Corrugated carton strength testing device and method

Abstract

The invention discloses a corrugated carton strength testing device and method, and relates to the technical field of strength testing, the corrugated carton strength testing device comprises an operation table, and a panel is fixedly arranged on the upper surface of the operation table. Through the arrangement of the operation table and the panel, a stable and horizontal working plane and a supporting foundation are provided for the whole testing device, the operation table serves as a rigid base to ensure that shaking is not generated in the testing process, and the panel provides a carton placing plane and a mounting and guiding reference of key moving parts; the testing mechanism is used for applying extrusion force to the interior of the corrugated carton, and the testing mechanism is fixedly arranged on the lower surface of the panel. A testing mechanism is arranged, is a power core and a data acquisition unit of the whole device and is responsible for generating controllable and measurable linear thrust and simulating lateral extrusion load borne by a carton in the storage stacking or transportation process, and an integrated detector is the key for achieving quantitative strength evaluation; and the effects of applying pressure to the interior of the corrugated carton and testing the strength are achieved.

Description

Technical Field

[0001] This invention relates to the field of strength testing technology, specifically to a device and method for testing the strength of corrugated cardboard boxes. Background Technology

[0002] Corrugated cardboard boxes are rectangular packaging containers made primarily of corrugated cardboard through processes such as die-cutting, creasing, stapling, or gluing. As one of the most basic packaging forms in modern logistics and commodity storage and transportation, its core structure consists of at least one layer of corrugated core paper sandwiched between two layers of flat cardboard. This unique design gives it excellent compression resistance, cushioning, and shockproof performance. Depending on the corrugated flute type (such as A, B, C, E, F, etc.), the rigidity, bursting strength, and planar compressive strength of the boxes vary, making them widely adaptable to the packaging needs of various goods, from lightweight electronic products to heavy industrial parts. Standard corrugated cardboard boxes have significant advantages such as light weight, high strength, ease of processing and forming, low cost, and recyclability, aligning with green environmental protection principles. Furthermore, their excellent printability facilitates the clear display of brand logos and product information.

[0003] In strength testing of corrugated boxes, standard compression testers typically apply uniform vertical pressure to the top or bottom of the box. While this measures overall compressive strength, it fails to assess the box's true load-bearing capacity when there are protruding products, irregular contents, or localized structural weaknesses. For example, when the hard corners or edges of items inside the box exert concentrated stress on a point on the box wall, the overall compression data cannot reflect the risk of early collapse in that area. The lack of ability to apply pressure at specific internal points means that the box's tolerance to non-uniform internal stress cannot be scientifically quantified, affecting the accurate assessment of the safety margin of packaging solutions and potentially leading to over-packaging or insufficient protection. Summary of the Invention

[0004] To achieve the above objectives, the present invention provides the following technical solution: a corrugated cardboard box strength testing device, comprising an operating table, wherein a panel is fixedly mounted on the upper surface of the operating table. By setting the operating table and the panel, a stable and level working plane and supporting foundation are provided for the entire testing device. The operating table, as a rigid base, ensures that no shaking occurs during the testing process, while the panel provides a plane for placing the cardboard box and a reference for the installation and guidance of key moving parts. The testing mechanism, which applies compressive force to the inside of the corrugated cardboard box, is fixed to the lower surface of the panel. This testing mechanism serves as the power core and data acquisition unit of the entire device, responsible for generating controllable and measurable linear thrust to simulate the lateral compressive load experienced by the cardboard box during storage, stacking, or transportation. Its integrated testing instrument is crucial for achieving quantitative strength evaluation. An adjustment mechanism, used to adjust the contact force with the inner walls of corrugated cardboard boxes of different sizes, is fixed to the upper surface of the testing mechanism. This adjustment mechanism is the core component enabling the test head to adaptively align and pre-contact corrugated cardboard boxes of different sizes. It can automatically adjust the horizontal position of the force application point according to the internal dimensions of the cardboard box, ensuring that the pressure is applied to the predetermined area, thus guaranteeing the consistency and comparability of the tests. The positioning mechanism is used to position the corrugated cardboard box to be tested. This positioning mechanism is a key component to ensure that the cardboard box remains in a fixed position during testing, preventing slippage or tilting. It constrains the cardboard box from the inside, providing stable support for precise force application. The testing mechanism includes a connecting frame fixed to the lower surface of the panel. A hydraulic cylinder is fixed to the lower surface of the connecting frame. The hydraulic cylinder integrates a detector for recording pressure data. A moving rod is provided at the output end of the hydraulic cylinder. A sliding frame is welded to the end of the moving rod away from the hydraulic cylinder. A track groove runs through the upper surface of the panel. The sliding frame is slidably connected to the lower surface of the track groove. A sliding tube is fixed to the end of the sliding frame. A piston rod is slidably connected to the inner cavity of the sliding tube. A connecting frame is welded to the top of the piston rod.

