Analysis of welding process design of automobile body (3)

2.1.5.2 Solder joint grouping

A number of solder joints are required for each assembly of the body. The solder joints must be grouped during the preparation process. The solder joints completed by one welding tong in one working cycle are divided into one solder joint group.

2.1.5.3 Preliminary selection of welding tongs

After the welding point grouping work is completed, the welding tongs can be selected, the number of welding point groups is determined as the minimum number of welding tongs, and the shape of the welding tongs (X shape, C shape) and throat depth and opening are determined according to the shape and size of the workpiece. The gear, stroke, electrode shape, and the hanging form of the welding tongs (horizontal, longitudinal, and swivel) are determined according to the position of the weld and the operating position. The selection of the welding tongs model shall be carried out after the design of the general drawing of the fixture, and the selection of the welding tongs shall be carried out according to the type spectrum provided by the selected welding tongs manufacturer. For the welding points where the suitable welding tongs are not found in the spectroscopy, it is required Redesign the welding tongs to match them. 2.2 Preparation process card

Under the premise, after the process analysis, the welding process card can be started. The process card is the guiding document for the whole process of designing, manufacturing and commissioning the welding wire. It is the basis for all the work of the welding wire. The depth and quality of the welding process card are designed and manufactured for the welding wire. The quality of the entire process of commissioning is even decisive.

2.2.1 Production beat

The general production beat can be calculated according to formula (1):

T section = year of workday x daily shift x shift per shift xK1 x

In the K2/year program (1), K1 is the working hour utilization rate, generally 0.9; K2 is the equipment utilization rate, generally 0.8-0.9.

2.2.2 Station setting and station production cycle

The station is the basic unit that constitutes the production line, and the production cycle of the station must be less than or equal to the beat of the production line. The working cycle of the station is the whole process time from the loading of the parts to be welded (installation) to the completion of all the work of the station and the removal of the workpiece, and the utilization of the working hours and the utilization of the equipment should be considered. The production cycle of the station has a great relationship with the proficiency of the operator. Generally, the exact production cycle of the station needs to be determined by actual measurement. The old design of the process should make the work cycle of all stations as equal as possible and close to the production cycle.

2.2.3 Working density

The working density refers to the number of welding equipment and the number of operators installed at one station, which are mainly determined by the workpiece dimensions, welding process and welding workload.

a. Determine the working density according to the external dimensions of the workpiece.

The outer dimensions are less than 1000mmxl500mm, the working density is 1; the outer dimension is less than 2000mmxl500mm, the working density is 1-2; the outer dimension is less than 3000mmx1500mm, the working density is 2-3; the outer dimension is less than 6000mmx 1500mm, and the working density is 3-4.

b. Determine the working density according to the welding workload and the production tempo.

2.2.4 Working time quota estimation

Working time quota = welding working time + auxiliary working time

The time quota of each station or process is generally composed of the assembly, clamping action clamping, welding, loosening of the fixture and the time to send the workpiece to the next station. It can also be obtained by amplifying the welding time, that is, the estimated quota. , process time quota (hours) = welding workload ÷ welding speed xK.

The following are the general conditions for the welding speed of several welding methods. The welding speed has a certain relationship with the spacing and distribution of the welding points and welds, the proximity of the welding tongs and the welding torch, and the ease of operation of the workers. Process preparation reference. a. Hand soldering pliers spot welding 15 points / min; b. Mechanical hand welding pliers spot welding 20 points / min; c.C02 semi-automatic welding 300mm / min; d. robot C02 automatic welding 400mm / min; e. stud welding (manual 8 / min; f. projection welding nut (manual) 3 /min; g. Copper brazing 100mm/min.

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