Paper wet bursting strength tester

Abstract

The invention provides a paper wet bursting strength tester which comprises a base, a height-adjustable flow guide assembly is arranged on the base, the flow guide assembly comprises a flow guide body, the flow guide body is provided with an upward conical surface structure, and a measuring cylinder is arranged below the flow guide body; a paper fixing assembly is arranged on the base, and a through hole is formed in the middle of the paper fixing assembly; the lower end of the measuring cylinder presses the edge of the through hole to form a sealing interface. According to the scheme, by redesigning a test instrument, a test error source is eliminated, and the core effects of accurate loading of the liquid pressure and flexible expansion of the measuring range are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of paper testing equipment, and particularly relates to a paper wet burst strength tester. BACKGROUND

[0002] Paper wet burst strength test is one of the core indicators for evaluating the performance of chemical analysis filter paper, and its test method is strictly regulated by the national standard GB / T 1914-2017. The current standard specifies the use of a Hertzberg format instrument as the test equipment. The original design of the instrument follows the GB / T 10340 "Determination of filtration speed of paper and paperboard" specification, and the core function is to measure the flow rate of liquid through paper. The structure of the Hertzberg format instrument includes a conical feeding piece, a measuring cylinder and a support frame. Liquid flows into the measuring cylinder through the feeding piece and penetrates the paper. The filtration speed is determined by calculating the volume of filtrate per unit time. However, the measurement principle and structural design of the instrument are both for the filtration speed test scenario. The height of the measuring cylinder is fixed and the maximum range is only 325 mm of water column, which cannot meet the high range customization requirements of the wet burst strength test.

[0003] In the wet burst strength test scenario, the ability of paper to resist liquid static pressure under saturated wet conditions needs to be accurately measured. The test principle is based on the liquid pressure formula (p=ρgh), and the unit measurement value of 1 mm water column=9.8 pa is obtained. The instrument is required to be able to stably generate and maintain a water column pressure of a certain height. When the liquid is selected as water, its density is constant, and the maximum pressure p max =ρgh max that the paper can withstand is calculated by F=pA. The pressure value F reflects the wet burst strength of the paper. However, the existing Hertzberg format instrument has three inherent defects: first, the contact interface between the measuring cylinder and the paper lacks sealing design, and the liquid is easy to leak from the edge, causing pressure loss and affecting the test accuracy; second, the feeding piece and the measuring cylinder are not provided with a liquid distribution structure, and the water flow directly impacts the local area of the paper, causing uneven stress; third, the height of the measuring cylinder is not adjustable and the range is narrow, which cannot adapt to the test requirements of filter paper of different strength grades. These defects lead to a complicated operation process, large test result fluctuations, and cannot be extended to the test scenario of high strength filter paper.

[0004] In the prior art, for example, the spherical burst resistance tester disclosed in Chinese Patent No. CN110514512B has a paper clamping mechanism, a ball head measuring rod is arranged corresponding to the paper clamping mechanism, the upper end of the ball head measuring rod is connected with a ball head lifting mechanism through a pressure sensor, a water distribution sleeve is sleeved on the ball head measuring rod, and the water distribution sleeve is connected with a metering liquid injection device through a hose joint and a hose. Although this scheme attempts to optimize the paper strength test equipment, it does not provide a comprehensive solution to the problems of sealing, uniformity of liquid distribution and adjustable range for wet burst resistance test. Therefore, there is an urgent need for a special instrument to meet the technical requirements of standardized wet burst resistance test through structural innovation. SUMMARY

[0005] The first invention of the present scheme is to solve the problems of liquid leakage due to lack of sealing, uneven flow, local stress on paper caused by uneven flow, and fixed range unable to adapt to different strength filter paper in existing wet burst resistance test. The present scheme redesigns the test instrument, eliminates the test error source, and realizes the core effects of accurate liquid pressure loading and flexible range expansion.

[0006] The second invention of the present scheme is to solve the problem of capturing water column height reading at the moment of paper rupture. The marking mechanism retains the water column height value at the moment of pressure drop, thereby obtaining accurate reading.

[0007] To achieve the above-mentioned purposes, the present application adopts the following technical solutions: A paper wet burst resistance tester, comprising a base, a height-adjustable flow guide assembly is arranged on the base, the flow guide assembly comprises a flow guide body, the flow guide body has an upward tapered surface structure, and a graduated cylinder is arranged below the flow guide body; a paper fixing assembly is arranged on the base, a through hole is formed in the middle of the paper fixing assembly; and the lower end of the graduated cylinder is press-fitted to the edge of the through hole to form a sealed interface.

