Adjustable preload spring mechanism and assembly method based on integrated stamping

Abstract

The present invention relates to the technical field of preload springs, and in particular to an adjustable preload spring mechanism and assembly method based on integral stamping. The assembly method comprises: determining a first detection step length based on the maximum working load of the spring to be assembled to determine a number of different detection external forces, performing a number of force-controlled force tests on the spring to be assembled to obtain a dimensional change trend, determining a second detection step length based on the dimensional change trend and the first detection step length to determine a number of different detection dimensions, performing a number of dimension-controlled force tests on the spring to be assembled to obtain a preload change trend, a loading path, and an unloading path; based on each loading path and unloading path, correcting the preload change trend; calibrating the preload value of a preload adjustment ruler, performing initial preload, and completing the assembly of the adjustable preload spring. The present invention improves the accuracy of preload adjustment of integrally stamped springs.

Description

Technical Field

[0001] The present invention relates to the technical field of preload springs, and in particular to an adjustable preload spring mechanism based on integral stamping and an assembly method. Background Art

[0002] For die springs used in integrated stamping (especially high-speed continuous stamping), designing and controlling pre-compression is crucial to ensuring stable die operation, extending spring life, and preventing product defects and even die damage. Pre-compression ensures initial pressing / ejection force. The moment the punch contacts the sheet, pre-compression is already present, providing sufficient pressing force (to prevent sheet movement and wrinkling) or ejection force (to ensure smooth demolding of the workpiece). Pre-compression also tauts the spring before it begins operating, enabling a quicker and more stable response to impact loads, reducing vibration and noise, preventing instantaneous overload or instability, and resisting shock, maintaining stability, and extending spring life. When the pre-compression is insufficient, the noise and vibration will be aggravated, and the initial pressing force will be insufficient. The movement of the sheet metal during punching or forming will cause the sheet metal to deflect and wrinkle. When the sheet metal deflects seriously, it will cause die gnawing and edge chipping. At the same time, the spring will be suddenly subjected to a huge impact from the relaxed state, and the stress peak may exceed the material limit, which will lead to the impact fracture of the spring. When the pre-compression is too large, it will cause the sheet metal or workpiece to be crushed, and will also accelerate the wear of the guide components (guide pillars, guide sleeves). At the same time, the initial stress is too high, which will greatly shorten the effective fatigue life of the spring.

[0003] Currently, the pre-tightening force of springs used for integral stamping is often completely dependent on the operator's experience, and the adjustment of the pre-tightening force is often repeated by adding or removing hardened gaskets, making it impossible to accurately control the pre-compression degree of the spring during the assembly process. Therefore, the development of a mechanism and assembly method that can precisely control the pre-compression degree of the spring is of great practical significance.

[0004] Chinese Patent Publication No.: CN110763384B discloses a spring preload force detection device and method. The detection device includes a base, a column, a crossbar, a pressure assembly, and a clamping assembly. By applying a positive pressure equal to the preload force to the clamping assembly in the detection device, and at the same time, the pressure assembly applies a force in the opposite direction of the positive pressure to the crossbar, the spring to be measured is compressed to a preloaded state, and the length of the two force arms on the crossbar is measured. According to the lever principle, the magnitude of the preload force applied to the spring to be measured can be calculated. It can be seen that the spring preload force detection device and method have the following problems: it is impossible to measure the deformation of the spring to be measured in real time while applying pressure to the spring to be measured, and it is impossible to obtain the relationship between the deformation of the spring to be measured and the corresponding preload force. Summary of the Invention

[0005] To this end, the present invention provides an adjustable preload spring mechanism based on integral stamping to overcome the problem in the prior art that the correspondence between the preload force of the adjustable preload spring and the spring deformation cannot be accurately identified, resulting in the inability to accurately adjust the preload force of the adjustable preload spring.

[0006] To achieve the above objectives, the present invention provides, on the one hand, an assembly method of an adjustable preload spring mechanism based on integral stamping, comprising:

[0007] Step S1, obtaining a maximum working load of a spring to be assembled, and determining a first detection step length of the spring to be assembled based on the maximum working load;

[0008] Step S2: determining a plurality of different test external forces using the first test step length, performing a plurality of force-controlled force tests on the spring to be assembled, obtaining dimensional change trends corresponding to the spring to be assembled under each test external force state, and determining a second test step length for the spring to be assembled based on the dimensional change trends and the first test step length;

[0009] Step S3, determining a plurality of different test dimensions using the second test step length, performing a plurality of dimension-controlled force tests on the spring to be assembled, and obtaining a corresponding preload force variation trend, preload force loading path, and preload force unloading path of the spring to be assembled under each test dimension state;

