Automotive fixture precision and positioning principle

Author：Web　Source：Web　Date：2018-07-07 19:55:05　Sentiment：71

Automotive fixture precision and positioning principle

First, the position precision of the main positioning pin is + / - 0.25mm, and the processing precision is -0.05mm.

The measurement point tolerance from the base level of the second fixture to the vertical direction of all fixtures is + / - 0.25mm.

The tolerance between the locating hole and the locating hole on the horizontal surface of the third point is + 0.05mm, and the roughness is 1.6um.

Fourth, the tolerance between all the positioning holes and the datum surface is + 0.05mm, and the roughness is 1.6um.

The accuracy between the 5th datum level is allowed to be plus or minus 0.1mm, and between the measuring surface is allowed to be plus or minus 0.2mm.

Flip in the first six institutions repetition in position precision of + / - 0.2 (Φ 200);

At the seventh point, the manufacturing precision of the jig is detected by using three coordinates, and the inspection records are filled into the inspection records of the equipment.

One, firstly, the same as the design basis of anchor point, positioning pin used for positioning holes must have the corresponding accuracy requirement, and must is not only the benchmark stamping, and testing and submit the benchmark, to ensure the design of welding the unification of the benchmark benchmark with the design of the product, to reduce the design error and is convenient to analyze the causes of error.

Second, the fixture with the logical relationship between the upper and lower processes must be unified with the upper and lower processes in the design, and should be unified with the positioning standards of the mold and the inspection tools.

Third, avoid areas with complex pit or surface changes to avoid the instability of the welded products caused by the instability of the stamping parts themselves.

Fourthly, in order to ensure the safety of use, when the clamping device is in the clamping state, it should be able to self-lock; The opening of the chuck should be limited, and the opening Angle should not be too large, generally less than 135o, except in special cases.

When the clamping surface of the chuck is inclined, a limit block must be installed at the clamping arm.

When positioning and welding of chuck, under the condition of positioning pin and inclined compression surface, it is necessary to consider installing the positioning block of technology at the clamping arm, and then welding after accurate positioning. Otherwise, it is impossible to ensure the precise positioning of chuck (when the plane is clamped, it is allowed not to add the positioning block of technology).

The clamping force of manual clamping head is generally greater than 50Kg. F (refer to the center of operation point).

The handle length of manual operation should be suitable, and the handle position of clamping device should be above water level.

Where the clamping operation has a sequence, the sequence shall be indicated on the handle.

All the supporting sites must ensure sufficient and reliable positioning of the workpiece, no deformation or movement of the workpiece under effective compression.

11. The surface quality of the workpiece shall not be damaged when clamping. When clamping thin-wall stamping parts, measures should be taken to limit the clamping force, increase the contact area of clamping heads, and increase copper and aluminum gaskets.

Where there is no supporting point at the clamping head with positioning pin or clamping head, a limiting block must be installed at the clamping head arm.

13. In the welding area far from the positioning clamping point, auxiliary support clamping point should be added to reduce the unqualified products caused by welding deformation.

The support clamping point near the welding point shall be designed with sufficient welding channels for the welding tongs or the welding gun. For arc welding equipment, the corresponding anti-splash device must be designed to protect the clamping surface of the support and extend the service life of the welding fixture.

The applied force point of the clamping device should be at the support point of the workpiece, and the fixing point should be arranged near the support point, so as to prevent the coupling formed by the supporting reaction force and clamping force, supporting reaction force and gravity, leading to the deformation of the workpiece.

When the inclined plane is pressed tightly, a clearance adjustment piece must be installed in two directions of force distribution. When the plane is compressed, a clearance adjustment piece must be installed below the vertical plane.

The diameter of the locating pin passes through 3~5mm on the upper surface of the workpiece. For two datum pins that locate a workpiece, in principle, one is round pin and the other is diamond pin.

18. The positioning block on the exterior surface of the positioning part is made of nylon or polyurethane material to prevent damage to the surface of the workpiece.