A method for improving the assembly accuracy of multi-stage lifting rod nut arrangement

Abstract

The present application relates to a kind of method for improving the accuracy of multi-stage lifting rod assembly nut arrangement combination, comprising: reference surface position size measurement: determine 5 reference surfaces: lifting rod lower end surface nut bottom plane, lifting rod upper end flange surface, locking sleeve upper end surface, locking mechanism inner ring end surface, locking mechanism outer ring end surface;Measure An, Bn, Cn;Size chain calculation;Equal pitch simulation assembly;Guiding key rotation dislocation compensation;Parallel set identification;Nut is assembled in lifting rod.The present application solves the nut assembly position arrangement path selection problem, improves the first pass rate;At the same time, ensure that the assembly process is standard, safe and reliable, reduce labor intensity, improve production efficiency.

Description

Technical Field

[0001] This invention relates to the field of servo drive precision assembly technology, and in particular to a method for improving the accuracy of nut arrangement and combination in multi-stage lifting rod assembly. Background Technology

[0002] With the increasing demand for high-altitude installation of electronic equipment, various lifting devices and lifting platforms have been widely adopted. Multi-stage lever-combined lifting mechanisms are currently the main structural form of lifting equipment, and their drive methods include screw drive, hydraulic drive, and wire rope pull.

[0003] The lifting rod based on screw drive rises by rotating the screw, which in turn raises the nut on the lifting rod, causing the corresponding first-stage lifting rod to rise accordingly. When the first-stage lifting rod reaches its position, it automatically locks with the second-stage lifting rod, causing the second-stage lifting rod to rise. During the ascent of the second-stage lifting rod, the nut on it is forced into the screw, and the combined force drives the second-stage lifting rod upward while the nut in the first-stage lifting rod disengages from the screw. The same mechanism is repeated, with the second-stage lifting rod driving the third-stage lifting rod upward, and so on, until the final lifting rod is reached.

[0004] This patent uses a 6-stage lifting rod assembly as an example. The arrangement of the nut assembly positions for the 6-stage lifting rod involves six threaded screw nuts with external splines arranged sequentially. Each nut has 10 selectable assembly positions (each nut has 10 splines corresponding to 10 keyways on the lifting rod base). Only one set of assembly arrangements yields the optimal result. Specifically, the 6-stage lifting rod has 6 nuts, each with 10 selectable assembly positions within its corresponding rod component, and the position selection is independent. Therefore, for a lifting device composed of 6-stage lifting rods, the total number of possible nut assembly combinations is 10 to the power of 6, or 10^6. This uniqueness of the arrangement results in a very low first-time pass rate for the nut assembly positions, leading to multiple rework and disassembly steps during the lifting rod assembly, affecting the assembly cycle and assembly pass rate. To improve the final assembly success rate, the traditional method is to conduct stage-by-stage assembly tests on the lifting rod to reduce rework; after two stages of assembly tests are passed, the next stage is installed, and this process is repeated until the final stage is completed. Step-by-step assembly testing still cannot guarantee successful assembly on the first attempt; it only involves rework at each stage and cannot guarantee that the assembly will be done correctly the first time. As the number of assembly stages increases, the amount of rework also increases. Step-by-step assembly is merely trial and error; problems can be clearly located, reducing the amount of overall disassembly and rework, and avoiding endless cycles of rework. Therefore, exploring a simple, efficient method for assembling six levels of nuts in parallel in one go is of great significance.

[0005] While there are numerous reports in the literature on automated lifting mast equipment with single-function operation, there are very few reports and patents on the assembly technology of nut placement and combination for multi-stage lifting masts. Summary of the Invention

[0006] To address the existing technical problems, this invention provides a method for improving the accuracy of nut arrangement and combination in multi-stage lifting rod assembly.