[0005] Preferably, there are two testing mechanisms, and the two testing mechanisms are symmetrically arranged on both sides of the lower surface of the panel. The sliding tube is slidably connected to the inner cavity of the track groove. The outer surface of the sliding tube is provided with two rings, and the two rings on the outer surface of the sliding tube are respectively frictionally adapted to the upper and lower surfaces of the track groove.

[0006] Preferably, a tee pipe is welded to the opening on the lower surface of the sliding tube, a control valve is welded to the end of the tee pipe, a telescopic pipe is fixed to the end of the control valve away from the tee pipe, a connecting pipe is fixed to the end of the telescopic pipe away from the control valve, the connecting pipe penetrates the inner wall of the operating table, and the end of the connecting pipe away from the telescopic pipe is connected to the air outlet of the external compressor.

[0007] Preferably, the adjustment mechanism includes a first fixed ring and a second fixed ring, which are respectively welded to the upper surfaces of the two connecting frames. A stepper motor is fixed in the inner cavity of the first fixed ring, and a rotating rod is mounted on the output end of the stepper motor through a coupling. A first rolling bearing is fixed at the end of the rotating rod, and the outer ring of the first rolling bearing is fixed in the inner wall of the second fixed ring.

[0008] Preferably, a first gear is fixed on the outer surface of the rotating rod, the positioning mechanism includes a support frame, the number of the support frames is two, and the two support frames are respectively welded to the upper surfaces of the first fixed ring and the second fixed ring. A second rolling bearing is fixed in the inner cavity of the support frame, a rotating cylinder is fixed in the inner ring of the second rolling bearing, and a second gear is fixed on the outer surface of the rotating cylinder. The second gear meshes with the first gear.

[0009] Preferably, a lead screw is threaded into the inner cavity of the rotating cylinder. The rotating cylinder is a double-cavity helical pipe joint, comprising a tubular body and a helical groove structure. The tubular body is a circular tube structure, and its interior is divided axially to form two independent chambers. The axes of the two chambers are parallel and both are parallel to the axis of the tubular body. Each chamber has a continuous helical groove structure on its inner wall. The pitch and cross-sectional shape of the helical groove structure match the external thread of the lead screw.

[0010] Preferably, a limiting rod is welded to the inner wall of the rotating cylindrical body, and the lead screw is a tubular structure with external threads on its outer surface, and the lead screw is slidably connected to the outer surface of the limiting rod.

[0011] Preferably, a connecting post is welded to the end of the lead screw, and a fixing frame is welded to the end of the connecting post away from the lead screw. A sliding plate is riveted to the upper surface of the fixing frame, and a sliding groove is formed on the upper surface of the sliding plate. A limiting ball is welded to the upper surface of the support frame, and the limiting ball is slidably connected to the sliding groove formed on the upper surface of the sliding plate.

[0012] Preferably, the upper surface of the fixed frame is fixed with a corner positioning member, which is integrally molded from rubber material and includes an L-shaped main body and a connecting part. The L-shaped main body of the corner positioning member has a right-angle bent plate structure and several anti-slip grooves on its outer surface. It has a first contact surface and a second contact surface that are perpendicular to each other for contacting the corners of the inner wall of the corrugated cardboard box. The connecting part is located at one end of the L-shaped main body and includes an extension section integral with the main body. The extension section is provided with a positioning groove for cooperating with the cardboard box.

[0013] A method for testing the strength of corrugated cardboard boxes includes the following steps: Step 1: Place the corrugated carton to be tested with its opening facing down on the control panel, positioning it roughly in the center of the device. Start the stepper motor of the adjustment mechanism to drive the rotating rod and the first gear to rotate, which in turn drives the second gear and the rotating cylinder to rotate synchronously. The spiral groove structure inside the rotating cylinder engages with the external thread on the lead screw, pushing the lead screw, connecting column, and fixed frame to extend horizontally outward along the direction perpendicular to the movement of the testing mechanism. The corner positioning parts on the upper surface of the fixed frame move accordingly until their two vertical mating surfaces are in close contact and fit against the corresponding corners of the inner wall of the corrugated carton. Step 2: Activate the two symmetrically arranged test mechanisms. The hydraulic cylinders work to push the moving rod and sliding frame to slide along the track groove on the panel. This drives the sliding tube and the piston rod, connecting frame, and adjustment mechanism to move horizontally towards the center of the carton. During this process, the corner positioning parts that have been unfolded on the adjustment mechanism enter the interior space of the carton together until the fixed frames on both sides and the corner positioning parts move to the predetermined test starting position, which is ready to apply pressure to the opposite side walls of the carton. Step 3: While maintaining the clamping state of the carton by the positioning mechanism, the testing mechanism continues to work, and the hydraulic cylinder continuously outputs thrust. This thrust is transmitted to the sliding tube through the moving rod and sliding frame, pushing the piston rod to move further inside the sliding tube. Thus, the pressure is finally transmitted to the positioned fixed frame and corner positioning parts through the connecting frame. The corner positioning parts convert the concentrated force into a uniform squeezing force on specific corner areas of the inner wall of the corrugated carton. The detector integrated in the hydraulic cylinder monitors and records the applied pressure data in real time. Step 4: After the test is completed, the hydraulic cylinder is depressurized and the moving rod is retracted, driving the entire test assembly to exit from the inside of the carton to the initial position. Subsequently, the stepper motor of the adjustment mechanism rotates in reverse, driving the lead screw to retract, causing the corner positioning parts to disengage from the inner wall of the carton. The corrugated carton under test is removed. Based on the pressure-time or pressure-displacement data recorded by the tester, combined with the deformation or damage of the carton after the test, the compressive strength, structural stability and maximum pressure bearing capacity of the corrugated carton are analyzed and evaluated to complete the test.

