The inspection method of welding fixtures is introduced.
Our factory is a national designated light-duty automobile manufacturer. According to the "multi-variety, small-batch" production and management policy formulated by the factory, we are based on B-type * F0RTA * (Fuda) light trucks as the main product. Continuous development and production of other types of models, participating in fierce market competition E2000 light 8-seater passenger car is our factory's key development project this year, its welding main line introduced the Japanese MAZDA technology transformation, we have undertaken the design and manufacture of welding fixtures.
The E2000 light bus body assembly is assembled from 4 parts, as shown.
Welding process arrangement According to the requirements of production volume, we decided to use 6 stations to complete the welding of the body assembly.
One station: complete the assembly of the floor assembly, which is composed of the front floor, middle floor, (left / right) rear side panel, and rear floor. Use floor welding fixtures to position, clamp, and complete the welding of some welding points.
Second station: repair welding of floor assembly.
Three stations: complete the assembly of the floor assembly, (left / right) side wall assembly, front wall assembly and welding of some welding points. The body welding fixture is used for positioning and clamping to form a body-in-white body without a roof.
Four stations: Assemble and weld the front / rear roof beam and roof assembly. The welding fixture on the car is also used for positioning. The key of this station is to ensure the size of the front windshield.
Six stations: (left / right) front door, (left / right) middle door and rear door assembly and adjustment.
Body assembly assembly welding fixture structure analysis 4.1 positioning selection The goal of selecting positioning is to ensure the accurate positioning of the four assemblies of the front wall, floor, side wall and top cover, and to ensure the assembly size of the door opening of the vehicle and the assembly size of the front windshield. Dimensional accuracy reduces the deformation of welded parts during assembly, assembly and welding, facilitates welding operations, and increases assembly and welding productivity. According to the welding process arrangement of the body assembly, the optimal number and optimal position of the positioning clamping components are determined, as shown.
Middle 0-4X position. The key to the front wall positioning is to ensure the dimensional accuracy of the front windshield. Two important process holes on the left and right sides of the front wall are selected as the hole positioning reference H1, and four faces and two clamping points are used as the limits in the F and Z directions.
In the floor assembly, 6 important craft holes and supporting surfaces Good 2, Good 3, // 4 (left-right symmetry) are used as positioning reference. In this part, the over-positioning form with 6 faces and 6 holes is used to verify and stabilize the floor stringers.
4.1.3 In the side wall assembly, the over-positioning and clamping methods of 2 positioning holes milk, booklet and 34 supporting surfaces (left-right symmetry) are used to prevent the side wall from deforming.
The side-turning part of the fixture has a total body length of 4.0m, and the body frame with long side-turning body is long. Two positions are selected for simultaneous lifting. It consists of two parts, the front group and the rear group, as shown.
Two columns are arranged in the X direction from 0-16X to form the front group column, and the two cylinders are used to control the positioning and clamping of the left / right front group columns to the parts and fall back; the two groups are arranged at 28-42X to form the rear group column , Two cylinders control the positioning clamping and falling back of the left / right rear group column to the parts, as shown.
The air path control is calculated by calculation. The total mass of the positioning and clamping part of the side wall of the fixture and the column frame is about 1.6t. Two cylinders are selected for the front and rear parts to control the front and rear groups of columns. The cylinder diameter is less than 150mm (cylinder thrust is 17.32kN when the air pressure is 0.49MPa). The cylinder uses the famous Taiwan brand * AirTAC *. In order to reduce costs, the control system uses simple manual control of the pneumatic circuit movement. When the column is raised as a whole (that is, positioning and clamping in place), it is 90 ° from the horizontal direction, and a mechanical limit block is added laterally; when the column is down and released, it is 120 * from the horizontal direction (guaranteeed by the limit block), from The working angle of the column up to the column release is 30 *, which is convenient for the side body of the body to go online, as shown.
Cushioning form The welding welding fixture has a large part of the side-turning body frame. In order to ensure safe and reliable use, the cushioning form is arranged as follows: install throttle valves at the inlet and exhaust ports of the cylinder to adjust the movement speed of the cylinder to avoid the column The clamping speed of the upper clamping element hits the sheet metal surface too fast.
Set up a mechanical limit block at the end of the column movement (that is, at a 90 * angle to the horizontal), and paste a buffer rubber on the limit block to reduce the impact of the column movement.
4.5 Locking form In order to ensure the accuracy and stability of the final welding fixture in place and the protection and safety in the case of air circuit cut off, the following two measures are used for double locking: a. Self-locking cylinder is selected. This method achieves the locking of the piston rod on the gas path to prevent the system from unloading.
Automobile technology and materials b. Four-bar manual fast clamp for clamping.
The inspection of the fixture is checked item by item according to the items listed in Table 1 to determine whether they meet the requirements, and the determination results are filled in Table 1. A qualified assembly welding fixture must meet the following two conditions: Conclusion This body assembly assembly welding fixture has a simple structure, convenient clamping, and is suitable for manual operation. The pneumatic circuit design adopts manual valve control, avoiding the complexity and high cost of solenoid valves and program controllers, which reduces the manufacturing cost of the fixture. The locking mechanism adopts self-locking cylinder plus manual clamping double insurance to ensure production safety. The design and manufacture of the whole set of fixtures revolves around the spirit of our factory's "small batch production" policy, achieving the goals of simplicity, precision, economy and convenience.
Table 1 Inspection table for body-mounted welding fixtures, item confirmation items and judgment criteria (yes / no) Number of problems 1 Whether the positioning block and clamping work smoothly 2 Whether the positioning and clamping block interfere with the function of the fixture during operation 3 4 Whether the positioning pin of the fixture is inserted smoothly Whether the accuracy tolerance of the positioning block is lower than *. 3nun5 Whether the pneumatic circuit is interlocked 6 Whether the speed of the cylinder has been adjusted 1 Whether the positioning of the sheet metal part is variated 2 Whether the positioning block will bite the sheet metal part And accuracy 3 Whether the positioning pins of the sheet metal parts are placed smoothly 4 Whether the contact between the sheet metal parts and the positioning block is good 5 Whether the accuracy before and after welding is variable Whether the sheet metal parts are easy to put in the workability of the fixture 2 Whether the positioning block interferes with the welding tongs 3 Do you see the dot position? 4 Is the rigidity of the sheet metal parts transported is it good? Is the sheet metal parts easy to be taken out? Is it safe? 2 Is there an unreasonable working posture? 3 Is it possible for the clamping block to pinch my fingers? Is there a non-round pin for maintenance? 2 Whether the trachea is scratched or stretched 3 Whether the bolts and nuts are locked in color 4 Whether the position of the throttle valve is easy to adjust (responsible editor)
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