Device for detecting cohesiveness of plasterboard covering paper and core material

Abstract

The utility model relates to the field of a device for detecting the cohesiveness of plasterboard covering paper and a core material. The device comprises a base, a stand column, an upper clamp, an adjustable horizontal electric lifting platform, a universal bearing platform, a force measuring device and a lower clamp, a force measuring device is placed on an adjustable horizontal electric lifting platform through a universal bearing platform, one end of an upper clamp is locked on a stand column through a locking bolt, the stand column is vertically fixed to a base, the other end of the upper clamp is provided with a chuck capable of clamping a test piece, and the included angle between the clamping face of the chuck and the vertical stand column is 45 degrees; the upper end of the test piece is fixed in the upper clamp, the lower end of the test piece is clamped in the lower clamp, a hanging ring is arranged at the bottom of the lower clamp, the force measuring device is connected through the hanging ring of the lower clamp, the adjustable horizontal electric lifting platform is started to control the force measuring device to descend at a certain speed, and a spring in the force measuring device is compressed; the elastic force is applied to the test piece through the connecting rod and the lower clamp, the load on the test piece is gradually increased along with the descending of the force measuring device until the surface protecting paper is torn off, and the maximum force value during tearing damage is recorded.

Description

Technical Field

[0001] The utility model relates to the field of construction engineering material detection, in particular to a device for detecting the adhesion between gypsum board facing paper and core material. Background Art

[0002] Gypsum board is a widely used auxiliary material in interior decoration construction. It consists of a facing paper and a gypsum core. The facing paper surface is typically subjected to finishing processes such as gluing, applying putty, and painting. Therefore, a certain bond strength between the facing paper and the gypsum core is required to prevent the facing paper and the finishing layer from falling off the gypsum core.

[0003] The national standard GB / T 9775-2008 / 5.9 sets technical requirements for the adhesion between the face paper and the core material, that is, the face paper and the core material should not peel off under the test load.

[0004] The current main method for testing the adhesion of gypsum board facing paper to the core material involves preparing a 120 x 50 mm strip of gypsum board. A single slit is cut on one side of the board, 20 mm from one longitudinal end, without penetrating the board, leaving the facing paper intact on the other side. The specimen is then secured in the upper fixture of the tester, with the board surface at a 45° angle to the vertical. The lower fixture is fixed 20 mm from the corresponding longitudinal end of the specimen. The load is gradually increased until the facing paper peels off. The adhesion between the facing paper and the core material is recorded for each board.

[0005] 1. The maximum load applied to the specimen is 3 kg;

[0006] 2. The load is applied gradually;

[0007] 3. During the application of load, the specimen cut should not be subjected to horizontal force.

[0008] The invention patent application with document number CN110836849A discloses a gypsum board core material and facing paper bonding tester. This technical solution mainly uses weights and scales as loads, and loads the test piece by manual mounting.

[0009] The invention patent application with document number CN108519327A discloses a reinforcement clamp, an adhesion tester and an adhesion detection method. The technical solution mentions a reinforcement clamp, and the loading method of the technical solution is: gradually adding weights on the weight plate to tear the face paper off the core material.

[0010] Both of the above loading methods have different defects:

[0011] 1. When mounting the weight and manual combination weight, releasing the mounting at once will generate a downward impact force, which does not meet the test requirement of gradually increasing the load. In addition, the impact force can easily cause the test piece to be instantly destroyed, thus leading to misjudgment of the results.

[0012] 2. Pre-assemble the weights and counterweights to the set load and slowly release the load. Since the load is gradually applied through manual control, the loading rate is uneven and difficult to control. It is also impossible to reproduce the test process.

[0013] 3. In both schemes, the specimens will be damaged prematurely due to the horizontal force acting on them during the loading process due to the swing of the weights, the shaking of the operator's hands, etc. Summary of the Invention

[0014] The purpose of the utility model is to solve the defects of the above-mentioned method for detecting the adhesion between the facing paper and the core material of the paper-faced gypsum board, and to provide a loading device for detecting the adhesion between the facing paper and the core material of the paper-faced gypsum board, so that the detection process is more in line with standard requirements.

