Hammering mechanism for detecting dynamic elastic modulus of wood / bamboo full-scale plate

Abstract

The utility model provides a hammering mechanism for detecting the dynamic elastic modulus of a wood / bamboo full-size plate, which can automatically knock the plate, a rubber hammer can quickly leave the plate after knocking, the knocking force of the rubber hammer can be adjusted, and the hammering mechanism comprises a shifting fork, a hammer handle, the rubber hammer, a mounting plate, a knocking motor, a pivot, an electromagnet, a magnet and a swing rod, one end of the hammer handle fixes the rubber hammer, and the other end is rotatably arranged on the mounting plate through a pivot; the shifting fork rotates on the mounting plate and is connected with the knocking motor; the electromagnet is fixed on the mounting plate, and the magnet is arranged on the hammer handle; the two ends of the first tension spring are connected with the mounting plate and the hammer handle respectively, when the electromagnet loses power and the first tension spring is in a normal state, the hammer handle rotates around the pivot to the state that the rubber hammer makes contact with the plate, and at the moment, the electromagnet and the magnet are staggered. When the electromagnet is electrified, the magnet on the hammer handle is attracted by the electromagnet and is opposite to the electromagnet, and the hammer handle is in a state that the rubber hammer is not in contact with a plate; the hammer handle is provided with a swing rod extending towards the shifting fork.

Description

Technical Field

[0001] This utility model relates to a hammering mechanism, specifically a hammering mechanism for striking full-size wood / bamboo boards used for dynamic elastic modulus testing. Background Technology

[0002] Traditionally, the elastic modulus of sheet metal is tested by suspending the sheet metal freely with an elastic rope. The operator then strikes the specimen at its midpoint or corner with a hammer to obtain the first-order bending frequency of the free sheet and calculate the elastic modulus. This method is complex and difficult to implement quickly and efficiently because the sheet metal is in a free state while suspended on the elastic rope.

[0003] To improve testing efficiency, an automated production line for testing the dynamic modulus of elasticity of full-scale wood / bamboo boards is needed. On this line, the boards are transported to a designated position by rotating conveyor rollers, then lifted, and finally tapped and tested. Traditional manual tapping is highly random, inevitably reducing the accuracy of test results. How to automate the tapping of the boards is a significant challenge. Utility Model Content

[0004] The purpose of this invention is to provide a hammering mechanism for testing the dynamic elastic modulus of full-size wood / bamboo boards. It can automatically strike the board and ensure that the rubber hammer quickly leaves the board after striking it. At the same time, it can adjust the striking force of the rubber hammer.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by this utility model is as follows:

[0006] A hammering mechanism for testing the dynamic elastic modulus of full-scale wood / bamboo boards includes a fork, hammer handle, rubber hammer, mounting plate, striking motor, pivot, electromagnet, magnet, and swing arm.

[0007] One end of the hammer handle is fixed to a rubber mallet, and the other end is pivotally mounted on a mounting plate. A fork rotates on the mounting plate and is connected to a striking motor that drives its rotation. An electromagnet is fixed to the mounting plate, and a magnet is mounted on the hammer handle. Two ends of a tension spring are connected to the mounting plate and the hammer handle, respectively. When the electromagnet is de-energized and the tension spring is in its normal state, the hammer handle rotates around the pivot until the rubber mallet contacts the plate, at which point the electromagnet and the magnet are out of contact. When the electromagnet is energized, the magnet on the hammer handle is attracted to the electromagnet, and the magnet and the electromagnet are opposite each other, so the hammer handle is in a state where the rubber mallet does not contact the plate. The hammer handle has a swing arm extending towards the fork.

[0008] When the electromagnet is de-energized, the fork rotates until it contacts the rocker arm. The fork continues to rotate, and the rocker arm and hammer handle rotate in the opposite direction around the pivot, overcoming the elastic force of the first tension spring. The rubber hammer gradually moves away from the plate. When the fork continues to rotate until it disengages from the rocker arm, the rocker arm and hammer handle rotate in the forward direction around the pivot under the elastic force of the first tension spring. The rubber hammer strikes the plate. Then the electromagnet is energized, and the rocker arm and hammer handle rotate in the opposite direction around the pivot, overcoming the elastic force of the first tension spring. The magnet on the hammer handle is opposite to the electromagnet, and the rubber hammer leaves the plate.

[0009] The aforementioned hammering mechanism for testing the dynamic elastic modulus of full-scale wood / bamboo boards also includes a second tension spring. The two ends of the second tension spring are connected to the mounting plate and the hammer handle, respectively. When the electromagnet is de-energized and the second tension spring is in its normal state, the hammer handle rotates around the pivot until the rubber hammer is separated from the board. However, when the electromagnet is de-energized and both the first and second tension springs are in their normal state, the hammer handle rotates around the pivot until the rubber hammer contacts the board lifted by the lifting mechanism.

