3D printing material yield stress automatic measuring device and calibration method

Abstract

The invention discloses an automatic measuring device for yield stress of a 3D printing material, and the device comprises a pedestal which is provided with a rotary test bench, and the rotary test bench is provided with a to-be-tested object placement cavity with an opening in the top; the column rod is arranged on the base; the cross beam is arranged at one end of the post away from the base; one end of the needle penetration testing mechanism is connected to the cross beam and located above the to-be-tested object placing cavity, and the other end of the needle penetration testing mechanism is placed in the to-be-tested object placing cavity during measurement and used for performing needle penetration testing on a material in the to-be-tested object placing cavity; the lifting mechanism is arranged on the cross beam, the side edge of the lifting mechanism is connected with the needle penetration testing mechanism, and the position of the needle penetration testing mechanism is adjusted through the lifting mechanism; the controller is electrically connected with the rotary test board and the needle penetration test mechanism; the controller is electrically connected with the lifting mechanism and the rotary test board, so that the descending height of the lifting mechanism and the rotating angle of the rotary test board are controlled through a computer, and intelligent and accurate control over the device is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of rheological property testing of building cementitious materials, and in particular to an automatic yield stress measuring device and a calibration method for 3D printing materials. Background Art

[0002] Compared with traditional construction technology, cement-based 3D printing technology can achieve customized and intelligent production, improve construction efficiency, reduce energy consumption and carbon emissions, and has broad application prospects. However, the flow properties and printing performance of cement-based 3D printing materials are the main factors restricting the rapid development of the cement-based 3D printing industry. Cement-based 3D printing materials are typical Bingham fluids. The rate of increase in the coagulation and hardening stress of the printing material must be greater than the load increment formed by the upper extrusion and accumulation, otherwise the printed body will collapse under the gravity of the upper material. Therefore, the rheological properties of the printing material are very high.

[0003] The commonly used method at present is to use a rheometer to test the yield stress value of the printing material, so as to determine whether the material can print out qualified components. However, in the process of using a rheometer for testing, there are disadvantages such as low test range, long test time, and high test cost. There are many methods for testing the flow properties of cement-based 3D printing, such as Vicat setting time test, slump test, jumping table expansion test, etc., but these can only be used to qualitatively evaluate the flow properties of printing materials. Moreover, none of the above commonly used test methods can realize automatic testing of printing materials within a certain time interval. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes an automatic measurement device and calibration method for yield stress of 3D printing materials.

[0005] According to an embodiment of the first aspect of the present invention, an automatic yield stress measurement device for 3D printing materials includes:

[0006] A base, wherein a rotating test table is provided on the base, and a cavity for placing an object to be tested with an opening at the top is provided on the rotating test table;

[0007] A column rod is arranged on the base;

[0008] A crossbeam, arranged at one end of the column away from the base;

[0009] A needle penetration test mechanism, one end of which is connected to the crossbeam and is located above the test object placement cavity, and the other end of which is placed in the test object placement cavity during measurement, and is used to perform a needle penetration test on the material in the test object placement cavity;

[0010] A lifting mechanism is arranged on the crossbeam, the side of the lifting mechanism is connected to the needle penetration testing mechanism, and the position of the needle penetration testing mechanism is adjusted by the lifting mechanism;

[0011] A controller is electrically connected to the rotary test table and the penetration test mechanism.

