It can be seen from the figure that the telescopic mechanism is composed of four parts: a retractable screw, an adjustable nut, a top wire and a fixing nut. The functions of each structure are: the telescopic rod is actually a sleeve which can be connected with the socket wrench at one end. Connect the studs of the quadrangular prism and adjust the position of the adjustable nut on the stud to achieve its telescopic purpose. At the same time, to prevent the adjustable nut position from changing, the adjusted nut is locked with the nail. At the position where the stud is adjusted, the lower end of the fixing nut is milled into a quadrangular prism, which can fit the square mounting hole on the beam. This prevents the nut from rotating with the telescopic bolt when tightening the bolt, and the purpose of tightening the bolt is achieved. .
However, in actual use, we found that: First, when the length of the retractable screw is properly adjusted, the mounting nut just closes the installed hole after stepping on the foot pedal.
Secondly, when the length adjustment of the retractable screw is unreasonable, the phenomenon that the installed nut and the bolt are not screwed together may occur. In severe cases, the nut and the bolt may not be screwed. The connection of the bolt is This is unfavorable. This article focuses on the above issues, and on the basis of analyzing the problems, proposes solutions to the problems.
2 analysis of the problem
Analysis of the above bolts can not be screwed together for the following reasons: 1 when pushing the installer, because it is not pushed into place (under or in place); 2 due to the unreasonable adjustment of the length of the retractable screw, after stepping on the pedal, due to The pin and the beam of the beam and the small axis of the beam and the column are not on a horizontal line, so that the mounted nut is not completely in contact with the outer side of the hole to be mounted, but causes local contact. There are usually two cases of such local contact: one is that when the telescopic mechanism is adjusted for a long time, the pedal is lightly stepped on, and the sleeve with the nut to be mounted is in contact with the outer lower surface of the bolt hole to be installed, in order to For convenience of explanation, since it is the right side of the sleeve, it is called a right contact.
Second, when the telescopic mechanism is adjusted to a short time, when the pedal is stepped on, the sleeve with the nut to be mounted will be in contact with the outer lower surface of the bolt hole to be installed. For the sake of explanation, since it is the left side of the sleeve In contact with it, it is called the left contact; the two contacts are not in the same straight line because the center of the screw and the center of the nut are inconvenient; the reason for the analysis is that the four on the fixing nut The clearance between the prism and the square hole on the beam is small, and the space for the expansion mechanism of the bolt is limited. It can only be used up and down with the beam, and cannot be oscillated slightly, so the outer surface of the mounted nut and the mounting hole will appear. Insufficient contact, that is, local contact, causes the center of the screw not to be in the same line as the center of the nut, which causes inconvenience to the normal installation of the bolt.
3 problem solving
For the problem (1) when pushing the installer, since there is no problem of pushing in place (under-in or over-position), the center of the nut to be mounted and the center of the bolt to be installed can be centered on the line by pushing and pulling the mount; for the problem (2) In the case of occurrence, the structure of the fixing nut can be changed, and the bolts and nuts to be mounted can be easily connected together, and the fixing nut can be mounted on the square hole of the beam, and the rotation can be appropriately performed, thereby solving the problem. The pin is symmetrically mounted on the front and rear of the square hole of the beam, and the C-shaped groove is milled on the front and rear of the square prism of the fixing nut, so that there is sufficient clearance between the fixing nut and the square hole, so that the fixing nut can be wound around the pin. Swing at a small angle on the beam to prepare the mounting nut for full contact with the mounting hole.
4 improvement of the fixed nut structure
In order to solve the above problems, an improvement is made to the structure of the fixing nut, so that the anti-torsion capability of the improved fixing nut is not weakened, and the actual length of the fixing nut and the beam hole can be changed by increasing the length of the fixing nut, and the fixing nut is given. The quadrangular prism is milled with a C-shaped groove, and the pin is attached to the contact point between the fixing nut and the beam, and the quadrangular prism of the fixing nut is matched with the hole in the beam, so that the fixing nut is stepping on the pedal After that, a small rotation occurs on the installation of the beam. This small rotation ensures that the mounted nut is in full contact with the outer lower mounting surface of the mounting hole to ensure the normal connection of the bolt and the nut. By comparison, the improved fixing nut is longer than the modified one, and the modified quadrangular prism has a symmetrical C-shaped groove at the front and rear. The C-shaped groove can swing left and right through the symmetrical pin on the beam to overcome the previous local Contact problems caused by contact.
5 Conclusion
In order to make the tool better, the cylindrical plastic foam film with a hole in the middle of the sleeve can be placed on the sleeve, so that the installed nut is placed on the sleeve and a part of the sleeve is beyond the sleeve, so that the pedal is stepped on. After the plate, since the plastic foam film is easily deformed during extrusion, the plastic nut is deformed to make the mounted nut completely adhere to the outer surface of the mounted hole, and at the same time, in order to prevent the plastic bubble film and the mounted nut from being installed The sleeve is dropped inside, and the contact surface (the plastic bubble film and the sleeve, the contact surface of the plastic bubble film and the nut to be mounted are greased) can make the mounted nut and the mounting hole well. Full contact under the outer surface, under the combined effect of these two factors, can ensure the smooth connection of the bolts.
The commonly used Pipette kits are mainly composed of a pipette and a pipette tip. The pipette tip is a single empty
Cavity reservoir; the pipette uses the principle of air displacement and controls the maximum displacement of the piston by rotating a screw with an ultra-fine thread
displacement, and then control the amount of liquid suction. There are the following problems when using the above kit for suction: 1. The suction volume is controlled by the pipette
After the pipette is sterilized or used for a period of time, it is easy to cause "hidden" failures, which cause the operator to be difficult to detect.
The actual suction volume is inaccurate, and it needs to be adjusted frequently, and the operation is cumbersome and time-consuming; 2. To improve the pipetting accuracy, the operator's
The operation requirements are high, and it is easily affected by factors such as the suction speed, the depth of the tip below the liquid level, and the inclination angle of the pipette.
The actual suction volume will be heard; 3. The actual suction volume will be affected because the suction head cover is not tight and leaking, and it will not be easily detected; 4.
When performing experiments that require high accuracy, such as analysis, in the operation of equal volume aspiration of liquids with different densities, the actual
The actual suction volume will be affected by the density itself; 5. In order to improve the accuracy, this type of pipette needs to carry out high
Cost-optimized design results in extremely high pipette costs.
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