[0010] The hammering mechanism described above for testing the dynamic elastic modulus of full-size wood / bamboo boards has the following structure for connecting the tension spring 2 to the mounting plate: a fixing block 2 is set on the mounting plate, and a guide hole 2 is opened on the fixing block 2. The end of the pull rod 2 that passes through the guide hole 2 and is away from the tension spring 2 is threadedly connected to the adjusting nut 2; the end of the pull rod 2 that is close to the tension spring 2 is connected to the tension spring 2, and the tension of the tension spring 2 can be adjusted by rotating the adjusting nut 2.

[0011] The hammering mechanism described above for testing the dynamic elastic modulus of full-size wood / bamboo boards has the following structure for connecting the tension spring to the mounting plate: a fixing block is set on the mounting plate, and a guide hole is opened on the fixing block. The end of the pull rod passing through the guide hole is threaded to the end away from the tension spring. The end of the pull rod close to the tension spring is connected to the tension spring. The tension of the tension spring can be adjusted by rotating the adjusting nut.

[0012] The aforementioned hammering mechanism for testing the dynamic elastic modulus of full-scale wood / bamboo boards has two centrally symmetrical levers in the fork. Each time the fork rotates, the two levers contact the swing arm once.

[0013] The aforementioned hammering mechanism for testing the dynamic elastic modulus of full-size wood / bamboo boards has a horizontal beam connected to vertical beams at both ends. The two vertical beams are fixed on both sides of the frame. The horizontal beam has a T-shaped groove, through which bolts pass and are connected to the mounting plate. When the bolts are loosened, the mounting plate and bolts can move along the T-shaped groove to change the position of the mounting plate in the left-right direction.

[0014] The beneficial effects of this utility model are as follows:

[0015] The fork rotates under the drive of the striking motor, thereby swinging the hammer handle and striking the plate. Because the fork can rotate continuously, it ensures that the rubber hammer can strike the plate repeatedly, thus ensuring the continuity of the operation.

[0016] By using tension spring one and tension spring two to apply torque in different directions (one counterclockwise and one clockwise) to the hammer handle, the elasticity of tension spring one or tension spring two can be changed as needed, making it easier to adjust the rotational torque of the hammer handle and adjust the striking force on the board.

[0017] The matching of the electromagnet and the magnet ensures that after the rubber mallet strikes the board once, the magnet is quickly attracted by the electromagnet, guaranteeing that the rubber mallet strikes the board only once.

[0018] Collect the tension of the second quick-adjusting spring, including the second adjusting nut and the second pull rod; collect the tension of the first quick-adjusting spring, including the first adjusting nut and the first pull rod.

[0019] The mounting plate can be moved on the crossbeam to change the position of the rubber mallet. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a standard free-plate transient excitation method device;

[0021] Figure 2 , Figure 3 This is a schematic diagram of the support position of a triangular pyramid based on the transient excitation method;

[0022] Figure 4 This is the midpoint spectrum diagram of the transient excitation method test of LVL specimen 1 (free plate).

[0023] Figures 5-7 This is the midpoint spectrum diagram of the LVL specimen 1 tested using the automated triangular pyramid support transient excitation method.

[0024] Figure 8 This is the midpoint spectrum diagram of the transient excitation method test of LVL specimen 2 (free plate).

[0025] Figures 9-11 This is the midpoint spectrum diagram of the LVL specimen 2 tested using the automated triangular pyramid support transient excitation method;

[0026] Figure 12 This is the midpoint spectrum diagram of the transient excitation method test of LVL specimen 3 (free plate).

[0027] Figures 13-16 This is the midpoint spectrum diagram of the LVL specimen 3 under the transient excitation method of automated triangular pyramid support;

[0028] Figure 17 , Figure 18 These are, respectively, a 3D view and a front view of an online inspection and quality grading production line for wood / bamboo boards based on transient excitation dynamic testing methods.

[0029] Figure 19 It is a 3D diagram of the production line (with the sheet metal removed).

[0030] Figure 20 This is a schematic diagram of the contact between the sheet metal and the blocking mechanism (part of the frame, some rollers, hammering mechanism, etc. have been removed).

[0031] Figure 21 This is a schematic diagram of the contact between the sheet metal and the blocking mechanism (part of the frame, some rollers, hammering mechanism, sheet metal, etc. have been removed).

[0032] Figure 22 This is a schematic diagram of the plate in the centering state (when the plate is in contact with the centering baffle).

