What is the positioning pin used?

The positioning pin is a part that can participate in limiting the degree of freedom of the object, and has certain applications in some mechanical motion equipment, mainly used for the position determination of two-dimensional space. The positioning pin takes the workpiece hole as the positioning reference, participates in the parts that limit the degree of freedom of the object, controls the linear movement of the object in the three axes of X, Y and Z, and the six degrees of free movement around the rotational movement of X, Y and Z. In a mold composed of two or more parts, a pin designed to accurately position two adjacent parts of the mold.

When the body is connected by multiple parts, and each part needs to maintain a precise position during processing and assembly, the positioning pin should be used for positioning. For example, the split box body is composed of a cover and a base, and the processing of the bearing hole has a high precision requirement. Therefore, in the design, two positioning pins far apart should be set on the split surface to ensure its processing and assembly accuracy.

Positioning pin classification and standard according to its different structure can be divided into: small positioning pin, fixed positioning pin, replaceable positioning pin and positioning pin. Reasonable Structure of Locating Pin Locating Pin In order to ensure the accuracy of the relative position between the two parts after installation, cylindrical pins or tapered pins are often used for positioning, so the requirements for pins and pin holes are higher. In order to facilitate the processing of pin holes and pins, the pin holes should be made into through holes as much as possible under possible conditions.

Dowel pin assembly structure

Positioning pin national standard positioning pin national standard is divided into two series of elastic pin series: 1. GB879-86 GB879.1/2-2000 DIN1481 ISO8752 specification elastic pin; 2. GB879 JIS2808 toothed elastic pin; 3. GB879.3/4/5-2000 DIN7343 ISO8748 ISO8750 rolled elastic pin; 4. English, Japanese, German, American and other elastic pins; Manganese steel or stainless steel or other customer-specified materials can be used for the materials above 5. Specifications φ1-φ50. Cylindrical pin series: 1. GB119 DIN6325 cylindrical pin; 2. GB120 DIN797 internal thread cylindrical pin; 3. GB117 DIN19 taper pin; 4. GB118DIN7978 internal thread taper pin; 5. hole pin GB880; Tail taper pin GB881; Pin GB882; The above products can be made of carbon steel or stainless steel or other customer-specified materials. Specifications φ1-φ50. Pins are also called dowel pins. Its use is the positioning of mold parts. Pins are available in straight and tapered types, respectively, and tapping types.

The JIS standard refers to it as a fixed pin for stamping die (B5062 straight rod type only). In addition, there are parallel pins (B1354) and tapered pins (B1352) as mechanical parts in JIS, which are less accurate than mold applications. The accuracy of the outer diameter, the surface roughness and the hardness of the material are the necessary conditions for the positioning pin. Locating pin should be quietly pressed into the hole for use. Adhere to the force by the positioning pin is pressed into the hole due to elastic deformation of the surface pressure and friction. Therefore, when the positioning pin is used, the relationship between the accuracy of the outer diameter of the positioning pin and the accuracy of the hole is very important. Since the pin diameter should be pressed into the aperture, the aperture should be slightly smaller. Assuming raw material and quenching material, if the aperture holding force and the pressing force of the positioning pin are not changed, there will be differences. Therefore, the pore size of the raw material should be reduced by 10 μm, and the pore size of the quenching material should be reduced by about 5 μm. The basic application method of positioning pin, please see, press 2 positioning pins into the board, pay attention to avoid dislocation.

Position as far away as possible is conducive to the progress of accuracy. Represents the relationship between the dowel pin and the hole. The relationship between the diameter and depth of the positioning pin to adhere to the length of the positioning pin is 2 times the diameter of the appropriate, the smaller should be equal to the diameter, the larger does not exceed the diameter of 3 times. If the depth of the hole is less than the diameter of the positioning pin, the positioning accuracy will be worse. If it exceeds 3 times the diameter of the positioning pin, it is difficult to stop the accurate hole processing. The two parts stop positioning is the basic method of using the positioning pin.

However, there are also cases where three plates are used. The holes on the middle plate are free size holes, avoiding the positioning pins. Since the middle of the positioning pin is not fixed, the positioning accuracy is poor. Due to the above reasons, from the accuracy of thinking, positioning pins can not be used for more than 4 plates. Generally more commonly used is a straight column type positioning pin, but sometimes also use a tapered positioning pin. Tapered dowel pin may be loose due to vibration and impact, please pay special attention. In addition, the use of the positioning pin to support the pressure applied from the side is not the purpose of the positioning pin itself, so do not hope that it can fully reach the purpose. Refer to the dimensions of the mating screw used to determine the diameter of the dowel pin. Generally use the same diameter as the screw size, or a diameter one size larger than the screw size.