[0010] Step S4, determining corresponding hysteresis characteristic data based on the preload path and the preload unload path in each dimensional control force test, and correcting the preload change trend using the hysteresis characteristic data to obtain a corrected preload change trend;

[0011] Step S5, obtaining a linear variation range and a nonlinear variation range of the preload force of the spring to be assembled based on an analysis of the variation trend of the corrected preload force, so as to determine a calibration range corresponding to the preload force adjustment ruler;

[0012] Step S6: calibrate the preload value of the preload adjustment ruler according to the calibration range, perform initial preload on the adjustable preload spring according to usage requirements, and complete the assembly of the adjustable preload spring.

[0013] Furthermore, the step S1 includes:

[0014] Step S11, determining the maximum allowable preload of the spring to be assembled according to the maximum working load;

[0015] Step S12, performing a reference force test on the spring to be assembled using the maximum allowable preload force to obtain a maximum preload dimension of the spring to be assembled under the maximum allowable preload force;

[0016] Step S13, determining a first detection frequency of the spring to be assembled based on the maximum pre-tightening size;

[0017] Step S14, determining a first detection step length of the spring to be assembled based on the maximum allowable preload force and the first detection frequency;

[0018] The first detection frequency is the total number of different external forces used in the force-variable force detection.

[0019] Furthermore, the first detection step length is a change in the detection external force applied to the spring to be assembled in adjacent times during the force-controlled force detection;

[0020] The second detection step is the change in the detection size of the spring to be assembled between adjacent times in the size-controlled force detection.

[0021] Furthermore, the step S2 includes:

[0022] Step S21, performing force-controlled force testing on the spring to be assembled at the first testing frequency using several different test external forces determined by the first testing step length, and obtaining dimensional data corresponding to the spring to be assembled in each force-controlled force testing;

[0023] Step S22, recording each detected external force and the corresponding dimensional data to form mapping data points of force-induced dimensional data-detected external force, so as to obtain the dimensional change trend of the spring to be assembled;

[0024] Step S23: determining the second detection step length of the spring to be assembled according to the size change trend and the first detection step length.

[0025] Furthermore, the step S23 includes:

[0026] Step S231, identifying the linear dimensional variation range and the nonlinear dimensional variation range of the spring to be assembled according to the slope variation characteristics of the dimensional variation trend;

[0027] Step S232: Calculate a reference second detection step length according to the maximum preload size and the first detection frequency;

[0028] Step S233, reducing the detection interval within the nonlinear size change range, and calculating a first sub-step length and a second sub-step length based on the reference second detection step length;

[0029] Step S234: Obtain the second detection step length according to the first sub-step length and the second sub-step length.

[0030] Furthermore, the step S231 includes:

[0031] Step S2311, performing a first-order derivative operation on the size change trend to obtain a first slope change sequence;

[0032] Step S2312, detecting a mutation point in the first slope change sequence, wherein the mutation point satisfies that the slope change value of the adjacent segment exceeds a preset mutation threshold;

[0033] Step S2313 : determining the preload force interval where the mutation point is located as the dimensional non-linear variation range, and determining the preload force intervals where the remaining points are located as the dimensional linear variation range.

[0034] Furthermore, step S3 includes:

[0035] Step S31, performing dimension-controlled force testing on the spring to be assembled at the second testing frequency using a plurality of different testing dimensions determined by the second testing step length, and synchronously collecting a preload force loading path and a preload force unloading path in each dimension-controlled force testing;

[0036] Step S32 , recording each detected dimension and the corresponding preload data to form mapping data points of preload data-detected dimension, so as to obtain the preload variation trend of the spring to be assembled.

[0037] Furthermore, the step S4 includes:

[0038] Step S41, determining hysteresis characteristic data corresponding to a plurality of compression amounts based on the absolute value of the difference between the preload force corresponding to the preload force loading path and the preload force unloading path at the same compression amount in a single size control force test;

[0039] Step S42, determining the hysteresis difference in the single size control force test according to the maximum value of each hysteresis characteristic data in the single size control force test;

[0040] Step S43, determining a maximum hysteresis difference according to the maximum value of the hysteresis differences in each size control force test;

[0041] Step S44, calculating a correction factor for the single size control force test based on the hysteresis difference and the maximum hysteresis difference in the single size control force test;

[0042] Step S45 , correcting the corresponding preload value in the preload variation trend by using the corresponding correction factor in each dimension control force detection to obtain a corrected preload variation trend.