[0012] According to an automatic yield stress measuring device for 3D printing materials of the present invention, a rotating test table is provided on a base, and a cavity for placing an object to be tested with a top opening is provided on the rotating test table, and the cavity for placing an object to be tested is a hollow cylindrical tube with one end open; a column is provided on the base; a crossbeam is provided on the end of the column away from the base; one end of a needle penetration test mechanism is connected to the crossbeam and is located above the cavity for placing the object to be tested; the needle penetration test mechanism provided on the crossbeam and the cavity for placing the object to be tested provided on the base can correspond in position; a lifting mechanism is provided on the crossbeam, and the side of the lifting mechanism is connected to the needle penetration test mechanism, and the position of the needle penetration test mechanism is adjusted by the lifting mechanism; The height of the needle penetration test mechanism is controlled by the lifting mechanism, so as to control the needle penetration test mechanism to puncture the material to be tested in the test object placement cavity up and down; and a rotating test table is arranged at the bottom of the test object placement cavity, and when the needle penetration test mechanism punctures the test material downward, the rotating test table can be opened to rotate the test object placement cavity on its top, thereby rotating the test material, so that the puncture position of the needle penetration test mechanism in the test material will be more and wider, making the measurement result of the device more accurate when in use; at the same time, through the setting of the controller, the controller can be connected to the computer to set the rotation speed of the rotating table and the distance that the lifting mechanism drives the needle penetration test mechanism to descend, so as to realize intelligent control.

[0013] According to some embodiments of the present invention, the rotary test table comprises: a rotary mechanism and a rotary table, wherein the rotary mechanism is disposed at the bottom of the rotary table;

[0014] The rotating mechanism comprises:

[0015] A rotating motor is disposed in the base and electrically connected to the controller;

[0016] A rotating screw has one end connected to the output shaft of the rotating motor, and the other end passes through the top of the base and is rotatably connected to the bottom of the rotating truncated table.

[0017] According to some embodiments of the present invention, arc-shaped side wings are arranged on both sides of the crossbeam, and the needle penetration testing mechanism is arranged at the bottom of the arc-shaped side wings.

[0018] According to some embodiments of the present invention, there are three needle penetration testing mechanisms, which are circular at the bottom of the arc-shaped wing, and two adjacent needle penetration testing mechanisms are evenly distributed with an interval of 120°.

[0019] According to some embodiments of the present invention, the needle penetration testing mechanism comprises:

[0020] A spring pressure mechanism, one end of which is connected to the bottom of the arc-shaped wing, and the side of the lifting mechanism is connected to the spring pressure mechanism;

[0021] A weight, one end of which is connected to an end of the spring pressure mechanism away from the arc-shaped wing;

[0022] A test needle has one end connected to an end of the weight away from the spring pressurizing mechanism.

[0023] According to some embodiments of the present invention, the spring pressing mechanism comprises:

[0024] A thin-walled cylinder, one end of which is connected to the bottom of the arc-shaped side wing, and a through groove is provided on a side of the thin-walled cylinder (411) close to the lifting mechanism;

[0025] An end gasket, the end gasket is arranged on the inner top wall of the thin-walled cylinder;

[0026] A spring, wherein the spring is disposed in the thin-walled cylinder and one end of the spring is connected to the end gasket;

[0027] A compression gasket, the compression gasket is arranged at the other end of the spring;

[0028] A connecting rod is arranged in the thin-walled cylinder and one end of the connecting rod is connected to the extrusion gasket.

[0029] According to some embodiments of the present invention, the lifting mechanism comprises:

[0030] A lifting motor, the lifting motor is arranged on the top of the beam, and the output shaft thereof passes through the beam and extends to the bottom of the beam;

[0031] A lifting screw, one end of which is connected to the output shaft of the lifting motor;

[0032] A lifting disc, wherein an internal thread is provided in the middle of the lifting disc, and the lifting disc is threadedly connected to the lifting screw through the internal thread;

[0033] A branch rod, wherein the branch rod is arranged on the side of the lifting disc, one end of the branch rod is connected to the lifting disc, and the other end is connected to the connecting rod through the through groove;

[0034] The number and arrangement positions of the branch rods correspond to the needle penetration testing mechanism.

[0035] According to some embodiments of the present invention, a wiring port is further included, wherein the wiring port is arranged on a side of the base and is electrically connected to the controller.

