Self made and application of air diaphragm for the

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Self making and application of air diaphragm for single machine

pneumatic pressure control of corrugating roll is the main mode of single-sided machine in paperboard production lines at home and abroad. The pressure between rolls of xdv-1030 single-sided machine is realized by the action of four cylinders distributed at both ends of the upper corrugating roll and the pressure roll. The pressure is adjusted according to the actual needs through the control valve and measuring instrument on the control panel

I. air diaphragm

the cylinder action is realized by compressed air passing through the air diaphragm in the cylinder. The air diaphragm is referred to as air bag for short. It is a diaphragm type part widely used in hydraulic and pneumatic devices. It can convert the uniform pressure transmitted by the compressed air into the thrust continuously acting on the cylinder connecting rod, so as to adjust or maintain the gap between the corrugating roll and the pressure roll, so as to ensure continuous and normal production

the air bag is a slightly inclined cylinder with a bottom circle diameter of 178 mm. The upper end is sealed with an opening at the lower end, with a height of 130 mm. The wall thickness of one side is about 0.75 mm. A layer of rubber is coated inside and outside, and a layer of woven fabric is sandwiched in the middle. It has good folding and sealing. It can transmit 6-12kg/cm2 pressure when used. If there is a slight air leakage during use, the product quality will be affected or the production of single-sided machine will be directly interrupted. Therefore, airbag is a very important vulnerable part

II. Preparation for trial production

technical investigation

requirements for airbag:

(1) no air leakage during the whole journey

(2) able to withstand certain pressure, temperature and lubricating oil

(3) good folding and long service life

(4) relatively reasonable price

requirements for airbag materials:

(1) under the given pressure, the rubber shall have sufficient strength, elasticity, notch impact resistance and wear resistance. No material fatigue under dynamic load

(2) the rubber has good processability, good fluidity, convenient vulcanization conditions and easy adhesion to the woven fabric

(3) at the maximum operating temperature, the rubber is neither soft nor hard, nor will it break due to the change of climate conditions

mold requirements: due to the limited number of air bags, the mold must be simple and practical. Considering the factors such as convenient mold manufacturing, reducing the accumulated operation intensity and process needs, it is specially designed into the upper, middle and lower segments. In order to ensure that the rubber coating layer does not leak, the initial wall thickness of one side is 1.5mm

III. test stage

1 There are two types of rubber: neoprene, which is resistant to aging and combustion and is suitable for air contact applications, and nitrile rubber, which has strong oil resistance and is suitable for compression but which is not compressed by air

2. A small number of comparative tests were carried out with different brands of rubber, cord fabric and nylon fabric of different thickness in batches

3. Find out the basic process flow

4. The lessons learned are as follows:

cloth clamping lessons:

(1) the airbag cannot be used normally without cloth clamping

(2) the dimming performance of cloth without reflective can be comparable to that of artificial high molecular materials, which can determine the narrow strip adhesive rubber, otherwise the cross overlap is thick and hard, which will directly affect the effect; At the same time, the narrower the cloth strip is, the more joints are, which is easy to produce leakage points and increase the processing difficulty

(3) the cloth clip shall be connected as a whole as far as possible. At present, the two-piece connection shall be sewed together with small pins before the glue is hung. Pay attention to the flatness of the joint

mold defects:

(1) the joint of the upper and middle molds is where the folding is used, and about half of the leakage points are distributed within 6mm around the joint, so the joint must be moved down

(2) the sealing groove is too shallow and the cover plate is easy to fall off, resulting in out of control shutdown; The two 0.7mm sealing thin lines are meaningless in practical use and can be simplified

(3) the capacity of the lower mold rubber groove is not large enough

(4) the mold centering shall be simple and reliable to avoid obvious uneven wall thickness caused by excessive micro movement during vulcanization and finalization, and the thin part is often the place where leakage occurs

(5) the transition fillet of the mold is too small, resulting in thicker fillet of the air bag, higher hardness, and easy damage or cracks during folding

in addition, the wall thickness of the air bag shall be less than 1.5mm, and the hardness of the glue shall be 30-35 degrees shore

IV. formal use

1 There are many problems in the first set of rework dies, so it is impossible to modify them to meet the use requirements. After that, another set of molds will be processed, the transition fillet will be changed from r10mm to r20mm, the glue overflow groove will be expanded to r1.5mm, the sealing groove will be more simple and practical, the upper and middle mold joints will be moved down by 25mm, and the air bag wall thickness will be set as 1.3mm

2. According to the practical statistics, all the imported spare parts were used up in 1992, but there was no original record. It is estimated that 3 to 5 pieces will be renewed every year, and each piece will be repaired at least 5 times. Since the self-made parts are cheap (80 yuan per piece), they are never repaired and are replaced as soon as they are damaged. They have stabilized from more than 50 pieces per year in the initial stage to 15 pieces per year after 1997. Their quality has improved significantly and basically achieved the expected goal

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