[0014] This invention provides a device and method for testing the strength of corrugated cardboard boxes. It has the following beneficial effects: I. The corrugated cardboard box strength testing device and method, by setting up a testing mechanism, is the power core and data acquisition unit of the entire device. It is responsible for generating controllable and measurable linear thrust to simulate the lateral compression load on the cardboard box during storage, stacking or transportation. Its integrated testing instrument is the key to realizing quantitative evaluation of strength.

[0015] II. The corrugated cardboard box strength testing device and method, through the setting of an adjustment mechanism, is the core of realizing the adaptive alignment and pre-contact of the test head with corrugated cardboard boxes of different sizes. It can automatically adjust the horizontal position of the force application point according to the internal size of the cardboard box to ensure that the pressure is applied to the predetermined area, thus ensuring the consistency and comparability of the test.

[0016] III. The corrugated cardboard box strength testing device and method, by setting up a positioning mechanism, is a key component to ensure that the cardboard box under test remains in a fixed position during the test and does not slip or tilt. It constrains the cardboard box from the inside and establishes a stable support for precise force application.

[0017] IV. The corrugated cardboard box strength testing device and method, by setting up a connecting frame, hydraulic cylinder, moving rod, sliding frame, track groove, sliding tube, piston rod and connecting frame, together constitute a rigid force transmission and precision guidance system of the testing mechanism. The connecting frame fixes the hydraulic cylinder, which serves as the power source and provides pressure feedback. The moving rod and sliding frame transmit the thrust and guide it precisely along the track groove. The sliding tube and piston rod form a sliding connection pair, allowing the upper adjustment and positioning mechanism to adjust within a certain range or provide buffering. The connecting frame is the interface for connecting with the upper adjustment mechanism.

[0018] V. This corrugated cardboard box strength testing device and method, through a detailed description of the unique structure of the rotating cylinder as a double-cavity helical tube joint, reveals the precision mechanical principle behind its synchronous drive of the two lead screws. Its internal two axially separated chambers allow for the parallel placement of two lead screws. The helical groove structure on the inner wall of each chamber precisely matches the external thread of the corresponding lead screw. When the rotating cylinder rotates, the two helical groove structures act like two internal threads, simultaneously driving the two lead screws in linear motion. This integrated double-cavity design fundamentally ensures the absolute synchronicity and identical displacement of the two lead screw movements, avoiding the asynchronous errors that may occur when using two independent motors, and is a key innovation for achieving high-precision symmetrical adjustment. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the external structure of a corrugated cardboard box strength testing device according to the present invention; Figure 2 This is a front view of the structure of a corrugated cardboard box strength testing device according to the present invention; Figure 3 This is a schematic diagram of the testing mechanism structure of the present invention; Figure 4 This is a partial structural diagram of the testing mechanism of the present invention; Figure 5 This is a partial cross-sectional structural diagram of the testing mechanism of the present invention; Figure 6 This is a schematic diagram of the adjustment mechanism structure of the present invention; Figure 7 This is a partial structural diagram of the adjustment mechanism of the present invention; Figure 8 This is a schematic cross-sectional view of the positioning mechanism of the present invention; Figure 9 This is a partial structural diagram of the positioning mechanism of the present invention.

[0020] In the diagram: 1. Control panel; 2. Control panel; 3. Track groove; 4. Testing mechanism; 41. Connecting frame; 42. Hydraulic cylinder; 43. Moving rod; 44. Sliding frame; 45. Sliding tube; 46. Connecting tube; 47. Control valve; 48. Telescopic tube; 49. Connecting tube; 410. Piston rod; 411. Connecting frame; 5. Adjustment mechanism; 51. First fixed ring; 52. Second fixed ring; 53. Stepper motor; 54. Rotating rod; 55. First gear; 56. Second rolling bearing; 57. Second gear; 6. Positioning mechanism; 61. Support frame; 62. Second rolling bearing; 63. Limiting ball; 64. Rotating cylinder; 65. Spiral groove structure; 66. Limiting rod; 67. Lead screw; 68. Connecting column; 69. Fixing frame; 610. Sliding plate; 611. Sliding groove; 612. Corner positioning component. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and design various embodiments with various modifications suitable for a particular purpose.

