Automatic detection production line for dynamic elastic modulus of wood / bamboo full-size plate and evaluation method thereof

Abstract

According to the automatic detection production line for the dynamic elastic modulus of the wood / bamboo full-size plate and the evaluation method of the automatic detection production line, the plate can be accurately positioned, the hammering device is adopted to knock the plate, the first-order bending frequency of the plate is measured, the measured and calculated dynamic elastic modulus value is used for carrying out quality grading on the finished plate, and the efficiency and the accuracy are high. The device comprises a rack, a plate conveying mechanism, a blocking mechanism, a detection analysis mechanism, a jacking mechanism and a hammering mechanism, wherein the plate conveying mechanism is used for driving a plate to move from back to front; when the blocking mechanism rises to a position higher than the roll shaft, the plate moves forwards until the front end of the plate is in contact with the blocking mechanism, and the plate stops moving forwards; the detection analysis mechanism comprises an accelerometer and a vibration and dynamic signal acquisition and analysis system; the jacking mechanism is used for jacking the plate which stops moving and making the upper surface of the corner of the plate make contact with the accelerometer, and the hammering mechanism is used for knocking the center point of the plate jacked by the jacking mechanism.

Description

Technical Field

[0001] The present invention relates to a testing device (production line) and method for dynamically testing the elastic modulus E of a plate using transient excitation, and a device and method for grading the quality of the plate according to the elastic modulus. Background Art

[0002] Wood and bamboo are environmentally friendly materials. In the wood and bamboo processing industry, solid wood and bamboo panels and their composite materials, such as fiberboard, particleboard, and plywood, offer excellent physical and mechanical properties, a high strength-to-weight ratio, good stability, smooth surface finish, and ease of decoration. They are widely used in transportation, construction, furniture, interior decoration, containers, packaging, outdoor flooring, and many other fields.

[0003] However, the traditional method for testing the elastic modulus of sheet metal is to suspend the sheet metal freely with elastic ropes and then strike the specimen's midpoint or corner with a hammer to obtain the first-order bending frequency of the free sheet metal and calculate the elastic modulus. Because the sheet metal suspended from the elastic ropes is in a free state, this method is complex to operate and difficult to achieve fast and efficient testing. Summary of the Invention

[0004] The present invention provides a production line for automatic detection of the dynamic elastic modulus of full-scale wood / bamboo boards. The production line can accurately position the boards, strike the boards with a hammering device, measure the first-order bending frequency of the boards, and then calculate an accurate elastic modulus E. The automatically calculated dynamic elastic modulus value is used to grade the quality of the finished boards. The production line is simple to operate, with a detection time of 10-15 seconds per board, and can realize online automatic detection of each board product, thereby improving work efficiency and test accuracy.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0006] The automatic detection production line for dynamic elastic modulus of full-scale wood / bamboo boards includes a frame, a board conveying mechanism, a blocking mechanism, a detection and analysis mechanism, a lifting mechanism, and a hammering mechanism.

[0007] The plate conveying mechanism is arranged on the frame and is used to drive the plate to move from the back to the front. It includes a plurality of rollers that rotate under the drive of the conveying power device. The rollers are parallel and spaced apart.

[0008] The blocking mechanism is arranged at the front end of the frame and can be lifted up and down. When the blocking mechanism rises to a position higher than the roller shaft, the plate moves forward until the front end of the plate contacts the blocking mechanism, and then the plate stops moving forward.

[0009] The detection and analysis mechanism includes an accelerometer and a vibration and dynamic signal acquisition and analysis system. The accelerometer is located above the left or right corner of the front end of the plate. The accelerometer is set on a bracket, and the bracket is set on the frame. The vibration and dynamic signal acquisition and analysis system analyzes and calculates the elastic modulus E of the plate based on the vibration signal collected by the accelerometer.

[0010] The lifting mechanism is located below the plate and is used to lift the stopped plate so that the plate is out of contact with the roller and the blocking mechanism, and to make the upper surface of the front left or right corner of the plate contact the accelerometer; it includes two support rods that move up and down driven by the lifting power device. When the support rods lift the plate, the two parallel support rods are in line contact with the lower surface of the plate. The distance between the two support rods and the front and rear ends of the plate is 0.224L.

[0011] The hammer mechanism is located above the plate and has a swinging rubber hammer for striking the center point of the plate lifted by the lifting mechanism.

[0012] The automatic detection production line for dynamic elastic modulus of full-size wood / bamboo panels includes a hammer mechanism comprising a shift fork, a hammer handle, a rubber hammer, a mounting plate, a striking motor, a pivot, an electromagnet, a magnet, and a pendulum;

[0013] A rubber hammer is fixed to one end of the hammer handle, and the other end is pivotally mounted on a mounting plate; a shift fork rotates on the mounting plate and is connected to a striking motor that drives it to rotate; an electromagnet is fixed to the mounting plate, and a magnet is mounted on the hammer handle; two ends of a tension spring are respectively connected to the mounting plate and the hammer handle; when the electromagnet is de-energized and the tension spring is in a normal state, the hammer handle rotates around the pivot until the rubber hammer contacts the plate lifted by the lifting mechanism, at which time the electromagnet and the magnet are misaligned; when the electromagnet is energized, the magnet on the hammer handle is attracted by the electromagnet, the magnet and the electromagnet are opposed, and the hammer handle is in a state where the rubber hammer does not contact the plate; the hammer handle is provided with a swing rod extending toward the shift fork;

[0014] When the electromagnet loses power, the shift fork rotates until it contacts the pendulum rod, and the shift fork continues to rotate. The pendulum rod and the hammer handle rotate in the opposite direction around the pivot to overcome the elastic force of the tension spring 1, and the rubber hammer gradually moves away from the plate. When the shift fork continues to rotate until it disengages from the pendulum rod, the pendulum rod and the hammer handle rotate forward around the pivot under the elastic force of the tension spring 1, and the rubber hammer hits the plate. Then the electromagnet is energized, and the pendulum rod and the hammer handle rotate in the opposite direction around the pivot to overcome the elastic force of the tension spring 1. The magnet on the hammer handle is opposite to the electromagnet, and the rubber hammer leaves the plate.