[0043] Furthermore, the step S5 includes:

[0044] Step S51, obtaining a preload linear variation range and a preload nonlinear variation range of the spring to be assembled based on the size linear variation range and the size nonlinear variation range of the spring to be assembled;

[0045] Step S52: obtaining a calibration scale of the preload adjustment ruler based on the second detection step length and the corresponding preload in the modified preload variation trend.

[0046] The preload force adjustment scale is marked with a linear working section and a nonlinear working section identifier divided based on the preload force linear variation range and the preload force nonlinear variation range.

[0047] On the other hand, the present invention further provides an integrally stamped adjustable preload spring mechanism, which is assembled by the above-mentioned integrally stamped adjustable preload spring assembly method, comprising:

[0048] Adjustable preload spring;

[0049] an adjusting bolt, which is in contact with one end of the adjustable preload spring and is used to adjust the compression of the adjustable preload spring by tightening / loosening the bolt, so as to adjust the preload force of the adjustable preload spring;

[0050] a fastening nut, which cooperates with the adjusting bolt to fix the position of the adjusting bolt to fix the compression amount of the adjustable preload spring;

[0051] The preload adjustment ruler is provided with size scales and corresponding preload values, which are used to indicate the preload value corresponding to the relative position of the current adjustment bolt.

[0052] Compared with the existing technology, the beneficial effect of the present invention lies in that, by constructing a force control-size control dual-mode collaborative detection mechanism and a hysteresis effect dynamic correction model, the present invention generates a preload adjustment scale with a nonlinear warning mark, thereby realizing high-precision preload assembly of the integrated stamping die spring under extreme working conditions, and significantly improving the dynamic stability and service life of the stamping die.

[0053] Furthermore, the present invention accurately matches the actual force range of the mold spring during the stamping process through an adaptive step size design based on the maximum working load, thereby avoiding the risk of preload failure under impact load in traditional empirical preload methods.

[0054] Furthermore, the present invention detects the slope mutation point, clearly marks the nonlinear danger zone on the preload adjustment scale and accurately defines the preload linear working area, thereby ensuring that the mold spring is always in the optimal stiffness range and reducing the dimensional deviation of the stamping part caused by the fluctuation of the spring stiffness.

[0055] Furthermore, the present invention effectively compensates for the force difference caused by internal friction of the die spring during high-speed stamping cycles by establishing a correction factor for dimensional hysteresis compensation, thereby ensuring consistency between the static preload setting value and the dynamic working holding force.

[0056] Furthermore, the present invention converts complex spring characteristics into a visual preload adjustment ruler, allowing operators to complete high-precision preload without professional instruments, significantly shortening the maintenance downtime of the stamping die. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 Schematic diagram of an adjustable preload spring formed by integral stamping according to an embodiment of the present invention;

[0058] Figure 2 This is a flow chart of an assembly method of an adjustable preload spring based on integral stamping according to an embodiment of the present invention;

[0059] Figure 3 This is a flow chart of step S1 of a method for assembling an adjustable preload spring formed by integral stamping according to an embodiment of the present invention;

[0060] Figure 4 This is a flow chart of step S2 of the method for assembling an adjustable preload spring based on integral stamping according to an embodiment of the present invention;

[0061] Figure 5 This is a flow chart of step S23 of the method for assembling an adjustable preload spring based on integral stamping according to an embodiment of the present invention;

[0062] In the figure, 1-preload adjustment ruler; 11-preload scale; 12-size scale; 2-adjusting bolt; 3-fastening nut; 4-adjustable preload spring; 5-upper clamp; 6-limiting plate. DETAILED DESCRIPTION

[0063] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0064] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0065] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside", and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0066] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0067] For illustration, the adjustable preload spring formed by integral stamping in this embodiment is a stamping die spring.

[0068] See also Figure 1 As shown, it is a schematic diagram of an adjustable preload spring based on integral stamping according to an embodiment of the present invention. This embodiment provides an adjustable preload spring based on integral stamping, comprising:

[0069] Adjustable preload spring 4;

[0070] an adjusting bolt 2, which is in contact with one end of the adjustable preload spring and is used to adjust the preload force of the adjustable preload spring according to its elongation;

[0071] A fastening nut 3, which is connected to the adjusting bolt and is used to fix the position of the adjusting bolt;

[0072] The preload adjustment ruler 1 is provided with size scales and corresponding preload values, so as to indicate the preload value corresponding to the current adjustment bolt.