[0022] like Figures 1-9 As shown, the present invention provides a technical solution: a corrugated cardboard box strength testing device, including an operating table 1, with a panel 2 fixed on the upper surface of the operating table 1. By setting the operating table 1 and the panel 2, a stable and horizontal working plane and supporting foundation are provided for the entire testing device. The operating table 1 serves as a rigid base to ensure that no shaking occurs during the test, while the panel 2 provides a cardboard box placement plane and a reference for the installation and guidance of key moving parts. The testing mechanism 4 is used to apply compressive force to the inside of the corrugated cardboard box. The testing mechanism 4 is fixed to the lower surface of the panel 2. By setting up the testing mechanism 4, it is the power core and data acquisition unit of the entire device. It is responsible for generating controllable and measurable linear thrust to simulate the lateral compressive load on the cardboard box during storage, stacking or transportation. Its integrated pressure sensor is the key to realizing quantitative evaluation of strength. Adjustment mechanism 5 is used to adjust the contact force with the inner wall of corrugated boxes of different sizes. Adjustment mechanism 5 is fixed on the upper surface of testing mechanism 4. The adjustment mechanism 5 is the core of realizing the adaptive alignment and pre-contact of the test head's force application point with corrugated boxes of different sizes. It can automatically adjust the horizontal position of the force application point according to the internal size of the box to ensure that the pressure is applied to the predetermined area, such as the corner or the center of the side panel, thus ensuring the consistency and comparability of the test. Positioning mechanism 6 is used to position the corrugated cardboard box to be tested. The positioning mechanism 6 is a key component to ensure that the cardboard box remains in a fixed position during testing, without slipping or tilting. It constrains the cardboard box from the inside, providing stable support for precise force application. The testing mechanism 4 includes a connecting frame 41, which is fixed to the lower surface of the panel 2. A hydraulic cylinder 42 is fixed to the lower surface of the connecting frame 41. The hydraulic cylinder 42 integrates a detector for recording pressure data. The core of this detector is a high-precision strain gauge pressure sensor. This sensor is deeply integrated with the hydraulic system and records data in the following ways: Sensing principle and integration: The sensor uses a piston-type sensing head with precision resistance strain gauges attached to its surface, forming a Wheatstone bridge. This sensing head is directly coupled to the piston working chamber or output oil circuit of the hydraulic cylinder 42, sensing the continuous change in oil pressure inside the cylinder in real time when thrust is applied. Pressure acts on the sensing head, causing the strain gauge to deform and resulting in a change in resistance. The bridge outputs a weak voltage signal proportional to the pressure. Signal processing and digitization: The detector has a built-in signal conditioning circuit (including an amplifier, filter, and temperature compensator) to amplify, reduce noise, and correct temperature drift in the millivolt-level analog signal output by the sensor. The conditioned signal is converted into a digital signal by a high-resolution analog-to-digital converter (ADC). An embedded microprocessor (MCU) receives the digital signal and converts it into an engineering pressure value based on the sensor's calibration parameters. Data recording and output: The MCU stores the real-time pressure value along with a timestamp in an integrated non-volatile memory (such as FLASH), achieving complete recording of the pressure-time curve during the test. The testing instrument is typically equipped with a standard industrial communication interface (such as RS-485, USB, or Ethernet) to upload the recorded pressure data to a host computer control system or data analysis software during or after the test for generating reports, plotting curves, and determining the carton's compression resistance. A moving rod 43 is provided at the output end of the hydraulic cylinder 42. A sliding frame 44 is welded to the end of the moving rod 43 away from the hydraulic cylinder 42. A track groove 3 runs through the upper surface of the panel 2. The sliding frame 44 is slidably connected to the lower surface of the track groove 3. A sliding tube 45 is fixed to the end of the sliding frame 44. A piston rod 410 is tightly slidably connected to the inner cavity of the sliding tube 45. A connecting frame 411 is welded to the top of the piston rod 410. By setting up a connecting frame 41, a hydraulic cylinder 42, a moving rod 43, a sliding frame 44, a track groove 3, a sliding tube 45, a piston rod 410, and a connecting frame 411, a rigid force transmission and precision guidance system for the testing mechanism 4 is formed. The connecting frame 41 fixes the hydraulic cylinder 42, which serves as a power source and provides pressure feedback. The moving rod 43 and the sliding frame 44 transmit the thrust and guide it precisely along the track groove 3. The sliding tube 45 and the piston rod 410 form a sliding connection pair, allowing the upper adjustment and positioning mechanism 6 to adjust within a certain range or provide buffering. The connecting frame 411 is the interface for connecting with the upper adjustment mechanism 5.

[0023] Two testing mechanisms 4 are symmetrically arranged on both sides of the lower surface of panel 2. A sliding tube 45 is slidably connected to the inner cavity of the track groove 3. Two rings are provided on the outer surface of the sliding tube 45, and these two rings are respectively frictionally adapted to the upper and lower surfaces of the track groove 3. By setting two testing mechanisms 4 and symmetrically arranging them, the typical working condition of simultaneous pressure on both sides of a carton during actual stacking is simulated, which can more realistically reflect the compressive strength of the carton and allows for parallel comparative testing. By clarifying the sliding connection method of the sliding tube 45 in the inner cavity of the track groove 3 and the frictional adaptation of its two outer rings with the upper and lower surfaces of the track groove 3, a high-precision linear motion constraint and anti-tipping structure for the sliding tube 45 is formed. The two rings form an upper and lower clamp, ensuring that the sliding tube 45 can still move smoothly along a straight line when subjected to huge thrust, without vertical jumping or radial swaying, greatly improving the accuracy of the force direction and ensuring the reliability of the test data.

