CN201070646Y - Core rod device for preventing oversize of chemical boat special pipe bending ellipse - Google Patents

Abstract

The utility model relates to a mandril mechanism avoiding the bending ovality oversize of a chemicals ship special pipe, and the mandril mechanism comprises a mandrel head and a mandrel pull rod, wherein, the mandrel head is the knurly mandrel head, the mandrel head is connected with the mandrel pull rod. In the process of bending the chemicals ship special pipe, the application of the utility model can avoid the ovality oversize effectively to reduce the shipbuilding cost and shorten the shipbuilding periods.

Description

Prevent that the chemical tanker particular tube from bending the excessive core bar device of ovality

Technical field

The utility model belongs to boats and ships pipe manufacture field, a kind of core bar device that ovality is excessive that prevents in the process that the chemical tanker particular tube bends of more specifically saying so.

Background technology

The chemical tanker that present most of shipyard is built, wherein the high pressure liquid pressure pipe all is external inlet tube.They have special thick carbon steel pipe and the stainless steel tube of thin-walled, particularly stainless steel (material trademark is 316L) large-diameter and thin-wall pipe (Ф 131 * 3), and its relative wall thickness is 2.2%, and it is bigger that it bends technical difficulty, and domestic shipyard does not have the experience that bends of this respect.In order to ensure the construction progress and the quality of this ship, therefore entrust these particular tube external special manufacturer to bend, transport to domestic the installation then.These particular tube are entrusted and are abroad bent, and not only we will bear expensive expense, and work as ship in process of production, in case problems such as pipeline revise, damaged tubular take place, then will entrust external processing once more, thereby cause bigger expense; Because it is the manufacturing of pipe is long service cycle, extremely inconvenient simultaneously for the organization of production of ship.

As shown in Figure 1, the stress when Figure 1 shows that tube bending, wherein: M---and tube bending moment, σ 1---tensile stress, σ 2---and compression stress, N1, N2---pipe is pressed inclined to one side power.Figure 2 shows that the ovalizing deflection behind the tube bending, Dw---pipe name external diameter, A---transverse, B-ellipse short shaft.

During tube bending, the madial wall at tube bending position is compression and tube wall will thicken; Outside tube wall produces stretcher strain and tube wall is wanted attenuation.Simultaneously, tube wall is under the effect of tension and compression stress, and the effect that the circle footpath direction at tube bending position is flattened promptly behind the tube bending, can produce the result of ovalizing deflection.

The stress intensity that produces in the tube wall during tube bending often depends on the size (Rx=R/d, R are the tube bending radius, and d is the external diameter of pipe) of pipe relative bending radius Rx.Rx is littler when relative bending radius, and then stress is bigger.Excessive stress, it is thin serious that the tube wall in the crooked position outside of pipe is drawn, and can reduce the intensity of pipe.Ovalizing deflection degree behind the tube bending not only will depend on the relative bending radius Rx of pipe, also will depend on the relative wall thickness Sx (d is the external diameter of pipe for Sx=s/d, s table pipe wall thickness) of pipe simultaneously.When pipe relative bending radius Rx under identical condition, relative wall thickness Sx littler (Circular Rigid of pipe is little), the ovalizing deflection behind the tube bending are bigger.Excessive ellipse behind the tube bending will change the flow area of pipe, can influence the attractive in appearance of tube bending position simultaneously.Thereby, the bending quality of control pipe, routine has been decided permission reduction F≤12% of pipe wall thickness and ovality E≤7% of pipe circle.

Improve the degree of crooked back ovalizing deflection, conventional method is to adopt chip bending is arranged, as shown in Figure 2.The cylindrical plug of bulb that chip bending is arranged is to have increased a strong point on the inwall in the tube bending point outside, prevents the flattening function of pipe, thereby reaches the circular rigidity that increases in the tube bending process.But when pipe is crooked continuously, at the position of brake forming, still exist the effect of flat pressure, just local a little bit smaller approximately compared with curved point, for light-wall pipe, it still causes the pipe flattening.Radius of curvature R=3 of the stainless steel tube of present chemical tanker, relative wall thickness Sx=0.022.Obviously adopt the cylindrical plug of simple bulb can't reach the ovality requirement of regulation.

The utility model content

The utility model can't satisfy the deficiency that pipe bends the circular ovality requirement of back pipe in order to solve prior art, and a kind of core bar device that ovality is excessive that prevents in the process that the chemical tanker particular tube bends is provided.

For realizing above purpose, the utility model has adopted following technical proposals:

A kind of chemical tanker particular tube that prevents bends the excessive core bar device of ovality, comprises core head and plug pull bar, and wherein, described core head is the more piece core head, and core head links to each other with the plug pull bar.More piece core head joint number is more than two joints or two save, and is preferable, and the more piece core head is two joint core heads or three joint core heads, preferred three joint core heads.

The operation principle of more piece plug is, it can the continuation effect at crooked position, and its core head may extend into the crooked position of pipe, makes in the BENDING PROCESS of pipe, prolongs the supporting role scope (length) of core print; This more piece core print that extends to the crooked position of pipe, when the tube bending end, when core print was extracted out in managing, core print can also carry out the set round effect to pipe.