[0073] In this embodiment, the adjustable preload spring 4, the adjusting bolt 2 and the fastening nut 3 are installed in the upper clamping plate 5 of the movable die of the stamping die. When adjusting the preload force of the adjustable preload spring 4, the compression amount of the adjustable preload spring 4 relative to the limit plate 6 of the movable die is adjusted by tightening or loosening the adjusting bolt 2. The position of the adjustable preload spring 4 corresponding to the current position of the adjusting bolt 2 is obtained through the size scale 12 on the preload adjustment ruler 1. The reading of the preload scale 11 of the preload adjustment ruler 1 can directly read the preload force corresponding to the current compression amount of the adjustable preload spring 4, so as to achieve the effect of accurately adjusting the preload force of the adjustable preload spring 4 by adjusting the position of the adjusting bolt 2 on the preload adjustment ruler 1.

[0074] See also Figure 2 As shown, it is a flow chart of an assembly method of an adjustable preload spring based on integral stamping according to an embodiment of the present invention, comprising:

[0075] Step S1, obtaining a maximum working load of a spring to be assembled, and determining a first detection step length of the spring to be assembled based on the maximum working load;

[0076] It can be understood that the maximum working load of the spring to be assembled is the maximum value of the working load calibrated for the spring to be assembled in the stamping die.

[0077] See also Figure 3 As shown, it is a flow chart of step S1 of the assembly method of the adjustable preload spring based on integral stamping according to an embodiment of the present invention. Specifically, step S1 includes:

[0078] Step S11, determining the maximum allowable preload of the spring to be assembled according to the maximum working load;

[0079] In a specific embodiment, according to the maximum working load F of the stamping die spring max , calculate the maximum allowable preload F through the preload safety factor q a , maximum allowable preload force F a The calculation formula is as follows:

[0080] ,

[0081] Among them, F a is the maximum allowable preload force, in Newton (N); F max is the maximum working load, in Newton (N); q is the preload safety factor, ranging from 0.1 to 0.3. Preferably, q is 0.2.

[0082] It is understood that the preload safety factor q is determined according to the safety margin requirements of the spring under dynamic load conditions during stamping work to ensure that the preload does not exceed the yield limit of the spring and avoid plastic deformation; the maximum working load F max Provided by the data sheet of the stamping machine on which the spring is to be assembled.

[0083] Step S12, performing a reference force test on the spring to be assembled using the maximum allowable preload force to obtain a maximum preload dimension of the spring to be assembled under the maximum allowable preload force;

[0084] In a specific embodiment, the reference force test is to apply the maximum allowable preload force F to the spring to be assembled on a universal material testing machine. a , maintain the pressure for 30 seconds and measure the compressed size of the spring, recorded as L max, unit is millimeter (mm); test conditions are: loading rate 60N / min (in compliance with the quasi-static test specification of "GB / T 23934-2015"), ambient temperature: 23°C (eliminating the influence of thermal expansion).

[0085] Step S13: determining a first detection frequency of the spring to be assembled based on the maximum preload size, wherein the first detection frequency is the total number of different detection external forces used in the force-variable force detection.

[0086] In a specific embodiment, the calculation formula for the first detection frequency is specifically:

[0087] ,

[0088] Wherein, N is the first detection frequency, which is the result of rounding up to ensure that the full range is covered; d is the dimensional resolution, the unit is millimeter (mm), preferably, d is 1 mm.

[0089] Step S14, determining a first detection step length of the spring to be assembled based on the maximum allowable preload force and the first detection frequency;

[0090] In a specific embodiment, the calculation formula of the first detection step length is specifically:

[0091] ,

[0092] Wherein, △F1 is the first detection step length, and the unit is Newton (N).

[0093] It can be understood that the equal step size ΔF1 makes the detection points evenly distributed in the working range of the spring to be assembled, which is used as a premise for the linear assumption of Hooke's law.

[0094] The present invention obtains the first detection step length based on the maximum preload force and maximum preload stroke of the spring to be tested and the spring accuracy grade, thereby ensuring that the sampling density of force-dimensional data matches the spring specifications, eliminating the detection blind spots caused by manual experience, establishing a reusable detection parameter system, and unifying the test process for springs of different specifications.

[0095] Step S2: determining a plurality of different test external forces using the first test step length, performing a plurality of force-controlled force tests on the spring to be assembled, obtaining dimensional change trends corresponding to the spring to be assembled under each test external force state, and determining a second test step length for the spring to be assembled based on the dimensional change trends and the first test step length;

[0096] See also Figure 4As shown, it is a flow chart of step S2 of the assembly method of the adjustable preload spring based on integral stamping according to an embodiment of the present invention. Specifically, step S2 includes:

[0097] Step S21, performing force-controlled force testing on the spring to be assembled at the first testing frequency using several different test external forces determined by the first testing step length, and obtaining dimensional data corresponding to the spring to be assembled in each force-controlled force testing;

[0098] In a specific embodiment, a servo press is used to apply a detection external force to the spring to be assembled, and the external force value is increased by a first detection step length ΔF1.