[0024] A three-way pipe 46 is welded to the opening on the lower surface of the sliding tube 45. A control valve 47 is welded to the end of the three-way pipe 46. A telescopic pipe 48 is fixed to the end of the control valve 47 away from the three-way pipe 46. A connecting pipe 49 is fixed to the end of the telescopic pipe 48 away from the control valve 47. The connecting pipe 49 penetrates the inner wall of the operating table 1. The end of the connecting pipe 49 away from the telescopic pipe 48 is connected to the air outlet of an external compressor. By setting up the three-way pipe 46, the control valve 47, the telescopic pipe 48, and the connecting pipe 49, an auxiliary functional module—a gas damping or auxiliary drive system—is formed that is synchronized with the movement of the testing mechanism 4. The three-way pipe 46 is connected to the lower opening of the sliding tube 45. The control valve 47 is used to control the on / off state and flow rate of compressed air. The telescopic pipe 48 adapts to the reciprocating motion of the testing mechanism 4. The connecting pipe 49 is connected to an external air source. Its functions may include: providing gas damping; adjusting the air pressure inside the sliding tube 45 by controlling the valve 47 when the piston rod 410 moves relative to the sliding tube 45 to form a controllable damping force, used to simulate different load characteristics or achieve smoother force application speed control; and assisting in driving or resetting by using compressed air to push the piston rod 410 as an aid to hydraulic drive or for rapid resetting.

[0025] The adjustment mechanism 5 includes a first fixed ring 51 and a second fixed ring 52, which are welded to the upper surfaces of two connecting frames 411 respectively. A stepper motor 53 is fixed in the inner cavity of the first fixed ring 51. A rotating rod 54 is mounted on the output end of the stepper motor 53 via a coupling. A first rolling bearing 56 is fixed to the end of the rotating rod 54, and the outer ring of the first rolling bearing 56 is fixed to the inner wall of the second fixed ring 52. The first fixed ring 51, the second fixed ring 52, the stepper motor 53, the rotating rod 54, and the first rolling bearing 56 form the drive and support positioning frame of the adjustment mechanism 5. The first fixed ring 51 and the second fixed ring 52 fix the two parts of the adjustment mechanism 5 to the connecting frames 411 of the two independent test mechanisms 4, so that the adjustment action is linked to the direction of the main thrust. The stepper motor 53 serves as the adjustment power source, providing precise angle control. The rotating rod 54 acts as a transmission shaft spanning the two fixed rings. The first rolling bearing 56 supports the distal end of the rotating rod 54 within the second fixed ring 52, ensuring smooth rotation and high coaxiality, and reliably transmitting the rotational motion of the stepper motor 53 to the entire adjustment mechanism 5.

[0026] A first gear 55 is fixed to the outer surface of the rotating rod 54. The positioning mechanism 6 includes two support frames 61, which are welded to the upper surfaces of the first fixed ring 51 and the second fixed ring 52, respectively. A second rolling bearing 62 is fixed to the inner cavity of the support frame 61, and a rotating cylinder 64 is fixed to the inner ring of the second rolling bearing 62. A second gear 57 is fixed to the outer surface of the rotating cylinder 64, and the second gear 57 meshes with the first gear 55. By setting the first gear 55, the support frames 61, the second rolling bearing 62, the rotating cylinder 64, and the second gear 57, a gear synchronous transmission system from the central drive to the two side execution units is formed. The first gear 55 is fixed to the central rotating rod 54. The two support frames 61 serve as the mounting base for the positioning mechanism 6. The second rolling bearing 62 provides rotational support for the rotating cylinder 64. The rotating cylinder 64 is the core execution element. The second gear 57 on its outer surface meshes with the first gear 55. When the stepper motor 53 drives the rotating rod 54 and the first gear 55 to rotate, the rotating cylinders 64 on both sides are simultaneously and synchronously driven to rotate within their respective support frames 61 through gear meshing, ensuring that the expansion or contraction of the positioning mechanisms 6 on the left and right sides is completely synchronized, which is crucial for ensuring the symmetry of the force applied to both sides of the carton.