[0008] The paper wet burst resistance tester in the scheme provides stable support through the base, the flow guide assembly is installed on two fixed frames that can be adjusted in height up and down, the fixed frames are arranged horizontally, the height of the assembly can be adjusted according to the test requirements, the end of the uppermost fixed frame is installed into the feeding piece for liquid injection, the fixed frame below the feeding piece is installed with the flow guide body, the flow guide body has an upward taper surface structure that can disperse the water flow, a measuring cylinder is arranged below the flow guide body to receive the liquid, a through hole is formed in the middle of the paper fixing assembly on the base, the lower end of the measuring cylinder is press-bonded to the edge of the through hole to form a sealed interface to prevent liquid leakage. The scheme solves the problem of liquid leakage of the existing Herzberg format instrument, because the sealed interface eliminates the gap, the liquid pressure is ensured to act on the middle part of the paper; the taper surface structure of the flow guide body makes the liquid uniformly distributed to the peripheral wall of the measuring cylinder, avoiding the direct impact of the water flow on the paper to cause local rupture; the detachable fixed frame supports the range customization, different strength filter paper is adapted by replacing the measuring cylinder with different heights or adjusting the position of the fixed frame, compared with the common scheme, the structure is optimized for wet burst resistance test, without complex electronic components, accurate measurement is realized only by mechanical cooperation, based on the liquid pressure formula p = ρgh, combined with F = pA, the pressure value F of the water column on the paper can be obtained, and the wet burst resistance of the paper is reflected by the pressure value F. The sealing and uniform distribution of the liquid during addition ensure the accuracy of the pressure loading, and the liquid flows into the measuring cylinder from the feeding piece through the flow guide body during operation, the water column height directly reflects the burst resistance of the paper, and the test error source of the existing equipment is eliminated.

[0009] Further, the paper fixing assembly includes a support column group, the support column group is fixed to the base, a pressing plate is sleeved on the support column group, a fixed bolt is arranged at the top end of the support column group, a through hole is formed in the middle of the pressing plate, and a compression spring is sleeved on the support column group and acts below the pressing plate. The through hole is coaxially aligned with the lower end of the measuring cylinder. This design allows the user to press down the pressing plate to compress the compression spring to insert or replace the paper, and when released, the compression spring pushes the pressing plate to reset, so that the edge of the through hole is tightly fitted with the lower end of the measuring cylinder to form a continuous sealing surface, preventing the liquid from leaking from the side during the test. The cooperation of the support column group and the compression spring ensures that the clamping force is uniform, avoiding the movement or deformation of the paper, compared with the simple clamping plate structure, the design provides self-adaptive pressure through spring loading, adapts to paper with different thicknesses, improves the test repeatability, and does not require additional adjusting components, simplifying the operation process.

[0010] As a preferred, the compression spring is compressed when the pressing plate is pressed down, separating the through hole from the measuring cylinder, and the spring returns to its original position when released, making the edge of the through hole flush with the lower end of the measuring cylinder. By using the mechanical properties of the spring, the user applies downward force to compress the spring, increasing the gap between the through hole and the measuring cylinder to place the paper, and the spring's elastic restoring force pushes the pressing plate upwards after release until the edge of the through hole is completely flush with the lower end of the measuring cylinder, eliminating any height difference or gap and ensuring the integrity of the sealing interface. This operation reduces the manual alignment step and reduces human error. At the same time, the linear response of the spring ensures consistent fitting force, avoiding damage to the paper or insufficient sealing that can cause leakage. Compared with fixed clamps, the dynamic fitting design effectively improves test efficiency, especially for continuous batch testing scenarios.

[0011] As a preferred, the base vertically fixes a longitudinal support rod, and at least two fixed frames are detachably arranged on the longitudinal support rod; the flow guide assembly includes a feeding member arranged at the end of the uppermost fixed frame; and a flow guide body is arranged in the fixed frame below the feeding member, and the flow guide body is a conical structure with a vertex of the conical surface being connected to a water outlet of the feeding member and a lower edge of the conical surface being circumferentially abutted against an inner wall of the measuring cylinder. The vertex of the conical surface is connected to the water outlet of the feeding member, and the lower edge of the conical surface is circumferentially abutted against the inner wall of the measuring cylinder, so that the liquid flows directly from the outlet of the feeding member to the vertex of the conical surface, then uniformly spreads along the conical surface to the entire circumference, and finally smoothly transitions to the wall of the measuring cylinder through the abutment point of the lower edge and the inner wall of the measuring cylinder, realizing uniform circumferential flow of the liquid and avoiding concentrated water flow impacting a local area of the paper. The vertex connection ensures that the liquid does not splash, and the lower edge abutment prevents the liquid from leaking from the gap. Compared with a planar flow guide plate, the conical design disperses kinetic energy according to the principle of fluid dynamics, reduces turbulence, ensures uniform stress on the paper, and improves test accuracy, and the liquid can be smoothly delivered without adding complex structures such as flow guide grooves. The fixed frames are detachable and can be adjusted in height and then locked again, so that the height of the flow guide assembly can be adapted to measuring cylinders of various specifications, improving the versatility of the device.

[0012] Further, the fixed frame includes a locking sleeve fixed to the longitudinal support rod at a predetermined height by a jackscrew. The jackscrew is screwed into a threaded hole in the side wall of the sleeve and abuts against the surface of the rod to generate a friction force to lock the position, allowing the user to slide the sleeve to the desired height and then tighten it. By providing stable support through mechanical locking, the relative height of the feeding member, the flow guide body, and the measuring cylinder can be easily adjusted to adapt to different range requirements. The jackscrew design is simple and reliable, and only needs to be tightened or loosened during operation without the need for tools for disassembly. Compared with welded or fixed supports, the jackscrew effectively enhances the flexibility of the instrument and supports rapid range switching.

[0013] As preferred, the paper fixing assembly comprises an upper clamping plate and a lower clamping plate, the upper clamping plate is fixedly connected with the longitudinal support rod through a fixing frame, a support column connected with the base at the bottom end is arranged through the lower clamping plate, a compression spring is sleeved on the support column, and the top end of the compression spring abuts against and supports the lower clamping plate; the through hole is arranged through the middle part of the upper clamping plate and the lower clamping plate. The double-clamping-plate structure disperses the clamping force, avoids paper folding or damage, and provides buffering through the compression spring to adapt to uneven paper surfaces. Compared with the single-pressing-plate design, the scheme enhances the sealing performance and durability, and is especially suitable for thick or rough filter paper testing.