[0015] In order to achieve the above purpose of the invention, the present utility model application adopts the following technical solutions:

[0016] A device for testing the adhesion between gypsum board facing paper and core material consists of a base, a column, an upper clamp, an adjustable level electric lifting platform, a universal support platform, a force measuring device, and a lower clamp;

[0017] The column is vertically mounted on the base, and the upper fixture can move up and down on the column. One end is provided with a locking bolt that can be locked on the column, and the other end is provided with a chuck that can hold the test piece. The clamping surface of the upper fixture chuck forms a 45° angle with the vertical column;

[0018] The upper end of the test piece is fixed in the upper fixture of the tester, and the lower end of the test piece is clamped in the lower fixture, and a lifting ring is provided at the bottom of the lower fixture;

[0019] The adjustable level electric lifting platform consists of a base and an electric lifting platform; wherein the electric lifting platform is driven by a motor to drive the moving component lead screw to control the extension and contraction of the scissor brace to achieve the lifting of the platform, and is fixed to the base; the base is composed of three horizontal adjustment bolts distributed in a triangle, a metal plate, and a lower level bubble, and is placed on the base platform;

[0020] The universal support is composed of a bottom plate, a top plate, a steel ball, and an upper level bubble, and is fixed to the top of the adjustable horizontal electric lifting platform;

[0021] The force-measuring device is essentially a weight with a force-measuring function. Its main body is cylindrical, its mass and dimensions will be described further. It is made of metal and has a non-slip rubber pad on the bottom. A through-hole is set in the center of the cylindrical body, with a rib at the top. A spring is installed in the through-hole, with the upper end of the spring supporting the rib, and the lower end of the spring supporting a cylindrical slider that can slide up and down in the through-hole. The slider is connected to a connecting rod, which passes between the ribs of the through-hole in the cylindrical body. A hook is provided at the top of the connecting rod, which can be connected to the lower clamp.

[0022] Two vertical steel columns are provided on the top surface of the cylindrical body, one of which is etched with a scale related to the spring coefficient. An active pointer and a passive pointer are provided on the connecting rod. The active pointer is a metal ring with two wings, and a screw hole is provided on its side. A top screw is provided in the screw hole. The active pointer can be locked or unlocked with the connecting rod by tightening or loosening the top screw. Magnets are provided at both ends of the passive pointer, and the magnets are arranged on the opposite side of the sliding surface of the passive pointer. The passive pointer is connected to the two steel columns through the magnetic force of the magnet and can slide up and down along the surface of the steel column.

[0023] Furthermore, the moving parts, the motor, the lead screw and the scissor brace are protected by an accordion cover.

[0024] Furthermore, the bottom plate and top plate are rigid and square, with enclosures set on all sides, wherein the upper surface of the bottom plate and the lower surface of the top plate are smooth and flat, the top plate is slightly larger than the bottom plate and completely covers the bottom plate, and a level bubble is provided on the outer side of the outer edge enclosure of the top plate to display the horizontal state of the top plate.

[0025] Furthermore, the steel balls are evenly arranged on the upper surface of the bottom plate, the lower surface of the top plate and the space formed by the baffle, and can roll freely. The diameter of the steel balls is greater than the height of the bottom plate enclosure, and the number of steel balls arranged is controlled according to the diameter-to-pitch ratio.

[0026] Furthermore, the diameter-to-pitch ratio is λ=n0.5*d / b, wherein b is the side length of the rigid base plate, d is the diameter of the steel ball, n is the number of steel balls, the diameter of the steel ball can be selected from 4-7 mm, and λ is controlled between 0.3-0.4.

[0027] Furthermore, the passive pointer is made of polytetrafluoroethylene, and the friction between the passive pointer and the steel column under the action of the magnetic steel can offset its own weight so that the passive pointer can be fixed at any height of the steel column without sliding down.

[0028] Furthermore, the scale on the steel column is related to the spring coefficient, the scale spacing is 1 mm / grid, the indication is 1 N / grid, the total length is 35 grids, and the measuring range is m-35 N, where m is the total mass of the lower clamp, connecting rod, active pointer, passive pointer, spring, and slider.

[0029] Furthermore, the upper clamp chuck and the lower clamp are both C-shaped and made of metal. A through-hole with an internal thread is provided in the middle of the outer frame. A movable slider is provided in the middle of the outer frame. The slider is connected to the outer frame by a screw. The screw is rotated clockwise or counterclockwise to drive the slider forward or backward to clamp or loosen the specimen.

[0030] Furthermore, the cylindrical body of the force measuring device has a diameter of 100 mm, a height of 55 mm, a central through hole diameter of 21 mm, and a mass of approximately 3.14*(10 2 -2.1 2 ) / 4*5.5*7.85 = 3240g. The spring has a diameter of 10mm and a spring constant of 1N / mm. The slider has a diameter of 20mm and a height of 10mm, and is made of metal. The connecting rod has a diameter of 5mm and is made of metal. It has a hook at the top and is connected to the slider by a thread at the bottom.