[0099] Step S22 , recording each detected external force and the corresponding dimensional data to form mapping data points of force-induced dimensional data-detected external force, so as to obtain the dimensional change trend of the spring to be assembled.

[0100] In a specific embodiment, a laser displacement sensor is used to record the spring compression size L corresponding to the external force detected in each force control force detection. i , generate a data point set, generate a data point set {(F0, L0), (F1, L1), (F2, L2), ..., (F i , L i )}, draw a force-size line graph based on the data point set, that is, the size change trend, with the horizontal axis being the detected external force F i , the vertical axis is the spring compression dimension L i ; It can be understood that, where i=0,1,2,3,4...N, where F i+1 =F i +ΔF1,F N =F a , F0=0.

[0101] In a single force control test, after applying external force, stabilize the pressure for 3 seconds and then read the corresponding spring compression size L. i To ensure the spring deformation is stable.

[0102] Step S23, determining the second detection step length of the spring to be assembled according to the dimensional change trend and the first detection step length;

[0103] See also Figure 5 As shown, it is a flow chart of step S23 of the assembly method of the adjustable preload spring based on integral stamping according to an embodiment of the present invention. Specifically, step S23 includes:

[0104] Step S231, identifying the linear dimensional variation range and the nonlinear dimensional variation range of the spring to be assembled according to the slope variation characteristics of the dimensional variation trend;

[0105] Specifically, step S231 includes:

[0106] Step S2311, performing a first-order derivative operation on the size change trend to obtain a first slope change sequence;

[0107] In a specific embodiment, the first-order derivative of the dimensional change trend is calculated as follows:

[0108] ,

[0109] The slope sequence is {k0,k1,k2,k3,...,k i-1}.

[0110] Step S2312, detecting a mutation point in the first slope change sequence, wherein the mutation point satisfies that the slope change value of the adjacent segment exceeds a preset mutation threshold;

[0111] In a specific embodiment, the determination of the mutation point is specifically as follows:

[0112] When k i satisfy When k i is the mutation point, where p is the preset mutation threshold, preferably 0.2.

[0113] It is understandable that the nonlinear deformation of the spring will cause the slope of the force-size curve to change. This embodiment quantifies this change through derivative calculation to accurately determine the nonlinear deformation area of ​​the spring.

[0114] Step S2313 : determining the preload force interval where the mutation point is located as the dimensional non-linear variation range, and determining the preload force intervals where the remaining points are located as the dimensional linear variation range.

[0115] In a specific embodiment, if there is a mutation point k i When [F i , F i+2 ] is the nonlinear size change range, and the preload range of the remaining points is defined as the linear size change range.

[0116] It is understandable that since the data obtained by the test are discrete points, the mutation point k i Indicates [F i , F i+1 ] differs from the previous slope by more than the preset mutation threshold, so [F i , F i+2 ] is the nonlinear size variation range to ensure F i+1 Located in the range of nonlinear size variation.

[0117] Step S232: Calculate a reference second detection step length according to the maximum preload size and the first detection frequency;

[0118] In a specific embodiment, the calculation formula of the reference second detection step length is specifically:

[0119] ,

[0120] Wherein, △L1 is the second benchmark detection step length, in millimeters (mm).

[0121] Step S233, reducing the detection interval within the nonlinear size change range, and calculating a first sub-step length and a second sub-step length based on the reference second detection step length;

[0122] In a specific embodiment, the first sub-step length ΔL within the nonlinear size variation range is 11 =a×△L1, where a is the density coefficient, preferably, it is 0.3 to 0.5.

[0123] The second sub-step length △L within the nonlinear size change range 12 =△L1.

[0124] Step S234: Obtain the second detection step length according to the first sub-step length and the second sub-step length.

[0125] In a specific embodiment, the first sub-step and the second sub-step are integrated to obtain a second detection step. It can be understood that the second detection step is a non-uniformly increasing detection size sequence. For example, the boundary point between a non-linear size change range and an adjacent linear size change range is L b , corresponding L must be set b The size control force detection is performed, and at least a size detection sequence that increases according to the corresponding sub-step length is set within two adjacent range dividing points according to the corresponding sub-step length.

[0126] It is understandable that high-density capture of data within the range of nonlinear dimensional changes can avoid missing failure risk points.