[0014] Further, the flow guide is fixed to the fixing frame below the feeding piece through a hoop-shaped installation slot. The hoop-shaped installation slot is a ring-shaped clamping seat, the flow guide is embedded in the clamping seat and is positionally constrained by the slot wall, so that deviation caused by vibration or liquid impact during testing is prevented, the conical surface of the flow guide is always aligned with the outlet of the feeding piece and the inlet of the measuring cylinder, the liquid flow path is kept stable, the hoop-shaped structure is simple and easy to install, and the flow guide can be quickly disassembled and replaced through bolts or buckles. Compared with welding or gluing, the scheme is more convenient to maintain and clean, and reduces the test error caused by flow deviation.

[0015] In addition, it is worth noting that the measuring cylinder further comprises a marking mechanism for marking the highest liquid level position in the measuring cylinder. The marking mechanism is used to capture the water level at the moment when the paper breaks, so as to avoid manual reading delay. The marking mechanism is connected to the measuring cylinder structure and does not interfere with the normal liquid flow. When the water column rises, the mechanism records the position, and after the rupture, the water level drops but the mark remains. The user can read it afterwards. This setting solves the problem of inaccurate measurement caused by rapid water level drop in the prior art, without the need for external equipment, and improves the practicability, especially in high-range testing.

[0016] As preferred, the marking mechanism comprises a longitudinal rack and a float assembly; the longitudinal rack is fixed to the inner wall of the measuring cylinder; and the float assembly is sleeved on the longitudinal rack and connected with the ratchet mechanism. The float assembly is sleeved on the longitudinal rack and connected with the ratchet mechanism. The float slides on the rack as the liquid level rises. The ratchet mechanism allows one-way movement. When the liquid level drops, the ratchet locks the position of the float by locking the rack, records the highest water level, and provides accurate guidance. The ratchet mechanism uses the mechanical self-locking principle to ensure instantaneous response. Compared with electronic sensors, the pure mechanical structure is more reliable and durable, has low cost, and is not affected by the properties of the liquid.

[0017] In another solution, the marking mechanism comprises a three-way valve and a siphon; the three-way valve is connected with the lower end opening of the measuring cylinder through the interface thread, the front interface communicates with the through hole, and the side interface is connected with the siphon; a conical valve core is arranged in the cavity of the three-way valve, and the bottom of the valve core is connected with a reset spring; the top end of the siphon is flush with the maximum scale line of the measuring cylinder. During normal testing, the valve core closes the side interface, and the liquid flows to the paper; when the paper is broken, the water flow accelerates to generate negative pressure, drives the valve core to move downward to open the side interface, triggers the siphon effect, and makes the liquid pause to maintain the water level; the reset spring subsequently pushes the valve core back, provides a reading time window through fluid control, and ensures effective triggering through the height matching of the siphon; compared with a complex valve system, the structure is simple and easy to implement.

[0018] The present application has the following beneficial effects: The lower end of the measuring cylinder is crimped with the through hole to form a sealed interface, which eliminates the lateral leakage of the liquid and ensures that the water column pressure acts on the middle part of the paper, thereby solving the test error problem caused by the gap leakage of the traditional instrument.

[0019] The vertex of the conical surface of the flow guide abuts against the feeding piece, and the lower edge abuts against the measuring cylinder, so as to guide the liquid to uniformly diffuse along the conical surface to the peripheral wall of the measuring cylinder, avoid the concentrated impact of the water flow on the local part of the paper, and improve the accuracy of the bursting degree test.

[0020] The height of the fixing frame is adjustable through the locking sleeve, and the flexible range adaptation of the measuring range is realized through the detachable measuring cylinder, so that the test requirements of filter papers with different strengths are met, and the limitation of the fixed measuring range is broken through.

[0021] The compression spring reset makes the pressing plate flush and fit with the edge of the measuring cylinder, forms a self-adaptive sealing structure, simplifies the paper clamping process, prevents the displacement or deformation of the paper, and improves the test efficiency and repeatability. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the present application in Example 1.

[0023] Figure 2 It is a structural schematic diagram of the present application in Example 2.

[0024] Figure 3 It is Figure 2 It is a local enlarged view of A in FIG. 1.