[0027] A lead screw 67 is threaded into the inner cavity of the rotating cylinder 64. The rotating cylinder 64 is a double-cavity helical pipe joint, comprising a tubular body and a helical groove structure 65. The tubular body has a circular tube structure, internally divided along the axial direction to form two independent chambers. The axes of the two chambers are parallel and both are parallel to the axis of the tubular body. Each chamber has a continuous helical groove structure 65 on its inner wall, and the pitch and cross-sectional shape of the helical groove structure 65 match the external thread of the lead screw 67. By describing in detail the unique structure of the rotating cylinder 64 as a double-cavity helical pipe joint, the precision mechanical principle of its synchronous drive of the two lead screws 67 is revealed. The two independent chambers internally divided along the axial direction allow the two lead screws 67 to be placed in parallel. The helical groove structure 65 on the inner wall of each chamber precisely matches the external thread of the corresponding lead screw 67. When the rotating cylinder 64 rotates, the two helical groove structures 65 act like two internal threads, simultaneously driving the two lead screws 67 to perform linear motion. This integrated dual-chamber design fundamentally ensures the absolute synchronicity and identical displacement of the two lead screws 67, avoiding the asynchronous errors that may occur when using two independent motors. It is a key innovation for achieving high-precision symmetrical adjustment.

[0028] A limiting rod 66 is welded to the inner wall of the tubular body of the rotating cylinder 64. The lead screw 67 is a tubular structure with external threads on its outer surface, and it is slidably connected to the outer surface of the limiting rod 66. By setting the limiting rod 66 and specifying that the lead screw 67 is a tubular structure slidably connected to the limiting rod 66, an anti-rotation and precise guiding mechanism for the lead screw 67 is formed. The limiting rod 66 is fixed to the inner wall of the rotating cylinder 64 and passes through the interior of the lead screw 67. This fit prevents the lead screw 67 from rotating with the rotating cylinder 64, forcing the lead screw 67, driven by the helical groove structure 65, to only extend or retract in a straight line along the axis of the limiting rod 66. This precisely converts the rotational motion of the rotating cylinder 64 into the linear displacement of the lead screw 67, providing a precise linear output for subsequent positioning actions.

[0029] A connecting post 68 is welded to the end of the lead screw 67. A fixed frame 69 is welded to the end of the connecting post 68 away from the lead screw 67. A sliding plate 610 is riveted to the upper surface of the fixed frame 69. A sliding groove 611 is formed on the upper surface of the sliding plate 610. A limiting ball 63 is welded to the upper surface of the support frame 61. The limiting ball 63 is slidably connected to the sliding groove 611 formed on the upper surface of the sliding plate 610. By setting the connecting post 68, the fixed frame 69, the sliding plate 610, the sliding groove 611, and the limiting ball 63, a connection, transition, and constraint system is formed between the linear movement of the lead screw 67 and the mounting platform of the final positioning component corner positioning part 612. The connecting post 68 connects the lead screw 67 and the fixed frame 69. The fixed frame 69 is the direct carrier of the positioning component. The sliding plate 610 is riveted to the fixed frame 69, and the sliding groove 611 on it and the limiting ball 63 fixed on the support frame 61 form a ball-groove pair. This design allows the fixed frame 69 to move horizontally under the drive of the lead screw 67, while the limiting ball 63 rolls in the sliding groove 611, providing low-friction support and constraining the fixed frame 69 to move only along a predetermined straight trajectory, preventing it from deflecting or jamming, and ensuring the straightness and stability of the movement of the positioning component.

[0030] A corner positioning component 612 is fixed to the upper surface of the fixed frame 69. This corner positioning component 612 is integrally molded from rubber and includes an L-shaped main body and a connecting part. The L-shaped main body of the corner positioning component 612 has a right-angle bent plate-like structure and several anti-slip grooves on its outer surface. It has a first and a second mutually perpendicular contact surface for contacting the corners of the inner wall of the corrugated cardboard box. The connecting part is located at one end of the L-shaped main body and includes an extension integral with the main body, with a positioning groove on the extension for mating with the cardboard box. By describing the material, structure, and function of the corner positioning component 612 in detail, its crucial role as the final actuator directly in contact with the cardboard box is clarified. The integral molding from rubber ensures its flexibility and durability. The two mutually perpendicular contact surfaces of the L-shaped main body are specifically designed for tight contact with the corners of the inner wall of the corrugated cardboard box, i.e., the junction of the two side panels, which is a critical load-bearing part in the cardboard box structure. The anti-slip grooves on the surface increase friction and prevent slippage during testing. The connecting part and its positioning groove facilitate reliable installation with the fixing frame 69. This design cleverly transforms the concentrated force applied by the testing mechanism 4 into surface pressure on the corner areas of the inner wall of the carton through the L-shaped rubber part, more realistically simulating the stress state of the carton corners during stacking. At the same time, the rubber material can protect the inner wall of the carton from scratches by hard objects and compensate for the small tolerances of the carton size.