[0031] How it works

[0032] The force measuring device in this scheme is placed on an adjustable horizontal electric lifting platform through a universal support platform. One end of the upper clamp is locked on the column by a locking bolt and can be moved up and down by adjusting the bolt. The column is vertically fixed on the base, and the other end is provided with a chuck for holding the specimen. The clamping surface of the upper clamp chuck is at a 45° angle to the vertical column; the upper end of the specimen is fixed in the upper clamp of the testing instrument, and the lower end of the specimen is clamped in the lower clamp. A lifting ring is provided at the bottom of the lower clamp; the force measuring device is connected to the lifting ring of the lower clamp, and the adjustable horizontal electric lifting platform is started to control the descent of the force measuring device at a certain rate. The spring in the force measuring device is compressed, and its elastic force is applied to the specimen through the connecting rod and the lower clamp. As the force measuring device descends, the load on the specimen gradually increases until the specimen protective paper is torn off, and the maximum force value at the time of tearing failure is recorded. Beneficial effects

[0033] This new solution utilizes an electric lifting platform to control the height of the force-measuring device at a constant speed, enabling the slow application of loads. This ensures a regular and reproducible loading process. Furthermore, a universal support allows the force-measuring device to freely move horizontally and upward as the specimen deforms, protecting the specimen from the effects of horizontal forces during loading. This solution effectively overcomes the shortcomings of existing solutions, improves test accuracy, and ensures that the test process is more consistent with standard requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is the overall structural diagram of the utility model;

[0035] Figure 2 This is an example of the use of the utility model in a gypsum board core and face paper bonding instrument;

[0036] Figure 3This is a structural diagram of the adjustable level electric lifting platform of the utility model;

[0037] Figure 4 This is an exploded view of the universal bearing structure of the utility model;

[0038] Figure 5 This is a structural diagram of the force measuring device of the present utility model;

[0039] Figure 6 It is a cross-sectional view of the force measuring device of the present utility model;

[0040] Figure 7 This is a structural diagram of the active pointer and passive pointer of the utility model;

[0041] In the figure: 1. Test piece, 2. Upper fixture, 3. Lower fixture, 4. Base, 5. Column, 6. Adjustable horizontal electric lifting platform, 6-1. Base, 6-2. Horizontal adjustment bolt, 6-3. Lower level bubble, 6-4. Electric lifting platform, 7. Universal support, 7-1. Bottom plate, 7-2. Top plate, 7-3. Steel ball, 7-4. Upper level bubble, 7-5. Enclosure, 8. Force measuring device, 8-1. Cylindrical body, 8-2. Spring, 8-3. Slider, 8-4. Connecting rod, 8-5. Steel column, 8-6. Steel column with scale, 8-7. Active pointer, 8-8. Passive pointer, 8-9. Side rib, 9. Magnet, 10. Top screw. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention.

[0043] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply 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 a limitation on the embodiments of the present invention.

[0044] In the description of the embodiments of the present invention, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on specific circumstances. Example 1

[0045] Combine Figure 1-7 It can be seen that a loading device for detecting the adhesion between the facing paper and the core material of a paper-faced gypsum board comprises a base (4), a column (5), an upper clamp (2), an adjustable horizontal electric lifting platform (6), a universal support (7), a force measuring device (8), and a lower clamp (3);

[0046] The column (5) is vertically mounted on the base (4), and the upper clamp (2) can move up and down on the column (5). One end of the clamp is provided with a locking bolt that can be locked on the column (5), and the other end is provided with a clamp that can hold the test piece (1). The clamping surface of the clamp of the upper clamp (2) is at an angle of 45° with the vertical column (5);

[0047] The upper end of the test piece (1) is fixed in the upper clamp (2) of the tester, and the lower end of the test piece (1) is clamped in the lower clamp (3), and a hanging ring is provided at the bottom of the lower clamp (3);

[0048] The adjustable horizontal electric lifting platform (6) is composed of a base (6-1) and an electric lifting platform (6-4); wherein the electric lifting platform (6-4) is driven by a motor to control the extension and contraction of the scissor braces by a screw rod of a moving part to achieve the lifting of the platform, and is fixed on the base (6-1); the base (6-1) is composed of three horizontal adjustment bolts (6-2) distributed in a triangular shape, a metal plate, and a lower level bubble (6-3), and is placed on the base (4) platform;

[0049] The universal support platform (7) is composed of a bottom plate (7-1), a top plate (7-2), a steel ball (7-3), and an upper level bubble (7-4), and is fixed to the top of the adjustable horizontal electric lifting platform (6).