[0025] In the figure: 1. Base; 2. Longitudinal support rod; 21. Fixing frame; 22. Feeding component; 23. Fluid guide; 24. Hoop-shaped mounting groove; 3. Measuring cylinder; 4. Paper fixing assembly; 41. Through hole; 42. Support column assembly; 43. Compression spring; 44. Pressure plate; 45. Fixing bolt; 46. Upper clamping plate; 47. Lower clamping plate; 48. Support column; 49. Reinforcing rod; 5. Marking mechanism; 51. Rack; 52. Buoy assembly; 521. Buoy plate; 53. Ratchet; 531. Connector; 532. Pawl; 6. Liquid collection cup. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0027] Example 1 like Figure 1 As shown, this embodiment discloses a paper wet bursting strength tester. The entire device includes a test stand, which includes a base 1 and a longitudinal support rod 2. A liquid cup is placed on the base 1, and a paper fixing part is provided above the liquid cup. The paper fixing part includes a paper clamping assembly, and a through hole is provided in the middle of the paper clamping assembly for liquid to permeate the paper and be collected into the measuring cup. The paper fixing part can be installed on the base 1 or on the longitudinal support rod 2 for fixing. Several height-adjustable fixing frames 21 are installed on the longitudinal support rod 2, including a first fixing frame provided at the top. The first fixing frame includes a horizontal support and a hoop-shaped placement groove 24 at the end of the horizontal support. A feeding component 22 can be placed in the hoop-shaped placement groove 24. The feeding component can be a feeding component or a hopper. A second fixing frame is provided below the first fixing frame. The second fixed frame is equipped with a guide fluid 23, which serves as a connector between the feed element 22 and the measuring cylinder 3. The guide fluid 23 directs the liquid at the bottom of the feed element 22 through the conical surface of the guide fluid 23 to the entire wall of the measuring cylinder 3, ensuring uniform circumferential flow of the liquid. Correspondingly, the heights of the first fixed frame and its feed element 22, and the second fixed frame and its guide fluid 23, can be adjusted according to the specifications of the measuring cylinder 3. The measuring cylinder 3 is open at both ends, and graduation lines are provided on the cylinder body from bottom to top. The bottom opening of the cylinder body abuts against the paper to be tested in the middle of the paper clamping assembly mounted on the base 1.

[0028] The paper clamping assembly can adopt a spring clamping structure, which comprises a support column 48 group 42 arranged upward from the base 1, a compression spring 43 sleeved on each support column 48 of the support column 48 group 42, a fixed bolt 45 at the top of the support column 48 group 42, and a pressing plate 44 arranged between the fixed bolt 45 and the compression spring 43. An operator can insert the paper to be tested between the pressing plate 44 and the lower opening of the measuring cylinder 3 by pressing the pressing plate 44, and use the restoring force of the compression spring 43 to press the paper, so as to ensure that the paper does not move during the entire test, and make the liquid gravity act on the paper.

[0029] A through hole 41 is arranged in the middle of the pressing plate 44, which is coaxial with the bottom opening of the cylinder body. The bottom opening of the cylinder body is flush with the edge of the through hole 41, so that when the pressing plate 44 and the measuring cylinder 3 clamp the paper to be tested, the paper is not squeezed by the up-down displacement, and at the same time, the gap between the bottom opening of the cylinder body and the paper is eliminated by the pressure provided by the compression spring 43, avoiding the measurement error caused by the water flowing out from the side. The paper clamping assembly includes but is not limited to a spring clamping type or a clamping plate type, which is used to fix the paper on the plane to avoid movement during the test process.

[0030] During the test, the operator pours liquid at a uniform speed into the feed member 22. In this embodiment, pure water is used. The liquid flows through the feed member 22 to the conical surface of the conical flow guide 23, is evenly distributed on the conical surface, and then flows evenly along the circumferential side wall of the measuring cylinder 3 to the top of the through hole and the paper, avoiding the impact of the liquid directly falling on the paper. Since the lower opening of the measuring cylinder 3 abuts against the paper, the gap is eliminated, and the liquid does not seep out from the side, but acts on the middle part of the paper. At this time, according to 1mm water column=9.8pa, the water column height value of the measuring cylinder 3 when the paper cannot bear the rupture can be read, and the bursting degree of the paper can be calculated. The bursting degree can use millimeter water column (mmH2O) as a unit to measure the quality of the paper.

[0031] Specifically, the paper wet burst strength tester disclosed in the embodiment, the base 1 is used as a bearing foundation and adopts a rectangular metal plate, four corners are provided with mounting holes for fixing the longitudinal support rod 2, the support rod is a cylindrical metal rod, and a height scale line is marked on the surface. Two fixing frames 21 are sleeved on the longitudinal support rod 2, and each fixing frame 21 is composed of a locking sleeve and a horizontal support rod. The inner diameter of the locking sleeve matches the outer diameter of the support rod, and a threaded hole is formed in the side wall. After a jack screw is screwed into the threaded hole, the jack screw can abut against the support rod to achieve height locking. The first fixing frame 21 is located at the top end, a hoop-shaped mounting groove 24 is welded at the end of the horizontal support rod of the first fixing frame 21, the hoop-shaped mounting groove 24 is in a semicircular arc shape, a rubber pad is attached to the inner wall of the hoop-shaped mounting groove 24, and the hoop-shaped mounting groove 24 is used for clamping the lower end neck of the feeding piece 22. The second fixing frame 21 is located 30 cm below the first fixing frame, a circular tray is welded at the end of the horizontal support rod of the second fixing frame 21, and a positioning pit is formed in the center of the tray. The flow guide 23 is a stainless steel cone, the bottom diameter of the flow guide 23 is consistent with the inner diameter of the measuring cylinder 3, the top angle of the cone is 60 degrees, the cone body is embedded into the pit of the tray and fixed by three-point bolts. The measuring cylinder 3 is a transparent glass cylinder, the cylinder body is etched with millimeter water column scales, the upper end opening has the same outer diameter as the bottom diameter of the flow guide 23, and the lower end opening edge is turned into a plane.