[0033] Figure 23 , Figure 24 , Figure 25 These are three-dimensional images of the impact on the board (part of the frame, rollers, and accelerometers have been removed).

[0034] Figure 26 , Figure 27 These are 3D diagrams of the accelerometer, support frame, etc.

[0035] Figure 28 , Figure 29 Three-dimensional diagram of the hammering mechanism.

[0036] Figure 30 This is a 3D diagram of the push plate, push plate frame, etc.

[0037] Figure 31 This is a 3D view of the blocking mechanism.

[0038] Figure 32 , Figure 33 These are the front view and side view of the hammering mechanism, respectively.

[0039] Figure 34 for Figure 32 BB section view in the middle.

[0040] Figure 35 , Figure 36 These are the front view and side view of the lifting mechanism, respectively.

[0041] Figure 37 for Figure 35 A magnified view of a portion of the image.

[0042] Figure 38 These are 3D diagrams of the lifting mechanism, etc.

[0043] In the picture,

[0044] Frame 100, sheet metal 200

[0045] 1. Sheet material conveying mechanism; 11. Conveying power unit; 12. Roller; 14. Drive chain; 15. Driven chain;

[0046] 2. Blocking mechanism; 21. Blocking frame; 22. Blocking bar; 23. Blocking cylinder;

[0047] Detection and analysis mechanism 3, accelerometer 31, vertical rod 32, longitudinal rod 33, horizontal rod 34, support 35, loosening clamping sleeve one 36, loosening clamping sleeve two 37, linear bearing 38, spindle 39, floating plate 310, retaining ring 311, spring 312;

[0048] 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.

[0049] Hammering mechanism 5; fork 51, hammer handle 52, rubber hammer 53, mounting plate 54, striking motor 55, electromagnet 56, magnet 57, swing arm 58, tension spring 1 59, tension spring 2 510, crossbeam 511, vertical beam 512, pivot 513, auxiliary rod 514, fixing block 1 515, pull rod 1 516, adjusting nut 1 517;

[0050] Centering mechanism 6; centering baffle 61, push plate frame 63, guide rod 64, push plate 65, push plate drive device 66. Detailed Implementation

[0051] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings.

[0052] Comparison of dynamic test values ​​of bending frequency under free suspension and wooden triangular pyramid support for full-scale product specimens

[0053] 1.1 Materials and Instruments

[0054] The test subject in this experiment was LVL product, and the specimen dimensions were 2700mm × 760mm × 27mm (length × width × height), with an air-dry density of 614kg / m³. 3 It has a moisture content of 10% and is produced in Guannan County, Lianyungang, Jiangsu Province.

[0055] The testing instruments used were: one CRAS vibration and dynamic signal acquisition and analysis system, mainly including: 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 one CA-YD-1182 accelerometer with a sensitivity of 10.04 mV / m / s². 2One CA-YD-1182 accelerometer sensor, manufactured by Yangzhou Jufeng Technology Co., Ltd.; one set of freeboard suspension device, several 15mm wide elastic ropes; one rubber hammer; two larch wood triangular pyramids, measuring 1100mm×50mm×30mm, with an air-dry density of 720kg / m³. 3 The moisture content is 12%.

[0056] 1.2 Test Methods and Principles

[0057] 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 strike the midpoint or corner of the specimen to obtain the first-order bending frequency of the free plate. When the plate specimen undergoes lateral vibration, the elastic modulus E and the first-order bending frequency f... b The relationship is shown in equation (1).

[0058] (1)

[0059] In formula (1): ρ is the air-dry density of the specimen, in kg / m³ 3 ;f b denoted as the first-order bending frequency in Hz; L as the specimen length in meters (m); and h as the specimen thickness in meters (m).

[0060] 1.3 Main Test Steps

[0061] (1) On the suspension device, ensure that the positions of the elastic ropes are set at 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), thereby forming a linear vibration system, such as Figure 1 As shown.

[0062] (2) Connect the relevant instruments and install the CA-YD-1182 accelerometer at any corner of the LVL rectangular plate.

[0063] (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, averaging times of 1, FFT length of 1024, acquisition mode of free run, and low-pass filter of 100Hz.

[0064] (4) Switch to the acquisition mode, use a force hammer to excite, fix the acceleration sensor at the right corner, use a rubber hammer to vertically strike the midpoint of the LVL plate, measure the frequency and collect data.

[0065] (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.

[0066] (6) Place the LVL board on the wooden triangular pyramid, ensuring that the position of the triangular pyramid is consistent with the position of the elastic rope.

