Threaded fasteners refer to parts that are connected and fastened by threads. Commonly used threaded fasteners are bolts, studs, screws, nuts, washers, etc., all of which are standard parts.
Second, the provisions of the threaded fastener logo
Fasteners are marked in two ways: complete marking and simplified marking. The complete tag form is as follows:
For example: bolt GB/T 5782-2000-M12× 80-8.8-A-O.
Indication: Nominal diameter d=M 12, nominal length 80, performance grade 8.8, product grade A, surface oxidation.
In general, fasteners are marked in simplified form, and the simplification principles are as follows:
(1) Category (name), standard years and the "-"before it are allowed to be omitted in whole or in part. The standard for omitting the year number shall be the current standard.
(2) The "-"sign in the mark is allowed to be omitted in whole or in part; The "×" before "other diameters or characteristics" in the mark can be omitted. However, ellipsis should not lead to misunderstanding of tags, and spaces are usually used instead.
(3) When only one product type, performance grade or hardness or material, product grade, wrench type and surface treatment are specified in the product standard, it is allowed to omit all or part.
(4) When two or more product types, performance grades, hardness or materials, product grades, wrench types and surface treatment are specified in the product standard, it is specified that one of them can be omitted, and the omitted simplified labeling is given in the labeling example of the product standard.
The marking of the above bolts can be simplified as: bolt GB/T 5782 M 12×80.
It can be further simplified as: GB/T 5782 M 12×80.
See relevant product standards for marking examples of commonly used fasteners.
Third, the drawing of threaded fasteners
1, the proportion of commonly used threaded fasteners
When drawing the part drawing and assembly drawing of threaded connectors, you can mark the parts according to the regulations (that is, standard code) and find out the dimensions required for drawing from the relevant standards. However, in order to improve the drawing speed, the proportional drawing method is usually adopted, that is, all the relevant dimensions of threaded fasteners are in a certain proportion to the major diameter d of the thread.
2. Drawing method of threaded fastener assembly drawing
Basic rules for drawing assembly drawings:
① Draw a thick solid line on the contact surface of two parts, and draw two lines on the non-contact surface.
② When the cutting plane passes through the axes of fasteners and solid parts (bolts, studs, screws, nuts, washers, keys, pins, shafts, balls, etc.). ), these parts are all drawn without cutting, that is, their shapes are still drawn.
(3) In the sectional view, the section lines of two adjacent parts should be in opposite directions or in the same direction but with different intervals. On the same drawing, the section line direction and spacing of the same part in each section should be the same.
Drawing method of (1) bolt connection assembly drawing
Bolt connection consists of bolt, nut and washer, which is used when the two parts to be connected are not thick enough to drill through holes. When connecting, first drill smooth holes in the two parts, then use bolts to pass through the smooth holes in the two parts, add washers, and finally tighten the nuts, as shown in the figure.
Attention should be paid to when drawing:
When drawing the assembly drawing, the nominal length (χ) of the bolt should be determined according to the type of the bolt, the major diameter of the thread and the thickness of the connected parts.
χ ≥ thickness of connecting parts (δ 1+δ2)+ thickness of washer (h)+ height of nut (M)+ height of bolt protruding from nut (b)
According to the calculated value of nominal length, the standard length is selected from the series values of bolt standards.
(2) Drawing the assembly drawing of stud connection.
Stud connection consists of stud, nut and washer, which is used when one of the two connection parts is thick or is not suitable for bolted connection due to structural limitation. When connecting, it is necessary to machine a screw hole in the thicker part first, and one end of the stud is screwed into this screw hole, which is called the threaded end. On the other hand, drill a through hole on the stud to cover it, and add a washer to tighten the nut. This end is called the fastening end, as shown in the figure.
Stud connection diagram
Places to pay attention to
When drawing the assembly drawing, the nominal length (χ) of the stud shall be determined according to the following formula.
χ≥ Thickness (δ) of machined through-hole parts+washer thickness (h)+ nut height (M)+ height of stud protruding from nut (b)
According to the calculated value of nominal length, select the standard length from the L series values of stud standards.
(3) Drawing method of threaded connection assembly drawing
Screws are generally used in places where the stress is not great and it is not necessary to disassemble them frequently. One of the connecting parts is provided with a screw hole, and the other part is provided with a through hole.