the first vacuum carrier by a transport mechanism (such as a robotic arm, a vacuum nozzle, etc.), and each product to be loaded is located directly above the corresponding adsorption hole, and the length direction of the product to be loaded is kept consistent with the arrangement direction of the adsorption holes in the adsorption hole group, and the non-functional surface of the product to be loaded is adsorbed and positioned by the negative pressure generated in the adsorption holes on the elastic carrier, and the functional surface (such as the coating surface) faces upward; Then, the rotating plate is driven by the rotating motor to rotate 180° to the second vertical position. At this time, the surface of the elastic carrier on the first vacuum carrier that adsorbs and clamps the product faces downward, and the surface of the elastic carrier on the second vacuum carrier that has the adsorption holes faces upward; The driving module drives the docking carrier to move to the bottom of the first vacuum carrier, and then the docking cylinder drives the docking carrier to move up and close to the first vacuum carrier; The vacuum in the first vacuum carrier is disconnected, so that the product on the first vacuum carrier is correspondingly transferred to the elastic carrier of the docking carrier, and the product is flipped so that the functional surface of the product is facing downward and covered. Then, the functional surface (such as the coating surface) of the flipped product is adsorbed and positioned through the negative pressure generated in the adsorption holes on the elastic carrier of the docking carrier, which is convenient for the transportation and unloading of the product. In this process, the functional surface of the product is covered and is not easily damaged. The vacuum adsorption method can ensure the stability of the product position before, after and during the flipping process. In the above process, when the external picking and connecting components come into contact with the product on the carrier, the carrier is simultaneously forced to move the compression spring, thereby buffering, balancing and absorbing part of the force acting on the product, improving the uniformity of the force on the product, and avoiding damage to the product caused by excessive local force; In addition, an elastic carrier is used to contact the product to protect the product from scratches and bumps. At the same time, the product is adsorbed and positioned by the adsorption holes opened on the elastic carrier, which is conducive to forming a negative pressure at the end where the adsorption hole contacts the product to increase the adsorption force, and can also improve the uniformity of the force acting on the product, avoiding the formation of adsorption marks and dirt on the surface where the product contacts the adsorption hole, thereby affecting the product quality; further, two contoured adsorption holes are arranged at intervals along the length direction of the product, and the size of the adsorption holes is controlled to match the product, which can prevent the adsorption hole from leaking due to being too large, resulting in insufficient adsorption force, and can also avoid damage to the product due to excessive adsorption force, thereby improving the stability of positioning of tiny products and the uniformity of product force; At the same time, at least one product can be transported to the upper surface of the second vacuum carrier by a product transport mechanism (such as a robot arm, a vacuum nozzle, etc.), and the product can be adsorbed and clamped by the vacuum generated in the adsorption holes thereon, and then the above steps are repeated to flip the product adsorbed on the second vacuum carrier; By operating the first vacuum carrier and the second vacuum carrier alternately at the same time, efficiency is improved, and the product can also be reversed and transported. The operation process is similar and will not be repeated.

[0024] When the above-mentioned material transport device for coating inspection is used, it can realize efficient flipping, docking and transportation of products and ensure the stability of product position before, after and during flipping, so as to facilitate the inspection and processing of the functional surface of the product and shield and protect the functional surface from damage when it is not necessary. Furthermore, while achieving adsorption and positioning of the product, it is conducive to forming an adsorption force that matches the product size in the area where the adsorption hole contacts the product, avoiding the situation where insufficient adsorption force causes product force deflection during subsequent processing or excessive adsorption force causes product damage, and can improve the uniformity of product force, and can avoid the formation of adsorption marks and dirt on the surface of the product in contact with the adsorption hole, which affects the product quality; In addition, when placing products on the carrier and docking and picking up products on the carrier, the force acting on the products can be buffered and balanced to avoid damage to the products caused by excessive local force.