[0007] The specific content of this invention is as follows: A method for improving the accuracy of the arrangement and combination of nuts in multi-stage lifting rod assembly, comprising the following steps:

[0008] Step 1: Measurement of reference plane positions and dimensions: Determine 5 reference planes: the bottom plane of the nut at the lower end of the lifting rod, the flange face at the upper end of the lifting rod, the upper end face of the locking sleeve, the inner ring end face of the locking mechanism, and the outer ring end face of the locking mechanism; Measure dimension A between the bottom plane of the nut and the upper end face of the locking sleeve. n Dimension B between the inner ring end face and the outer ring end face of the locking mechanism n Dimension C between the bottom plane of the nut and the upper flange face of the lifting rod n n is a positive integer, referring to the nth level of the lifting rod;

[0009] Step 2: Dimension chain calculation: Calculate the dimension between the bottom planes of the two nuts of the n-stage lifting rod and the n+1-stage lifting rod when the upper end face of its locking sleeve contacts the inner ring end face of the locking mechanism.

[0010] Step 3: Simulated Assembly with Equal Pitch: To simultaneously install n-grade nuts onto the lead screw, adjust the spacing D between adjacent nuts. n Adjust the spacing D between adjacent nuts in sequence. n+1 D n+2 …;

[0011] Step 4: Guide key rotation misalignment compensation: Measure the rotation misalignment compensation value G of the guide key for each independent tube and record it accordingly;

[0012] Step 5: Parallel Assembly Marking: Install n-level nuts simultaneously onto the lead screw and adjust the spacing D between adjacent nuts. n The relative assembly positions of the n-level nuts in the lifting rod are marked sequentially and level by level.

[0013] Step Six: Assemble the nuts in the lifting rod: Install the marked splines at their relative positions on the same straight line along the axial direction.

[0014] Furthermore, in step two, the dimension L between the bottom planes of the two nuts of the n-level lifting rod and the n+1-level lifting rod is... n-（n+1） =C n+1 -(A n -B n )

[0015] Further, in step 3, adjust the spacing D between adjacent nuts n =L n-（n+1） -k×P; wherein k is an integer, P is the lead of the screw shaft, and the value of k is selected to ensure that D n is greater than the thickness of the nut, thereby ensuring that there is a spacing between adjacent nuts.

[0016] Further, in step 4, during measurement, for the same single independent tube, any one of the guide keys is selected for measurement, and the rotation angle value and direction are recorded and calculated.

[0017] Further, in step 5, after inspection and confirmation, rotational misalignment reverse rotation compensation is performed correspondingly on all stages of nuts in sequence; with the same direction on the same side of the axis of the screw shaft as the reference, the relative position line of the same direction axis is marked on the external spline outer circle of the nut outer circle.

[0018] The present invention provides a new method for simultaneous assembly of multi-stage lifting rod nuts and ensuring accurate arrangement and combination of positions, which solves the problem of selecting the arrangement path for nut assembly positions and improves the first-pass yield through the five-step method of "dimension measurement of reference surfaces of single rod assemblies, dimension chain calculation for combined assembly, equal-magnification lead simulation assembly, rotational misalignment compensation for guide keys, and marking for simultaneous assembly". Meanwhile, it ensures that the assembly process is standardized, safe and reliable, reduces labor intensity, and improves production efficiency. Description of Drawings

[0019] Specific embodiments of the present invention are further illustrated below with reference to the accompanying drawings.

[0020] Figure 1 is a schematic diagram of the driving principle of a lifting device based on screw-nut transmission, wherein A) only schematically shows the relative positions of a two-stage lifting rod in an initial state; Figure B) schematically shows that the first-stage lifting rod rises under the drive of the screw shaft; Figure C) schematically shows that after the first-stage lifting rod rises in place, the locking mechanism is triggered to lock and connect the first-stage and the second-stage together for interlocking movement; Figure D) schematically shows that the second-stage lifting rod can rise in an interlocked manner driven by the first-stage lifting rod, and the drive nut of the second-stage lifting rod gradually sleeves onto the screw shaft; Figure E) schematically shows that the drive nut of the first-stage lifting rod gradually disengages from the screw shaft, and the first-stage lifting rod can rise in an interlocked manner driven by the second-stage lifting rod, completing the lifting relay transmission;

[0021] Figure 2 is a schematic diagram of positional dimensions between measurement reference surfaces (5 pieces);

[0022] Figure 3 is a schematic diagram of rotational misalignment compensation measurement for a guide key;

[0023] Figure 4 is a schematic diagram of the installation position of a single nut in the base of a lifting rod;

[0024] Figure 5This diagram illustrates the lifting boom in its locked and unlocked states.

