Gas Cylinder Manufacturing (3) - Gas Cylinder Quality Inspection

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(2) typical process

5. Heal

The figure is a plan view of the preform spinning machine shut. Shut the machine can be completed preforms or spinning tube shut, closing the bottom step. Process is as follows, the lifting device by passing inspection bench cold and is trimmed preform tube into the blast furnace or car, the car will end preform or tube into the hole of the heating furnace, heated length generally equal to the heated preform or tube diameter, the heating temperature of about 1 100 ℃ or so, then quickly along the rail turning fall within the v-shaped rack. In this case the pusher cylinder or tube preform advance within the rotating hosts ejection pusher cylinder length is adjustable to be fixed and the same after adjustment. At this time the host will preform or hydraulic jaws clamped tube is rotated upward swing cylinder mold driven by the heated end of the preform or tube will be spinning molding, the mold to 900 positions, forming complete . Die quickly return the starting position, then release the clamp host, the material will preform cylinder or tube onto the stacker rack, stacker driven by rises in the cylinder, or preform tube will fall rail rack away. Closed end or shut the process is nearing completion. The following figure and the figure were left the bottle and the bottle forming process Fig. At right is shut mold, closing the mold bottom planar type.

Mold material is wear-resistant stainless steel. Mold shut during the installation, the test should be adjusted so that the bottle after spinning small outside diameter less than 45mm, the lower portion of the blade portion of the mold shut, shut is cut by more than expected, and I expected to cut too long or too short will cause the inner hole is too large enough processing capacity. Further, when receiving the bottom (sometimes also used when shut), in order to maintain preform or parison end has sufficient temperature to weld the bottom, the compensation should be heated using a flame, while rotating, - while heating. Spinning machine from the host (with a hydraulic clamping mechanism), mold swing head, feed cylinder, the material cylinder, stacker unit, consisting of the main part of the rail access to materials, control agencies. Cylinder powered by compressed air, hydraulic system consists of a vane pump as a power source, cylinders and cylinder were manipulated on stage by an electric valve control, base steel plate welded structure. Spinning machine technical parameters:

1. Host motor power 30kW;
2. spindle rotation 948tad / min;
3. cylinder working pressure 2.9MPa;
4. cylinder working pressure 0.29 ~ 0.49MPa;
5. mold spinning time ~ 40s;
6. spinning workpiece diameter φ219mm;
7. spinning workpiece length 600-1700mm.

Now domestic cylinder manufacturer, used spinning machines, molds are scrapers, therefore, when shut, cylinder shoulder appear shuttle

Now domestic cylinder manufacturer, used spinning machines, molds are scrapers, therefore, when shut, cylinder shoulder appear shuttle angle (shoulder with the barrel not smooth transition), the lip crack resistance defects, and forming the shape of the shoulder is inconsistent. One can imagine the stress state of the cylinder edges appear good, and very beautiful but also influence the realization hit stamp mechanization; crack defects, you have to cut off the bottle mouth shut again, re-heat treatment, resulting in smaller volume cylinders , waste steel, energy, man-hours. In order to eliminate the above drawbacks, foreign gas cylinders are used wheeled roller shut shut mold spinning machine, as shown below:

With this machine shut shut, no edges, no cracks the lip defect, and consistent shoulder shape and create conditions for playing stenciled mechanization. Our Anshan pressure vessel plant and Huaan Machinery Plant have introduced such a shut machine, now trial production. The device properties are as follows :( Model EN500)