[0025] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A material transport device for coating inspection, characterized in that: include: A first vacuum carrier (41), a second vacuum carrier (42) and a docking carrier (5), wherein the docking carrier (5) arranged corresponding to the first vacuum carrier (41) and the second vacuum carrier (42) is mounted on a piston rod of a docking cylinder (6), and the docking cylinder (6) is mounted on a driving module (7). The first vacuum carrier (41) and the second vacuum carrier (42) are respectively mounted on two ends of a rotating plate (3), and the rotating plate (3) rotatably mounted on a bracket (1) is connected to an output shaft of a rotating motor (2) mounted on the bracket (1); The first vacuum carrier (41), the second vacuum carrier (42), and the docking carrier (5) all further comprise: a base (21) provided with a vacuum channel (24), a substrate (22) mounted on the base (21), and an elastic carrier (27) disposed on the side of the substrate (22) opposite to the base (21), wherein at least two groups of adsorption holes are disposed on the upper surface of the elastic carrier (27) for adsorption contact with the product (100) to be transported, and the first vacuum carrier (41) and the second vacuum carrier (42) are disposed opposite to each other so that their respective elastic carriers (27) are separated from each other; Each of the adsorption hole groups corresponding to the product (100) to be transported is composed of a plurality of adsorption holes (23) arranged at intervals, one end of the adsorption hole (23) in contact with the product (100) to be transported and the other end of the adsorption hole (23) is connected to the vacuum channel (24) on the base (21) through a through hole (28) provided on the base plate (22), and each of the adsorption hole groups is composed of two adsorption holes (23) arranged at intervals along the length direction of the product (100) to be transported, the shape of the adsorption hole (23) is the same as the shape of the product (100) to be transported, and the area ratio between each adsorption hole (23) and the product (100) to be transported is 1:2.5-4.

2. The material transport device for coating inspection according to claim 1, characterized in that: The first vacuum carrier (41) and the second vacuum carrier (42) are each mounted on a side of the rotating plate (3) opposite to the rotating motor (2) via at least one set of mutually cooperating slide rails (81) and sliders (82); a stopper (9) is provided on each side of the first vacuum carrier (41) and the second vacuum carrier (42) opposite to the adsorption hole (5); and a spring (10) extending along the moving direction of the first vacuum carrier (41) and the second vacuum carrier (42) is provided between the stopper (9) mounted on the rotating plate (3) and the corresponding first vacuum carrier (41) and the second vacuum carrier (42).

3. The coating inspection jig according to claim 2, characterized in that: A support block (11) is mounted on the surface of each of the first vacuum carrier (41) and the second vacuum carrier (42) on the side facing the stopper (9); the support block (11) and the rotating plate (3) are connected in cooperation with each other via a slide rail (81) and a slide block (82).

4. The coating inspection tool according to claim 3, characterized in that: The spring (10) is connected between the support block (11) and the stop block (9).

5. The material conveying device for coating inspection according to claim 1 or 2, characterized in that: The through holes (28) on the substrate (22) are arranged in one-to-one correspondence with the adsorption holes (23) directly above the substrate (22).

6. The material conveying device for coating inspection according to claim 1 or 2, characterized in that: The through hole (28) having the same shape as the adsorption hole (23) has a smaller area than the adsorption hole (23).

7. The material transport device for coating inspection according to claim 1 or 2, characterized in that: The number of the vacuum channels (24) is the same as the number of adsorption hole groups, and two adsorption holes (23) located in the same adsorption hole group are connected to the same vacuum channel (24).

8. The material transport device for coating inspection according to claim 1 or 2, characterized in that: The vacuum channel (24) further comprises: a vacuum groove portion (241) provided on the upper surface of the base (21), a vertical communication portion (242) whose upper end is connected to the vacuum groove portion (241), and a horizontal communication portion (243) connected to the lower end of the vertical communication portion (242), wherein one end of the horizontal communication portion (243) opposite to the vertical communication portion (242) is connected to a gas pipe joint (25) mounted on the side surface of the base (21).

9. The material transport device for coating inspection according to claim 8, characterized in that: The adsorption hole (23) that penetrates from top to bottom is connected to the vacuum groove portion (241) of the vacuum channel (24) via a correspondingly arranged through hole (28); the shape of the vacuum groove portion (241) is the same as that of the adsorption hole (23), and the edge of the vacuum groove portion (241) is located outside the adsorption hole (23).

10. The material conveying device for coating inspection according to claim 1 or 2, characterized in that: The base plate (22) is mounted on the base (21) via a cover plate (29); the cover plate (29) whose upper surface is flush with the elastic carrier plate (27) is provided with a through hole (291) for the elastic carrier plate (27) to pass through.

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