[0025] Figure 6 This is a schematic diagram showing the measurement and adjustment of the spacing when n-grade nuts are installed simultaneously on the lead screw. Detailed Implementation

[0026] This invention discloses a method for improving the accuracy of nut arrangement in multi-stage lifting rod assembly. This method involves measuring the relative positional dimension A of the nuts in each stage of the lifting rod. n B n (n is the nth level lifting rod), through dimensional chain calculations, the dimension C of the nut reference surface and the positioning surface of the lifting rod as it rises and falls to the locked state in each level of the lifting rod is obtained. n According to size C n C n+1 Calculate the dimension L when the nuts of two adjacent lifting rods pass through the lead screw simultaneously. n-（n+1） This serves as the simulated assembly dimension for equal-pitch screw threads. Nuts used for assembling adjacent lifting rods are labeled with the corresponding lifting rod part numbers and simultaneously screwed into the screw thread for simulated assembly. Measurements are taken to ensure the distance between the reference surfaces of the two nuts is L. n-（n+1） Meanwhile, since the key inside the lifting rod rotates during the stretching process, this will be reflected in the fact that the nut rotates with the key during the lifting rod's ascent after assembly. Therefore, it is necessary to measure the rotational deviation of the key at the upper and lower ends of the rod and then compensate for the installation position of the nut (based on the position of the spline in the circumferential direction).

[0027] After confirming the nut position, mark the relative position lines on the circumference of the nut's outer circumference with splines; mark each level sequentially to complete the n-level nut position confirmation marking; when the n-level rod is formally assembled, ensure that the relative position lines marked on the nuts correspond to the assembly of each level of the lifting rod, and that the position lines marked on the n-level nuts are in the same lateral axis direction and tend to be on a straight line; this multi-level assembly position arrangement and combination ensures that when the lifting rod nuts are raised and lowered to the locked state, the distance between adjacent nuts is equal to a multiple of the thread pitch, thus improving the assembly first-pass yield.

[0028] The specific steps are as follows:

[0029] Step 1: Measurement of Reference Surface Position Dimensions: This refers to the measurement of the spatial position dimensions between all assembly positioning surfaces that affect the relative distance between the nuts on the two lifting rods after the nth lifting rod has been raised and lowered into position and locked with the n+1th lifting rod. Details are as follows:

[0030] Five reference surfaces are defined: the bottom plane of the nut at the lower end of the lifting rod (reference surface 1), the flange surface at the upper end of the lifting rod (reference surface 2), the upper end face of the locking sleeve (reference surface 3), the inner ring end face of the locking mechanism (reference surface 4, mating surface with the upper end of the locking sleeve), and the outer ring end face of the locking mechanism (reference surface 5, mating surface with the flange at the upper end of the lifting rod).

[0031] 1) Measure dimension A between “bottom plane of nut 1” and “upper end face of locking sleeve 3”. n ;

[0032] 2) Measure dimension B between “the inner ring end face of the locking mechanism (the mating surface with the upper end of the locking sleeve) 4” and “the outer ring end face of the locking mechanism (the mating surface with the upper flange of the lifting rod) 5”. n ;

[0033] 3) Measure the dimension C between "nut bottom plane 1" and "lifting rod upper flange face 2". n ;

[0034] Step Two: Dimension Chain Calculation: Determine which components make up the dimension chain and measure them individually; then calculate the relative distance between nuts on adjacent lifting rods by combining the dimension chains. Details are as follows:

[0035] Calculate the dimension L between the two "nut bottom planes 1" of the n-stage lifting rod and the n+1-stage lifting rod when the "upper end face 3 of the locking sleeve" contacts the "inner ring end face of the locking mechanism (mating surface with the upper end of the locking sleeve) 4". n-（n+1） =C n+1 -(A n -B n );

[0036] Step 3: Simulated Assembly with Equal Pitch: The nuts are assembled on the lead screw to simulate the "relative distance value" of the actual working state, thus ensuring that the two nuts are spaced "equal pitches" apart. This method seeks the unique position of two adjacent nuts in the circumferential direction; the arrangement of nuts for other stages of assembly follows the same method. Details are as follows:

[0037] To install n-grade nuts simultaneously on the lead screw (note the orientation of the nut's bottom surface), adjust the spacing D between adjacent nuts. n =L n-（n+1） -k×P; k is an integer, P is the screw pitch, and the value of k is chosen to ensure D n If the value is greater than the nut thickness value, ensure that there is a gap between adjacent nuts; adjust the gap D between adjacent nuts sequentially. n+1 D n+2 …

[0038] Do not directly use the spacing dimension L between adjacent nuts n-（n+1） It is because of L n-（n+1） The value is too large, making it impossible to guarantee that n-grade nuts can be installed on the same lead screw simultaneously.

[0039] Step Four: Guide Key Rotation Misalignment Compensation: During the nut's ascent with the lifting rod, straightness errors in the guide key during the forming process cause the nut to spiral upwards. This results in a deviation between the theoretical and actual positions of the nut after the two-stage lifting rod is locked. By measuring the rotational deviation values ​​of the keys at the upper and lower ends of the rod, a reverse compensation method is applied to the nut's installation position to ensure the nut returns to the position of the "equal pitch simulated assembly" assembly. Details are as follows:

[0040] Because the rotation angle deviation of the inner key (guide key) of each independent tube is inconsistent during the forming process, it is necessary to measure the rotation misalignment compensation value G of each tube separately and record it accordingly. At the same time, since the four inner keys in the same tube are stretched and formed simultaneously by the same mold, the rotation values ​​of the four inner keys in the same tube are equal. When measuring, it is only necessary to select any one key to measure, record and calculate the rotation angle value and direction (clockwise or counterclockwise).

[0041] Step 5: Parallel Assembly Identification: This includes: a set of nuts assembled in the lead screw to simulate the actual working state (equal pitch) and an identification mark for the simulated assembled state. Details are as follows:

[0042] Wait until all n-grade nuts are installed on the lead screw, and adjust the spacing D between adjacent nuts. n After inspection and confirmation, perform reverse rotation compensation for each level of nut in sequence to compensate for rotational misalignment (rotational misalignment compensation value G; the original position should be marked before compensation for easy measurement and inspection). This ensures that when the nut is raised or lowered to the locked position, the pitch is still equal to the original pitch.

[0043] Using the same direction on the same side of the lead screw axis as a reference, mark the relative position lines of the axis in the same direction on the outer circle of the nut with splines; mark them level by level to complete the marking of the relative assembly position of the n-level nuts in the lifting rod.

[0044] Step Six: Assemble the nut in the lifting rod.

[0045] For the assembly of n-level nuts in the lifting rod, there are 10 keyways corresponding to the installation position of a single nut in the lifting rod base. If there are no markings, there are 10 selectable assembly positions. However, only one assembly arrangement is correct. To correctly install the relative position of the n-level nuts in the lifting rod, simply install the "relative position of the marked splines on the same straight line along the axial direction".

[0046] The method of this application will be further explained below with reference to a specific example.

[0047] Example: Assembly of a 6-stage lifting rod based on screw drive, such as... Figure 1 The lifting assembly structure shown includes components such as a 6-stage lifting rod, a 6-stage nut, a 5-stage locking mechanism, and a lead screw. Specific steps are as follows (all dimensions are in mm):

[0048] Step 1: Measurement of the position and dimensions of the reference plane

[0049] according to Figure 2 The measurement dimensions are shown in the diagram. Measure and record the dimensions respectively:

[0050] 1) Measure the dimension A1 between “the bottom plane of the nut 1” and “the upper end face of the locking sleeve 3” to be 287.9.