[0031] A method for testing the strength of corrugated cardboard boxes includes the following steps: Step 1: Place the corrugated carton to be tested with its opening facing down on the panel 2 of the operating table 1, so that it is roughly in the middle of the device. Start the stepper motor 53 of the adjustment mechanism 5 to drive the rotating rod 54 and the first gear 55 to rotate, which in turn drives the second gear 57 and the rotating cylinder 64 to rotate synchronously. The spiral groove structure 65 in the inner cavity of the rotating cylinder 64 engages with the external thread on the lead screw 67, pushing the lead screw 67, the connecting column 68 and the fixing frame 69 to extend horizontally outward along the direction perpendicular to the movement of the testing mechanism 4. The corner positioning parts 612 on the upper surface of the fixing frame 69 move accordingly until their two vertical mating surfaces are in close contact and fit against the corresponding corners of the inner wall of the corrugated carton. Step 2: Activate the two symmetrically arranged test mechanisms 4. The hydraulic cylinder 42 works, pushing the moving rod 43 and the sliding frame 44 to slide along the track groove 3 on the panel 2. This drives the sliding tube 45 and the piston rod 410, connecting frame 411, and adjusting mechanism 5 to move horizontally towards the center of the carton. During this process, the corner positioning piece 612 that has been unfolded on the adjusting mechanism 5 enters the interior space of the carton along with it until the fixed frames 69 on both sides and the corner positioning piece 612 move to the predetermined test starting position, which is ready to apply pressure to the opposite side walls of the carton. Step 3: While maintaining the clamping state of the carton by the positioning mechanism 6, the testing mechanism 4 continues to work, and the hydraulic cylinder 42 continuously outputs thrust. This thrust is transmitted to the sliding tube 45 through the moving rod 43 and the sliding frame 44, pushing the piston rod 410 to move further within the sliding tube 45. Thus, the pressure is finally transmitted to the positioned fixed frame 69 and the corner positioning member 612 through the connecting frame 411. The corner positioning member 612 converts the concentrated force into a uniform squeezing force on a specific corner area of ​​the inner wall of the corrugated carton. The detector integrated in the hydraulic cylinder 42 monitors and records the applied pressure data in real time. Step 4: After the test is completed, the hydraulic cylinder 42 is depressurized and the moving rod 43 is retracted, driving the entire test assembly, including the adjustment mechanism 5, to exit from the inside of the carton to the initial position. Subsequently, the stepper motor 53 of the adjustment mechanism 5 rotates in reverse, driving the lead screw 67 to retract, causing the corner positioning piece 612 to disengage from the inner wall of the carton. The corrugated carton under test is removed. Based on the pressure-time or pressure-displacement data recorded by the tester, combined with the deformation or damage of the carton after the test, the compressive strength, structural stability, and maximum pressure bearing capacity of the corrugated carton are analyzed and evaluated to complete the test.

[0032] Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art and related fields based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described and explained in the present invention, unless otherwise specified or limited, shall be implemented according to conventional means in the art.

Claims

1. A corrugated cardboard box strength testing device, characterized in that, include: An operating table (1) is provided with a panel (2) fixed on its upper surface. Test mechanism (4), which is used to apply compressive force to the inside of the corrugated carton, is fixed to the lower surface of the panel (2); Adjustment mechanism (5), which is used to adjust the contact force with the inner wall of corrugated cardboard boxes of different sizes, is fixed on the upper surface of the testing mechanism (4); Positioning mechanism (6), which is used to position the corrugated carton to be tested; The testing mechanism (4) includes a connecting frame (41), which is fixed on the lower surface of the panel (2). A hydraulic cylinder (42) is fixed on the lower surface of the connecting frame (41). The hydraulic cylinder (42) integrates a detector for recording pressure data. The core of the detector integrated inside the hydraulic cylinder (42) is a high-precision strain gauge pressure sensor. A moving rod (43) is provided at the output end of the hydraulic cylinder (42). A sliding frame (44) is welded to the end of the moving rod (43) away from the hydraulic cylinder (42). A track groove (3) runs through the upper surface of the panel (2). The sliding frame (44) is slidably connected to the lower surface of the track groove (3). A sliding tube (45) is fixed at the end of the sliding frame (44). A piston rod (410) is tightly slidably connected to the inner cavity of the sliding tube (45). A connecting frame (411) is welded to the top of the piston rod (410).

2. The corrugated cardboard box strength testing device according to claim 1, characterized in that: The number of the test mechanism (4) is two, and the two test mechanisms (4) are symmetrically arranged on both sides of the lower surface of the panel (2). The sliding tube (45) is slidably connected to the inner cavity of the track groove (3). The outer surface of the sliding tube (45) is provided with two rings, and the two rings on the outer surface of the sliding tube (45) are respectively rubbed and adapted to the upper and lower surfaces of the track groove (3).

3. The corrugated cardboard box strength testing device according to claim 1, characterized in that: A three-way pipe (46) is welded to the opening on the lower surface of the sliding tube (45). A control valve (47) is welded to the end of the three-way pipe (46). A telescopic pipe (48) is fixed to the end of the control valve (47) away from the three-way pipe (46). A connecting pipe (49) is fixed to the end of the telescopic pipe (48) away from the control valve (47). The connecting pipe (49) penetrates the inner wall of the operating table (1). The end of the connecting pipe (49) away from the telescopic pipe (48) is connected to the outlet of the external compressor.

4. The corrugated cardboard box strength testing device according to claim 1, characterized in that: The adjustment mechanism (5) includes a first fixed ring (51) and a second fixed ring (52). The first fixed ring (51) and the second fixed ring (52) are respectively welded to the upper surfaces of the two connecting frames (411). A stepper motor (53) is fixed in the inner cavity of the first fixed ring (51). A rotating rod (54) is installed at the output end of the stepper motor (53) through a coupling. A first rolling bearing (56) is fixed at the end of the rotating rod (54). The outer ring of the first rolling bearing (56) is fixed in the inner wall of the second fixed ring (52).