[0015] The wood / bamboo board online inspection and quality grading production line based on the transient excitation dynamic testing method, the hammer mechanism also includes a second tension spring, the two ends of which are respectively connected to the mounting plate and the hammer handle. When the electromagnet is de-energized and the second tension spring is in a normal state, the hammer handle rotates around the pivot until the rubber hammer is separated from the board lifted by the lifting mechanism; but when the electromagnet is de-energized and both the first and second tension springs are in normal states, the hammer handle rotates around the pivot until the rubber hammer is in contact with the board lifted by the lifting mechanism.

[0016] The electromagnet loses power. When the shift fork rotates until it contacts the pendulum rod, the shift fork continues to rotate. With the help of tension spring 2, the pendulum rod and the hammer handle rotate in the opposite direction around the pivot to overcome the elastic force of tension spring 1, and the rubber hammer gradually moves away from the plate. When the shift fork continues to rotate until it disengages from the pendulum rod, the pendulum rod and the hammer handle overcome the elastic force of tension spring 2 and rotate forward around the pivot under the elastic force of tension spring 1. The rubber hammer hits the plate. Then the electromagnet is energized, the pendulum rod and the hammer handle overcome the elastic force of tension spring 1 around the pivot and rotate in the opposite direction around the pivot with the help of tension spring 2. The magnet on the hammer handle is opposite to the electromagnet, and the rubber hammer leaves the plate.

[0017] The automatic detection production line for the dynamic elastic modulus of full-size wood / bamboo panels comprises a lifting mechanism including a support rod, a lifting frame, a guide column, a support leg, and a lifting power device; support rods are provided above the front and rear parts of the lifting frame, guide columns are fixed below the front and rear parts of the lifting frame, and each guide column is slidably provided on a support leg; a lifting power device is provided between the support leg and the lifting frame to drive the lifting frame to move up and down.

[0018] The automatic detection production line for the dynamic elastic modulus of full-size wood / bamboo panels, the jacking mechanism also includes a synchronization device, the synchronization device includes a synchronization shaft, a bearing seat, a synchronization wheel, and meshing teeth. The synchronization shaft rotates simultaneously and is arranged on the bearing seat located on the front and rear legs. The front and rear synchronization wheels fixed on the synchronization shaft are engaged with the meshing teeth on the front and rear guide columns.

[0019] The automatic detection production line for the dynamic elastic modulus of full-size wood / bamboo boards has a cylindrical guide column, two rotating upper guide rollers on the upper part of each leg, and a rotating lower guide roller on the upper part of each leg. The two upper guide rollers on the same leg are located on both sides of the guide column axis, and the lower guide roller and synchronous wheel on the same leg are located on both sides of the guide column axis. The generatrix of the upper guide roller and the lower guide roller are both arcs that contact the outer periphery of the guide column.

[0020] The automatic dynamic elastic modulus testing production line for full-scale wood / bamboo panels has four guide posts and four legs, two at the front and two at the back. The two front legs are fixedly connected by a cross brace, and the two rear legs are fixedly connected by another cross brace. The lifting power device is a lifting cylinder. There are two lifting cylinders at the front and back.

[0021] The blocking mechanism of the automatic detection production line for dynamic elastic modulus of full-size wood / bamboo panels includes a blocking bar and a blocking cylinder that drives the blocking bar to move up and down.

[0022] The automatic dynamic elastic modulus testing line for full-scale wood / bamboo panels comprises a centering mechanism comprising a centering baffle and two front and rear transverse push-plate devices. The centering baffle is arranged perpendicularly to the roller axis on one side of the frame and is higher than the roller axis. The transverse push-plate device comprises a push-plate frame fixed to the other side of the frame. A guide rod is mounted on the push-plate frame and slides left and right in a direction parallel to the roller axis. The end of the guide rod secures a push plate, which is positioned between two adjacent roller axes, with the upper end of the push plate protruding from the roller axis. The lower end of the push plate is connected to a push-plate drive device that drives the push plate left and right in a direction parallel to the roller axis. The push-plate drive device is a push-plate cylinder.

[0023] In the automatic detection production line for the dynamic elastic modulus of full-size wood / bamboo panels, the accelerometer is connected to the bracket in a floating manner in the vertical direction via a floating connection mechanism; the upper end of the accelerometer is connected to a floating plate, which is arranged on the bracket for sliding up and down via a linear bearing; a core shaft passes through the lower end of the floating plate, a retaining ring is provided, and the upper end of the core shaft is connected to the bracket; a spring surrounding the core shaft is located between the upper end of the floating plate and the bracket, and the spring causes the floating plate to contact the retaining ring when in normal state.

[0024] The automatic detection production line for the dynamic elastic modulus of full-size wood / bamboo boards comprises a bracket including vertical rods, longitudinal rods, and transverse rods. The lower ends of the vertical rods are connected to the frame via supports. The vertical rods and longitudinal rods perpendicular to each other are simultaneously inserted into the axial holes of the first loosening clamping sleeve to be loosened or clamped by the first loosening clamping sleeve. The longitudinal rods and transverse rods perpendicular to each other are simultaneously inserted into the axial holes of the second loosening clamping sleeve to be loosened or clamped by the second loosening clamping sleeve. A linear bearing and a core shaft are connected to the transverse rod.

[0025] The automatic detection production line for the dynamic elastic modulus of full-size wood / bamboo boards has each roller rotatably arranged on a frame, two sprockets are fixed to one end of each roller, a sprocket on the last roller is connected to a driving sprocket fixed to the output shaft of a conveying motor via a driving chain; the two sprockets on two adjacent rollers are connected by a driven chain; the conveying motor rotates, driving the rollers through the driving sprocket, the driving chain, the sprocket, and the driven chain.

[0026] The present invention also provides a method for grading full-size wood / bamboo boards, comprising the following steps:

[0027] a. The plate moves from back to front along the longitudinal direction of the plate under the drive of multiple rotating rollers until the front end of the plate contacts the raised blocking mechanism higher than the rollers, the rollers stop rotating, and the plate stops moving;

[0028] b. The blocking mechanism drops below the roller axis and does not block the plate from moving forward;

[0029] c. The lifting mechanism located below the plate rises, and the two support rods on the upper part of the lifting mechanism pass through the rollers and move upward, lifting the plate so that the plate is out of contact with the rollers and the blocking mechanism. The upper surface of the front left or right corner of the plate contacts the accelerometer. The two parallel support rods are in line contact with the lower surface of the plate. The distance from one support rod to the rear end of the plate is 0.224L, and the distance from the other support rod to the front end of the plate is also 0.224L.