[0067] Repeat the above steps, changing the striking method to automated striking (using hammer mechanism 5), and measure the first-order bending frequency at the midpoint multiple times. This is used to compare the effects of the free plate and the automated triangular pyramid support on the first-order bending frequency of the specimen, and the differences in the resulting frequency values.

[0068] 1.4 Results and Analysis

[0069] Several LVL specimens were tested using the transient excitation method with a standard free plate and an automated triangular pyramid support. The first-order bending frequency results for three specimens are shown in Tables 1-3.

[0070] Table 1. First-order bending frequency values ​​of specimen 1 (free plate and automated triangular pyramid support) tested by transient excitation method.

[0071]

[0072] The standard first-order bending frequency of LVL specimen 1 measured on the standard free plate was 16.75 Hz. The automated triangular pyramid testing system accurately measured the first-order bending frequency of the plate, closely matching the standard value of 16.75 Hz for the free plate, with generally small errors. Most test results showed errors within the range of +0.78% to +0.79%, demonstrating high stability. Particularly in the automated triangular pyramid support tests 1-6 to 1-10, the results were completely consistent with the standard values, indicating that the automated triangular pyramid testing system could achieve the standard values ​​under these support conditions. However, the error in the automated triangular pyramid support test 1-5 was larger, reaching +1.45%, indicating that the automated system might have fluctuations or errors in individual tests, but the errors were still very small. Overall, for LVL specimen 1, the automated triangular pyramid testing system basically met the requirements for dynamic modulus of elasticity testing and possessed good repeatability and reliability.

[0073] Table 2. First-order bending frequency values ​​of specimen 2 (free plate and automated triangular pyramid support) tested by transient excitation method.

[0074]

[0075] The standard first-order bending frequency of test piece 2 on the standard free plate is 16.50 Hz. The automated triangular pyramid support testing system can accurately measure the first-order bending frequency of the plate, and most test results are very close to the standard value of 16.50 Hz, with generally small errors. The error of most test results is between +0.00% and +1.50%, indicating that the system has high accuracy and stability in most cases. In particular, in the tests of automated triangular pyramid supports 2-1, 2-9, and 2-10, the results are completely consistent with the standard value, showing good repeatability. However, in the tests of automated triangular pyramid supports 2-2, 2-3, and 2-4, the error is +1.50%, while in the tests of automated triangular pyramid supports 2-5, 2-7, and 2-8, the error is -1.50%, and the error range is still small. Overall, the automated triangular pyramid support testing system can provide accurate and stable results when testing the first-order bending frequency of test piece 2, and shows good reliability and consistency.

[0076] Table 3. First-order bending frequency values ​​of specimen 3 (free plate and automated triangular pyramid support) tested by transient excitation method.

[0077]

[0078] The standard first-order bending frequency of LVL specimen 3, measured on the standard free plate, was 16.88 Hz. The automated triangular pyramid support testing system was able to measure the first-order bending frequency of the plate relatively accurately, and most test results were close to the standard value of 16.88 Hz, with generally small errors. The errors of most test results were between -0.78% and +0.00%, demonstrating high stability. Particularly in the tests of automated triangular pyramid supports 3-4 and 3-5, the results were completely consistent with the standard values, indicating that the system could reach the standard values ​​under these test conditions. In the tests of automated triangular pyramid supports 3-7 and 3-8, the error was -1.50%, while in the test of automated triangular pyramid support 3-10, the error was -2.25%. This indicates that in individual tests, the automated triangular pyramid support testing system experienced fluctuations, leading to frequency deviations, but these deviations were small. Overall, when testing the first-order bending frequency of specimen 3, the automated triangular pyramid support testing system produced mostly test results close to the standard value with a small error range, demonstrating good accuracy and reliability.

[0079] Based on the first-order bending frequency results, overall, this automated triangular pyramid testing system still meets the requirements for dynamic elastic modulus testing and exhibits good repeatability and stability. It can accurately achieve online automatic quality inspection and grading of wood / bamboo boards and their composite materials. Figure 2 , 3 As shown.

[0080] 1.5 Spectral Results

[0081] The impact midpoint spectra of full-scale LVL plate specimens 1-3, measured using the transient excitation method under standard free plate and automated triangular pyramid support, can be referenced respectively. Figures 4-7 , Figures 8-11 and Figures 12-16 The image shown is the midpoint spectrum of the first-order bending frequency tested by the transient excitation method of the standard free plate and the automated triangular pyramid support. Other spectrums are not shown for the same values.

[0082] 2. Design and Application of an Automatic Production Line for Dynamic Elastic Modulus Detection and Quality Assessment of Full-Scale Wood / Bamboo Boards

[0083] See Figure 17-19 The production line for automatic detection and quality assessment of dynamic elastic modulus of full-size wood / bamboo boards includes a frame 100, a board 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.