[0127] Step S3, determining a plurality of different test dimensions using the second test step length, performing a plurality of dimension-controlled force tests on the spring to be assembled, and obtaining a corresponding preload force variation trend, preload force loading path, and preload force unloading path of the spring to be assembled under each test dimension state;

[0128] It is understood that during a single dimension-controlled force test, the test dimensions corresponding to the test dimension sequence are used as the compression of the spring to be assembled, and the corresponding preload value of the spring to be assembled is obtained under each test dimension state. Preferably, after each compression is maintained for 3 seconds, the corresponding spring force value is read as the preload value to ensure stable spring deformation.

[0129] Specifically, step S3 includes:

[0130] Step S31, performing dimension-controlled force testing on the spring to be assembled at the second testing frequency using a plurality of different testing dimensions determined by the second testing step length, and synchronously collecting a preload force loading path and a preload force unloading path in each dimension-controlled force testing;

[0131] Step S32 , recording each detected dimension and the corresponding preload data to form mapping data points of preload data-detected dimension, so as to obtain the preload variation trend of the spring to be assembled.

[0132] Specifically, the second detection step is the change in the detection size of the spring to be assembled between adjacent times in the size-controlled force detection;

[0133] In a specific embodiment, a servo press is used to apply a test external force to the spring to be assembled, and the test mode is set to the displacement control mode. According to the second test step sequence ΔL (including the first sub-step sequence ΔL of the nonlinear section) determined in step S2, 11 and the second sub-step sequence △L of the linear segment 12 and demarcation point sequence) for stepwise compression, and generate a data point set {(L0, F0), (L1, F1), (L2, F2), ..., (L j , F j )}, draw a dimension-force line graph based on the data point set, that is, the preload force change trend, and its horizontal axis is the detection dimension L j , the longitudinal axis is the preload force F j .

[0134] Among them, when the servo press compresses the spring to be assembled to the current detection size, it maintains a stable state for 2 seconds (eliminating creep interference) and records the loading force F displayed by the real-time value of the sensor. load , obtain the loading path curve under the detection size, release the spring to the zero load state, re-compress it to the same detection size, release the spring to the zero load state again, and record the unloading force F displayed by the real-time value of the sensor unload , the unloading path curve under the detection size is obtained, where the loading force F is recorded with the size resolution d as the step size load and unloading force Funload .

[0135] Step S4, determining corresponding hysteresis characteristic data based on the preload path and the preload unload path in each dimensional control force test, and correcting the preload change trend using the hysteresis characteristic data to obtain a corrected preload change trend;

[0136] Specifically, step S4 includes:

[0137] Step S41, determining hysteresis characteristic data corresponding to a plurality of compression amounts based on the absolute value of the difference between the preload force corresponding to the preload force loading path and the preload force unloading path at the same compression amount in a single size control force test;

[0138] In a specific embodiment, for any L j , its hysteresis characteristic data is {Δf1, Δf2, Δf3, ..., Δf s}, where the loading force F is recorded with a resolution d as the step size load and unloading force F unload Therefore, the total amount of hysteresis characteristic data s=L j / d, it can be understood that Δf s =|F load -F unload |.

[0139] Step S42, determining the hysteresis difference in the single size control force test according to the maximum value of each hysteresis characteristic data in the single size control force test;

[0140] In a specific embodiment, take each detection size L j The maximum value in the corresponding hysteresis characteristic data is recorded as the detection size L j Hysteresis difference Δf j .

[0141] Step S43, determining a maximum hysteresis difference according to the maximum value of the hysteresis differences in each size control force test;

[0142] In a specific embodiment, take all detection dimensions L j The corresponding hysteresis difference Δf j The maximum value among them is recorded as the maximum hysteresis difference Δf max .

[0143] Step S44, calculating a correction factor for the single size control force test based on the hysteresis difference and the maximum hysteresis difference in the single size control force test;

[0144] In a specific embodiment, the correction factor t jThe calculation formula is as follows:

[0145] ,

[0146] Wherein, b is the hysteresis attenuation coefficient, and its value range is 0.2 to 0.3, and preferably, it is 0.2.

[0147] Step S45 , correcting the corresponding preload value in the preload variation trend by using the corresponding correction factor in each dimension control force detection, to obtain a corrected preload variation trend.

[0148] In a specific embodiment, for each preload force F j , with corrected preload F j '=F j ×t j ;

[0149] According to the test size and corresponding corrected preload of each compressed spring in each size-controlled force test, a data point set {(L0, F0'), (L1, F1'), (L2, F2'), ..., (L j , F j ')}, draw a size-force line graph based on the data point set, that is, the trend of the change of the modified preload force, and its horizontal axis is the detection size L j , the longitudinal axis is the preload force F j '.