[0036] According to a second aspect of an embodiment of the present invention, a calibration method for an automated yield stress measurement device for 3D printing materials comprises:

[0037] According to the pre-test results of the material to be tested, a matching test needle, weight and spring are selected so that the penetration depth of the test needle into the material to be tested after stirring is close to the depth of the cavity where the material to be tested is placed;

[0038] According to the parameters of the pre-tested test needle, weight and spring, the theoretical calculation formula between the needle penetration and the yield stress of the material to be tested is calculated theoretically;

[0039] The rheological properties of the tested material are tested at different times to determine its yield stress; the needle penetration of the material is tested at different times, and the theoretical calculation formula is corrected by fitting to obtain a corrected calculation formula between the yield stress and needle penetration of the tested material;

[0040] The modified calculation formula is input into the device, and the yield stress of the test material at different times can be obtained through program calculation.

[0041] According to a calibration method of an automatic measuring device for yield stress of 3D printing materials of the present invention, first, a pre-test is performed on the 3D printing material to be tested, and a suitable test needle, weight and spring are selected through the pre-test; so that the test needle can penetrate the material to be tested to a depth close to the depth of the cavity where the object to be tested is placed after stirring. The theoretical calculation formula between the penetration and the yield stress of the material to be tested is obtained through theoretical calculation according to the parameters of the test needle, weight and spring used in the pre-test; secondly, the rheological properties of the material to be tested are tested at different times, and its yield stress and corresponding penetration at different times are measured, and the correction calculation formula between the yield stress and penetration of the material to be tested is obtained by fitting the theoretical calculation formula obtained above to the penetration and the corresponding yield stress, and the correction calculation formula is input into the device, and the yield stress corresponding to the penetration of the test material at different times can be obtained through program calculation, thereby completing the calibration of the device.

[0042] According to some embodiments of the present invention, the theoretical calculation formula is:

[0043]

[0044] The correction calculation formula is:

[0045]

[0046] Where τ0 represents the yield stress of the material to be tested, H represents the penetration depth of the test needle, R represents the radius of the test needle, h2 represents the length of the test needle, m represents the mass of the test needle and the weight, k is the compression coefficient of the spring, x is the compressed length of the spring, and a and b are correction coefficients.

[0047] According to the present invention, an automatic measuring device and calibration method for yield stress of cement-based 3D printing materials have the following beneficial effects:

[0048] (1) By setting up a rotatable rotating test table, the position of the material to be tested can be automatically changed, thereby achieving a wider test range of the device and more accurate test results;

[0049] (2) By setting up multiple groups of needle penetration test mechanisms, it is possible to measure simultaneously under the same conditions and obtain multiple groups of data. By calculating the average value, the measurement accuracy of the device is higher;

[0050] (3) By setting up a controller to be electrically connected to the lifting mechanism and the rotating test bench, the descending height of the lifting mechanism and the rotating speed of the rotating test bench can be controlled by a computer, thereby realizing intelligent and precise control of the device;

[0051] (4) By implanting program control in the controller to realize continuous automatic testing, the law of change of yield stress of the material to be tested with time can be obtained.

[0052] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0054] Figure 1 This is a schematic structural diagram of an automatic yield stress measurement device for 3D printing materials according to an embodiment of the present invention;

[0055] Figure 2 This is a schematic diagram of the internal structure of an automatic measurement device for yield stress of 3D printing materials according to an embodiment of the present invention;

[0056] Figure 3 A schematic diagram of a portion of the internal structure of a device for automatically measuring the yield stress of 3D printing materials according to an embodiment of the present invention;

[0057] Figure 4A schematic diagram of theoretical calculation of yield stress in a calibration method of an automated yield stress measurement device for 3D printing materials according to an embodiment of the present invention;

[0058] Figure 5 The test result of yield stress in the calibration method of the automatic measurement device of yield stress of 3D printing materials in the embodiment of the present invention is

[0059] Figure 6 The corresponding result of the corrected fitting needle penetration and yield stress in the calibration method of the automatic measurement device of the yield stress of 3D printing materials according to the embodiment of the present invention;

[0060] Figure 7 This is a schematic diagram of measurement results of an automatic measurement device for yield stress of 3D printing materials according to an embodiment of the present invention.