[0050] The force measuring device (8) is essentially a weight with a force measuring function. Its cylindrical body (8-1) is cylindrical, and its mass and size will be further described. It is made of metal and has a non-slip rubber pad on the bottom. A through hole is set in the center of the cylindrical body (8-1), and a retaining edge (8-9) is set at the upper end of the through hole; a spring (8-2) is set in the through hole, and the upper end of the spring (8-2) supports the through hole retaining edge (8-9), and the lower end of the spring (8-2) supports a cylindrical slider (8-3) that can slide up and down in the through hole. The slider (8-3) is connected to the connecting rod (8-4), and the connecting rod (8-4) passes through the spring (8-2) and passes through the through hole of the cylindrical body (8-1). The upper end of the connecting rod (8-4) is provided with a hook that can be connected to the lower clamp (3);

[0051] Two vertical steel columns (8-5) (8-6) are provided on the top surface of the cylindrical body (8-1), one of the steel columns (8-6) is etched with a scale related to the spring coefficient of the spring (8-2), and an active pointer (8-7) and a passive pointer (8-8) are provided on the connecting rod (8-4). The active pointer (8-7) is a metal ring with two wings, and a screw hole is provided on its side. A top screw (10) is provided in the screw hole. The active pointer (8-7) can be locked or unlocked with the connecting rod (8-4) by tightening or loosening the top screw (10). Magnets (9) are provided at both ends of the passive pointer (8-8), and the magnets (9) are arranged on the opposite side of the sliding surface of the passive pointer (8-8). The passive pointer (8-8) is connected to the two steel columns (8-5) (8-6) through the magnetic force of the magnet (9) and can slide up and down along the surfaces of the steel columns (8-5) and (8-6).

[0052] Furthermore, the electric lifting platform (6-4) is a 150-type desktop electric lifting platform.

[0053] Furthermore, the moving parts motor, screw rod, scissor brace are protected by accordion covers. The moving parts motor, screw rod, scissor brace are purchased from the market and will not be described in detail here.

[0054] Furthermore, the bottom plate (7-1) and the top plate (7-2) are rigid and square, and are surrounded by enclosures (7-5), wherein the upper surface of the bottom plate (7-1) and the lower surface of the top plate (7-2) are smooth and flat, and the top plate (7-2) is slightly larger than the bottom plate (7-1) and completely covers the bottom plate (7-1), and an upper level bubble (7-4) is provided on the outer side surface of the outer edge enclosure of the top plate for indicating the horizontal state of the top plate (7-2).

[0055] Furthermore, the steel balls (7-3) are evenly arranged in the space formed by the upper surface of the bottom plate (7-1), the lower surface of the top plate (7-2) and the baffle, and can roll freely. The diameter of the steel balls (7-3) is greater than the height of the baffle (7-5) of the bottom plate (7-1), and the number of arranged steel balls (7-3) is controlled according to the diameter-to-pitch ratio.

[0056] Furthermore, the diameter-to-pitch ratio is λ=n0.5*d / b, wherein b is the side length of the rigid base plate (7-1), d is the diameter of the steel ball (7-3), n is the number of the steel balls (7-3), the diameter of the steel ball (7-3) can be selected to be 4-7 mm, and λ is controlled between 0.3-0.4.

[0057] Furthermore, the outer dimension side length of the bottom plate (7-1) of the embodiment is 180 mm, the outer dimension side length of the top plate (7-2) is 200 mm, the thickness of the enclosure (7-5) is 1 mm, the height of the enclosure (7-5) is 4 mm, the diameter of the steel ball (7-3) is 6 mm, the diameter-to-spacing ratio is 0.37, and the number is 121.

[0058] Furthermore, the passive pointer (8-8) is made of polytetrafluoroethylene, and the friction between it and the steel columns (8-5) and (8-6) under the action of the magnetic steel (9) can offset its own weight so that the passive pointer (8-8) can be fixed at any height of the steel columns (8-5) and (8-6) without sliding down.

