Acetylene cylinders are the leading products of a company and are prone to defects during manufacturing. This paper elaborates on the defects that are easy to produce in the manufacture of acetylene cylinders and the working principle and machine structure of the acetylene cylinder barrel rounding machine designed to solve these problems.
Defects and their Impact on product quality
The structure of the acetylene cylinder and the defects that are easy to produce during manufacture and the impact on product quality
The acetylene cylinder body consists of three parts: the upper and lower heads and the barrel.
The upper and lower heads are formed from sheet metal forming, and the barrel body is cut by a steel plate and rolled into a circular barrel shape by a 3-roller Bending machine. The three sections are joined together by automatic submerged arc welding, leaving two girth welds and one longitudinal weld on the body. It is easy to form a large amount of misalignment and a large ellipticity at the mouth of the barrel.
As shown in Figure 2. Due to the presence of misalignment and ellipticity and thermal deformation during welding, a peach shape is formed after the barrel is welded. As shown in Figure 3. The wrong side fi produced by the barrel body and the upper and lower heads is shown in Fig. 4, where (a) is the cross-sectional view of the maximum diameter of the barrel and the head, and (b) is the minimum diameter of the barrel and the seal. Head docking profile.
When the amount of misalignment of the weldment is large, a very thick weld can be formed, which is easy to wear when the welding is performed, and the current is small and easy to weld; the large elliptical workpiece has a different distance from the workpiece during the rotation, and the arc is unstable. The same phenomenon occurs in solder leakage and soldering. In addition, the large amount of misalignment leads to a small overlap area, insufficient weld strength, easy-to-open welding, and the appearance is not beautiful, which seriously affects product quality and sales.
In order to eliminate rickets caused by the docking of the barrel and the head, the production workshop uses the inner core expansion method to calibrate the barrel after the barrel is welded and formed, and a press is used to complete the process. However, if the core process is large, the material and weld of the barrel itself are affected by the tensile stress, and the strength is affected. If the core is small, the elastic modulus of the barrel material itself cannot be overcome. After the core is out, the workpiece is again Restored to the original state; this process did not play its due role. Therefore, the production workshop improved this method and switched to the press barrel method. That is, a concave touch is installed on each of the punching machines, the oval length of the barrel is placed in the concave shape in the axial direction for pressing, and the barrel is rotated several times on the press. However, the roundness of the barrel did not change much in the calibration circle, and the roundness of the barrel and the corners of the weld joint were not eliminated. Its appearance does not meet the requirements of GB5100-94 for school angle, wrong amount, and non-circularity. Since the production of dissolved acetylene cylinders, the intrinsic performance has been the best in the country, and the appearance is always lacking. If this problem is not solved, it will have a great impact on sales and even production. Therefore, it is imperative to design and manufacture the ideal acetylene cylinder calibration machine.
design ideas for the calibration machine
The standard 3-roller Bending Machine and the 3-roller Rounding Machine made by a factory are used as prototypes to improve and design more ideal equipment.
Structural analysis of related equipment
The 3-roller Bending Machine rolls the steel sheet into a round barrel shape, and the steel sheet is not subject to any binding force during the winding process. The strength of the steel sheet during the deformation process is not broken by the tensile force, and the steel sheet is only deformed during the winding process. The 3-roller Bending Machine consists of two upper and lower rolls and one side roller that can be raised and lowered. As shown in Figure 5, the upper and lower rolls are active rolls, and the lifting side rolls can reach any diameter required by the workpiece. The closer the circle is, the smaller the circle is rolled. On the contrary, the circle that is rolled is larger. However, the effect of the calibration of this structure is not satisfactory, because the three rollers are asymmetrical.
The calibration machine of a factory in the same industry is a three-roll symmetrical type, that is, two active lower rolls and one passive upper roll. As shown in Fig. 6, the three rolls constitute an isosceles triangle, which can adjust the distance between the upper roll and the lower roll. To achieve the roundness of the school drum. This structure has a good calibration effect, but there are two disadvantages in production.
The main drive mechanism is not stiff enough
As shown in Figure 7, the motor drives the reducer and the output speed of the reducer is given to the lower roller. The engine and reducer are belt driven, the transmission ratio is 1:3, and the reducer is a three-stage gear reducer. The engine and reducer are all overextended beam structures with poor stability and vulnerability. The gear unit is often active in production, significantly if the base of the gear unit is damaged. The reason is that during the calibration process, when the bead is straight through the barrel, the thickening of the weld bead is thickened, and the instantaneous load of the equipment is increased to cause overload.
The irrationality of the auxiliary transmission mechanism.
The auxiliary transmission mechanism is also a V-belt transmission type. To adjust the parallelism between the upper roller and the lower roller, the transmission shaft is made into a half-shaft form and combined with the wheel flange, as shown in Fig. 8. The upper roller is the main component that causes the steel plate to become an external force applied to the barrel. The transmission mechanism of the upper and lower rollers is also the main component of the force. To achieve the ideal state of the barrel, the upper roller needs to exert a large load on the steel plate. Therefore, the auxiliary transmission mechanism is also subjected to a large load, and the V-belt in the belt transmission is fatigued and elongated. Therefore, the position of the motor must be adjusted frequently during production to ensure the tightness of the V-belt to ensure the normal operation of the auxiliary transmission mechanism. To make the upper roller and the lower roller parallel, the transmission shaft is formed into a semi-axle form with a pair of flanges, and the structure is unreasonable, resulting in a low balance accuracy of the pulley, the shaft is easy to bend during the rotation, and the transmission is unstable.
Reasonable structure design
The result of the above analysis: It is determined that the new rounding machine adopts a symmetrical three-roller structure, the main transmission mechanism uses a planetary reducer, the shaft of the reducer is lengthened, and the output end forms a support. Because the planetary reducer has a large transmission ratio, the deceleration can be completed at one time, and The output shaft is double-supported, which increases the stability and rigidity of the transmission and is compact. See Figure 9.
The auxiliary transmission mechanism is a through shaft type, and the speed reduction mechanism is a box type. The motor and the speed reducer are connected to the opposite wheel, the gear box is placed in the middle of the through shaft, and the rigidity of the drive shaft is increased. To make the upper roller and the lower roller parallel, a slidable clutch is designed on the through shaft to meet the requirements, the adjustment is convenient and the structure is reasonable. See Figure 10.
The design makes the main transmission mechanism replace the V-belt transmission with a planetary reducer, which achieves the effect of stable transmission, durability, and reduced maintenance. The slidable clutch is designed on the through shaft of the auxiliary transmission mechanism, and the intermediate shaft is decelerated. The box can ensure the upper roller’s parallelism and increase the transmission shaft’s rigidity. It is compact, reasonable, and durable. The school circular machine has played a huge role since it was put into production. The cylinders that have been tested have a roundness of less than or equal to 1.0 mm and a shuttle angle of ≤1.5 mm. The 40-liter acetylene cylinders produced have reached the national standard, and the amount of misalignment with the head is reduced. It is 35% higher than the original.