[0061] Reference numerals:

[0062] 100, base; 110, rotating test table; 112, rotating round table; 1111, rotating motor; 1112, rotating screw; 120, chamber for placing the object to be tested;

[0063] 200, pole;

[0064] 300, crossbeam; 310, curved flank;

[0065] 400, needle penetration test mechanism; 410, spring pressure mechanism; 411, thin-walled cylinder; 412, end gasket; 413, spring; 414, extrusion gasket; 415, connecting rod; 420, weight; 430, test needle;

[0066] 500, lifting mechanism; 510, lifting motor; 520, lifting screw; 530, lifting disc; 540, branch rod;

[0067] 600, controller;

[0068] 700. Wiring port. DETAILED DESCRIPTION

[0069] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0070] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0071] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0072] Example 1

[0073] See also Figure 1-Figure 3 As shown, a 3D printing material yield stress automatic measurement device comprises:

[0074] A base 100, on which a rotating test table 110 is disposed, and on which a test object placement cavity 120 with a top opening is disposed;

[0075] The column 200 is arranged on the base 100;

[0076] The crossbeam 300 is disposed at an end of the column 200 away from the base 100;

[0077] A needle penetration test mechanism 400, one end of which is connected to the crossbeam 300 and is located above the test object placement cavity 120, and the other end of which is placed in the test object placement cavity 120 during measurement, and is used to perform a needle penetration test on the material in the test object placement cavity 120;

[0078] A lifting mechanism 500 is disposed on the crossbeam 300 , and a side of the lifting mechanism 500 is connected to the penetration test mechanism 400 , and the position of the penetration test mechanism 400 is adjusted by the lifting mechanism 500 ;

[0079] A controller 600, the controller 600 is electrically connected to the rotary test table 110 and the penetration test mechanism 400;

[0080] Furthermore, in order to rotate the rotary test table 110 and drive the test object placement cavity 120 to rotate, the rotary test table 110 includes: a rotating mechanism and a rotating round table 112, and the rotating mechanism is arranged at the bottom of the rotating round table 112;

[0081] The rotating mechanism includes:

[0082] The rotating motor 1111 is disposed in the base 100 and is electrically connected to the controller 600;

[0083] A rotating screw 1112, one end of which is connected to the output shaft of the rotating motor 1111, and the other end of which passes through the top of the base 100 and is rotatably connected to the bottom of the rotating truncated table 112;

[0084] It should be noted that, by rotating the output shaft of the rotating motor 1111, its output shaft is connected to the rotating screw 1112, thereby driving the rotating screw 1112 to rotate, and the rotating screw 1112 is connected to the rotating table 112, thereby driving the rotating table 112 to rotate, and finally causing the test object placement cavity 120 set on the rotating table 112 to rotate.

[0085] Furthermore, in order to provide a larger area to install more penetration test mechanisms 400, arc-shaped side wings 310 are provided on both sides of the crossbeam 300, and the penetration test mechanisms 400 are provided at the bottom of the arc-shaped side wings 310;

[0086] It should be noted that, by providing the arc-shaped side wing 310 , a plurality of penetration test mechanisms 400 can be arranged in a circular shape on the arc-shaped side wing 310 .

[0087] Optionally, there are three needle penetration test mechanisms 400 , which are circular at the bottom of the arc-shaped wing 310 , and two adjacent needle penetration test mechanisms 400 are evenly distributed and spaced 120° apart.

