CN107175421B - A kind of compressive pre-stress bimetal centrifugal is cast the welding procedures of compound pipe end flanges - Google Patents
A kind of compressive pre-stress bimetal centrifugal is cast the welding procedures of compound pipe end flanges Download PDFInfo
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- CN107175421B CN107175421B CN201710547901.6A CN201710547901A CN107175421B CN 107175421 B CN107175421 B CN 107175421B CN 201710547901 A CN201710547901 A CN 201710547901A CN 107175421 B CN107175421 B CN 107175421B
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- flange
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K31/00—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups
- B23K31/02—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups relating to soldering or welding
- B23K31/027—Making tubes with soldering or welding
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- Butt Welding And Welding Of Specific Article (AREA)
- Arc Welding In General (AREA)
Abstract
Cast the welding procedure of compound pipe end flanges the invention discloses a kind of compressive pre-stress bimetal centrifugal, the technique the following steps are included: flange welding surface bevel, uniformly preheating is allowed to warm to certain temperature before being welded to flange；Flange is mounted on to the end of bimetal centrifugal casting multiple tube again, flange is fixed on bimetal centrifugal casting multiple tube using spot welding mode；Then boxing connection is carried out to flange and composite bimetal pipe.Certain compression can be formed to multiple tube using the flange that the technique is welded, caused by this can be effectively prevented from after composite bimetal pipe end flange is welded because of welding residual stress the problem of multiple tube interlaminar separation, the reliability of the double-deck bimetal centrifugal casting compound pipeline complex pipeline flanged joint connector is greatly improved.
Description
Technical field
The present invention relates to specialty metal tubing preparation technical fields, and in particular to a kind of compressive pre-stress bimetal centrifugal casting
Compound pipe end flanges welding procedure.
Background technique
Compressive pre-stress bimetal centrifugal multiple tube of casting widely is answered dredging, adopt the industries such as sand, mining, cement and have
With being a kind of in recent years fast-developing specialty metal pipeline.Under normal conditions, the internal layer of bimetal centrifugal casting multiple tube is by resistance to
Mill property and the higher rich chromium cast iron composition of corrosion resistance, brittle property are larger；And outer layer is then by the higher stainless steel of obdurability or low
Carbon steel composition.It usually there will be what some centrifugal castings generated in the process between the inside and outside layer of this heterogeneous composite bimetal pipe
It is mingled with, so that the binding performance at interface is poor.Under normal conditions, multiple tube can all use certain technology hand during the preparation process
Section makes outer layer generate certain compression to internal layer, to avoid separating or cracking between the inside and outside layer of composite bimetal pipe.Always
For body, compared to traditional monometallic tubing, bimetal centrifugal casting multiple tube because had both that obdurability is big, wearability is high and
The strong advantage of corrosion resistance and have longer service life.
Due to the limitation of preparation process, the single tube limited length of composite bimetal pipe is needed in actual use in multiple tube
End welded flange, then multiple tube is connected by flange again.However, being poured using traditional handicraft in bimetal centrifugal
When casting the end welded flange of multiple tube, the weld seam between flange and multiple tube can generate very big drawing in solidification process and answer
Power separates even crackle so that generating between the outer layer of multiple tube and internal layer.This will reduce rushing for multiple tube rich chromium cast iron internal layer
Resistance is hit, to greatly shorten the service life of composite bimetal pipe.Therefore, in compound tube end welded flange, to the greatest extent may be used
The girth joint that avoids of energy is the key that improve multiple tube service life to compound outer tube layer generation tensile stress.
Summary of the invention
It is an object of the invention to solve in the compound pipe end flanges welding procedure of existing bimetal centrifugal casting because of connector
Bimetallic interlaminar separation or problem of Cracking caused by residual stress, it is desirable to provide a kind of novel compressive pre-stress bimetal centrifugal casting
Compound pipe end flanges welding procedure.
To achieve the goals above, the compressive pre-stress bimetal centrifugal designed by the present invention is cast compound pipe end flanges
Welding procedure is characterized in that, comprising the following steps:
A, in the welding surface bevel of flange, weld preheating is carried out to flange and is allowed to warm to certain temperature；
B, flange is mounted on to the end of bimetal centrifugal casting multiple tube, flange is fixed on by double gold using spot welding mode
Belong on centrifugal casting multiple tube；
C, boxing connection is carried out to flange and composite bimetal pipe.
Further, flange weld preheating temperature is calculated by the following relationship and obtains in the step a:
TY≥T+TL
T in formulaY--- flange weld preheating temperature；
T --- flange theory preheating temperature；
TL--- the temperature reduction in flange assembly, welding process；
T0--- environment temperature.