[0051] 2) Measure the dimension B1 = 20.2 between “the inner ring end face of the locking mechanism (the mating surface with the upper end of the locking sleeve) 4” and “the outer ring end face of the locking mechanism (the mating surface with the upper flange of the lifting rod) 5”.

[0052] 3) Measure the dimension C2 = 3560 between “the bottom plane of the nut 1” and “the upper flange face of the lifting rod 2”;

[0053] Note: Since the dimensions between the assembly reference surfaces of the nuts of pipe 1 and pipe 2 are measured and calculated, C1 does not need to be measured;

[0054] 4) Measure and record the dimensions between the other reference planes.

[0055] Step 2: Dimension Chain Calculation

[0056] The dimensions between adjacent "nut bottom plane 1" of the first-stage lifting rod and the sixth-stage lifting rod are calculated as follows: when the "upper end face 3 of the locking sleeve" contacts the "inner ring end face of the locking mechanism (mating surface with the upper end of the locking sleeve) 4".

[0057] Table 1 Dimensions between adjacent “nut bottom plane 1”

[0058] Step 3: Simulated assembly with equal pitch

[0059] like Figure 6 As shown, install grade 6 nuts simultaneously on the lead screw (lead screw thread length 3360, pitch P=16; lead screw nut thickness=65); adjust the spacing D between adjacent nuts. n =L n-（n+1） -k (k is an integer) × P (lead screw pitch); the value of k is chosen to ensure D n The value is greater than the pitch value P; taking the minimum spacing value of the 5-6 tube combination as an example, the value of k is evaluated and calculated as follows:

[0060] k = (3059.4 - 65) / 16 = 187.15. Since k is an integer, and we need to ensure D... n >P, take k=186;

[0061] Calculate D accordingly n for:

[0062] D1 = 3292.3 - 186 × 16 = 316.3

[0063] D2 = 3250 - 186 × 16 = 274

[0064] D3 = 3189 - 186 × 16 = 213

[0065] D4 = 3121.4 - 186 × 16 = 145.4

[0066] D5 = 3059.4 - 186 × 16 = 83.4

[0067] Step 4: Parallel assembly onto the lead screw

[0068] Install all 6 grade nuts on the lead screw at the same time, and adjust the spacing D1, D2, D3, D4, D5 between adjacent nuts. After checking and confirming, mark the relative position lines of the axis in the same direction on the outer circle of the nut with spline, using the same direction as the reference along the same axis of the lead screw.

[0069] Step 5: Compensation for misalignment of guide key rotation

[0070] like Figure 3 As shown, based on the measured values:

[0071] G1 = 6.52︒ (clockwise)

[0072] G2 = 6.57︒ (clockwise)

[0073] G3 = 6.50︒ (clockwise)

[0074] G4 = 6.55︒ (clockwise)

[0075] G5 = 6.55︒ (clockwise)

[0076] G6 = 6.56︒ (clockwise)

[0077] Perform rotational misalignment compensation on the grade 6 nuts in sequence (mark the original position before compensation for easy measurement and inspection) to ensure that the pitch is still equal when the nut is raised or lowered to the locked position.

[0078] Step Six: Marking the Relative Position of Grade 6 Nuts

[0079] After the compensation is confirmed, the nuts are marked sequentially at each level to complete the marking of the relative assembly positions of the 6-level nuts in the lifting rod.

[0080] Step 7: Assemble the nut in the lifting rod.

[0081] Assemble the 6-level nuts in the lifting rod in sequence, according to the "relative position of the marked splines on the same straight line along the axial direction";

[0082] The lifting booms were assembled step by step, and lifting tests were conducted to ensure successful lifting on the first attempt.