[0088] Further, in order to enable the penetration test mechanism 400 to puncture the material to be tested, the penetration test mechanism 400 is configured to include:

[0089] The spring pressure mechanism 410 has one end connected to the bottom of the arc-shaped side wing 310, and the side of the lifting mechanism 500 is connected to the spring pressure mechanism 430;

[0090] A weight 420, one end of which is connected to an end of the spring pressure mechanism 410 away from the arc-shaped side wing 310;

[0091] A test needle 430, one end of which is connected to an end of the weight 420 away from the spring pressure mechanism 410;

[0092] It should be noted that the lifting mechanism 500 drives the spring pressure mechanism 410 to move upward, thereby driving the weight 420 and the test needle 430 to move upward, squeezing the spring pressure mechanism 410; when the lifting mechanism no longer rises, the spring pressure mechanism 410 pushes the weight 420 and the test needle to move downward due to the squeezing force;

[0093] Furthermore, in order to realize that the spring pressure mechanism 410 can store pressure when the lifting mechanism 500 rises and release pressure when the lifting mechanism 500 descends, the spring pressure mechanism 410 includes:

[0094] A thin-walled cylinder 411, one end of which is connected to the bottom of the arc-shaped side wing 310, and a through groove is provided on the side of the thin-walled cylinder 411 close to the lifting mechanism 500;

[0095] The end gasket 412 is arranged on the inner top wall of the thin-walled cylinder 411;

[0096] A spring 413, wherein the spring 413 is disposed in the thin-walled cylinder 411, and one end of the spring 413 is connected to the end gasket 412;

[0097] A compression gasket 414, which is disposed at the other end of the spring 413;

[0098] A connecting rod 415, which is disposed in the thin-walled cylinder 411 and has one end connected to the extrusion gasket 414;

[0099] It should be noted that the lifting mechanism 500 drives the connecting rod 415 to move upward, and the top of the connecting rod 415 is connected to the extrusion gasket 414, the top of the extrusion gasket 414 is connected to the spring 413, and the other end of the spring 413 is connected to the end gasket 412 set on the top of the thin-walled cylinder 411. Therefore, when the lifting mechanism 500 drives the connecting rod 415 to move upward, the extrusion gasket 414 on the connecting rod 415 will squeeze the spring 413 upward, thereby causing a certain elastic force to be stored in the spring. When the lifting mechanism 500 no longer provides upward movement, the spring 413 recovers, releasing the downward elastic force, pushing the weight 420 and the test needle 430 to move downward.

[0100] Further, in order to realize that the lifting mechanism 500 drives the connection rod 415 to move up and down, thereby driving the test needle 430 to move up and down, the lifting mechanism 500 includes:

[0101] A lifting motor 510, the lifting motor 510 is arranged on the top of the beam 300, and its output shaft passes through the beam 300 and extends to the bottom of the beam 300;

[0102] A lifting screw 520, one end of which is connected to the output shaft of the lifting motor 510;

[0103] A lifting disc 530, wherein an internal thread is provided in the middle of the lifting disc 530, and the lifting disc 530 is threadedly connected to the lifting screw 520 through the internal thread;

[0104] A branch rod 540, which is disposed on the side of the lifting disc 530, with one end connected to the lifting disc 530 and the other end connected to the connecting rod 415 through a through groove;

[0105] The number of the branches 540 corresponds to the position of the penetration test mechanism 400;

[0106] It should be noted that the lifting motor 510 rotates, driving the lifting screw 520 connected to its output shaft to rotate. The lifting screw 520 is arranged in a lifting disc 530 with an internal thread in the middle. Since the lifting screw 520 itself does not move up and down, it will only rotate with the rotation of the lifting motor 510. However, the lifting disc 530 mounted on the lifting screw 520 is threadedly connected to the lifting screw 520. Therefore, when the lifting screw 520 rotates, the lifting disc 530 will move up and down due to the transmission between the threads, and the branch rod 540 is arranged on the side of the lifting disc 530, so the branch 540 also moves up and down accordingly; since one end of the branch 540 is connected to the connecting rod 415, it drives the connecting rod 415 to move up and down.

[0107] Furthermore, in order to achieve the connection between the device and the computer, a wiring port 700 is provided, which is provided on the side of the base 100 and is electrically connected to the controller 600 .