[0150] It is understandable that the mold spring produces a hysteresis effect due to the internal friction of the material and the structural deformation during operation, which causes the loading path and the unloading path to separate, causing the preload setting value to deviate from the actual stiffness. j Quantify the hysteresis intensity of each size point, reflect the local nonlinearity of the spring, and dynamically attenuate the preload weight in the high hysteresis area. The larger the hysteresis value (the more serious the energy loss), the corresponding correction factor t j The smaller it is, the stronger the reduction of the corresponding preload force is, which achieves targeted suppression of nonlinear errors, makes the measured value close to the ideal linear response, and suppresses the influence of unreliable data.

[0151] Step S5, obtaining a linear variation range and a nonlinear variation range of the preload force of the spring to be assembled based on an analysis of the variation trend of the corrected preload force, so as to determine a calibration range corresponding to the preload force adjustment ruler;

[0152] Specifically, step S5 includes:

[0153] Step S51, obtaining a preload linear variation range and a preload nonlinear variation range of the spring to be assembled based on the size linear variation range and the size nonlinear variation range of the spring to be assembled;

[0154] In a specific embodiment, the dimensional linear change range and the dimensional nonlinear change range obtained in step S23 are directly mapped to the modified preload force change trend curve. The preload force interval corresponding to the dimensional linear change range is marked on the modified preload force change trend curve as the preload force linear change range, and the preload force interval corresponding to the dimensional nonlinear change range is marked as the preload force nonlinear change range.

[0155] Step S52: obtaining a calibration scale of the preload adjustment ruler based on the second detection step length and the corresponding preload in the modified preload variation trend.

[0156] The preload force adjustment scale is marked with a linear working section and a nonlinear working section identifier divided based on the preload force linear variation range and the preload force nonlinear variation range.

[0157] In a specific embodiment, the second detection step sequence ΔL is used as the scale interval, and the size scale is marked on the ruler body. The corresponding corrected preload value (read from the corrected preload change trend curve) is marked next to each size scale, and according to the division result of step S51, the working section is marked with color on the ruler body: preferably, the linear working section is marked in green, and the nonlinear working section is marked in red, so as to make a clear distinction.

[0158] The present invention converts the complex mechanical properties of the spring (linear / non-linear areas) into a scale tool that can be directly read by assemblers and uses color marking to forcibly distinguish between the safe area (linear area) and the dangerous area (non-linear area), avoiding reliance on experience.

[0159] Step S6: calibrate the preload value of the preload adjustment ruler according to the calibration range, perform initial preload on the adjustable preload spring according to usage requirements, and complete the assembly of the adjustable preload spring.

[0160] In this embodiment, the required preload is selected on the preload adjustment scale, and the adjustment bolt 2 is rotated to the preload scale 11 corresponding to the required preload to complete the initial preload. In subsequent use, the spring preload is adjusted by rotating the adjustment bolt 2 to the corresponding preload scale value.

[0161] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A method for assembling an adjustable preload spring based on integral stamping, characterized in that: include: Step S1, obtaining the maximum working load of the spring to be assembled, and determining the first detection step length of the spring to be assembled based on the maximum working load, including: Step S11, determining the maximum allowable preload of the spring to be assembled according to the maximum working load; Step S12, performing a reference force test on the spring to be assembled using the maximum allowable preload force to obtain a maximum preload dimension of the spring to be assembled under the maximum allowable preload force; Step S13, determining a first detection frequency of the spring to be assembled based on the maximum pre-tightening size; Step S14, determining a first detection step length of the spring to be assembled based on the maximum allowable preload force and the first detection frequency; Step S2, determining a plurality of different detection external forces with the first detection step length, performing a plurality of force-controlled force tests on the spring to be assembled, obtaining a dimensional change trend corresponding to the spring to be assembled under each detection external force state, and determining a second detection step length of the spring to be assembled based on the dimensional change trend and the first detection step length, including: Step S21: performing force-controlled force testing on the spring to be assembled at the first testing frequency using a plurality of different testing external forces determined by the first testing step length, and obtaining dimensional data corresponding to the spring to be assembled in each force-controlled force testing, wherein the first testing frequency is the total number of different testing external forces used in the force-controlled force testing; and the first testing step length is the amount of change in the testing external force applied to the spring to be assembled between adjacent force-controlled force testing times. Step S22, recording each detected external force and the corresponding dimensional data to form mapping data points of force-induced dimensional data-detected external force, so as to obtain the dimensional change trend of the spring to be assembled; Step S23, determining the second detection step length of the spring to be assembled according to the dimensional change trend and the first detection step length; Step S3, determining a plurality of different test dimensions using the second test step length, performing a plurality of dimension-controlled force tests on the spring to be assembled, and obtaining a corresponding preload force variation trend, a preload force loading path, and a preload force unloading path of the spring to be assembled under each test dimension state, wherein the second test step length is a variation in the test dimension of the spring to be assembled between adjacent times in the dimension-controlled force test; Step S4, determining corresponding hysteresis characteristic data based on the preload path and the preload unload path in each dimensional control force test, and correcting the preload change trend using the hysteresis characteristic data to obtain a corrected preload change trend; Step S5, obtaining a linear variation range and a nonlinear variation range of the preload force of the spring to be assembled based on an analysis of the variation trend of the corrected preload force, so as to determine a calibration range corresponding to the preload force adjustment ruler; Step S6: calibrate the preload value of the preload adjustment ruler according to the calibration range, perform initial preload on the adjustable preload spring according to usage requirements, and complete the assembly of the adjustable preload spring.

