Commonly used standard parts in mechanical equipment-keys and pins

No matter what equipment, standard parts will be used in large quantities. Standard parts are the product of the development of the machinery industry. Its production greatly improves production efficiency and reduces production costs. Standard parts are parts (parts) that are standardized in structure, size, surface quality, and expression methods. For example, threaded fasteners, keys, pins, rolling bearings and springs, etc.

This article mainly introduces the types, uses, drawing methods and markings of keys and pins in standard parts.

1 key

The

key is used to connect the shaft and the transmission parts (gears, pulleys, etc.) on the shaft, and plays the role of transmitting torque.

(1) Classification of keys

The size of the key is determined by the size of the shaft hole to be connected and the torque transmitted. Commonly used keys include flat keys, half-round keys and wedge keys, among which ordinary flat keys are the most widely used.

(2) Classification of ordinary flat keys

Ordinary flat keys have three types: Type A (round head), Type B (square head) and Type C (single round head).

(3) The drawing method of common flat key connection

When used for shaft hole connection, there is a gap between the top surface of the key and the bottom surface of the keyway in the hub. Two lines should be drawn; the two sides of the key are in contact with the keyway on the shaft and both sides of the keyway on the hub. A line; the bottom surface of the key is also in contact with the bottom surface of the keyway on the shaft, and a line should be drawn. In the following figure, a is the drawing method of the shaft with keyway characteristics, b is the drawing method of the hole, and c is the drawing method of the flat key connection in the assembly drawing. (Guide: Choosing a good tool can increase the efficiency of the machining center by 30%)

(4) key mark

The mark of the key consists of three parts: standard number, name, type and size.

For example, A type (round head) ordinary flat key, bu003d12mm, hu003d8mm, Lu003d50mm, its mark is: GB/T1096-2003 key 12850

C type (single round head) ordinary flat key, bu003d18mm, hu003d11mm, Lu003d100mm, its mark is: GB/T1096-2003 key C1811100

In the mark, the word A of the A-type key is omitted, and the B-type and C-type should be marked with B and C.

2 pins

The commonly used pins include cylindrical pins, tapered pins and split pins.

(1) Cylindrical pins and tapered pins

Cylindrical pins and tapered pins can be used for positioning and connection.

(2) Split pin

Through the groove on the hexagonal slotted nut and the hole on the screw to prevent the nut from loosening or limit the position of other parts in the assembly.

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