[0032] The paper fixing assembly 4 includes four support columns 48 which are vertically welded at four corners of the base 1, and the top end of each support column 48 is turned into an external thread. The pressing plate 44 is a square steel plate, four corners of the pressing plate 44 are provided with through holes for sleeving the support columns 48, the middle part of the pressing plate 44 is laser cut into a circular through hole 41, and the hole diameter is equal to the outer diameter of the lower end of the measuring cylinder 3. The compression spring 43 is sleeved on each support column 48, the upper end of the compression spring 43 abuts against the lower surface of the pressing plate 44, and the lower end of the compression spring 43 abuts against the base 1. The fixing bolt 45 is screwed into the top end thread of the support column 48 to limit the maximum displacement of the pressing plate 44. When the pressing plate 44 is in a natural state, the edge of the through hole 41 is in the same horizontal plane as the lower end plane of the measuring cylinder 3.

[0033] Before testing, an operator presses down the pressing plate 44, the compression spring 43 is compressed to make the through hole 41 move downward to form a gap. The filter paper to be tested is laid on the lower end of the measuring cylinder 3, the compression spring 43 pushes the pressing plate 44 to move upward after the pressing plate 44 is loosened, until the edge of the through hole 41 is tightly attached to the lower end plane of the measuring cylinder 3, at this time, the filter paper is uniformly pressed between the two. After the feeding piece 22 injects pure water, the water is uniformly dispersed along the inner wall of the measuring cylinder 3 through the cone surface of the flow guide 23. Since the lower end of the measuring cylinder 3 and the filter paper form a mechanical seal, the water column static pressure is completely applied to the middle part of the filter paper. When the pressure generated by the water column height exceeds the strength limit of the filter paper, the filter paper breaks and the water level stops rising instantly, at this time, the scale value of the measuring cylinder 3 is read as the wet burst strength.

[0034] The embodiment realizes multi-aspect optimization. The longitudinal support rod 2 is sleeved with the fixed frame 21, allowing the position of the flow guide assembly to be adjusted according to the height of the measuring cylinder 3. Different height measuring cylinders 3 can be replaced to expand the range, for example, a 600 mm range measuring cylinder 3 corresponds to a 50 cm fixed position of the support rod, and a 1000 mm range is raised to an 80 cm fixed position. In this embodiment, a 600 mm range measuring cylinder 3 is used. The transition fit of the conical surface of the flow guide 23 and the measuring cylinder 3 eliminates liquid splashing. The accurate alignment of the conical top with the outlet of the feeding piece 22 ensures that the water flow is vertically incident. The conical surface angle enables the water flow to be converted into circumferential flow, avoiding direct impact on the filter paper. The automatic alignment mechanism of the pressing plate 44 and the measuring cylinder 3 is realized by the linear restoring force of the compression spring 43. When the pressing stroke is 15 mm, the spring compression amount generates a constant pressure of 5 N, ensuring that different thickness papers can be stably sealed.

[0035] After the device is assembled, the longitudinal support rod 2 is vertically fixed at the center position of the base 1. The first fixed frame 21 is installed at the uppermost end of the support rod, and the semicircular hoop groove at the end stably clamps the thin neck part of the feeding piece 22. The second fixed frame 21 is located directly below the first fixed frame, and the distance between the two is adjusted according to the specifications of the measuring cylinder 3. The circular tray at the end of the support accurately supports the bottom plane of the flow guide 23. The upper end opening of the measuring cylinder 3 is sleeved on the lower edge of the conical surface of the flow guide 23, forming a smooth transition joint surface. The lower end plane of the measuring cylinder 3 is vertically pressed against the edge of the through hole 41 in the middle of the pressing plate 44. When the pressing plate 44 is in a naturally lifted state, the upper surface of the through hole 41, the lower end surface of the measuring cylinder 3, and the filter paper clamped in between are all in the same horizontal plane without any height difference.

[0036] The water flow follows a specific path to complete the test cycle: the operator uniformly injects pure water into the feeding piece 22. The water flow first falls vertically from the bottom outlet of the feeding piece 22 to the top vertex of the conical top of the flow guide 23, then spreads around along the conical surface, forming a uniform water film on the inner wall of the measuring cylinder 3, and finally concentrates on the central area of the filter paper. The broken liquid flows into the liquid collection cup 6 provided on the base 1 through the through hole 41 for recovery.

[0037] In this embodiment, when operating the tester, the tester first unscrews the top screw of the second fixed frame 21, lowers the tray of the flow guide 23 to the lowest position. Place the glass measuring cylinder 3 corresponding to the range above the base 1, and slowly sleeve the upper end opening on the cylinder body into the lower edge of the conical surface of the flow guide 23, ensuring that the cylinder wall is completely matched with the conical surface. Then raise the tray to the level of the lower surface of the flow guide 23, tighten the top screw to fix the height of the support. Then process the paper fixing assembly 4: press the square pressing plate 44 to compress the compression spring 43 on the support column 48, and the through hole 41 moves downward to form a gap of about 15 mm. Place a standard diameter 35 mm circular filter paper flat on the lower end opening of the measuring cylinder 3. After releasing the pressing plate 44, the compression spring 43 pushes it to move upward until the edge of the through hole 41 is tightly matched with the hard plane at the lower end of the measuring cylinder 3. At this time, the filter paper is evenly clamped between the two.