[0030] d. The hammer mechanism located above the plate is actuated. The rubber hammer in the hammer mechanism strikes the upper surface of the plate, with the striking point being the center of the plate. During the striking, the vibration and dynamic signal acquisition and analysis system obtains the first-order bending frequency of the plate based on the vibration signal collected by the accelerometer, and calculates the elastic modulus E of the plate according to formula (1). The plates are then graded according to the size of the elastic modulus E.

[0031] (1)

[0032] Where ρ is the air-dry density of the board, in kg / m 3 ;f b is the first-order bending frequency, in Hz; L is the length of the plate, in m; h is the thickness of the plate, in m;

[0033] e. The lifting mechanism descends, the plate loses contact with the accelerometer, the plate falls onto the roller, and the support rod loses contact with the plate;

[0034] f. The roller rotates, driving the plate forward until the rear end of the plate does not hinder the lifting and lowering of the blocking mechanism in the up and down directions.

[0035] The method for grading full-size wood / bamboo boards includes the following steps after step a and before step b:

[0036] a1: Push the plate in the left and right directions to center the plate in the left and right directions.

[0037] The beneficial effects of the present invention are:

[0038] Compared with the method of testing the first-order bending frequency of the plate by using free suspension of the plate (the distance from the rear suspension rope to the rear end of the plate is 0.224L, and the distance from the front suspension rope to the front end of the plate is 0.224L), the present invention supports the plate from the bottom of the plate with two support rods (the distance from the rear support rod to the rear end of the plate is 0.224L, and the distance from the front support rod to the front end of the plate is 0.224L). When the center point of the plate is tapped, the deviation of the measured first-order bending frequency of the plate is minimized based on the vibration of the corners of the plate, thereby obtaining an accurate elastic modulus E, which lays the foundation for quality grading of the plates.

[0039] The online inspection and quality grading production line realizes the automated flow operation of plate conveying, positioning, lifting, knocking, inspection and grading with high efficiency and high speed.

[0040] In the hammering mechanism, the shift fork rotates under the drive of the striking motor so that the hammer handle swings and strikes the plate. Because the shift fork can rotate continuously, it ensures that the rubber hammer can strike the plate repeatedly, ensuring the continuity of the operation.

[0041] Tension spring 1 and tension spring 2 are used to apply torques in different directions (one counterclockwise and the other clockwise) to the hammer handle. The elastic force of tension spring 1 or tension spring 2 can be changed as needed, which makes it more convenient to adjust the rotational torque of the hammer handle and the striking force on the plate.

[0042] The matching of the electromagnet and the magnet can ensure that the magnet is quickly attracted by the electromagnet after the rubber hammer hits the plate once, ensuring that the rubber hammer only hits the plate once.

[0043] The jacking mechanism uses a synchronization device to ensure that the lifting heights of the two support rods are consistent, ensuring the horizontality of the plate and thus ensuring the accuracy of the test.

[0044] The busbar of the guide rollers (upper guide roller and lower guide roller) is an arc in contact with the outer circumference of the cylindrical guide column, which reduces the friction resistance between the guide rollers and the guide column. The lower guide roller and the synchronous wheel are located on both sides of the guide column, and the two upper guide rollers are located on both sides of the guide column, ensuring the up and down movement direction of the guide column and the synchronous lifting and lowering of each guide column at the same time. The structure is simple and ingenious.

[0045] In order to facilitate the automatic centering of the plate, a horizontal push plate device is used to push the plate into contact with the centering baffle.

[0046] The accelerometer is connected to the bracket in a floating manner in the up and down directions through a floating connection mechanism, which ensures good contact between the accelerometer and the plate and the accuracy of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a schematic diagram of the standard free plate transient excitation method device;

[0048] Figure 2 、 Figure 3 This is a schematic diagram of the triangular pyramid support position based on the transient excitation method;

[0049] Figure 4 This is the midpoint spectrum diagram of the LVL specimen 1 free plate transient excitation method test;

[0050] Figure 5-Figure 7 This is the midpoint spectrum diagram of the LVL specimen 1 tested using the automated triangular pyramid support transient excitation method.

[0051] Figure 8This is the midpoint spectrum diagram of the LVL specimen 2 free plate transient excitation method test;

[0052] Figures 9-11 This is the midpoint spectrum diagram of the LVL specimen 2 tested using the automated triangular pyramid support transient excitation method.

[0053] Figure 12 This is the midpoint spectrum diagram of the LVL specimen 3 free plate transient excitation method test;

[0054] Figure 13-16 This is the midpoint spectrum diagram of the LVL specimen 3 automated triangular pyramid support transient excitation method test;

[0055] Figure 17 、 Figure 18 They are the stereoscopic diagram and main view of the online inspection and quality grading production line for wood / bamboo panels based on the transient excitation dynamic testing method.

[0056] Figure 19 This is a three-dimensional diagram of the production line (without the plate).

[0057] Figure 20 This is a schematic diagram of the plate in contact with the blocking mechanism (part of the frame, part of the roller, hammer mechanism, etc. are removed).

[0058] Figure 21 This is a schematic diagram of the plate in contact with the blocking mechanism (part of the frame, part of the roller, hammer mechanism, plate, etc. are removed).

[0059] Figure 22 This is a schematic diagram of the plate in the centering state (when the plate is in contact with the centering baffle).

[0060] Figure 23 、 Figure 24 、 Figure 25 They are three-dimensional images when hitting the plate (part of the frame, part of the roller, part of the accelerometer, etc. are removed).

[0061] Figure 26 、 Figure 27 These are three-dimensional diagrams of the accelerometer, bracket, etc.

[0062] Figure 28 、 Figure 29 Three-dimensional diagram of the hammer mechanism.

[0063] Figure 30 It is a three-dimensional diagram of the push plate, push plate frame, etc.

[0064] Figure 31 It is a three-dimensional diagram of the blocking mechanism.

[0065] Figure 32 、 Figure 33 They are the main view and side view of the hammer mechanism, etc.

[0066] Figure 34 for Figure 32 BB cross-section view in.

[0067] Figure 35 、 Figure 36 They are the main view and side view of the jacking mechanism, etc.

[0068] Figure 37 for Figure 35 A partial enlarged view of the .

[0069] Figure 38 They are three-dimensional diagrams of the jacking mechanism, etc.

