What is the positioning method of the positioning components of the inspection tool?
Usually hole positioning, surface positioning, contour positioning or a combination of the above methods are used. The order of priority is hole positioning, hole+surface positioning, hole+contour positioning, surface positioning, surface+contour positioning, and contour positioning. The selection of the positioning system must be consistent with the model system (including positioning holes and positioning surfaces).
Hole positioning: Two holes are used for positioning, hole + surface positioning or hole + contour positioning. The main positioning (H) is a conical positioning pin (referred to as a tapered pin), and the secondary positioning (h) is a diamond-shaped positioning pin (abbreviated as a diamond pin). When using positioning pins alone for positioning, use at least 2 positioning pins for positioning.
If one positioning pin is used, other auxiliary positioning methods, such as stoppers, must be used. When the positioning hole is implanted for positioning, the diameter of the positioning pin is the diameter of the positioning hole D-0.02mm. When the positioning pin is a tapered positioning pin for positioning, the positioning taper should ensure that the diameter of the middle of the positioning pin is the same as the diameter of the positioning hole under ideal conditions.
What is the positioning pin placement method?
Before the part is clamped and inspected, the part is first positioned, so the positioning pin is used to accurately position the part on the gage.
The location of the positioning holes is determined according to the part drawing datum (usually two positioning holes are set for each part). The positioning pin is composed of guide, positioning and handle to ensure that the guiding part of the pin can enter and exit freely in the positioning hole. According to the characteristics of the reference point of the part and the shape of the reference hole, the positioning pins are set as tapered pins and column pins, and the matching parts can be different according to the actual loading method. In the positioning hole, in order to ensure the accurate positioning of the positioning pin, a guide bush must be installed, and the guide bush and the inspection tool must be fixed. The positioning accuracy of the center of the guide bush relative to the coordinate line of the vehicle body is controlled within plus or minus 0.05. The structure of the positioning pin and the corresponding guide bush has different requirements according to the shape of the hole, and it is divided into anti-rotation structure and non-rotation structure. The positioning of parts on the inspection tool usually adopts 2 positioning holes, and the positioning method and position are specified according to the RPS description in the drawing.
Usually the following two positioning methods are used:
Four-position positioning pin --- generally defined as RPS on the drawing: Hxy, Hxz or Hyz
Two-position positioning pin---generally defined as RPS on the drawing: Hx, Hy or Hz
The positioning pin A1 (four-direction positioning pin) usually adopts the same structure on the inspection tool and the measuring bracket.
The positioning pin A2 (two-position positioning pin) needs to adopt different structural forms according to the different forms of the inspection tool and the measuring bracket. For the inspection tool, the structure of the positioning pin A2 is a pin with two ends, one end for positioning and one end for detection. For the measurement bracket, the positioning pin A2 is a single-headed pin, which is only used for positioning.