[0038] Test procedure initiation: distilled water at 23±1℃ is injected into the feed piece 22 at a constant rate, and the water falls vertically through the bottom outlet of the feed piece 22 to the top of the conical tip of the flow guide 23. The liquid spreads circumferentially along the conical surface to form a continuous water film on the inner wall of the measuring cylinder 3, which flows uniformly and finally converges in the central area of the filter paper. As the water level rises, the static pressure of the water column continuously acts on the filter paper, and the operator visually observes the change in the scale of the measuring cylinder 3. When the fiber structure of the filter paper cannot withstand the pressure, it ruptures, and the water level stops rising. At this time, the highest water column scale value in the measuring cylinder 3 is quickly read, and the burst resistance is calculated according to 1 millimeter of water column = 9.8 pascal. The liquid after the rupture flows into the collection cup 6 provided on the base 1 through the through hole 41, completing a single test cycle.

[0039] In the continuous test scenario, the operator presses the pressure plate 44 again to replace the new filter paper, and the compression spring 43 resets to automatically rebuild the sealing interface. When the range is switched, the top screw of the first fixed frame is loosened, the height of the feed piece 22 is adjusted to match the new measuring cylinder 3. The residual water stains on the conical surface of the flow guide 23 can be wiped with a cotton cloth, and the water scale on the inner wall of the measuring cylinder 3 can be removed every month by soaking in a citric acid solution. On the actual production line, the device can realize 3 tests per minute with an automatic water injection system, and the pressure plate 44 reset mechanism allows single-handed operation to replace the filter paper. The sealing structure maintains a leakage of less than 1 milliliter within 2000 test cycles.

[0040] The key point of this embodiment is that the hard flat surface of the lower end of the measuring cylinder 3 and the through hole 41 of the pressure plate 44 closely fits, forming a mechanical sealing interface under the pressure of the compression spring 43, completely blocking the lateral leakage of the liquid. According to the standard test conditions specified in the national standard GB / T 1914-2017, this sealing structure can ensure that the test area of the circular filter paper with a diameter of 110 cm can withstand the complete water pressure. The conical surface of the flow guide 23 converts the point water flow into a uniform liquid film, so that the water flow covers the entire filter paper test surface in a laminar state, avoiding early rupture caused by local impact. The height adjustable mechanism of the fixed frame 21 cooperates with the series of measuring cylinders 3, which can cover the range of 50 millimeters to 1000 millimeters of water column, and in this embodiment, a 600 millimeter measuring cylinder 3 is used. 6 groups of tests were conducted on 19 batches of paper, and the average value was taken to obtain the test results in Table 1 below.

[0041] Table 1 Practical application has proved that this scheme can meet the full series test requirements of A to D level filter paper in the standard. The entire device relies on pure mechanical structure to realize the measurement function, and only the conical surface of the flow guide 23 and the sealing contact surface need to be cleaned for daily maintenance, without the need for professional equipment maintenance.

[0042] Example 2 As Figure 2 , 3As shown, in this embodiment, different from embodiment 1, the paper fixing assembly 4 comprises an upper clamping plate 46 and a lower clamping plate 47, the upper clamping plate 46 is fixedly connected with the longitudinal support rod 2 through a fixing frame 21, the lower clamping plate 47 is provided with a support column 48 connected to the base 1 at the bottom, the support column 48 is sleeved with a compression spring 43, the top end of the compression spring 43 abuts against and supports the lower clamping plate 47, and the through hole 41 is provided in the middle of the upper clamping plate 46 and the lower clamping plate 47. This embodiment further comprises a liquid level marking mechanism 5 based on the basic structure of embodiment 1, a longitudinal rack 51 is installed in the measuring cylinder 3, a float assembly 52 is arranged on the rack 51, the float piece 521 in the float assembly 52 is connected with the rack 51 through a ratchet wheel 53, the float piece can be lifted in one direction with the liquid surface of the measuring cylinder 3, but cannot be lowered, and the float piece with one-way action can be kept at the highest position of the liquid surface when the paper to be measured cannot withstand the water pressure and breaks, even if the liquid in the measuring cylinder 3 instantaneously drops into the liquid collecting cup 6 below the measuring cylinder 3, the accurate liquid surface height record value can also be read by the operator. After one test is completed, the float piece only needs to be continuously moved upward, so that the ratchet wheel 53 is separated from the upper end of the longitudinal rack 51, and the float piece can continue the next test with the ratchet wheel 53 by being sleeved with the lower end of the rack 51 again. The rack 51 is parallel to the measuring cylinder 3, and the specification of the rack 51 can be selected according to the range of the measuring cylinder 3.

[0043] Specifically, in this embodiment, the longitudinal support rod 2 is vertically fixed to the base 1, the fixing frame 21 bears the feeding member 22 and the flow guide 23, considering the increase of the range of the measuring cylinder 3, the fixing frame 21 further fixes the measuring cylinder 3, the reinforcing rod 49 is arranged between the upper and lower fixing frames 21 to improve the stability of the device, the lower end of the measuring cylinder 3 is pressed to the paper fixing assembly 4, and the installation of the rack 51 of the marking mechanism 5 does not affect the diffusion of the liquid in the measuring cylinder 3 to the cylinder wall. The core of the marking mechanism 5 comprises the longitudinal rack 51, the float piece and the ratchet wheel 53 assembly. The longitudinal rack 51 is a stainless steel strip-shaped component, and a suction cup is arranged on the back of the rack 51 to realize fixation by suction to the inner wall of the measuring cylinder 3. The front of the rack 51 is milled with equidistant triangular tooth grooves, the depth of the tooth grooves is 1.2 mm, and the tooth pitch is consistent with the minimum scale interval of the measuring cylinder 3. The length of the rack 51 covers the full range of the measuring cylinder 3, and when the measuring cylinder 3 with different heights is replaced, the matching rack 51 is also replaced synchronously.