[0059] Furthermore, the scale on the steel column (8-6) is related to the spring (8-2) stiffness coefficient, the scale spacing is 1 mm / grid, the indication value is 1 N / grid, the total length is 35 grids, and the measuring range is m-35 N, where m is the total mass of the lower fixture (3), the connecting rod (8-4), the active pointer (8-7), the passive pointer (8-8), the spring (8-2), and the slider (8-3).

[0060] Furthermore, the clamp head of the upper clamp (2) and the lower clamp (3) are both C-shaped and made of metal. A through hole with an internal thread is provided in the middle of the outer frame. A movable metal block is provided in the middle of the outer frame. The metal block is connected to the outer frame through a screw. The screw is rotated clockwise or counterclockwise to drive the metal block forward or backward to clamp or loosen the test piece (1).

[0061] Furthermore, the cylindrical body (8-1) of the force measuring device (8) has a diameter of 100 mm, a height of 55 mm, a central through hole diameter of 21 mm, and a mass of approximately 3.14*(10 2 -2.1 2 ) / 4*5.5*7.85=3240g. Spring (8-2) has a diameter of 10mm and a spring constant of 1N / mm. Slider (8-3) has a diameter of 20mm and a height of 10mm and is made of metal. Connecting rod (8-4) has a diameter of 5mm and is made of metal. It has a hook at its upper end and is connected to slider (8-3) at its lower end via threads.

[0062] Furthermore, the total mass of the lower clamp (3) does not exceed 300g.

[0063] Example 2

[0064] The method for performing a loading test using the aforementioned loading device for testing the adhesion between the facing paper and the core material of the gypsum board is specifically implemented as follows:

[0065] S1: Before the test, calibrate the spring (8-2) and select the spring (8-2) with a spring constant within the range of 1±1%N / mm; weigh the total mass m of the lower fixture (3), connecting rod (8-4), active pointer (8-7), passive pointer (8-8), spring (8-2), and slider (8-3) and convert it into force unit N; assemble the force measuring device (8) and loosen the top screw (10) of the active pointer (8-7). At this time, the active pointer (8-7) and the connecting rod (8-4) are in an unlocked state. Place the force measuring device (8) horizontally, use the force measuring device to pull the connecting rod (8-4) until the measuring device indicates a value slightly greater than m, and use the top screw (10) to lock the position of the active pointer (8-7) at the starting point of the scale; continue to pull the connecting rod (8-4) and confirm whether the value indicated by the force measuring device (8) is accurate when the measuring device indicates m+10N, m+20N, and m+30N.

[0066] S2: During the test, the confirmed force measuring device (8) is placed on an adjustable horizontal electric lifting platform (6) through the universal support (7). The force measuring device (8) is connected to the lower clamp (3). The lower clamp (3) is clamped at the lower end of the test piece (1). The test piece (1) is fixed in the upper clamp (2) of the tester. The three horizontal adjustment bolts (6-2) of the base (6-1) of the utility model are adjusted until the universal support (7) is in a horizontal state. The passive pointer (8-8) is installed so that its lower edge is aligned with the active pointer. The upper edge of the pointer (8-7) is flush; the adjustable horizontal electric lifting platform (6) is started to slowly lower the force measuring device (8), and the spring (8-2) in the force measuring device (8) is compressed. Its elastic force is applied to the test piece (1) through the connecting rod (8-4) and the lower clamp (3). The active pointer (8-7) on the connecting rod (8-4) pushes the passive pointer (8-8) to move upward relative to the steel column (8-5) (8-6) to indicate the force value. As the force measuring device (8) descends, the load on the test piece (1) gradually increases.

[0067] According to step S2 in the above method, the adjustable horizontal electric lifting platform (6) is started to slowly lower the force measuring device (8), and the spring (8-2) in the force measuring device (8) is compressed. As the force measuring device (8) descends, the load on the test piece (1) gradually increases until the face paper of the test piece (1) is torn off; the adjustable horizontal electric lifting platform (6) is started to rise until the force measuring device (8) is unhooked from the lower clamp (3). At this time, the active pointer (8-7) returns, and the passive pointer (8-8) remains in place to indicate the maximum force value that occurs during the test. The maximum force value at the time of tearing failure is recorded. The value at this time is the bonding strength value between the face paper and the gypsum core material.