The joint number of more piece plug the more, the core head length that extends to crooked position is longer, prevents that the effect that pipe flattens will be better.In the tube bending process, produce strong friction owing to supporting the core head of tube wall with tube wall, so this more piece plug can strengthen pipe moving resistance when bending, if frictional resistance is excessive, pipe is slided at preceding chuck place, cause the pipe can't be crooked; When core print is extracted out in the pipe of bending after the tube bending process finishes, same resistance (with the frictional resistance of tube wall and the core head set round active force to pipe) can be much larger than general core head, so the oil cylinder of loosing core that its cylinder diameter need of loosing core are used greater than general core head can guarantee that just the smooth and easy of the process of loosing core carries out.

Because the positive effect of more piece plug: the circularity that improves crooked pipe.Its negative role of while: increase the frictional resistance of swan-neck, the clamping difficulty of chuck before causing.As long as guarantee under the crooked circularity situation, the joint number of more piece plug is more lacked better.For the stainless bending of Ф 131 * 3,, select for use three joint plugs comparatively desirable by the curved test of the reality of pipe.

The beneficial effects of the utility model are: improved the circularity of crooked pipe greatly, the manufacturing cycle of pipe is shortened greatly, thereby produced good effect for reducing the shipbuilding cost and shortening shipbuilding period.On high performance ship, for the pipeline of some low pressure, select for use large-diameter and thin-wall pipe can reduce the tubing consumption, thereby alleviate the ship deadweight, for those nonferrous metal tubes (the non-ferrous alloy pipe of stainless steel tube and high corrosion resistant), more can bring considerable economic especially.

Description of drawings

Fig. 1: the stress schematic diagram during tube bending

M-tube bending moment

σ 1-tensile stress

σ 2-compression stress

N1, N2-pipe are pressed inclined to one side power

Fig. 2: the ovalizing deflection schematic diagram behind the tube bending

Dw-pipe name external diameter

The A-transverse

The B-ellipse short shaft

Fig. 3: the schematic diagram of the conventional cylindrical plug swan-neck of bulb

Fig. 4: the schematic diagram of the crooked pipe of the utility model

Reference numeral:

1: pipe 2: core head

3: plug pull bar 4: curved mould

The specific embodiment

Below in conjunction with accompanying drawing specific embodiment of the utility model is done a detailed description:

Be illustrated in figure 3 as an embodiment of the present utility model, a kind ofly in the process that the chemical tanker particular tube bends, prevent the core bar device that ovality is excessive, comprise three joint core head 2 and plug pull bars 3.

Pipe is in BENDING PROCESS, when curved mould 4 rotates, pipe 1 is given and is moved together around curved mould 4, manage 1 son give the peripheral velocity of mobile linear velocity and curved mould 4 should be consistent, therefore behind the tight pipe 1 of pipe fore-clamp head-clamp on the curved mould 4, drawing pipe 1 mould 4 motion of going for a stroll, must no any sliding phenomenon.Because the circularity rigidity of light-wall pipe is little, when the preceding chuck of inner chamber circle compressed, pipe produced distortion, and pipe is reduced by the tractive force that preceding chuck produces; Bend owing to light-wall pipe but then, guarantee bending quality, adopt core bar device, promote plug pull bar 3 core head 2 is advanced, and extend to the crooked position of pipe 1, the moving resistance of pipe is increased, so the tractive force that pipe moves is bigger than conventional bending, when the tube bending end, when core head 2 was extracted out in managing, core head 2 can also carry out the set round effect to pipe.

For chuck before preventing swan-neck skids, should adopt the method that reduces the swan-neck moving resistance and increase the resistance to sliding at preceding chuck place.Reduce the swan-neck moving resistance, can adopt the little and anti abrasive material of coefficient of friction to make plug such as (as bronze).The surface smoothness of plug must improve (more height better) simultaneously, when bending, is added with enough lubricating grease between rubbing surface simultaneously, forms lubricating oil film as much as possible between rubbing surface.For the resistance to sliding method at chuck place before increasing, can adopt under bending condition allows, increase the chuck width as much as possible, improve the work area of chuck, thereby improve its resistance to sliding; Be processed with anti-slip tank (line) at preceding chuck inner chamber; Method such as placing sand cloth between chuck and pipe.Certainly all methods are principle for not damaging bend pipe wall surface and tubular shape all.

Because the fineness of plug is higher, so the surface of swan-neck and the cleaning of inwall must be added on attention, in case between rubbing surface jagged or solids foul etc., cause the damage of plug most probably, thereby cause the increasing of tube bending frictional resistance and the surface damage of swan-neck.

Claims (2)

1. one kind prevents that the chemical tanker particular tube from bending the excessive core bar device of ovality, comprises core head and plug pull bar, it is characterized in that described core head is the more piece core head, and core head links to each other with the plug pull bar.

2. prevent according to claim 1 that the chemical tanker particular tube from bending the excessive device of ovality, it is characterized in that described more piece core head is two joint core heads or three joint core heads.

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