[0084] The sheet material conveying mechanism 1 is mounted on the frame 100 and is used to drive the sheet material 200 to move from back to front. It includes multiple 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 rotatably mounted on the frame 100. Two sprockets are fixed to the left end of each roller 12. One sprocket on the last roller is connected to a drive sprocket fixed to the output shaft of the conveying motor via a drive chain 14. The two sprockets on adjacent rollers are connected by a driven chain 15. The rotation of the conveying motor drives the rollers to rotate via the drive sprocket, drive chain, sprockets, and driven chain. The sheet material conveying mechanism 1 is conventional technology and will not be described in detail further.

[0085] See Figure 31 The blocking mechanism 2 includes a blocking frame 21 extending to the left and right, two blocking bars 22 extending to the 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.

[0086] The blocking frame 21 is slidably mounted on the front end of the machine 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, the plate moves forward until the front end of the plate contacts the blocking bar 22, at which point the plate stops moving forward.

[0087] Testing and analysis organization 3, see Figure 26 , 27It includes four accelerometers 31 and a vibration and dynamic signal acquisition and analysis system. Each accelerometer is located above the four corners of the plate and is mounted on a bracket. The bracket includes a vertical rod 32, a longitudinal rod 33, and a horizontal rod 34. The lower end of the vertical rod is connected to both sides of the frame through a support 35. The vertical rod and longitudinal rod, which are perpendicular to each other, can be released or clamped by the first clamping sleeve 36 when inserted into the shaft hole. The longitudinal rod and horizontal rod, which are perpendicular to each other, can be released or clamped by the second clamping sleeve 37 when inserted into the shaft hole. The end of the horizontal rod is directly or indirectly connected to a linear bearing 38 and a spindle 39. The accelerometer 31 is fixed at its upper end to a floating plate 310, which slides up and down relative to a crossbar via a linear bearing. A mandrel 39 passes through the lower end of the floating plate and is fitted with a retaining ring 311. The upper end of the mandrel is directly or indirectly connected to the crossbar 34. A spring 312 surrounding the mandrel is located between the upper part of the floating plate and the crossbar. Under normal conditions, the spring 312 keeps the floating plate 310 in contact with the retaining ring 311. The vibration and dynamic signal acquisition and analysis system analyzes and calculates the elastic modulus E of the plate based on the acquired vibration signals from the accelerometer.

[0088] See 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 corner of the plate is in contact with the accelerometer.

[0089] The lifting mechanism 4 includes a support rod 41, V-shaped blocks 42, a lifting frame 43, guide columns 44, support legs 45, a lifting power device 46, and a synchronization device 47. The synchronization device 47 includes a synchronization shaft 472, a bearing seat 473, a synchronization wheel 471, and meshing teeth. Multiple V-shaped blocks 42 are installed on the upper front and rear sides of the lifting frame 43. Each support rod 41, with a square cross-section, rests on the V-groove of several V-shaped blocks 42. Each support rod 41 and the V-shaped block 42 below it are located between two adjacent rollers. Four cylindrical guide columns are fixed below the lifting frame, two at the front and two at the rear. The lower end of each guide column extends into the upper part of a hollow square support leg. The two front support legs are fixedly connected by a cross brace, and the two rear support legs are fixedly connected by another cross brace. The lifting power device 46 consists of two lifting cylinders, one at the front and one at the rear. The cylinder body of the lifting cylinder is fixed to the cross brace, and the piston rod is connected to the lifting frame 43.

[0090] The guide post 44 has meshing teeth forming a rack, which meshes with the synchronous pulley 471. The front synchronous pulley and the rear synchronous pulley are fixed together on the synchronous shaft 472, and the front and rear ends of the synchronous shaft 472 are rotatably mounted on the bearing seats 473 fixed on the front and rear support legs.

[0091] Each support leg 45 has two upper guide rollers 48 mounted on its upper two sides via bearings, rotating around their own axis. The two upper guide rollers 48 on the same support leg are located on both sides of the axis of the guide column 44. Each support leg has a lower guide roller 49 mounted on its lower side via bearings, rotating around its own axis. The lower guide roller 49 and the synchronous pulley 471 on the same support leg are located on both sides of the axis of the guide column 44. The generatrices of the upper guide rollers 48 and lower guide rollers 49 are arcs that contact the outer periphery of the guide column. Of course, slots are opened on the sides of the support legs at positions corresponding to the upper guide rollers 48, lower guide rollers 49, and synchronous pulleys 471, so that the upper guide rollers 48, lower guide rollers 49, and synchronous pulleys 471 pass through the slots and engage with the guide column inside the support leg.