2. The assembly method of the adjustable preload spring based on integral stamping according to claim 1, characterized in that: The step S23 includes: Step S231, identifying the linear dimensional variation range and the nonlinear dimensional variation range of the spring to be assembled according to the slope variation characteristics of the dimensional variation trend; Step S232: Calculate a reference second detection step length according to the maximum preload size and the first detection frequency; Step S233, reducing the detection interval within the nonlinear size change range, and calculating a first sub-step length and a second sub-step length based on the reference second detection step length; Step S234: Obtain the second detection step length according to the first sub-step length and the second sub-step length.

3. The assembly method of the adjustable preload spring based on integral stamping according to claim 2, characterized in that: The step S231 includes: Step S2311, performing a first-order derivative operation on the size change trend to obtain a first slope change sequence; Step S2312, detecting a mutation point in the first slope change sequence, wherein the mutation point satisfies that the slope change value of the adjacent segment exceeds a preset mutation threshold; Step S2313 : determining the preload force interval where the mutation point is located as the dimensional non-linear variation range, and determining the preload force intervals where the remaining points are located as the dimensional linear variation range.

4. The assembly method of the adjustable preload spring based on integral stamping according to claim 3, characterized in that: The step S3 comprises: Step S31, performing dimension-controlled force testing on the spring to be assembled at a second testing frequency using a plurality of different testing dimensions determined by the second testing step length, and synchronously collecting a preload force loading path and a preload force unloading path in each dimension-controlled force testing; Step S32 , recording each detected dimension and the corresponding preload data to form mapping data points of preload data-detected dimension, so as to obtain the preload variation trend of the spring to be assembled.

5. The assembly method of the adjustable preload spring based on integral stamping according to claim 4, characterized in that: The step S4 comprises: Step S41, determining hysteresis characteristic data corresponding to a plurality of compression amounts based on the absolute value of the difference between the preload force corresponding to the preload force loading path and the preload force unloading path at the same compression amount in a single size control force test; Step S42, determining the hysteresis difference in the single size control force test according to the maximum value of each hysteresis characteristic data in the single size control force test; Step S43, determining a maximum hysteresis difference according to the maximum value of the hysteresis differences in each size control force test; Step S44, calculating a correction factor for the single size control force test based on the hysteresis difference and the maximum hysteresis difference in the single size control force test; Step S45 , correcting the corresponding preload value in the preload variation trend by using the corresponding correction factor in each dimension control force detection to obtain a corrected preload variation trend.

6. The assembly method of the adjustable preload spring based on integral stamping according to claim 5, characterized in that: The step S5 comprises: Step S51, obtaining a preload linear variation range and a preload nonlinear variation range of the spring to be assembled based on the size linear variation range and the size nonlinear variation range of the spring to be assembled; Step S52: obtaining a calibration scale of the preload adjustment ruler based on the second detection step length and the corresponding preload in the modified preload variation trend. The preload force adjustment scale is marked with a linear working section and a nonlinear working section identifier divided based on the preload force linear variation range and the preload force nonlinear variation range.

7. An integrally stamped adjustable preload spring mechanism, assembled using the assembly method for an integrally stamped adjustable preload spring according to any one of claims 1 to 6, characterized in that: include: Adjustable preload spring; an adjusting bolt, which is in contact with one end of the adjustable preload spring and is used to adjust the compression of the adjustable preload spring by tightening / loosening the bolt, so as to adjust the preload force of the adjustable preload spring; a fastening nut, which cooperates with the adjusting bolt to fix the position of the adjusting bolt to fix the compression amount of the adjustable preload spring; The preload adjustment ruler is provided with size scales and corresponding preload values, which are used to indicate the preload value corresponding to the relative position of the current adjustment bolt.

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