[0083] Compared to traditional assembly methods, this invention offers the following advantages: By employing a five-step method—"single-rod component reference surface dimension measurement, combined assembly dimension chain calculation, equal-pitch simulation assembly, guide key rotation misalignment compensation, and parallel assembly marking"—it solves the problems of trial-and-error assembly and cyclical rework inherent in traditional methods, ensuring that the multi-stage lifting rod nut assembly position arrangement path passes through the lifting process in a single operation. This significantly shortens the assembly cycle while improving product assembly quality and production safety. The equal-pitch simulation assembly method and misalignment compensation method provide a convenient assembly path and operational standard for selecting multi-stage nut assembly combinations for similar products. The parallel nut assembly marking also provides operational identification and standards for subsequent user disassembly and assembly during product repair and maintenance.

[0084] Many specific details have been set forth in the foregoing description to provide a thorough understanding of the present invention. However, the above description is merely a preferred embodiment of the present invention, and the present invention can be implemented in many other ways different from those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed above. Furthermore, any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, using the methods and techniques disclosed above, without departing from the scope of the present invention. Any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A method for improving the accuracy of the arrangement and combination of nuts in multi-stage lifting rod assembly, characterized in that: Includes the following steps: Step 1: Measurement of reference plane positions and dimensions: Determine 5 reference planes: the bottom plane of the nut at the lower end of the lifting rod, the flange face at the upper end of the lifting rod, the upper end face of the locking sleeve, the inner ring end face of the locking mechanism, and the outer ring end face of the locking mechanism; Measure dimension A between the bottom plane of the nut and the upper end face of the locking sleeve. n Dimension B between the inner ring end face and the outer ring end face of the locking mechanism n Dimension C between the bottom plane of the nut and the upper flange face of the lifting rod n n is a positive integer, referring to the nth level of the lifting rod; Step 2: Dimension chain calculation: Calculate the dimension between the bottom planes of the two nuts of the n-stage lifting rod and the n+1-stage lifting rod when the upper end face of its locking sleeve contacts the inner ring end face of the locking mechanism. Step 3: Simulated Assembly with Equal Pitch: To simultaneously install n-grade nuts onto the lead screw, adjust the spacing Dn between adjacent nuts, and then sequentially adjust the spacing D between adjacent nuts. n+1 D n+2 …; Step 4: Guide key rotation misalignment compensation: Measure the rotation misalignment compensation value G of the guide key for each independent tube and record it accordingly; Step 5: Parallel Assembly Marking: Install n-level nuts simultaneously onto the lead screw and adjust the spacing D between adjacent nuts. n The relative assembly positions of the n-level nuts in the lifting rod are marked sequentially and level by level. Step Six: Assemble the nuts in the lifting rod: Install the marked splines at their relative positions on the same straight line along the axial direction.

2. The method for improving the accuracy of the arrangement and combination of nuts in the multi-stage lifting rod assembly according to claim 1, characterized in that: In step two, the dimension L between the bottom planes of the two nuts of the n-level lifting rod and the n+1-level lifting rod is... n-（n+1） =C n+1 -(A n -B n ).

3. The method for improving the accuracy of the arrangement and combination of nuts in the multi-stage lifting rod assembly according to claim 1, characterized in that: In step three, adjust the spacing Dn=L between adjacent nuts. n-（n+1） -k×P; where k is an integer, P is the screw pitch, and the value of k is chosen to ensure D n If the value is greater than the nut thickness value, it will ensure that there is a gap between adjacent nuts.

4. The method for improving the accuracy of the arrangement and combination of nuts in the multi-stage lifting rod assembly according to claim 1, characterized in that: In step four, during the measurement, for the same independent tube, select any one of the guide keys to measure, record and calculate the rotation angle value and direction.

5. The method for improving the accuracy of the arrangement and combination of nuts in the assembly of multi-stage lifting rods according to claim 1, characterized in that: In step five, after inspection and confirmation, the rotational misalignment of each nut is compensated by reverse rotation in sequence; taking the same direction on the same side of the screw axis as the reference, the relative position lines of the axis in the same direction are marked on the outer circle of the nut with splines.

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