[0044] The float piece is a hollow cylindrical polypropylene material, and a rectangular through hole is formed at the end. Stainless steel connecting pieces 531 are embedded in the two side walls of the through hole, the center shaft of the ratchet wheel 53 is fixed in the middle of the connecting piece 531, and a plurality of equally divided pawls 532 are arranged on the outer edge of the ratchet wheel 53. The pawls 532 are pressed to the tooth grooves of the rack 51 through micro torsional springs, when the float piece is floated by buoyancy, the pawls 532 slide over the inclined surface of the tooth grooves without resistance, and when the liquid level drops, the pawls 532 are vertically blocked in the vertical wall of the tooth grooves to prevent downward movement. A red indicating ring is embedded on the float piece, and the lower edge of the indicating ring is aligned with the scale line of the measuring cylinder 3.

[0045] The ratchet 53 assembly includes a brass shell wrapped around the rotating shaft and pawl 532. The float piece is installed by fitting it into the top end of the rack 51. In the initial state, the pawl is in the open position. After sliding to the working position, the pawl automatically fits the tooth surface under the action of the torsional spring. When disassembling, the float piece needs to be pushed to the top end of the rack 51 to the limit position. At this time, the pawl is forced to open by touching the limiting boss to disengage from the rack 51.

[0046] The marking mechanism 5 in this embodiment forms an integrated structure with the measuring cylinder 3: the rack 51 is attached parallel to the inner wall of the measuring cylinder 3, and the float piece is sleeved on the rack 51 and has an outer diameter smaller than the inner diameter of the measuring cylinder 3, ensuring free floating without touching the cylinder wall. Before testing, the float piece is placed at the bottom of the measuring cylinder 3, and the red indicator ring is zeroed. The rising water level pushes the float piece to float up, and the pawl slides through the tooth groove without obstruction. When the water level drops suddenly due to filter paper rupture, the pawl is instantly locked in the tooth groove locking position. At this time, the scale marked by the red indicator ring is the water level value at the moment of rupture. Practical application shows that the mechanical locking mechanism proposed in this embodiment locks the float within 0.2 seconds after the filter paper ruptures, solving the problem of manual reading delay. The tester can comfortably read the position of the red indicator ring, avoiding visual errors caused by rapid water level drop. The double calibration of the rack 51 scale and the measuring cylinder 3 scale ensures millimeter-level reading accuracy.

[0047] The operation method of the tester in this embodiment is as follows: first, the tester selects the corresponding rack 51 according to the current height of the measuring cylinder 3. Hold the rack 51 and insert it into the bottom of the measuring cylinder 3, then the back suction cup is aligned with the inner wall of the measuring cylinder 3 and is sucked. Then take the float piece, align the central rectangular hole with the bottom end of the rack 51, and push it upwards until the top of the float piece touches the upper end limiting block of the rack 51. At this time, the pawl is opened by the top inclined surface of the rack 51, and the pawl is continuously pushed to pass the limiting boss. The float piece naturally falls to the working position, and the pawl automatically engages the tooth surface under the action of the torsional spring.

[0048] In this embodiment, during the test preparation stage, the height of the fixed frame 21 needs to be adjusted to match the measuring cylinder 3, and the filter paper is placed by pressing the pressing plate 44. After releasing, a sealed interface is formed. After uniform water injection into the feed piece 22, the liquid surface pushes the float piece to float up, and the red indicator ring displays the water level height in real time. When the filter paper ruptures, the liquid level drops rapidly, driving the float piece to move downward, and the pawl is locked in the tooth groove vertical wall. The red indicator ring is locked at the highest water level scale. The operator directly reads the scale value to complete the recording.

[0049] After a single test, the marking mechanism 5 needs to be reset. Push the float piece upwards with your hand, and the pawl slides along the tooth groove without obstruction. When the float piece touches the top end limiting block of the rack 51, the pawl is forced to open and disengage from engagement by contacting the limiting boss. At this time, the float piece is removed from the top end of the rack 51, and it can be reinstalled from the bottom to start the next test. When changing the range, loosen the rack 51 positioning pin, remove the original rack 51 along the sliding groove, and then fix the new rack 51 after replacement.

[0050] In actual production line application, the tester completes the reading record within 5 seconds after the filter paper breaks, and then resets the float. Experience shows that the total time for a skilled person to replace the filter paper and reset the float is about 12 seconds. The double reference of the scale of the rack 51 and the scale of the cylinder 3 avoids misreading of a single scale.

[0051] The water flow dynamic process is consistent with that of Example 1: the injection rate is controlled at 100 milliliters per minute, and the tapered surface of the flow guide 23 forms a stable liquid film. The float piece maintains vertical movement in the liquid flow, and the buoyancy of the polypropylene material ensures that it always floats on the liquid surface. When the 1000 millimeter range cylinder 3 is used, it takes about 15-20 seconds for the float piece to rise from the bottom to the top end, and during this period, the liquid flow is stable and there is no turbulent interference with the reading. After the break, it takes about 3 seconds for the liquid in the cylinder 3 to flow into the recovery cavity through the through hole 41, and by this time the locking mechanism has already completed the position fixation in advance.