[0092] See Figure 28 , 29 The hammering mechanism 5 includes a 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 swing arm 58, a tension spring 1 59, a tension spring 2 510, a crossbeam 511, and a vertical beam 512.

[0093] The two ends of the crossbeam 511 are connected to the vertical beams 512, and the two vertical beams 512 are fixed to both sides of the frame. T-shaped grooves are cut into the crossbeams, and bolts pass through these grooves to connect to the mounting plate. When the bolts are loosened, the mounting plate and bolts can move along the T-shaped grooves to change the left-right position of the mounting plate.

[0094] One end of the hammer handle 52 is fixed to the rubber hammer 53, and the other end is rotatably mounted on the mounting plate 54 via a pivot 513. The fork 51 rotates on the mounting plate and is connected to the striking motor 55 that drives its rotation. The housing of the striking motor 55 is fixed on the mounting plate 54. The electromagnet 56 is fixed on the mounting plate 54, and the magnet is located on the hammer handle 52 or an auxiliary rod 514 fixed integrally with the hammer handle. The two ends of the tension spring 59 are connected to the mounting plate 54 and the hammer handle 52 respectively, and the two ends of the tension spring 510 are connected to the mounting plate 54 and the hammer handle 52 respectively. The tension spring 59 causes the hammer handle to rotate counterclockwise around the pivot, and the tension spring 510 causes the hammer handle to rotate clockwise around the pivot.

[0095] The structure connecting tension spring 59 to mounting plate 54 is as follows: a fixing block 515 is provided on the mounting plate, and a guide hole is opened on the fixing block 515. The end of the pull rod 516 passing through the guide hole is threadedly connected to the end away from tension spring 59, and the end of the pull rod 516 near tension spring 59 is connected to tension spring 1. The tension of tension spring 59 can be adjusted by rotating the adjusting nut 517 relative to the pull rod 516. The structure connecting tension spring 510 to mounting plate 54 is the same and will not be described further.

[0096] When electromagnet 56 is de-energized and tension springs 59 and 510 are in normal condition, hammer handle 52 rotates counterclockwise around the pivot until rubber hammer 53 contacts the plate being lifted by the lifting mechanism. At this time, electromagnet 56 and magnet are out of contact. When electromagnet 56 is energized, the magnet on hammer handle 52 is attracted by electromagnet 56, hammer handle rotates clockwise, magnet and electromagnet 56 are opposite each other, and hammer handle 52 is in a state where rubber hammer 53 is not in contact with the plate. Hammer handle 52 has a swing rod 58 extending towards shift fork 51.

[0097] When electromagnet 56 is de-energized, fork 51 rotates until it contacts rocker arm 58. Fork 51 continues to rotate, and with the assistance of tension spring 510, rocker arm 58 and hammer handle 52 rotate clockwise around the pivot, overcoming the elastic force of tension spring 59. Rubber hammer 53 gradually moves away from the plate. When fork 51 continues to rotate until it disengages from rocker arm 58, rocker arm 58 and hammer handle 52 rotate counterclockwise around the pivot, overcoming the elastic force of tension spring 510 and under the elastic force of tension spring 59. Rubber hammer 53 strikes the plate. Then electromagnet 56 is energized, and rocker arm 58 and hammer handle 52 rotate clockwise around the pivot, overcoming the elastic force of tension spring 59 and with the assistance of tension spring 510. The magnet on hammer handle 52 is opposite to electromagnet 56, and rubber hammer 53 leaves the plate.

[0098] See Figure 24 , 30 The centering mechanism 6 includes a centering baffle 61 and two transverse pusher devices. The centering baffle 61 is perpendicular to the roller shaft and positioned on the left side of the frame, higher than the roller shaft and covering the sprocket on the roller shaft. The transverse pusher devices include a pusher frame 63 fixed to the right side of the frame, a guide rod 64 sliding left and right on the pusher frame 63 in a direction parallel to the roller shaft, and a pusher 65 extending upwards fixed to the right end of the guide rod 64. The pusher 65 is located between two adjacent roller shafts, with its upper end extending above the roller shaft and facing the centering baffle 61. The lower end of the pusher is connected to a pusher drive device 66 that drives the pusher to move left and right in a direction parallel to the roller shaft. The pusher drive device 66 is a pusher cylinder, with its cylinder barrel fixed to the pusher frame 63 and its piston rod connected to the pusher 65. The maximum transverse distance between the centering baffle 61 and the pusher 65 is greater than the width of the sheet metal.