μ --- stiffness coefficient；
D --- flange inner diameter；
α1--- the thermal expansion coefficient of multiple tube cladding material；
α2--- the linear expansion coefficient of flange；
qw--- unit length weld seam heat input；
L0--- the difference of flange excircle radius and inner circle radius；
C --- flange specific heat capacity；
ρ --- flange density；
A --- flange hole area；
Further, in the step a flange in weld preheating to TYAfterwards, suitably to guarantee that it is pre- that flange is uniformly heated to
Hot temperature, soaking time t, is calculated by following formula:
T=k δ
In formula: t --- preheating insulation chronomere: min；
K --- heat insulating coefficient unit: min/mm
δ --- flange thickness flange thickness.
Still further, the installation gap of flange and multiple tube after preheating in step b is less than 1.5mm.In favor of flange
Fast Installation and positioning after preheating are reduced with reducing the temperature of flange, and can effectively reduce eccentricity when flange installation.
Still further, the welding method in step b and step c can be arc welding, laser welding and electron beam welding.
Still further, the temperature of flange should be higher than that flange theory preheating temperature T after girth welding in step c.It can
Guarantee welding residual stress is compressive stress state, multiple tube compound interface separation cracking is effectively prevent, by improving practical preheating
The measures such as temperature, rapid welding, flange radiating surface covering insulation material guarantee that flange welding terminates the middle portion temperature of rear flange and answers
Higher than theoretical preheating temperature T, to guarantee that flange is heat-shrinked to weld seam parameter action of compressive stress.
The present invention has the advantages that
1, the postwelding residual tension that can be effectively reduced connector is welded again after flange preheating or even be changed into compression；
2, it is covered again after flange preheating and is filled to composite bimetal pipe end, the cooling after-contraction of flange welding can apply multiple tube
On the one hand certain compression can offset the tensile stress generated in weld seam solidification process, on the other hand can reinforced composite pipe
Outer layer is to the compression of internal layer, to avoid separation or the generation of crackle between the inside and outside layer of multiple tube.
3, cover is filled to composite bimetal pipe end again after flange preheating, flange after cooling by banding composite bimetal pipe,
To increase the installation strength of flange.
Detailed description of the invention
Fig. 1 is position while welding schematic diagram when compressive pre-stress bimetal centrifugal casting multiple tube and flange assemble.
In figure: compressive pre-stress bimetal centrifugal casting multiple tube 1, flange 2, welding ring-shaped fillet weld 3.
Specific embodiment
The present invention is described in further detail in the following with reference to the drawings and specific embodiments:
Compressive pre-stress bimetal centrifugal casting multiple tube is made of rich chromium cast iron internal layer and stainless steel outer layer, and flange material is
No. 20 steel, the outer dimension of compressive pre-stress bimetal centrifugal casting multiple tube and its welding portion between flange are shown in Fig. 1.
In figure, compressive pre-stress bimetal centrifugal casting multiple tube 1, flange 2, welding ring-shaped fillet weld 3, the casting of compressive pre-stress bimetal centrifugal is again
The specific welding process of welding procedure for closing pipe end flanges is as follows:
1, flange theory calculation of preheating temperature: flange theory Preheating T is calculated using following formula:
μ in formula --- stiffness coefficient；
D --- flange inner diameter；
α1--- the thermal expansion coefficient of stainless steel；
α2--- the linear expansion coefficient of flange；
qw--- unit length weld seam heat input；
L0--- hem width before flange welds；
C --- flange specific heat capacity；
ρ --- flange density；
A --- flange endoporus area；
T0--- environment temperature；
Specific calculating process is as follows:
As shown in Figure 1, flange endoporus area A:
A=π D δ
=π × 800mm × 50mm=0.126m2
In formula: D --- flange inner diameter；
δ --- flange thickness
Weld heat input qw:
In formula: qw--- unit length weld seam heat input, i.e. weld heat input
η --- welding thermal efficiency
U --- arc voltage
I --- welding current
V --- speed of welding
Flange theory preheating temperature T:
In the present embodiment, blue assembly, the temperature reduction T in welding process are followed the example ofL=100 DEG C；Then practical preheating temperature
TY:
TY≥T+TL=285 DEG C+100 DEG C=385 DEG C
Temperature reduction T in flange assembly, welding processL, flange, which preheats, in order to prevent loses circle, bending deformation and high temperature
Oxidation, TY600 DEG C should be not higher than.In actual implementation, can by quick assembling positioning, rapid welding, in flange non-welded part
Add the measures such as Insulation to reduce TL, and then reduce practical preheating temperature TY。
(2) pre-welding treatment
Flange and multiple tube are machined before welding preheating, and process welding groove, room temperature shape in the welding surface of flange
State is transition fit.Be pre- Warm status in flange, when multiple tube room temperature state its with clearance fit is combined into, gap takes 1.5mm.
It first treats welding method orchid and compressive pre-stress bimetal centrifugal casting multiple tube carries out welding pretreatment, using physics or change
Method clears up the oil rust in flange and composite tube welding face.Flange is placed in electric furnace and is heated, heating rate be 10 DEG C/
Min keeps the temperature 50 minutes after temperature rises to 385 DEG C, then takes out flange using fork truck, and flange sleeve is quickly mounted in multiple tube
End.
