The main factors affecting double curling are as follows:

1.Appropriate sealing pressure

During the rotation of the can body, the rolling force P of the roller groove at the junction with the can lid is the combination of the radial force Pr, the axial force Pa and the tangential force Pt in three different directions. Among them, the first-pass sealing force P1 is mainly manifested as the bending deformation of the surrounding material of the can body and lid, and the second-pass sealing force P2 compression is mainly manifested as plastic deformation. The calculation of the two rolling forces is carried out through energy balance and plastic deformation. Generally, the sealing force of the second pass is 2 to 3 times that of the first pass.
　　
In the actual operation process, the proper sealing force is achieved by the proper matching position relationship between the sealing roller, the indenter and the can tray (such as the adjustment of the inner and outer gaps between the roller and the indenter, etc.).
　　
　　
1. The appearance requirements of the tinplate barrel sealing process are mainly manifested in: (1) The double crimping should be uniform and smooth, and the surface should be free of obvious oil and damage; (2) The crimping part must not have slip seals, false rolls, and crimping cracks. , Double lines, extrusion and other defects; specifications and size requirements are mainly manifested in: (1) the curling size of different can types must meet the corresponding process size requirements; (2) the splicing length and splicing rate, tightness, and seam Cover hook complete rate.
　　
The sealing structure of double crimping can be sampled by a can edge cutter, and it will be displayed on the projector.

2. Correct operation and adjustment of the operator
　　
The skilled technical skills and operation level of the operator, as well as the necessary daily maintenance and maintenance are also a factor that affects the double hemming. For example, when you need to make necessary adjustments when changing the tank type or when there is an abnormality in the roll seal, correct and reasonable adjustments are also very important in addition to replacing the necessary parts. Generally, under the proper driving force of the can tray, first check the Tc value of the head edge width (2.20±0.10mm), and then visually observe the tightness of the curling edge around the can lid. Check appearance defects and various size and craft requirements. Make correct analysis and judgment for the causes of different defects before making adjustments.

3. Process size of empty cans
　　
The lid hooks and can body flanging of different can shapes should meet the corresponding process requirements. For example, poor welding (>0.5mm tailing, welding cracks) before sealing, and too large or small flanging will affect the empty can. Roll seal performance.
　　
4, the groove shape and material requirements of the sealing roller
　　
Generally speaking, the sealing rollers of different can types have different groove shapes. Generally, the groove of the first roller is deep and narrow, and the groove of the second roller is wide and shallow. At present, the commonly used reels of domestic can sealing equipment are mostly medium carbon steel, such as 45#, 40Cr, with short service life, and the output is only limited to 200 to 300,000 cans; the commonly used reels for more advanced sealing equipment are generally 4Cr13, 9Cr18, etc. Stainless steel is made by vacuum heat treatment. It has high hardness, good wear resistance and long life. It can make about tens of millions of cans.
　　
Among the three elements of sealing, the sealing roller is a vulnerable part. It should be polished or replaced with 1 000# or 1 200# water-based sandpaper in time depending on the production situation, so as not to affect the process performance of the curling and sealing.
　　
5, the coating state of the sealing paint
　　
The correct coating position distribution of the plastic film in the crochet side of the can lid is: about 70% in the crochet side and about 30% in the flat surface. In addition, the size of the rubber modulus must meet its own process requirements. If the amount of glue is too large, it is easy to form squeezed glue, and if the amount of glue is too small, it will not function as a sealing filler.
　　
6. The correct operation and adjustment of the operator
　　
The skilled technical skills and operation level of the operator, as well as the necessary daily maintenance and maintenance are also a factor that affects the double hemming. For example, when you need to make necessary adjustments when changing the tank type or when there is an abnormality in the roll seal, correct and reasonable adjustments are also very important in addition to replacing the necessary parts. Generally, under the proper driving force of the can tray, first check the Tc value of the head edge width (2.20±0.10mm), and then visually observe the tightness of the curling edge around the can lid. Check appearance defects and various size and craft requirements. Make correct analysis and judgment for the causes of different defects before making adjustments.
　　
Note: (1) The size specifications are measured by anatomical experiments; (2) The first hemming is the basis and premise of the second hemming, and it is generally checked at least once a week during normal production.
　　
7. The integrity of the equipment
　　
The integrity of the sealing equipment directly affects the sealing performance of the sealing process, which is related to the correct operation and maintenance of the operator.