[0108] According to an automatic yield stress measuring device for 3D printing materials of the present embodiment, a rotating test table 110 is provided on a base 100, and a test object placement cavity 120 with a top opening is provided on the rotating test table 110; a column 200 is provided on the base 100; a crossbeam 300 is provided on the end of the column 200 away from the base 100; one end of a needle penetration test mechanism 400 is connected to the crossbeam 300, and is located above the test object placement cavity 120; the needle penetration test mechanism 400 provided on the crossbeam 300 and the test object placement cavity 120 provided on the base 100 can correspond in position; a lifting mechanism 500 is provided on the crossbeam 300, and the side of the lifting mechanism 500 is connected to the needle penetration test mechanism 400, and the position of the needle penetration test mechanism 400 is adjusted by the lifting mechanism 500; thereby The lifting mechanism 500 controls the height of the needle penetration test mechanism 400, thereby controlling the needle penetration test mechanism 400 to puncture the test material in the test object placement cavity 120 up and down; and a rotating test table 110 is arranged at the bottom of the test object placement cavity 120, and when the needle penetration test mechanism 400 punctures the test material downward, the rotating test table 110 can be opened to rotate the test object placement cavity 120 on its top, thereby rotating the test material, so that the puncture position of the needle penetration test mechanism 400 in the test material will be more and wider, making the measurement result of the device more accurate when in use; at the same time, through the setting of the controller 600, the controller can be connected through a computer to set the rotation speed of the rotating table and the distance that the lifting mechanism drives the needle penetration test mechanism to descend, thereby realizing intelligent control.

[0109] Example 2

[0110] A calibration method for an automated yield stress measurement device for 3D printing materials, the method comprising:

[0111] Step S100: According to the pre-test results of the material to be tested, a matching test needle, weight and spring are selected so that the penetration depth of the test needle into the material to be tested after stirring is close to the depth of the cavity for placing the object to be tested;

[0112] Step S200: according to the parameters of the pre-tested test needle, weight and spring, a theoretical calculation formula between the needle penetration and the yield stress of the material to be tested is calculated theoretically;

[0113] Step S300: testing the rheological properties of the material to be tested at different times to determine its yield stress; and testing the needle penetration of the material at different times, and correcting the theoretical calculation formula by fitting to obtain a corrected calculation formula between the yield stress and needle penetration of the material to be tested;

[0114] Step S400: input the modified calculation formula into the device, and obtain the yield stress of the test material at different times through program calculation.

[0115] Furthermore,

[0116] The theoretical calculation formula is:

[0117]

[0118] The correction calculation formula is:

[0119]

[0120] Where τ0 represents the yield stress of the material to be tested, H represents the penetration depth of the test needle, R represents the radius of the test needle, h2 represents the length of the test needle, m represents the mass of the test needle and the weight, k is the compression coefficient of the spring, x is the compressed length of the spring, and a and b are correction coefficients.

[0121] The parameters used in the device of this embodiment are as follows: the minimum division is 0.01mm; the measuring range is 0-40mm; the total weight of the weight and the test needle connecting rod assembly should be (50±0.05)g, the needle rod diameter is 3.2mm, and the needle rod length is 38mm; the needle diameter is 1.00mm, the needle length is 50mm, one end of the needle tip is a 9° cone, the spring elastic coefficient is 1N / cm, and the spring compression length is positioned at 25mm;

[0122] See also Figure 4 The yield stress calculation diagram shown in the figure shows that the fitting formula under this parameter is calculated according to the theoretical formula:

[0123]

[0124] Four groups of test materials were prepared, M0 as the basic group, the main components of which were cement, fine sand, water, thickener and PP fiber in a ratio of 1:0.22:0:36:0.004 and 0.001; M1, M2 and M3 groups added NT with contents of 1%, 2% and 3% respectively on the basis of M0.