[0070] In the figure,

[0071] Rack 100, plate 200,

[0072] Plate conveying mechanism 1; conveying power device 11, roller 12, driving chain 14, driven chain 15;

[0073] Blocking mechanism 2: blocking frame 21, blocking bar 22, blocking cylinder 23;

[0074] Detection and analysis mechanism 3, accelerometer 31, vertical rod 32, longitudinal rod 33, horizontal rod 34, support 35, loosening clamping sleeve 1 36, loosening clamping sleeve 2 37, linear bearing 38, core shaft 39, floating plate 310, retaining ring 311, spring 312;

[0075] Lifting mechanism 4; support rod 41, V-shaped support block 42, lifting frame 43, guide column 44, support leg 45, lifting power device 46; synchronization device 47, synchronization wheel 471, synchronization shaft 472, bearing seat 473, upper guide roller 48, lower guide roller 49;

[0076] Hammering mechanism 5; shift fork 51, hammer handle 52, rubber hammer 53, mounting plate 54, striking motor 55, electromagnet 56, magnet 57, pendulum rod 58, tension spring 1 59, tension spring 2 510, horizontal beam 511, vertical beam 512, pivot 513, auxiliary rod 514, fixing block 1 515, pull rod 1 516, adjusting nut 1 517.

[0077] Centering mechanism 6; centering baffle 61, push plate frame 63, guide rod 64, push plate 65, push plate driving device 66. DETAILED DESCRIPTION

[0078] The specific embodiments of the present invention are further described below with reference to the accompanying drawings.

[0079] 1. Comparison of the dynamic test of the single bending frequency value of the free suspension of the full-scale product specimen and the wooden triangular pyramid support

[0080] 1.1 Materials and Instruments

[0081] The test object of this test is LVL product, the specimen size is 2700mm×760mm×27mm (length×width×height), and the air-dry density is 614kg / m 3 , moisture content is 10%, and the origin is Guannan County, Lianyungang, Jiangsu.

[0082] The test instruments used were: a CRAS vibration and dynamic signal acquisition and analysis system, including the AZ-408 data acquisition box, AZ-802 signal conditioning box, CRAS AdCras data acquisition and processing software, and CRAS SsCras signal and system analysis software, designed and manufactured by Nanjing Anzheng Software Engineering Co., Ltd.; and a CA-YD-1182 accelerometer with a sensitivity of 10.04mV / m / s. 2 , one CA-YD-1182 acceleration sensor, manufactured by Yangzhou Jufeng Technology Co., Ltd.; one set of free-plate suspension device, several elastic ropes with a width of 15 mm; one rubber hammer; two larch triangular pyramids, with specifications of 1100 mm × 50 mm × 30 mm and an air-dry density of 720 kg / m 3 , the moisture content is 12%.

[0083] 1.2 Test methods and principles

[0084] The principle of testing the elastic modulus E of a free plate is as follows: when the plate specimen is suspended by an elastic rope and in a free state, a hammer is used to hit the midpoint or corner of the specimen to obtain the first-order bending frequency of the free plate. When the plate specimen vibrates laterally, the elastic modulus E is related to the first-order bending frequency f b The relationship is shown in formula (1).

[0085] (1)

[0086] In formula (1): ρ is the air-dry density of the specimen, in kg / m 3 ;f b is the first-order bending frequency, in Hz; L is the specimen length, in m; h is the specimen thickness, in m.

[0087] 1.3 Main test steps

[0088] (1) Ensure that the positions of the elastic ropes are set to 0.224L (the distance between the left elastic rope 7 and the left end of the plate is 0.224L) and 0.776L (the distance between the right elastic rope 8 and the left end of the plate is 0.776L, or the distance between the left elastic rope 7 and the right elastic rope 8 is 0.552L) on the suspension device, thereby forming a linear vibration system, as shown in FIG. Figure 1 shown.

[0089] (2) Connect the relevant instruments and install the CA-YD-1182 acceleration sensor at any corner point of the LVL rectangular plate.

[0090] (3) Start the SsCars software and set the necessary parameters. The main settings include: correction factor of 1, voltage range of -2500mV to 2500mV, analysis frequency of 100Hz, average number of times of 1, FFT length of 1024, acquisition mode of free run, and low-pass filter of 100Hz.

[0091] (4) Switch to the acquisition mode, fix the accelerometer at the right corner through hammer excitation, and use a rubber hammer to vertically hit the midpoint of the LVL plate to measure the frequency and collect data.

[0092] (5) The vibration signal collected by the accelerometer is converted into an electrical signal, which is then amplified and filtered by the dynamic signal acquisition and analysis system and converted into a digital signal. Finally, the SsCars software processes the signal and displays the spectrum, reading the first-order bending frequency f.

[0093] (6) Place the LVL board on the wooden triangular pyramid, making sure the position of the triangular pyramid is consistent with the position of the elastic rope.

[0094] Repeat the above steps, changing the tapping method to automated tapping (using hammer mechanism 5), and measure the first-order bending frequency at the midpoint multiple times. This allows comparison of the effects of the free plate and the automated triangular pyramid support on the first-order bending frequency of the specimen, as well as the differences in the resulting frequency values.

[0095] 1.4 Results and Analysis

[0096] Several LVL specimens were tested using a standard free plate and automated triangular pyramid support transient excitation method. The first-order bending frequency results for three of the specimens are shown in Tables 1-3.

[0097] Table 1 First-order bending frequency values ​​of specimen 1 tested by transient excitation method with free plate and automated triangular pyramid support

[0098]

[0099] The standard first-order bending frequency of LVL specimen 1 measured using a standard free plate was 16.75 Hz. The automated triangular pyramid testing system was able to accurately measure the first-order bending frequency of the plate, which was close to the standard value of 16.75 Hz for free plates, with generally small errors. The errors for most test results were within the range of +0.78% to +0.79%, demonstrating high stability. In particular, the results for automated triangular pyramid support tests 1-6 to 1-10 were completely consistent with the standard values, demonstrating that the automated triangular pyramid testing system was able to achieve the standard values ​​under these support conditions. However, the error for automated triangular pyramid support tests 1-5 was larger, reaching +1.45%, indicating that the automated system may have fluctuations or errors in individual tests, but the errors are still very small. Overall, for LVL specimen 1, the automated triangular pyramid testing system was able to basically meet the requirements for dynamic elastic modulus testing and exhibited good repeatability and reliability.

