2 practical application and analysis
In order to make the pedal bolt installer work better in practical applications, it can prevent the weak link in the transmission mechanism of the bolt installer force from being too strong and too strong when stepping on the pedal, such as the pin shaft. Cutting, beam deformation, etc., will bring certain difficulties to the normal use of the bolt installer, and even affect the normal use of the installer. Our requirements for stepping on the pedal are: the heel first touches the ground, and then the heel is used as the fulcrum. Stepping on the pedals, the test proved that the best effect of pedaling is that the sole of the foot falls 20~30mm at the front end of the pedal. There are two reasons for the best effect on this position: 1 stepping on this position is not easy to slip off. And this position is easy to find; (the way to find this position is to move the foot of the pedal to the ground and touch the upper installer, then lift the foot forward and move 20~30mm forward, then the sole of the foot presses on the foot. The pedal can be used. 2 Stepping on this position. Because the mechanism can ensure the maximum power arm, the force of the beam to squeeze the mounting nut is also the largest, and the beam lifting can be supplemented by the unreasonable adjustment of the telescopic mechanism.
3 theoretical analysis
From the theoretical knowledge of the principle of leverage, we can know the formula of the principle of leverage: power arm × power = resistance arm × resistance In order to facilitate the clear explanation of the problem, we simplify the force diagram on the beam. Applying the principle of lever to the pedal bolt installer should be: N × L 1 = F × L 2 In theory, the longer the beam, the greater the pressure of the beam on the nut seat, and the nut is attached by the mounting nut. The tighter the hole is installed, the easier it is to install the bolt, but if the beam is longer, it will bring the following practical difficulties: (1) The bolt installer is too large and heavy, which is the movement and use belt of the bolt installer. It is difficult.
(2) If the volume is too large, larger than the allowable space of the installation space, the bolt installer will not work properly, which is contrary to the original intention of our design bolt installer.
Therefore, the visible beam is short, the beam is short, the bolt installer is small in size, light in weight, easy to move and move, so it is necessary to choose a reasonable value between large and small, and for this optimal value The selection basis is: under the condition that the bolt can be normally connected under special conditions, the size of the bolt installer is small, which limits the length of the beam. Considering that the bolt installer is stepping on the foot, considering the actual use effect, The length of the beam is 300mm, and the volume of the bolt mounter is taken as (300×100×150).
4 selection of position parameters of each fulcrum of the lever
There are three fulcrums on the beam, which are the fixed nut and beam square hole pin fulcrum, the beam and column pin fulcrum and the beam and the tie rod pin fulcrum. When the length of the beam is 300mm, how can these three points be distributed? To achieve the best results, we believe that the criteria for evaluating the best results should be: (1) Under the pressure of the foot, the beam can generate a large pressure, so that the installed nut is closely attached to the hole to be installed.
(2) In order to better compensate the adjustment length of the telescopic mechanism, the upper and lower movement ranges of the left and right ends of the beam are large, which is convenient for making up for the insufficient adjustment of the telescopic mechanism; in actual use, the beam pin is fixed by the C-shaped groove of the fixing nut. The position is limited, and the size of the fixing nut is limited by the diameter of the telescopic bolt. In order to tighten the bolt, the retractable bolt should not be screwed, that is, it should have a certain strength. After theoretical calculation, the diameter of the telescopic bolt is 6mm. (Quasi 6 can meet the strength requirements), the fixing nut is mounted on the telescopic bolt, and the unilateral margin is 2mm in the diameter direction. Therefore, the distance from the four edges of the fixing nut to the center of the bolt is 4.5mm. The nut has a certain installation clearance in the square hole of the beam, and considering the effect of machining error, the distance is 4.7mm, that is, the installation position of the first pin is 4.7mm from the left end of the beam, and the beam and the tie rod pin The connecting pin of the shaft should be at a minimum distance of 5 mm from the right end of the beam, so that the pin fixed to the beam and the beam and the tie rod are fixed in cooperation with the fixing nut. Set the distance between the pin nut on the beam and the pin between the column and the beam as L1. The distance between the pin of the beam and the pin of the beam is L 2, then L 1 +L 2 =290.3; for the convenience of explanation , suppose that the pressure of the foot-to-foot pedal is F, the pressure of the beam to the nut seat is N; the principle of the lever is: N × L 1 = F × L 2 to meet the requirements of the upper beam condition, take N = 1.5 F can meet the actual installation requirements, and substitute N=1.5 F into the principle of leverage: L 1 = 116.12mm, take L 1 =116mm, then L 2 =290.3-116=174.3mm, thus determining the three points on the beam The specific value on it. In this way, we determine the exact position of the best three points on the beam, namely: the first fulcrum (ie, the contact point between the C-groove of the fixing nut and the pin on the beam) is 4.7 mm from the left end of the beam, and the second fulcrum (ie The position of the joint between the beam and the column is 4.7+116=120.7 mm, which is 120.7 mm from the left end of the beam. The specific position of the third fulcrum (ie the position of the beam and the tie rod connection point) is 120.7 + 174.3 = 295 mm from the left end of the beam. The purpose of selecting the left end of the beam is to keep the reference uniform, that is, the principle of unifying the dash reference and the measurement datum during processing. The purpose of using the datum uniform principle is to ensure the dimensional accuracy of each hole of the workpiece, thereby improving the dimensional accuracy between the fulcrums on the beam. To ensure the use of the workpiece.
The main problems involved in this paper have been basically solved. The empirical calculation of N/F=F 2 /F 1 =174.3/120.7=1.45 achieves the expected effect of N>F in our design.
5 Conclusion
In order to make the bolt installer perform better, firstly, the mechanisms that slide and rotate each other should be periodically lubricated to ensure flexible and reliable mutual movement, and the length of the retractable mechanism can be adjusted on the basis of calculating the length of the retractable mechanism. When stepping on the pedal, first insert the mounting rod into the center hole of the mounting nut through the mounting hole, and then extend the foot to the installer. After the toe is placed on the mounter, the foot is grounded and the foot is lifted forward to move 20~30mm. Then step on the pedals.
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