 1. shut diameter 70 ~ 275mm;
2. shut thickness 2-13mm;
3. The center height of 1 000mm;
The longitudinal slide moving distance 250mm;
5. Turn the slide rotation angle of 100 degrees;
6. longitudinal slide minimum feed 0.1mm;
7. Turn the slide minimum feed 0.1 degrees;
8. The longitudinal slide maximum speed 215mm / s;
9. The maximum rotational speed of the rotary slide 0.9rad / s; 10. The longitudinal slide maximum output 140kN;
11. The rotary slide largest tough moments 26kN · m;
12. The auxiliary heater stroke 1 800mm;
13. The auxiliary heating power injector 4.7kN @ maximum clamping (radial) Stroke 17mm;
14. The radial clamping power 358kN;
15. The main motor 110kW;
16. The maximum load (peak load) 200 (450) KVA;
17 .. work cycle 80;
18. The spindle rotation 6283rad / min;
19. cooling water 75L, / rain;
20. The heated gas (LPG) OzU ~ C2H2;
21. GW 23 000kg.

When shut the process: before shut debris inside the preform addition to the net, and then sent to the intermediate frequency induction furnace heating, heated length of the preform diameter, the heating temperature is 800 ~ 1240 ℃, the heated preform into the bottle-carrying car, then fed shut machine spindle hole, after clamping, the forming roller, seven operation, complete shut processes. Two medium frequency induction furnace, 200kW, frequency 3500Hz. LPG must use additional heating when shut.

6. Heat Treatment

Thus, thermal processing seamless gas cylinders has been completed, the bottle has also been formed, the need for heat treatment bottle. The purpose of heat treatment is to get the bottle needed microstructure and grain refinement, eliminate stress, to achieve the desired mechanical properties and toughness of 40Mn2 steel cylinders (40 liters), currently generally be normalized. Bottle normalizing temperature is generally ^ C ~ Itai boundary point of the material above about 70C. 40Mn2 steel 40 liters cylinders actual temperature control in the 830 ~ 870 ℃, heating specification as follows:

Influence bottle of mechanical properties and microstructure is heating norms and cooling specifications. A bottle body heat treatment 'generally has a dedicated heat treatment furnace, or activity at the end, or continuous hearth or muffle-type furnace chamber shape. There are heavy oil and gas and other fuel difference. Beijing high-pressure cylinder factory heat treatment furnace hearth is tilted, the bottle in the furnace bottom slope by rolling their own, while using pneumatic and pneumatic door dial feeder, temperature measured by thermocouple and electronic potentiometer, and automatic record; adjust the temperature using artificial; high-pressure jet nozzles. Up to 40 bottles furnace, heating 50rain, 5rain out of every four bottles. The main technical data are as follows:

1. furnace brick size 10.10 × 3.765 × 3.256m;
2. The furnace temperature of 900 ~ 920 ℃;
3. bottle temperature 830 ~ 870 ℃ The calorific value of gas 17.1MJ;
5. Gas pressure 0.029MPa;
6. The gas flow 600mS / h;
7. The gas nozzle diameter / number φ56mm / 14 pcs;
8. The bottom slope 1:10.

Bottle came out quickly after entering the cooling bed, cold bed generally about 20m, with intermittent transmission chain. Cooling bed unit is equipped with a plurality of axial fans. Bottle while rolling in the cooling bed, while advancing to obtain uniform cooling of the bottle body, and each bottle to be separated by more than 40mm spacing; to prevent or fell to the ground where there is water, not water to speed cooling. Practice found that the same kinds of steel, various steel products, the treatment performance is different. Factory in production for the first time into the plant material (that is, the same steel), should be small furnace heat treatment tests to guide the production of molded cable specification. At present the domestic cylinder manufacturer heat treatment heating devices are using a variety of fuel-fired furnace, the heating method: The temperature is not easy to control, the bottle is heated unevenly, while the oxidation serious, likely to cause decarburization tolerance, bottle machinery performance can not be ensured. Foreign cylinder manufacturer are based on heat treatment furnace heated, high quality heating and mechanical properties can be guaranteed. Anshan plant the introduction of US pressure vessel of a cylinder electrically heated heat treatment furnaces, as follows:

This machine can be chrome-molybdenum steel cylinders quenching and tempering treatment. Bottom of step-heating resistor element for the plate, hung on both sides of the furnace wall. After the cylinder into the furnace, the first in the quenching furnace heated to a predetermined temperature and maintained released after a certain time. With the feed roller to the flip-top, vertical into the quenching medium quenching, hardening over, removed from the reversing machine, on a feed rollers, fed back to the tempering furnace. Heated to a predetermined temperature, holding a certain time cooled baked. Quenching media: The United States Houghton produced by AQ251 quenching medium as a coolant. Heat treatment furnace technical performance:

1. hardening furnace

a. maximum heating capacity of 7500kg / h;
b. Maximum operating temperature 1 000 ℃; c. Hardening machine line speed 1.5m / s.

2. furnace

a. The maximum heating capacity 7500kg / h;
b. Use the highest temperature 710 ℃;

3. The cooling fan 10HP

The furnace temperature electronic automatic potentiometer automatic adjustment, the range is 1 093 ℃. 30CrMo, 34Mn2V, 40Mn2 three steel cylinders of transfer of heat treatment specifications:
1.30CrMo steel cylinders
880 + 100 ℃ quenching and tempering furnace temperature furnace temperature 550 + 10 ℃ bottle quenching and tempering temperature of 870 + 10 ℃ heating temperature of 5404 + 10 ℃ quenching medium 25-50 ℃, the concentration of 13% to 16%, the quenching time 37min, tempering heating time 48min.
2.34Mn2V steel cylinders
Offend Stove 890 + 10 ℃ temperature tempering furnace 690 + 10 ℃ bottle quenching temperature 8804 + 100 ℃; bottle tempering heating temperature 6804 + 10 ℃ quenching medium temperature 25 ~ 50 ℃; concentration quenching medium from 13% to 16% ; quenching and tempering heating time heating time 37min 48min.
3.40Mn2 steel cylinders
Quenching Furnace 840 + 10 ℃; tempering furnace 540 + 10 ℃ bottle quenching temperature 8304 + 10 ℃ bottle tempering heating temperature 5354 + 10 ℃ quenching medium temperature 25 ~ 50 ℃, medium concentration of 13% to 16% Quenching time 37min, tempering heating time 48min, the three materials come out from the hardening furnace, quenching liquid medium must be immersed within 30 seconds. When the cylinder into the quenching liquid, the temperature of the cylinder must be higher than each ACs point. All in 30 seconds or 30CrMo cylinder temperature is below 830 ℃, 34Mn2V cylinder temperature is below 840 ℃, 40Mn2 cylinder temperature is below 760 ℃ quenching liquid into the cylinders must be tempered, and should be fully re-heat treatment.

After the heat treatment of gas cylinders, by sampling doing mechanical properties and microstructure after passing the examination, the next step is the finish machining, the inner diameter of the cone and cylinder valve thread with an outer diameter of the bottle collar, flat car port.

The figure is a diagram of the bottle bottle screw, end of the thread diameter φ27.8mm, thread taper 3:25, when the number of threads per 14 teeth, pitch 1.814mm, (measured along the bus), thread profile angle 55 bottle thread processing in many ways, such as a lathe pick deduction, deduction, and so milling. Since the external taper thread tapered thread easy to process, and first inspection pass rate higher, for the majority of seamless steel gas cylinders manufacturers tap-tapping buckle, better thread quality. Because welding cylinders and cylinder valve seat collar liquefied petroleum gas cylinders are processed after another in the head with welding, clamping by tapping methods difficult and uneconomical, so are working with pick deduction method.

Seamless cylinders taper threads bottle after bottle valve installed, required to withstand the hydrostatic test 22.5MPa, and 15MPa air tightness test without leakage, it is working to ensure that the bottle is the key process rigor. Domestic plants most self-made multi-station machining bottle, there are vertical and horizontal, and some generic conversion process after turning the bottle. Bottle processing comprising the steps of:

(1) car diameter
(2) car face
(3) Drilling center hole
(4) trucks or thread milling or tapping.

( Editor: Peter )