[0100] Table 2 First-order bending frequency values ​​of specimen 2 tested by transient excitation method with free plate and automated triangular pyramid support

[0101]

[0102] The standard first-order bending frequency of specimen 2, tested using a standard free plate, is 16.50 Hz. The automated triangular pyramid support testing system accurately measured the first-order bending frequency of the plate, with most test results closely approximating the standard value of 16.50 Hz, and generally exhibiting a small error. The error for most test results ranged from +0.00% to +1.50%, demonstrating the system's high accuracy and stability in most situations. In particular, the results for automated triangular pyramid supports 2-1, 2-9, and 2-10 were completely consistent with the standard value, demonstrating good repeatability. However, the errors for automated triangular pyramid supports 2-2, 2-3, and 2-4 were +1.50%, while the errors for automated triangular pyramid supports 2-5, 2-7, and 2-8 were -1.50%, remaining within a relatively small error range. Overall, the automated triangular pyramid support testing system provided accurate and stable results for testing the first-order bending frequency of specimen 2, demonstrating good reliability and consistency.

[0103] Table 3 First-order bending frequency values ​​of specimen 3 tested by transient excitation method with free plate and automated triangular pyramid support

[0104]

[0105] The standard first-order bending frequency of LVL specimen 3 measured using a standard free plate is 16.88 Hz. The automated triangular pyramid support test system accurately measures the first-order bending frequency of the plate, with most test results close to the standard value of 16.88 Hz, and the error is generally small. The error for most test results ranges from -0.78% to +0.00%, demonstrating high stability. In particular, the results for automated triangular pyramid supports 3-4 and 3-5 are completely consistent with the standard values, demonstrating that the system can achieve the standard values ​​under these test conditions. The error for automated triangular pyramid supports 3-7 and 3-8 is -1.50%, while the error for automated triangular pyramid support 3-10 is -2.25%. This indicates that the automated triangular pyramid support test system exhibits fluctuations in individual tests, resulting in frequency deviations, but these deviations are minor. Overall, the automated triangular pyramid support test system achieves a high degree of accuracy and reliability when measuring the first-order bending frequency of specimen 3, with most test results close to the standard value, and the error range is relatively small.

[0106] Judging from the first-order bending frequency results, in general, the automated triangular pyramid testing system can still meet the requirements of dynamic elastic modulus testing, and has good repeatability and stability, and can accurately achieve the purpose of online automatic quality inspection and grading of wood / bamboo boards and their composite materials, such as Figure 2 、 3 shown.

[0107] 1.5 Spectrum Results

[0108] The midpoint frequency spectra of the full-scale LVL plate specimens 1-3 measured by the transient excitation method under the standard free plate and the automated triangular pyramid support can be referred to as Figure 4-Figure 7 、 Figures 8-11 and Figure 12-16 As shown, it is the midpoint spectrum diagram corresponding to the first-order bending frequency tested by the transient excitation method of the standard free plate and the automated triangular pyramid support. Other spectrum diagrams are no longer shown when the values ​​are the same.

[0109] 2 Design and application of a production line for automatic detection and quality assessment of dynamic elastic modulus of full-scale wood / bamboo panels

[0110] See also Figure 17-19 , a production line for automatic detection and quality assessment of dynamic elastic modulus of full-size wood / bamboo panels, including a frame 100, a panel conveying mechanism 1, a blocking mechanism 2, a detection and analysis mechanism 3, a lifting mechanism 4, a hammering mechanism 5, and a centering mechanism 6.

[0111] The plate conveying mechanism 1 is mounted on a frame 100 and is used to drive the plate 200 from back to front. The mechanism includes a plurality of rollers 12 that rotate under the drive of a conveying power unit 11, i.e., a conveying motor. The rollers 12 are arranged in parallel and spaced apart, and are all rotatably mounted on the frame 100. Two sprockets are fixed to the left end of each roller 12. The sprocket on the last roller is connected to a driving sprocket fixed to the output shaft of the conveying motor via a driving chain 14; the two sprockets on two adjacent rollers are connected via a driven chain 15; the conveying motor rotates, driving the rollers through the driving sprocket, driving chain, sprocket, and driven chain. The plate conveying mechanism 1 is conventional technology and will not be described in detail.

[0112] See also Figure 31 The blocking mechanism 2 includes a blocking frame 21 extending left and right, two blocking bars 22 extending left and right at the rear end of the blocking frame, and a blocking cylinder 23 that drives the blocking frame 21 to move up and down.

[0113] The blocking frame 21 is slidably arranged at the front end of the frame, and the piston rod of the blocking cylinder 23 is connected to the blocking frame. When the blocking frame 21 and the blocking bar 22 rise to a position higher than the roller shaft, the plate moves forward until the front end of the plate contacts the blocking bar 22, and the plate stops moving forward.

[0114] Testing and analysis agency 3, see Figure 26 、 27 The system comprises four accelerometers 31 and a vibration and dynamic signal acquisition and analysis system. Each accelerometer is located above one of the four corners of the plate and is mounted on a bracket. The bracket comprises vertical rods 32, longitudinal rods 33, and transverse rods 34. The lower ends of the vertical rods are connected to both sides of the frame via supports 35. The vertical and longitudinal rods, which are perpendicular to each other, simultaneously extend into the axial holes of a first loosening clamping sleeve 36 and can be loosened or clamped by the first loosening clamping sleeve 36. The longitudinal and transverse rods, which are perpendicular to each other, simultaneously extend into the axial holes of a second loosening clamping sleeve 37 and can be loosened or clamped by the second loosening clamping sleeve. The ends of the transverse rods are directly or indirectly connected to a linear bearing 38 and a core shaft 39. The upper end of the accelerometer 31 is fixed to a floating plate 310, which slides up and down relative to the crossbar via linear bearings. A core shaft 39 passes through the lower end of the floating plate and is provided with a retaining ring 311. The upper end of the core shaft is directly or indirectly connected to the crossbar 34. A spring 312 surrounding the core shaft is located between the upper portion of the floating plate and the crossbar. Under normal conditions, spring 312 ensures contact between the floating plate 310 and retaining ring 311. The vibration and dynamic signal acquisition and analysis system analyzes and calculates the plate's elastic modulus E based on the vibration signals collected by the accelerometer.