[0099] The online inspection and quality classification method for wood / bamboo boards based on transient excitation dynamic testing includes the following steps:

[0100] a. When the conveying power device 11, i.e., the conveying motor, is started, the roller shaft rotates, and the plate 200 moves from back to front along the longitudinal direction of the plate under the drive of multiple rotating roller shafts until the front end of the plate contacts the blocking bar in the blocking mechanism higher than the roller shaft; the push plate drive device 66, i.e., the push plate cylinder, is activated, driving the push plate to move to the left, pushing the plate 200 to contact the centering baffle 61; when the conveying motor stops, the roller shaft stops rotating, and the push plate cylinder drives the push plate to move to the rightmost right side;

[0101] b. The blocking cylinder 23 drives the blocking frame to descend. The blocking bar and blocking frame descend to below the roller shaft and will not block the plate from moving forward.

[0102] 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 leg 45. The two support rods pass through the roller shaft and move upward, lifting the plate so that the plate is separated from the roller shaft. 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 from the two support rods to the front and rear ends of the plate is 0.224L.

[0103] d. When the electromagnet 56 is de-energized, the striking motor 55 drives the fork 51 to rotate until the fork 51 and the swing arm 58 begin to contact. The 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 fork 51 continues to rotate until the fork 51 disengages from the swing arm 58, the hammer handle 52 overcomes the elastic force of the second tension spring 510 and rotates counterclockwise around the pivot under the elastic force of the first tension spring 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 detached from the plate. During 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 of the accelerometer and calculates the elastic modulus E of the plate according to formula (1).

[0104] (1)

[0105] Where ρ is the air-dry density of the board, in kg / m³. 3 It can be measured in advance; f b is the first-order bending frequency, in Hz; L is the length of the sheet material, in meters; h is the thickness of the sheet material, in meters.

[0106] Then, the sheets are graded according to their elastic modulus E. For example, sheets with E > 2200 MPa are grade one, sheets with 1900 MPa < E < 2200 MPa are grade two, and sheets with E < 1900 MPa are grade three. Grading sheets based on their elastic modulus E is existing technology.

[0107] e. The lifting power device 46, i.e. the lifting cylinder, is activated, which drives the lifting frame 43, support rod 41, plate 200, etc. to descend. The plate loses contact with the accelerometer, the plate 200 falls onto the roller 12, the support rod loses contact with the plate, and the plate is removed.

[0108] f. The roller rotates, causing the plate 200 to move forward until the rear end of the plate no longer obstructs the lifting and lowering of the blocking mechanism in the vertical direction.

[0109] Compared to testing the first-order bending frequency of a board using a free-suspension method (where the distance from the rear suspension rope to the rear end of the board is 0.224L and the distance from the front suspension rope to the front end of the board is 0.224L), this invention supports the board from below using two support rods (where the distance from the rear support rod to the rear end of the board is 0.224L and the distance from the front support rod to the front end of the board is 0.224L). When the center point of the board is struck, the first-order bending frequency of the board measured based on the vibration at the corner of the board has the smallest deviation, thus obtaining an accurate elastic modulus E, thereby laying the foundation for the quality grading of the board.

[0110] The online inspection and quality grading production line realizes automated assembly line operation of sheet material conveying, positioning, lifting, tapping, inspection, and grading, which is highly efficient and fast.

[0111] In the hammering mechanism, the shift fork rotates under the drive of the striking motor, thereby realizing the swing of the hammer handle and striking the plate. Because the shift fork can rotate continuously, it ensures that the rubber hammer can strike the plate repeatedly, thus ensuring the continuity of the operation.

[0112] By using tension spring one and tension spring two to apply torque in different directions (one counterclockwise and one clockwise) to the hammer handle, the elastic force of tension spring one or tension spring two can be changed as needed, making it easier to adjust the rotational torque of the hammer handle.

[0113] The matching of the electromagnet and the magnet ensures that after the rubber mallet strikes the board once, the magnet is quickly attracted by the electromagnet, guaranteeing that the rubber mallet strikes the board only once.

[0114] The lifting mechanism employs a synchronization device to ensure that the lifting height of the two support rods is consistent, thus ensuring the levelness of the plate and guaranteeing the accuracy of the test.

[0115] The generatrix of the guide rollers (upper guide roller and lower guide roller) is an arc that contacts the outer circumference of the cylindrical guide column, which reduces the frictional resistance between the guide roller 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, which ensures the direction of the up and down movement of the guide column, and at the same time, the synchronous lifting and lowering of each guide column. The structure is simple and ingenious.

[0116] To facilitate automatic alignment of the sheet metal, a transverse pusher is used to push the sheet metal into contact with the alignment baffle.