[0052] Example 3 In this embodiment, the reading convenience and accuracy of the tester are further optimized based on Example 1. A marking mechanism 5 is added, which uses a three-way valve connected to the lower end of the cylinder 3 to control the flow direction of the liquid. The main body of the three-way valve is a T-shaped metal piece, the upper end is connected to the lower end outlet of the cylinder 3 through a threaded interface, the front end passage is directly connected to the through hole 41 of the paper test area, and the lateral passage is connected to the siphon tube through a flange. The valve core is a conical structure, the tapered surface is downwardly aligned with the opening of the lateral passage, the bottom of the valve core is connected to a reset spring, and the other end of the spring is fixed to the bottom of the valve cavity. Under normal circumstances, the spring tension pushes the valve core to close the lateral passage. The siphon tube is a transparent flexible tube, the top curved part is strictly aligned with the maximum scale line of the cylinder 3, and the end is connected to the liquid collection cup 6 provided on the base 1.

[0053] When operating, first check the position of the valve core to confirm that the lateral passage is closed. After uniform water injection into the feed piece 22, the liquid normally flows to the filter paper through the front end passage of the three-way valve. When the filter paper breaks, the water flow accelerates through the front end passage to generate a negative pressure suction, and the valve core overcomes the spring tension to open the lateral passage. At this time, the siphon effect is triggered, and the liquid in the cylinder 3 flows back through the siphon tube. Due to the height limitation of the top end of the siphon tube, the water level is maintained at the scale position at the moment of breakage. After the operator reads the stable water level value, he manually presses the reset rod on the top of the valve core to make it return to its original position, and the spring re-closes the lateral passage. Actual application tests show that this structure can effectively maintain the water level after the filter paper breaks. When installing the siphon tube, a positioning caliper is used to ensure that it is aligned with the scale of the cylinder 3, and the top end height is calibrated to be consistent with the cylinder 3.

Claims

1. A paper wet bursting strength tester, characterized in that, The device includes a base, on which a height-adjustable flow guiding component is provided. The flow guiding component includes a flow guiding fluid with an upward conical structure, and a measuring cylinder is provided below the flow guiding fluid. A paper fixing component is provided on the base, and a through hole is opened in the middle of the paper fixing component. The lower end of the measuring cylinder is pressed against the edge of the through hole to form a sealing interface.

2. The paper wet bursting strength tester according to claim 1, characterized in that, The paper fixing assembly includes a support column assembly fixed to the base; a pressure plate is sleeved on the support column assembly, and a through hole is opened in the middle of the pressure plate; a compression spring is sleeved on the support column assembly and acts below the pressure plate; a fixing bolt is set at the top of the support column assembly and abuts against the top of the pressure plate; the through hole is coaxially aligned with the lower end of the measuring cylinder.

3. The paper wet bursting strength tester according to claim 2, characterized in that, When the pressure plate is pressed down, it compresses the spring to separate the through hole from the measuring cylinder. When it is released, the spring returns to its original position, making the edge of the through hole flush with the lower edge of the measuring cylinder.

4. The paper wet bursting strength tester according to claim 1, characterized in that, The base is vertically fixed with a longitudinal support rod, and at least two fixing frames are detachably mounted on the longitudinal support rod; the flow guiding assembly includes a feed component placed at the end of the uppermost fixing frame; the flow guiding fluid is disposed in the fixing frame below the feed component, and the flow guiding fluid has a conical structure, with the apex of the conical surface of the flow guiding fluid connecting with the outlet of the feed component, and the lower edge of the conical surface abutting against the inner wall of the measuring cylinder circumferentially.

5. The paper wet bursting strength tester according to claim 1, characterized in that, The fixing frame includes a locking sleeve, which is fixed to the longitudinal support rod at a preset height by a set screw.

6. The paper wet bursting strength tester according to claim 1, characterized in that, The paper fixing assembly includes an upper clamp and a lower clamp. The upper clamp is fixedly connected to a longitudinal support rod via a fixing frame. A support column with its bottom end connected to the base is provided through the lower clamp. A compression spring is sleeved on the support column, and the top end of the compression spring abuts against and supports the lower clamp. The through hole is provided through the upper clamp and the lower clamp.

7. The paper wet bursting strength tester according to claim 1, characterized in that, The guide fluid is fixed to the fixing frame below the feeder via a hoop-shaped mounting groove.

8. The paper wet bursting strength tester according to any one of claims 1-7, characterized in that, The graduated cylinder also includes a marking mechanism for marking the highest liquid level position inside the graduated cylinder.

9. The paper wet bursting strength tester according to claim 8, characterized in that, The marking mechanism includes a longitudinal rack and a buoy assembly; the longitudinal rack is fixed to the inner wall of the measuring cylinder; the buoy assembly is sleeved on the longitudinal rack and connected to the longitudinal rack through a ratchet mechanism.

10. The paper wet bursting strength tester according to claim 8, characterized in that, The marking mechanism includes a three-way valve and a siphon tube; the upper interface of the three-way valve is threaded to the lower opening of the measuring cylinder, the front interface is connected to the through hole, and the side interface is connected to the siphon tube; a conical valve core is provided in the cavity of the three-way valve, and a return spring is connected to the bottom of the valve core; the top of the siphon tube is flush with the maximum scale line of the measuring cylinder.

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