[0115] See also Figures 35-38 The lifting mechanism 4 is located below the plate and is used to lift the plate that has stopped moving so that the plate is out of contact with the roller and the blocking mechanism, and so that the upper surface of the plate corner is in contact with the accelerometer;

[0116] The lifting mechanism 4 comprises support rods 41, V-shaped support blocks 42, a lifting frame 43, guide columns 44, legs 45, a lifting power unit 46, and a synchronizer 47. The synchronizer 47 comprises a synchronization shaft 472, a bearing block 473, a synchronization wheel 471, and meshing gears. Multiple V-shaped support blocks 42 are positioned above the front and rear portions of the lifting frame 43. Each support rod 41, with a square cross-section, rests on the V-grooves of several V-shaped support blocks 42. Each support rod 41 and the V-shaped support block 42 beneath it are positioned between two adjacent rollers. Four cylindrical guide columns are fixed beneath the lifting frame, two at the front and two at the rear. The lower end of each guide column extends into the upper portion of a hollow square leg. The front two legs are fixedly connected by a cross brace, and the rear two legs are fixedly connected by another cross brace. The lifting power unit 46 consists of two front and rear lifting cylinders. The cylinder bodies of the lifting cylinders are fixed to the cross brace, and the piston rods are connected to the lifting frame 43.

[0117] The guide post 44 is provided with meshing teeth to form a rack, which meshes with a synchronous wheel 471. A synchronous wheel in front and a synchronous wheel in the back are fixed on a synchronous shaft 472, and the front and rear ends of the synchronous shaft 472 are rotatably arranged on a bearing seat 473 fixed on the front and rear legs.

[0118] Two upper guide rollers 48, which rotate about their own axes, are mounted on the upper side of each leg 45 via bearings. The two upper guide rollers 48 on the same leg are located on either side of the axis of the guide post 44. A lower guide roller 49, which rotates about its own axis, is mounted on the lower side of each leg via bearings. The lower guide roller 49 and the synchronous pulley 471 on the same leg are located on either side of the axis of the guide post 44. The generatrix of each upper guide roller 48 and lower guide roller 49 is an arc that contacts the outer periphery of the guide post. Slots are provided on the side of the leg at positions corresponding to the upper guide rollers 48, 49, and synchronous pulley 471, allowing them to pass through the slots and engage with the guide post within the leg.

[0119] See also Figure 28 、 29 The hammering mechanism 5 includes a shift fork 51, a hammer handle 52, a rubber hammer 53, a mounting plate 54, a striking motor 55, a pivot 513, an electromagnet 56, a magnet 57, a rocker 58, a tension spring 1 59, a tension spring 2 510, a horizontal beam 511, and a vertical beam 512.

[0120] The ends of the horizontal beam 511 are connected to the vertical beams 512, which are fixed to the two sides of the frame. The horizontal beams have T-shaped slots, through which bolts pass to connect to the mounting plate. When the bolts are loosened, the mounting plate and the bolts can move along the T-shaped slots, changing the left and right position of the mounting plate.

[0121] A rubber hammer 53 is fixed to one end of the hammer handle 52, and the other end is pivotally mounted on a mounting plate 54 via a pivot 513. A shift fork 51 rotates on the mounting plate and is connected to a striking motor 55 that drives its rotation. The striking motor 55 housing is fixed to the mounting plate 54. An electromagnet 56 is fixed to the mounting plate 54, and the magnet is mounted on the hammer handle 52 or on an auxiliary rod 514 integral with the hammer handle. Tension spring 1 59 has two ends connected to the mounting plate 54 and the hammer handle 52, respectively. Tension spring 2 510 has two ends connected to the mounting plate 54 and the hammer handle 52, respectively. Tension spring 1 59 causes the hammer handle to rotate counterclockwise about the pivot, while tension spring 2 510 causes the hammer handle to rotate clockwise about the pivot.

[0122] The connection between tension spring 1 59 and mounting plate 54 is as follows: a fixing block 1 515 is provided on the mounting plate, with a guide hole 1 defined in fixing block 1 515. A pull rod 1 516 passes through guide hole 1 and is threadedly connected to an adjustment nut 1 517 at its end away from the tension spring 1. The end of pull rod 1 516 near the tension spring 1 is also connected to the tension spring 1. The tension of tension spring 1 59 can be adjusted by rotating adjustment nut 1 517 relative to pull rod 1 516. The connection between tension spring 2 510 and mounting plate 54 is similar and will not be described further.

[0123] When the electromagnet 56 loses power and the tension spring 1 59 and the tension spring 2 510 are in normal state, the hammer handle 52 rotates counterclockwise around the pivot until the rubber hammer 53 contacts the plate lifted by the lifting mechanism. At this time, the electromagnet 56 and the magnet are staggered; when the electromagnet 56 is energized, the magnet on the hammer handle 52 is attracted by the electromagnet 56, and the hammer handle rotates clockwise. The magnet and the electromagnet 56 are opposite, and the hammer handle 52 is in a state where the rubber hammer 53 does not contact the plate; the hammer handle 52 has a rocker 58 extending toward the shift fork 51.

[0124] The electromagnet 56 loses power. When the shift fork 51 rotates until it contacts the rocker arm 58, the shift fork 51 continues to rotate. With the help of the second tension spring 510, the rocker arm 58 and the hammer handle 52 rotate clockwise around the pivot to overcome the elastic force of the first tension spring 59. The rubber hammer 53 gradually moves away from the plate. When the shift fork 51 continues to rotate until the shift fork 51 is disengaged from the rocker arm 58, the rocker arm 58 and the hammer handle 52 overcome the elastic force of the second tension spring 510 and rotate counterclockwise around the pivot under the elastic force of the first tension spring 59. The rubber hammer 53 hits the plate. Then the electromagnet 56 is energized. The rocker arm 58 and the hammer handle 52 overcome the elastic force of the first tension spring 59 and rotate clockwise around the pivot with the help of the second tension spring 510. The magnet on the hammer handle 52 is opposite to the electromagnet 56, and the rubber hammer 53 leaves the plate.