[0125] The rheological properties of the above four groups of printing pastes were measured using Anton Paar electromagnetic rheometer, and the yield stress test results were obtained as shown in the attached figure. Figure 5 The above materials were tested by needle penetration, as shown in the following table (1):

[0126] Table (1) Yield stress and penetration test results of printed mortar

[0127] name M0 M 1 M2 M3 <![CDATA[Yield stress τ0 (Pa)]]> 3431 33 41 5225 645328 9598.15 Needle penetration H(mm) 3477 3032 2514 18.34

[0128] Substitute the test results into the above formula for fitting, such as Figure 6 The relationship between yield stress and needle penetration can be obtained.

[0129] The system is as follows:

[0130]

[0131] The device is set to test the results once every 10 minutes, and each group of samples is tested continuously for two hours, and the corresponding test results can be obtained as follows: Figure 7 As shown, it can be seen that the device can automatically test the yield stress of the printed material within a certain period of time.

[0132] Example 3

[0133] A method for measuring and using a 3D printing material yield stress automatic measuring device, comprising:

[0134] S10: According to the calibration results, the calibration formula program is input and the program related parameters are preset;

[0135] S20: After the device is installed, lift the penetration test mechanism according to the test requirements and compress the pressure spring to the specified height;

[0136] S30: placing a glass plate at the bottom of the test object placement cavity, then filling the test object placement cavity with the test material, placing it on the rotating test table, and adjusting the bottom of the test needle to align with the test object placement cavity;

[0137] The object-to-be-tested cavity may be a hollow cylinder with one end open;

[0138] S40: Start the test. Three test needles are inserted into the material to be tested at the same time under the action of gravity and spring pressure. After 10 seconds, the penetration depth is automatically read and the average value is calculated. Then the test needles are raised to the original height.

[0139] S50: setting the test time interval, repeating step S40 to obtain multiple sets of penetration test data, and obtaining the corresponding yield stress data through the input calibration formula program.

[0140] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the invention.

[0141] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0142] Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Mentioning "embodiment" in this article means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present embodiment application. The appearance of this phrase in various positions in the specification is not necessarily the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It can be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0143] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. An automated yield stress measuring device for 3D printing materials, characterized in that: include: A base (100), wherein a rotating test table (110) is provided on the base (100), and a test object placement cavity (120) with a top opening is provided on the rotating test table (110); A column rod (200) is arranged on the base (100); A crossbeam (300) is arranged at one end of the column (200) away from the base (100); A needle penetration test mechanism (400), one end of which is connected to the crossbeam (300) and is located above the test object placement cavity (120), and the other end of which is placed in the test object placement cavity (120) during measurement, and is used to perform a needle penetration test on the material in the test object placement cavity (120); A lifting mechanism (500) is arranged on the crossbeam (300), the side of the lifting mechanism (500) is connected to the needle penetration testing mechanism (400), and the position of the needle penetration testing mechanism (400) is adjusted by the lifting mechanism (500); A controller (600) is electrically connected to the rotary test table (110) and the penetration test mechanism (400).

2. The automatic yield stress measuring device for 3D printing materials according to claim 1, characterized in that: The rotary test table (110) comprises: a rotary mechanism and a rotary truncated table (112), wherein the rotary mechanism is arranged at the bottom of the rotary truncated table (112); The rotating mechanism comprises: A rotating motor (1111) is disposed in the base (100) and is electrically connected to the controller (600); A rotating screw rod (1112) has one end connected to the output shaft of the rotating motor (1111), and the other end passes through the top of the base (100) and is rotatably connected to the bottom of the rotating truncated table (112).

3. The automatic yield stress measuring device for 3D printing materials according to claim 2, characterized in that: Arc-shaped side wings (310) are arranged on both sides of the crossbeam (300), and the needle penetration testing mechanism (400) is arranged at the bottom of the arc-shaped side wings (310).

4. The automatic measuring device for yield stress of 3D printing materials according to claim 3, characterized in that: There are three needle penetration test mechanisms (400), which are circular at the bottom of the arc-shaped wing (310), and two adjacent needle penetration test mechanisms (400) are evenly distributed and spaced 120 degrees apart.

