Nuts and bolts operation method

Tighten bolts and nuts according to the following standards. There is a lot of work to tighten threads when assembling mechanical parts. In fastening operations, tools play an important role, through the correct use of the most suitable tool for the operation, can carry out the correct operation, which can not only form the optimal function of the machine, but also improve the efficiency of the operation. If the wrong tool is used or the wrong method is used, the operation can not only be incorrect and inefficient, but also cause injury or damage to products and tools.

There are many kinds of fastening tools, here is the most commonly used tools, its basic operation, as well as fastening, loosening operation of the construction method of the basic matters are explained.

1. General fastening operation

The ordinary fastening operation specified here refers to the operation of fastening the mechanical part by bolts, nuts, washers, etc., using a wrench and other fastening tools, without torque limit but only simple fastening operation.

1), a wrench

When using a fixed caliber wrench, it is very important to use a tool that is consistent with the size of the bolt or nut of the working object. If the bolt head is too large, the bolt head will be deformed and the wrench cannot be clamped.

In addition, the length of the wrench is determined by the force applied to the wrench, so methods such as connecting to lengthen the handle and stacking with another wrench to apply more force cannot be used.

The following is an example of a wrench:

The wrench shown in Figure 2 is very dangerous to use.

Place the wrench in the position shown by the line, and twist it at an acute Angle with the line AB of the mechanical part. If the bayonet comes out, or the bolt is broken due to excessive force, it will clamp the hand. As shown by the dotted line, AB line is safer if it is obtuse. Also, it is best to use pulling force, not pressing force, on a wrench. In any case, it is safe to press firmly with the palm of your hand and with your fingers out.

This can be used for all spanners, such as double-headed plum wrenches, ratchet handles, pipe pliers, adjustable wrenches and torque wrenches.

2) Sleeve for socket wrench

Casing with identical diameter should be used. That is, bushings that use metric threads for metric threads and bushings that use uniform standard threads should be clearly classified.

This matter also applies to all spanners of other fixed diameters used to set the simple spanner sleeve.

2. Fastening operation required to control the torque

Torque wrenches should be used when tightening forces need to be controlled. According to the size and material of the bolt and nut, the fastening force (torque) is determined. If the screw is too light, it will become loose. If the screw is too tight, it will cause the load and cause the bolt to break.

For this reason, torque wrenches must be used to measure tightening forces at functionally important locations. Torque is generally N? M to represent, torque wrench is divided into these kinds, installed to display the index of the display board and pointer should change type, dial type indicator or torque preset type.

Bolts or nuts are temporarily tightened using a wrench, and then, using a torque wrench, are formally tightened and the torque is measured.

Torsion measurement must be noted that the bolt or nut size of the casing installed on the torque wrench, measurement must hold the handle handle, apply force.

3. Methods to prevent loosening of bolts and nuts

In the vibration of the mechanical part, measures must be taken to prevent loosening, bolts, nuts for anti-loosening treatment. In the anti-loosening treatment, the following methods are generally adopted.

1) Installation of gasket, as shown below:

2) installation of split pin

The general items of the cotter are as follows.

The shape of the cotter pin should be confirmed to conform to the drawings.

The installation of cotter pins is performed according to the following instructions after confirming that the nuts are fastened according to the standard torque.

● Confirm whether the insertion direction of cotter pin is correct and the cotter pin hole of bolt.

● Screw the slotted nut, insert the cotter pin into the bolt hole, knock it into the pin foot with a steel chisel, and pry it open with a hand or hammer.

When reassembling after disassembly, sometimes the hole will not match, at this time, with a steel file slightly file off the inside of the nut, and then aligned with the next screw slot. The installation diagram is as follows:

3) installation of anti-rotating steel wire

As shown in the figure, when the number of bolts is even, every two bolts should be installed in a pair; if the number is odd, two bolts should be installed in a pair, and the remaining three bolts should be installed as a group. Wire cutters are generally used to install anti-swivel wires.

4, the use of thread fastening agent

The thread fastening agent is applied to the bonded part of the nut or bolt and slowly hardens to prevent loosening of the nut or bolt due to vibration or impact.

The coating on the thread can be applied to either the outer thread only or the inner thread only. The steps are as follows:

(1) Degreasing, cleaning: use trichloroethylene, acetone, ether and alkali solution and other volatile good cleaning items. Degreasing should be as thorough as possible. Do not use gasoline, light oil, kerosene and other volatile goods.

②, natural drying: to be completely dry detergent.

(3) glue coating: on one or both sides with the following method, in order to make the cement to fill the gap between the thread or bite surface.

● Coating directly from the container nozzle;

● Impregnation (such as thread, using a tray);

● Use a brush or brush for coating (such as occlusion, use a tray);

In addition, do not pour the liquid medicine back into the container when mixed with metal foreign body or poured into the tray for use.

(4) assembly: after gluing, tighten in accordance with the original method.

5. Installation of stop nut

As shown in the figure, use two nuts, as shown in Figure 1 and 2. After tightening the two nuts together, jam the upper nut with a wrench and tighten the lower nut as much as possible. In this way, the gaps prone to shaking become as shown in Figure 4, which can prevent loosening. Note: Arrows indicate the direction of applying force.

5. Installation of tongue washer

After inserting and tightening the tongue washer between the mechanical part connected to the nut or bolt, bend the root of the washer as shown to prevent loosening.

In the operation of bending the root, the ear is pried up with a chisel and a hammer, and the tip of the chisel is pressed against the opposite side of the nut or bolt and the right Angle of the mechanical part. When using the steel chisel to pry up the ear, pay attention to avoid the head of the steel chisel and the root.

6. Fastening operation and matters needing attention

The contact surface of bolts and nuts must be flat. If the contact surface is poor, it should be countersunk. (Use flat gaskets if necessary)

② When specifying the fastening sequence of bolts and nuts, do not make a mistake. Generally, when using multiple bolts to tighten mechanical parts, as shown in the figure, tighten them in equal order according to the diagonal position, without bias.

③ In the process of fastening, if you feel laborious, do not operate brutally. The reason for this is that it may cause a broken tooth or hot glue. At this time, loosen the bolt, nut, the thread of the two sides of the use of tap or die for inspection, the situation is not good one side must be adjusted to become the correct thread.

When both sides are in good condition, apply appropriate lubricant, and then tighten.