[0125] See also Figure 24 、 30The centering mechanism 6 includes a centering baffle 61 and two front and rear transverse push-plate devices. The centering baffle 61 is positioned perpendicular to the roller axis on the left side of the frame, above the roller axis and covering the sprocket on the roller axis. The transverse push-plate device includes a push-plate frame 63 fixed to the right side of the frame. A guide rod 64 is mounted on the push-plate frame 63 and slides left and right in a direction parallel to the roller axis. The right end of the guide rod 64 is fixed to an upwardly extending push plate 65. The push plate 65 is located between two adjacent roller axes, with its upper end protruding above the roller axis and facing left and right of the centering baffle 61. The lower end of the push plate is connected to a push-plate drive device 66 that drives the push plate to move left and right in a direction parallel to the roller axis. The push-plate drive device 66 is a push-plate cylinder. The cylinder barrel of the push-plate cylinder is fixed to the push-plate frame 63, and the piston rod is connected to the push plate 65. Of course, the maximum transverse distance between the centering baffle 61 and the push plate 65 is greater than the width of the plate.

[0126] The method for online inspection and quality grading of wood / bamboo panels based on transient excitation dynamic testing method includes the following steps:

[0127] a. The conveying power device 11, i.e., the conveying motor, is started, the rollers rotate, and the sheet 200 is driven by the rotating rollers to move from back to front along the longitudinal direction of the sheet until the front end of the sheet contacts the blocking bar in the blocking mechanism that is higher than the rollers; the push plate driving device 66, i.e., the push plate cylinder, is actuated, driving the push plate to move leftward, pushing the sheet 200 into contact with the centering baffle 61; the conveying motor is stopped, the rollers stop rotating, and the push plate cylinder drives the push plate to move rightward to the rightmost side;

[0128] b. The blocking cylinder 23 drives the blocking frame to descend, and the blocking bars and blocking frame descend to below the roller shaft, which will not block the plate from moving forward;

[0129] c. The lifting power device 46, i.e., the lifting cylinder, is activated, driving the lifting frame 43, guide column 44, etc. to rise relative to the support legs 45. The two support rods pass through between the rollers and move upward, lifting the plate so that the plate is out of contact with the rollers. The upper surface of one corner of the plate contacts an accelerometer. The two parallel support rods are in line contact with the lower surface of the plate. The distance between the two support rods and the front and rear ends of the plate is 0.224L.

[0130] d. When the electromagnet 56 loses power, the striking motor 55 drives the shift fork 51 to rotate until the shift fork 51 begins to contact the rocker 58. The shift fork 51 continues to rotate, the hammer handle 52 rotates clockwise around the pivot, and the rubber hammer 53 gradually moves away from the plate. When the shift fork 51 continues to rotate until the shift fork 51 is separated from the rocker 58, the hammer handle 52 overcomes the elastic force of the tension spring 2 510 and rotates counterclockwise around the pivot under the elastic force of the tension spring 1 59. The rubber hammer 53 strikes the plate. Then, the electromagnet 56 is energized, the magnet 57 is attracted by the electromagnet 56, the hammer handle 52 rotates clockwise, the magnet 57 is in a position opposite to the electromagnet 56, and the rubber hammer 53 on the hammer handle is in a position away from the plate. In this process, the rubber hammer strikes the upper surface of the plate once, and the striking point is the center point of the plate. The vibration and dynamic signal acquisition and analysis system obtains the first-order bending frequency of the plate based on the vibration signal collected by the accelerometer, and calculates the elastic modulus E of the plate according to formula (1).

[0131] (1)

[0132] Where ρ is the air-dry density of the board, in kg / m 3 , can be measured in advance; f b is the first-order bending frequency, in Hz; L is the length of the plate, in m; h is the thickness of the plate, in m;

[0133] The boards are then graded based on their elastic modulus E. For example, E > 2200mpa is first-class, 1900mpa < E < 2200mpa is second-class, and E < 1900mpa is third-class. Grading the quality of boards based on the elastic modulus E is a prior art technique.

[0134] e. The lifting power device 46, i.e., the lifting cylinder, is activated to drive the lifting frame 43, the support rod 41, the plate 200, etc. to descend, the plate is disengaged from the accelerometer, the plate 200 falls onto the roller 12, the support rod is disengaged from the plate, and the plate is removed.

[0135] f. The roller rotates, driving the plate 200 to move forward until the rear end of the plate does not hinder the lifting and lowering of the blocking mechanism in the vertical direction.

[0136] The protection scope of the present invention includes but is not limited to the above embodiments. The protection scope of the present invention is based on the claims. Any replacement, deformation, and improvement of the technology that can be easily thought of by those skilled in the art fall within the protection scope of the present invention.

Claims

1. Automatic testing production line for dynamic elastic modulus of full-scale wood / bamboo panels, characterized by: Including frame, plate conveying mechanism, blocking mechanism, detection and analysis mechanism, lifting mechanism, hammering mechanism, The plate conveying mechanism is arranged on the frame and is used to drive the plate to move from the back to the front. It includes a plurality of rollers that rotate under the drive of the conveying power device. The rollers are parallel and spaced apart. The blocking mechanism is arranged at the front end of the frame and can be lifted up and down. When the blocking mechanism rises to a position higher than the roller shaft, the plate moves forward until the front end of the plate contacts the blocking mechanism, and then the plate stops moving forward. The detection and analysis mechanism includes an accelerometer and a vibration and dynamic signal acquisition and analysis system. The accelerometer is located above the left or right corner of the front end of the plate. The accelerometer is set on a bracket, and the bracket is set on the frame. The vibration and dynamic signal acquisition and analysis system analyzes and calculates the elastic modulus E of the plate based on the vibration signal collected by the accelerometer. The lifting mechanism is located below the plate and is used to lift the stopped plate so that the plate is out of contact with the roller and the blocking mechanism, and to make the upper surface of the front left or right corner of the plate contact the accelerometer; it includes two support rods that move up and down driven by the lifting power device. When the support rods lift the plate, the two parallel support rods are in line contact with the lower surface of the plate. The distance between the two support rods and the front and rear ends of the plate is 0.224L. The hammer mechanism is located above the plate and has a swinging rubber hammer for striking the center point of the plate lifted by the lifting mechanism.