[0117] The accelerometer is floatingly connected to the bracket in the vertical direction via a floating connection mechanism, ensuring good contact between the accelerometer and the plate and the accuracy of the test.

[0118] The scope of protection of this utility model includes, but is not limited to, the above embodiments. The scope of protection of this utility model is defined by the claims. Any substitutions, modifications, or improvements to this technology that are easily conceived by those skilled in the art shall fall within the scope of protection of this utility model.

Claims

1. A hammering mechanism for testing the dynamic elastic modulus of full-scale wood / bamboo boards, characterized by: Includes a shift fork, hammer handle, rubber hammer, mounting plate, striking motor, pivot, electromagnet, magnet, and swing arm; One end of the hammer handle is fixed to a rubber mallet, and the other end is pivotally mounted on a mounting plate. A fork rotates on the mounting plate and is connected to a striking motor that drives its rotation. An electromagnet is fixed to the mounting plate, and a magnet is mounted on the hammer handle. Two ends of a tension spring are connected to the mounting plate and the hammer handle, respectively. When the electromagnet is de-energized and the tension spring is in its normal state, the hammer handle rotates around the pivot until the rubber mallet contacts the plate, at which point the electromagnet and the magnet are out of contact. When the electromagnet is energized, the magnet on the hammer handle is attracted to the electromagnet, and the magnet and the electromagnet are opposite each other, so the hammer handle is in a state where the rubber mallet does not contact the plate. The hammer handle has a swing arm extending towards the fork. When the electromagnet is de-energized, the fork rotates until it contacts the rocker arm. The fork continues to rotate, and the rocker arm and hammer handle rotate in the opposite direction around the pivot, overcoming the elastic force of the first tension spring. The rubber hammer gradually moves away from the plate. When the fork continues to rotate until it disengages from the rocker arm, the rocker arm and hammer handle rotate in the forward direction around the pivot under the elastic force of the first tension spring. The rubber hammer strikes the plate. Then the electromagnet is energized, and the rocker arm and hammer handle rotate in the opposite direction around the pivot, overcoming the elastic force of the first tension spring. The magnet on the hammer handle is opposite to the electromagnet, and the rubber hammer leaves the plate.

2. The hammering mechanism for testing the dynamic elastic modulus of full-scale wood / bamboo boards as described in claim 1, characterized in that: The hammering mechanism also includes a second tension spring, the two ends of which are connected to the mounting plate and the hammer handle, respectively. When the electromagnet is de-energized and the second tension spring is in its normal state, the hammer handle rotates around the pivot until the rubber hammer is separated from the plate. However, when the electromagnet is de-energized and both the first and second tension springs are in their normal state, the hammer handle rotates around the pivot until the rubber hammer contacts the plate lifted by the lifting mechanism.

3. The hammering mechanism for testing the dynamic elastic modulus of full-scale wood / bamboo boards as described in claim 2, characterized in that: The structure connecting the tension spring 2 to the mounting plate is as follows: a fixing block 2 is set on the mounting plate, and a guide hole 2 is opened on the fixing block 2. The end of the pull rod 2 that passes through the guide hole 2 and is away from the tension spring 2 is threadedly connected to the adjusting nut 2; the end of the pull rod 2 that is close to the tension spring 2 is connected to the tension spring 2. The tension of the tension spring 2 can be adjusted by rotating the adjusting nut 2.

4. The hammering mechanism for testing the dynamic elastic modulus of full-scale wood / bamboo boards as described in claim 1, characterized in that: The structure connecting the tension spring 1 to the mounting plate is as follows: a fixing block 1 is set on the mounting plate, a guide hole 1 is opened on the fixing block 1, and the end of the pull rod 1 that passes through the guide hole 1 and is away from the tension spring 1 is threadedly connected to the adjusting nut 1; the end of the pull rod 1 that is close to the tension spring 1 is connected to the tension spring 1, and the tension of the tension spring 1 can be adjusted by rotating the adjusting nut 1.

5. The hammering mechanism for testing the dynamic elastic modulus of full-scale wood / bamboo boards as described in claim 1, characterized in that: The shift fork has two centrally symmetrical levers. Each time the shift fork rotates, the two levers contact the swing arm once.

6. The hammering mechanism for testing the dynamic elastic modulus of full-scale wood / bamboo boards as described in claim 1, characterized in that: The two ends of the crossbeam are connected to the vertical beams, and the two vertical beams are fixed on both sides of the frame. The crossbeam has a T-shaped groove, and the bolts pass through the T-shaped groove to connect with the mounting plate. When the bolts are loosened, the mounting plate and bolts can move along the T-shaped groove to change the position of the mounting plate in the left and right directions.

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