(3) welding process is assembled
Using CO2Electrogas process carries out spot welding to flange and multiple tube and fixes, then to flange and multiple tube it
Between forward and backward welding ring-shaped fillet weld simultaneously welding.Wherein fillet weld 1 select welding current be 180-260A, voltage 26-30V,
Speed of welding is 16-20cm/min, and weld heat input is 1.26-2.63 × 106J/m；The welding current of fillet weld 2 is 160-
180A, weldingvoltage 24-28V, speed of welding 18-22cm/min, weld heat input are 0.94-1.68 × 106J/m, choosing
Welding wire model is H12Cr24Ni13Si.Postwelding carries out sanding and polishing processing to flange and compound end surfaces, and uses and answer
Become the post-weld stress of piece measurement endface different parts.On the outside of the weld seam at 9mm, the range of stress on flange measured is
22.4MPa-44.7MPa；On the inside of the weld seam at 9mm, measuring the range of stress on compound outer tube layer stainless steel is 0.3MPa-
1.2MPa, the range of stress on weld seam are 22.7MPa-45.9MPa.
(4) postwelding is observed
Using the method for the present invention preparation multiple tube and flange welding connector, to flange welding after, compound inner tube layer
It is tightly combined between outer layer, observation weld flawless is qualification.
Although the present invention is described in detail referring to the foregoing embodiments, for those skilled in the art,
It can still modify to technical solution documented by previous embodiment, or be equal to part of technical characteristic
Replacement, all within the spirits and principles of the present invention, any modification, equivalent replacement, improvement and so on should be included in this hair
Within bright protection scope.
Claims (4)
- The welding procedure of compound pipe end flanges 1. a kind of compressive pre-stress bimetal centrifugal is cast, which is characterized in that including following Step:A, in the welding surface bevel of flange, weld preheating is carried out to flange and is allowed to warm to certain temperature；B, by flange be mounted on bimetal centrifugal casting multiple tube end, using spot welding mode by flange be fixed on bimetallic from The heart is cast on multiple tube；C, boxing connection is carried out to flange and composite bimetal pipe；The middle portion temperature that boxing welding terminates rear flange should be higher than that flange Theoretical preheating temperature T；Wherein flange weld preheating temperature is calculated by the following relationship and obtains in the step a:TY≥T+TLT in formulaY--- flange weld preheating temperature；T --- flange theory preheating temperature；TL--- the temperature reduction in flange assembly, welding process；T0--- environment temperature；μ --- stiffness coefficient；D --- flange inner diameter；α1--- the thermal expansion coefficient of multiple tube cladding material；α2--- the linear expansion coefficient of flange；qw--- unit length weld seam heat input；L0--- the difference of flange excircle radius and inner circle radius；C --- flange specific heat capacity；ρ --- flange density；A --- flange hole area.
- The welding procedure of compound pipe end flanges 2. compressive pre-stress bimetal centrifugal as described in claim 1 is cast, feature Be: flange keeps the temperature a period of time after weld preheating to certain temperature in the step a, and the soaking time is calculated by following formula It obtains:T=k δIn formula: t --- preheating insulation chronomere: min；K --- heat insulating coefficient unit: min/mmδ --- flange thickness.
- The welding procedure of compound pipe end flanges 3. compressive pre-stress bimetal centrifugal as claimed in claim 2 is cast, feature Be: the installation gap of flange and multiple tube after preheating in step b is less than 1.5mm.
- The welding of compound pipe end flanges 4. compressive pre-stress bimetal centrifugal according to any one of claims 1 to 3 is cast Technique, it is characterised in that: the welding method in step b and step c includes arc welding, laser welding and electron beam welding.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201710547901.6A CN107175421B (en) | 2017-07-06 | 2017-07-06 | A kind of compressive pre-stress bimetal centrifugal is cast the welding procedures of compound pipe end flanges |
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| CN201710547901.6A CN107175421B (en) | 2017-07-06 | 2017-07-06 | A kind of compressive pre-stress bimetal centrifugal is cast the welding procedures of compound pipe end flanges |
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| CN101592265A (en) * | 2009-07-03 | 2009-12-02 | 郑州神牛铸造有限公司 | Bimetal wear resistant composite tube |
| US20120214016A1 (en) * | 2011-02-22 | 2012-08-23 | General Electric Company | Constrained metal flanges and methods for making the same |
| CN102829254B (en) * | 2012-08-23 | 2017-02-01 | 枣庄市凯博机械制造有限公司 | Metallurgical fused composite concrete conveying pipe and manufacturing method thereof |
| CN105689857A (en) * | 2014-11-28 | 2016-06-22 | 重庆基石机械有限公司 | Tower drum manufacturing welding process |
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