5. The automatic yield stress measuring device for 3D printing materials according to claim 4, characterized in that: The needle penetration testing mechanism (400) comprises: A spring pressurizing mechanism (410), one end of which is connected to the bottom of the arc-shaped side wing (310), and a side of the lifting mechanism (500) is connected to the spring pressurizing mechanism (430); A weight (420), one end of which is connected to an end of the spring pressure mechanism (410) away from the arc-shaped wing (310); A test needle (430) has one end connected to an end of the weight (420) away from the spring pressure mechanism (410).

6. The automatic yield stress measuring device for 3D printing materials according to claim 5, characterized in that: The spring pressure mechanism (410) comprises: A thin-walled cylinder (411), one end of the thin-walled cylinder (411) is connected to the bottom of the arc-shaped side wing (310), and a through groove is provided on a side of the thin-walled cylinder (411) close to the lifting mechanism (500); An end gasket (412), wherein the end gasket (412) is arranged on the inner top wall of the thin-walled cylinder (411); A spring (413), wherein the spring (413) is disposed in the thin-walled cylinder (411), and one end of the spring (413) is connected to the end gasket (412); A compression gasket (414), wherein the compression gasket (414) is arranged at the other end of the spring (413); A connecting rod (415), wherein the connecting rod (415) is disposed in the thin-walled cylinder (411) and one end of the connecting rod is connected to the extrusion gasket (414).

7. The automatic yield stress measuring device for 3D printing materials according to claim 6, characterized in that: The lifting mechanism (500) comprises: A lifting motor (510), wherein the lifting motor (510) is arranged on the top of the crossbeam (300), and an output shaft thereof passes through the crossbeam (300) and extends to the bottom of the crossbeam (300); A lifting screw (520), one end of which is connected to the output shaft of the lifting motor (510); A lifting disc (530), wherein an internal thread is provided in the middle of the lifting disc (530), and the lifting disc (530) is threadedly connected to the lifting screw (520) via the internal thread; A branch rod (540), wherein the branch rod (540) is arranged on the side of the lifting disc (530), one end of the branch rod is connected to the lifting disc (530), and the other end is connected to the connecting rod (415) through the through groove; The number and arrangement positions of the branch rods (540) correspond to those of the penetration testing mechanism (400).

8. The automatic yield stress measuring device for 3D printing materials according to claim 7, characterized in that: It also includes a wiring port (700), which is arranged on the side of the base (100) and is electrically connected to the controller (600).

9. A calibration method for an automated yield stress measuring device for 3D printing materials, capable of realizing the calibration of an automated yield stress measuring device for cement-based 3D printing materials as claimed in any one of claims 1 to 8, characterized in that: The method comprises: According to the pre-test results of the material to be tested, a matching test needle, weight and spring are selected so that the penetration depth of the test needle into the material to be tested after stirring is close to the depth of the cavity where the material to be tested is placed; According to the parameters of the pre-tested test needle, weight and spring, the theoretical calculation formula between the needle penetration and the yield stress of the material to be tested is calculated theoretically; The rheological properties of the tested material are tested at different times to determine its yield stress; the needle penetration of the material is tested at different times, and the theoretical calculation formula is corrected by fitting to obtain a corrected calculation formula between the yield stress and needle penetration of the tested material; The modified calculation formula is input into the device, and the yield stress of the test material at different times can be obtained through program calculation.

10. The calibration method of the automatic measurement device for yield stress of 3D printing materials according to claim 9, characterized in that: The theoretical calculation formula is: The correction calculation formula is: Where τ0 represents the yield stress of the material to be tested, H represents the penetration depth of the test needle, R represents the radius of the test needle, h2 represents the length of the test needle, m represents the mass of the test needle and the weight, k is the compression coefficient of the spring, x is the compressed length of the spring, and a and b are correction coefficients.

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