The quality of a wrench is determined by inspection. So how do you check a wrench? This article will give you a detailed introduction to the wrench inspection methods and standards

A wrench is a commonly used installation and removal tool. It is a manual tool used to tighten the opening or casing firmware of bolts, screws, nuts and other threads by turning them on the principle of leverage. Wrenches are usually made of carbon or alloy structural steel.

The wrench is usually provided with an opening or sleeve hole to hold the bolt or nut at one or both ends of the handle. When used, the external force is applied in the handle along the direction of thread rotation to turn the bolt or nut. The quality of a wrench is determined by inspection. So how do you check a wrench? This article will give you a detailed introduction to the wrench inspection methods and standards, I hope you have learned.

1, classification use

There are basically two kinds of wrenches, dead wrenches and loose wrenches. The former refers to the wrench that has a fixed number written on it, the latter is the adjustable wrench. 1. A fixed wrench: one or both ends are provided with openings of a fixed size for turning nuts or bolts of a certain size. 2. Box wrench: both ends have hexagonal holes or twelve corner holes, suitable for small working space, can not use ordinary wrench occasions. 3. Dual-use wrench: One end is the same as a single-use wrench and the other end is the same as a box wrench. Twist the bolts or nuts of the same specifications at both ends. 4. Adjustable wrench: The opening width can be adjusted within a certain size range, and can turn bolts or nuts of different specifications. The structure of the wrench is made of a flat clamp concave with fine teeth. One end of the moving pliers is made into a flat pliers; The other end is made of concave pliers with fine teeth; Press down the worm, the moving jaws can be quickly removed, exchange the jaws position. 5. Hook wrench: also known as crescent wrench, used to turn the thickness of the limited flat nuts. 6. Socket wrench: It is composed of a plurality of sockets with hexagonal holes or twelve corner holes and is equipped with a variety of accessories such as a handle, connecting rod and so on. It is especially suitable for twisting the position is very narrow or depressed very deep bolts or nuts. 7. Hexagon wrench: an L-shaped hexagon bar wrench, specially used for turning hexagon screws. The type of hexagon wrench is in accordance with the size of the opposite side of the six, the size of the bolt has a national standard. Purpose: Specially used for fastening or disassembling round nuts on machine tools, vehicles and mechanical equipment. 8. Torque wrench: it can show the applied torque when turning the bolt or nut; Or when the applied torque reaches a specified value, it will emit a light or sound signal. Torque wrenches are suitable for assemblies where the amount of torque is clearly specified.

wrench

2. Overview

The wrench is one of the indispensable tools in the assembly work of the machinery manufacturing industry, and is also a common tool in all kinds of repair work. According to the different structure, it can be divided into a stay wrench, box wrench, dual wrench and socket wrench, in addition to the special purpose wrench such as percussion wrench.

(1) Fixed wrenches, box wrenches and dual wrenches: mainly used for pulling bolts or nuts. Due to the different widths of the opening at the two ends, a single wrench can pull bolts or nuts of two sizes. When the space around the nut or bolt head is too small to accommodate an ordinary wrench, use a box wrench. The above three wrenches are commonly used in assembly and repair work. Its type can be divided into metric wrench and British wrench two kinds. There are 5 sets, 6 sets, 7 sets, 8 sets and 10 sets of rigid wrenches. The specifications of box wrenches include 5 sets, 6 sets, 8 sets and 12 sets. The specifications of dual-purpose wrenches are 5 sets, 6 sets, 7 sets, 8 sets, 9 sets, 11 sets and 14 sets.

3. Inspection items

The inspection standards for fixed wrenches, box wrenches, and dual-purpose wrenches are GB4388-4393.

① Appearance quality inspection: the wrench should not have cracks, burrs, obvious cracks, cut marks, oxide skin and other defects, and the handle should be straight. The surface of the wrench shall be electroplated, blackened or otherwise finished. The surface of the electroplated wrench should be uniform in color, without pores, leakage plating, burning, lamination and other defects, and the coating shall not be less than 8μm. The surface of the wrench that has been blackened should have a uniform black oxide layer, and there should be no yellow, green, red spots and outcropping phenomenon.

② Size inspection: the size of the wrench should meet the relevant provisions of the GB4388 and GB4389 standards. The tolerance of wrench opening and wrench hole shall conform to GB4390 standard.

③ Hardness test: the hardness of the wrench should meet the requirements of Table 6-10-95.

③ Hardness test: the hardness of the wrench should meet the requirements of Table 6-10-95.

Table 6-10 -- 95 Hardness of wrenches

Opposite side dimension S Hardness (HRC)

Dumb wrench Box wrench Knock the wrench

Carbon steel alloy steel carbon steel alloy steel carbon steel

36 > 39 or less 39-48 39 39-48 > > > 36 34

> 36 36-45 39-45

Note: The hardness of 40Cr steel shall be assessed according to the hardness of 45 steel and 50 steel.

④ Torque test: the torque of the wrench should meet the relevant provisions in the GB4393 standard.

The symmetry of the opening and head width test: the deviation of the symmetry of the opening and head width of the wrench should conform to the relevant provisions of the GB4393 standard.

⑥ Surface roughness inspection: the surface roughness Ra value of both sides of the wrench opening should not be greater than 12.5μm, the surface roughness Ra value of the wrench hole is not greater than 25μm.

(2) Socket wrench: When the ordinary wrench cannot work due to the limitation of the position of nuts or bolts, this wrench must be used. It is often used in the assembly, replacement and repair of vehicles and agricultural machinery. A socket wrench is a set of tools mainly composed of handles, joints, and socket heads of different sizes. Specifications include 9 sets, 10 sets, 13 sets, 15 sets, 17 sets, 28 sets and 32 sets. Inspection item: The inspection standard of socket wrench is GB3390.1-3390.5.

(1) Size inspection: with general measuring tools and full-shape special measuring tools inspection, size deviation should meet the standard provisions.

② Surface quality inspection: the surface of the sleeve shall be treated by electroplating or other surface treatment, and the thickness of the electroplating shall be no less than 10μm. The outer surface shall be uniform in color and color, and there shall be no defects such as leakage, singeing and peeling. The inner surface allows spraying of silver powder. The inner and outer surfaces of the sleeve shall not have defects such as cracks and spot scars that affect the performance, and the corners of the hexagonal or twelve-angle shall be clear.

(3) Precision test: insert the tenon into the connected square hole for 5 consecutive times, and then lift the tenon sleeve shall not fall off. Each piece should be reliably combined, assembly and disassembly should be flexible, steel ball and steel pin shall not fall off.

④ Hardness test: when the size of hexagonal socket or twelveangle opposite side is less than or equal to 32mm, its hardness should be 39-48HRC. When the size of hexagonal socket or twelveangle opposite side is greater than 32mm and less than or equal to 55mm, its hardness shall be 35-44HRC. The hardness of the joint tenon and square hole should be 39-48HRC.

Surface roughness inspection: the surface roughness Ra value of square tenon and square hole, hexagonal or dodecagon hole should not be more than 25μm.

⑥ Torque test: according to the standard method of torque test, the sleeve shall not produce cracks, hexagonal or twelve Angle hole opposite side size and square hole opposite side size shall not exceed the standard requirements of the tolerance range. Each connection shall not be damaged or permanently deformed.

4. Packaging, storage and transportation

The wrench parts shall be put into the packing box with protective liner to avoid collision and scattering of parts, and then the packing box shall be put into the packing box lined with moisture-proof paper. There shall be separate layers between the packing boxes. The packing boxes should be strong and suitable for long distance transportation. Storage and transportation should pay attention to moisture, do not rain, to prevent rust.