Claims

1. A device for detecting the adhesion between gypsum board facing paper and core material, characterized in that: It includes base, column, upper fixture, adjustable level electric lifting platform, universal bearing platform, force measuring device and lower fixture; The column is vertically mounted on the base, and the upper fixture can move up and down on the column. One end is provided with a locking bolt that can be locked on the column, and the other end is provided with a chuck that can hold the test piece. The clamping surface of the upper fixture chuck forms a 45° angle with the vertical column; The upper end of the test piece is fixed in the upper fixture of the tester, and the lower end of the test piece is clamped in the lower fixture, and a lifting ring is provided at the bottom of the lower fixture; The adjustable level electric lifting platform consists of a base and an electric lifting platform; wherein the electric lifting platform is driven by a motor, and the moving component screw rod controls the extension and contraction of the scissor braces to achieve the lifting of the platform, and is fixed to the base; the base is composed of three bolts distributed in a triangle for adjusting the level, a metal plate, and a spirit level, and is placed on the base platform; The universal support is composed of a bottom plate, a steel ball, and a top plate, and is fixed to the top of the adjustable horizontal electric lifting platform; The force measuring device is essentially a weight with a force measuring function. The main body is cylindrical and made of metal, with a non-slip rubber pad on the bottom surface. A through hole is set in the center of the cylindrical main body, and a rib is set at the upper end of the through hole. A spring is set in the through hole, and the upper end of the spring supports the rib of the through hole. The lower end of the spring supports a cylindrical slider that can slide up and down in the through hole. The slider is connected to a connecting rod. The connecting rod passes through the ribs of the through hole of the cylindrical main body. A hook is set at the upper end of the connecting rod and can be connected to the lower clamp. Two vertical steel columns are provided on the top surface of the cylindrical body, one of which is etched with a scale related to the spring coefficient. An active pointer and a passive pointer are provided on the connecting rod. The active pointer is a metal ring with two wings, and a screw hole is provided on its side. A top screw is provided in the screw hole. The active pointer can be locked or unlocked with the connecting rod by tightening or loosening the top screw. Magnets are provided at both ends of the passive pointer, and the magnets are arranged on the opposite side of the sliding surface of the passive pointer. The passive pointer is connected to the two steel columns through the magnetic force of the magnet and can slide up and down along the surface of the steel column.

2. The device for detecting the adhesion between the gypsum board facing paper and the core material according to claim 1, characterized in that: The moving parts, the motor, the lead screw and the scissor brace are protected by an accordion sleeve.

3. The device for detecting the adhesion between the facing paper and the core material of a gypsum board according to claim 1, characterized in that: The bottom plate and top plate are rigid and square, with enclosures set around them. The upper surface of the bottom plate and the lower surface of the top plate are smooth and flat. The top plate is slightly larger than the bottom plate and completely covers the bottom plate. An upper level bubble is provided on the outer side of the outer edge enclosure of the top plate to show the horizontal state of the top plate.

4. The device for detecting the adhesion between the gypsum board facing paper and the core material according to claim 1, characterized in that: The steel balls are evenly arranged on the upper surface of the bottom plate, the lower surface of the top plate and the space formed by the enclosure and can roll freely. The diameter of the steel balls is greater than the height of the bottom plate enclosure, and the number of steel balls arranged is controlled according to the diameter-to-pitch ratio.

5. The device for detecting the adhesion between the facing paper and the core material of a gypsum board according to claim 4, characterized in that: The diameter-to-pitch ratio is λ=n0.5*d / b, where b is the side length of the rigid base plate, d is the diameter of the steel ball, n is the number of steel balls, the diameter of the steel ball can be selected from 4 to 7 mm, and λ is controlled between 0.3 and 0.

4.

6. The device for detecting the adhesion between the gypsum board facing paper and the core material according to claim 1, characterized in that: The passive pointer is made of polytetrafluoroethylene. Under the action of the magnetic steel, the friction between the passive pointer and the steel column can offset its own weight so that the passive pointer can be fixed at any height of the steel column without sliding down.

7. The device for detecting the adhesion between the facing paper and the core material of a gypsum board according to claim 1, characterized in that: The scale on the steel column is related to the spring coefficient, the scale spacing is 1mm / grid, the indication value is 1N / grid, the total length is 35 grids, and the measuring range is m-35N, where m is the total mass of the lower clamp, connecting rod, active pointer, passive pointer, spring, and slider.

8. The device for detecting the adhesion between the gypsum board facing paper and the core material according to claim 1, characterized in that: The upper clamp chuck and the lower clamp are both C-shaped and made of metal. A through hole with an internal thread is provided in the middle of the outer frame. A movable slider is provided in the middle of the outer frame. The slider is connected to the outer frame through a screw. Rotating the screw clockwise or counterclockwise drives the slider forward or backward to clamp or loosen the specimen.

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