2. The automatic dynamic elastic modulus detection production line for full-scale wood / bamboo boards according to claim 1, characterized in that: The hammering mechanism includes a shift fork, a hammer handle, a rubber hammer, a mounting plate, a striking motor, a pivot, an electromagnet, a magnet, and a pendulum rod; A rubber hammer is fixed to one end of the hammer handle, and the other end is pivotally mounted on a mounting plate; a shift fork rotates on the mounting plate and is connected to a striking motor that drives it to rotate; an electromagnet is fixed to the mounting plate, and a magnet is mounted on the hammer handle; two ends of a tension spring are respectively connected to the mounting plate and the hammer handle; when the electromagnet is de-energized and the tension spring is in a normal state, the hammer handle rotates around the pivot until the rubber hammer contacts the plate lifted by the lifting mechanism, at which time the electromagnet and the magnet are misaligned; when the electromagnet is energized, the magnet on the hammer handle is attracted by the electromagnet, the magnet and the electromagnet are opposed, and the hammer handle is in a state where the rubber hammer does not contact the plate; the hammer handle is provided with a swing rod extending toward the shift fork; When the electromagnet loses power, the shift fork rotates until it contacts the pendulum rod, and the shift fork continues to rotate. The pendulum rod and the hammer handle rotate in the opposite direction around the pivot to overcome the elastic force of the tension spring 1, and the rubber hammer gradually moves away from the plate. When the shift fork continues to rotate until it disengages from the pendulum rod, the pendulum rod and the hammer handle rotate forward around the pivot under the elastic force of the tension spring 1, and the rubber hammer hits the plate. Then the electromagnet is energized, and the pendulum rod and the hammer handle rotate in the opposite direction around the pivot to overcome the elastic force of the tension spring 1. The magnet on the hammer handle is opposite to the electromagnet, and the rubber hammer leaves the plate.

3. The automatic dynamic elastic modulus detection production line for full-scale wood / bamboo boards according to claim 1, characterized in that: The hammer mechanism also includes a second tension spring, the two ends of which are respectively connected to the mounting plate and the hammer handle. When the electromagnet is de-energized and the second tension spring is in a normal state, the hammer handle rotates around the pivot until the rubber hammer is separated from the plate lifted by the jacking mechanism; but when the electromagnet is de-energized and both the first and second tension springs are in a normal state, the hammer handle rotates around the pivot until the rubber hammer is in contact with the plate lifted by the jacking mechanism.

4. The automatic dynamic elastic modulus detection production line for full-scale wood / bamboo boards according to claim 1, characterized in that: The jacking mechanism includes a support rod, a jacking frame, a guide column, a support leg, and a jacking power device; support rods are arranged above the front and rear parts of the jacking frame, and guide columns are fixed below the front and rear parts of the jacking frame. Each guide column is set on a support leg for sliding up and down; a jacking power device is set between the support leg and the jacking frame to drive the jacking frame up and down.

5. The automatic dynamic elastic modulus detection production line for full-scale wood / bamboo boards according to claim 4, characterized in that: The lifting mechanism also includes a synchronization device, which includes a synchronization shaft, a bearing seat, a synchronization wheel, and meshing teeth. The synchronization shaft rotates simultaneously on the bearing seat located on the front and rear legs, and the front and rear synchronization wheels fixed on the synchronization shaft engage with the meshing teeth on the front and rear guide columns.

6. The automatic dynamic elastic modulus detection production line for full-scale wood / bamboo boards according to claim 5, characterized in that: The guide column is cylindrical, with two rotating upper guide rollers on the upper part of each leg, and a rotating lower guide roller on the upper part of each leg. The two upper guide rollers on the same leg are located on both sides of the guide column axis, and the lower guide roller and synchronous wheel on the same leg are located on both sides of the guide column axis. The busbars of the upper guide roller and the lower guide roller are both arcs in contact with the outer periphery of the guide column.

7. The automatic dynamic elastic modulus detection production line for full-scale wood / bamboo boards according to claim 1 is characterized by: The centering mechanism includes a centering baffle and two front and rear transverse push plate devices; The centering baffle is arranged perpendicularly to the roller shaft on one side of the frame, and the centering baffle is higher than the roller shaft; the horizontal push plate device includes a push plate frame fixed on the other side of the frame, and the guide rod is set on the push plate frame for sliding left and right in a direction parallel to the roller shaft. The push plate is fixed at the end of the guide rod, and the push plate is located between two adjacent roller shafts. The upper end of the push plate is higher than the roller shaft, and the lower end of the push plate is connected to a push plate driving device that drives the push plate to move left and right in a direction parallel to the roller shaft.

8. The automatic dynamic elastic modulus detection production line for full-scale wood / bamboo boards according to claim 1, characterized in that: The accelerometer is connected to the bracket in a floating manner in the vertical direction through a floating connection mechanism; the upper end of the accelerometer is connected to a floating plate, and the floating plate is set on the bracket by sliding up and down through a linear bearing. The core shaft passes through the lower end of the floating plate and a retaining ring is set. The upper end of the core shaft is connected to the bracket. The spring surrounding the core shaft is located between the upper part of the floating plate and the bracket. When the spring is in normal state, the floating plate is in contact with the retaining ring.

9. Method for grading full-size wood / bamboo boards, characterized by: The steps include: a. The plate moves from back to front along the longitudinal direction of the plate under the drive of multiple rotating rollers until the front end of the plate contacts the raised blocking mechanism higher than the rollers, the rollers stop rotating, and the plate stops moving; b. The blocking mechanism drops below the roller axis and does not block the plate from moving forward; c. The lifting mechanism under the plate rises, and the two support rods on the upper part of the lifting mechanism pass through the rollers and move upward, lifting the plate so that the plate is out of contact with the rollers and the blocking mechanism. The upper surface of the front left or right corner of the plate contacts the accelerometer; the two parallel support rods are in line contact with the lower surface of the plate, and the distance from the two support rods to the front and rear ends of the plate is 0.224L; d. The hammer mechanism located above the plate is actuated. The rubber hammer in the hammer mechanism strikes the upper surface of the plate, with the striking point being the center of the plate. During the striking, the vibration and dynamic signal acquisition and analysis system obtains the first-order bending frequency of the plate based on the vibration signal collected by the accelerometer, and calculates the elastic modulus E of the plate according to formula (1). The plates are then graded according to the size of the elastic modulus E. （1） Where ρ is the air-dry density of the board, in kg / m 3 ;f b is the first-order bending frequency, in Hz; L is the length of the plate, in m; h is the thickness of the plate, in m; e. The lifting mechanism descends, the plate loses contact with the accelerometer, the plate falls onto the roller, and the support rod loses contact with the plate; f. The roller rotates, driving the plate forward until the rear end of the plate does not hinder the lifting and lowering of the blocking mechanism in the up and down directions.

10. The method for grading full-size wood / bamboo boards according to claim 9, wherein: After step a and before step b, there are the following steps: a1: Push the plate in the left and right directions to center the plate in the left and right directions.

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