5. The corrugated cardboard box strength testing device according to claim 4, characterized in that: The outer surface of the rotating rod (54) is fixed with a first gear (55). The positioning mechanism (6) includes a support frame (61). There are two support frames (61), and the two support frames (61) are respectively welded to the upper surfaces of the first fixed ring (51) and the second fixed ring (52). The inner cavity of the support frame (61) is fixed with a second rolling bearing (62). The inner ring of the second rolling bearing (62) is fixed with a rotating cylinder (64). The outer surface of the rotating cylinder (64) is fixed with a second gear (57). The second gear (57) meshes with the first gear (55).

6. The corrugated cardboard box strength testing device according to claim 5, characterized in that: The rotating cylinder (64) is threaded with a lead screw (67) in its inner cavity. The rotating cylinder (64) is a double-cavity spiral pipe joint, including a tubular body and a spiral groove structure (65). The tubular body is a circular tube structure, and its interior is divided along the axial direction to form two independent chambers. The axes of the two chambers are parallel and are both parallel to the axis of the tubular body. Each chamber has a continuous spiral groove structure (65) on its inner wall. The pitch and cross-sectional shape of the spiral groove structure (65) match the external thread of the lead screw (67).

7. The corrugated cardboard box strength testing device according to claim 6, characterized in that: The inner wall of the tubular body of the rotating cylinder (64) is welded with a limiting rod (66), and the lead screw (67) is a tubular structure with external threads on its outer surface. The lead screw (67) is slidably connected to the outer surface of the limiting rod (66).

8. The corrugated cardboard box strength testing device according to claim 7, characterized in that: A connecting post (68) is welded to the end of the lead screw (67). A fixing frame (69) is welded to the end of the connecting post (68) away from the lead screw (67). A sliding plate (610) is riveted to the upper surface of the fixing frame (69). A sliding groove (611) is opened on the upper surface of the sliding plate (610). A limiting ball (63) is welded to the upper surface of the support frame (61). The limiting ball (63) is slidably connected to the sliding groove (611) opened on the upper surface of the sliding plate (610).

9. The corrugated cardboard box strength testing device according to claim 8, characterized in that: The upper surface of the fixed frame (69) is fixed with a corner positioning member (612). The corner positioning member (612) is integrally formed of rubber material and includes an L-shaped main body and a connecting part. The L-shaped main body of the corner positioning member (612) has a right-angle bent plate structure and several anti-slip grooves on its outer surface. It has a first contact surface and a second contact surface that are perpendicular to each other and is used to contact the corners of the inner wall of the corrugated cardboard box. The connecting part is set at one end of the L-shaped main body and includes an extension section integral with the main body. The extension section is provided with a positioning groove for cooperating with the cardboard box.

10. A method for testing the strength of corrugated cardboard boxes, characterized in that, The corrugated cardboard box strength testing device according to any one of claims 1 to 9 includes the following steps: Step 1: Place the corrugated carton to be tested with its opening facing down on the panel (2) of the operating table (1), so that it is roughly in the middle of the device. Start the adjustment mechanism (5) until the positioning end of the positioning mechanism (6) is in close contact with and fits the corresponding corner of the inner wall of the corrugated carton. Step 2: Start the two symmetrically set test mechanisms (4), the hydraulic cylinder (42) works, push the moving rod (43) and the sliding frame (44) to slide along the track groove (3) on the panel (2). During this process, the positioning mechanism (6) that has been unfolded on the adjustment mechanism (5) enters the internal space of the carton together until the positioning ends on both sides move to the predetermined test start position, that is, to prepare to apply pressure to the opposite side wall of the carton. Step 3: Keep the positioning mechanism (6) clamping the carton, the testing mechanism (4) continues to work, the hydraulic cylinder (42) continuously outputs thrust, which is transmitted to the sliding tube (45) through the moving rod (43) and the sliding frame (44), pushing the piston rod (410) to move further in the sliding tube (45), thereby finally transmitting the pressure to the positioned positioning mechanism (6), converting the concentrated force into a uniform squeezing force on a specific corner area of ​​the inner wall of the corrugated carton, and the detector integrated in the hydraulic cylinder (42) monitors and records the applied pressure data in real time; Step 4: After the test is completed, the hydraulic cylinder (42) is depressurized and the moving rod (43) is retracted, driving the entire test assembly to exit from the inside of the carton to the initial position. Then, the adjusting mechanism (5) rotates in reverse, causing the positioning mechanism (6) to disengage from the inner wall of the carton. The corrugated carton under test is removed. Based on the pressure-time or pressure-displacement data recorded by the tester, combined with the deformation or damage of the carton after the test, the compressive strength, structural stability and maximum pressure bearing capacity of the corrugated carton are analyzed and evaluated to complete the test.

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