WO2014106358A1

WO2014106358A1 - Split screw pile and welding method thereof

Info

Publication number: WO2014106358A1
Application number: PCT/CN2013/070520
Authority: WO
Inventors: 吴克耀
Original assignee: 广东保威新能源有限公司
Priority date: 2013-01-07
Filing date: 2013-01-16
Publication date: 2014-07-10
Also published as: CN103061333B; JP2015507109A; CN103061333A

Abstract

A split screw pile comprises a pile body (2) and a submerging tip (1) which are split. The submerging tip (1) comprises a sharp end (102) and a truncated-cone-shaped tail (101). An insert part (101a) of the submerging tip is inserted into a socket hole of the pile body so that a circular welding groove (3) is formed between a slant part (101b) of the submerging tip and an open end surface (203) of the pile body. The pile body is welded to the circular welding groove of the submerging tip to form an integrated structure. The welding method of the split screw pile comprises the following steps: 1) performing connector butting; 2) cleaning before welding; 3) preheating; 4) welding: namely performing manual argon tungsten arc welding to complete bottoming by nickel-base welding wires ERNiCrMo-3, and performing manual arc welding to complete filling and capping; 5) performing heat treatment after welding. Therefore, the effective welding between the Q235B pile body and the 12Cr1MoV submerging tip is achieved, and the butt joint of connectors is simple and reliable.

Description

Split type spiral pile and welding method thereof

The present invention relates to a spiral pile, and in particular to a split type spiral pile and a welding method thereof. Background technique

The application of piles in engineering construction is relatively large, and it is widely used in construction industries such as solar photovoltaic and wind energy. The pile is a connection main structure commonly used in the construction and steel frame structure industries to connect the ground. The existing spiral piles adopt an integrated structure, the pile body is a tubular structure, the periphery of the pile body is connected with spiral blades, and the front end of the pile body has a pointed structure. The whole spiral pile can only be applied to soil with single characteristics. When encountering other characteristic soils, such spiral piles lose their use value, which limits the scope of use of the piles on the one hand, and When the spiral piles are used to construct the frozen soil with high hardness, the spiral piles need to adopt superhard materials as a whole, which has the problems of high cost and waste of resources. For example, Chinese Patent Application No. "201110194483. X" discloses a rotary drilling prefabricated composite pile and a construction method thereof, including a pile body and a pile tip, the pile tip being tapered, and the outer surface of the pile is provided with a level thereof a blade having an acute cross-section, the blade being at least one piece, the blade being in the shape of a spiral, a fan blade or a coulter, which is continuously or intermittently distributed along the axial direction of the outer surface of the pile, on the outer surface of the pile The spiral plate is spaced apart, and the spiral plate is continuously or intermittently disposed within 360 degrees of the outer surface of the pile, and the pile body is connected to the pile tip through a flange or a welded joint. However, the spiral pile uses a conventional welding method. When constructing a high-hardness frozen land, it is necessary to use a super-hard material (such as UCrlMoV) as a whole, which has high cost and waste of resources. Question.

In order to solve the above problems, the inventors first proposed welding a pile of Q235 carbon steel and a pile tip of 12CrlMoV steel to achieve cost reduction. However, since the groove form of the conventional welded joint is generally a V-shaped or U-shaped groove, it is necessary to perform the groove processing on both the pile body and the pile tip, there is trouble in processing and docking, the effective welding area is small, and the weld strength is poor. The disadvantage of low welding efficiency. At the same time, UCrlMoV steel belongs to pearlitic heat-resistant steel. Due to the carbon content and alloying elements, the weld and heat-affected zone are prone to hardened structure, which reduces plasticity and toughness, and deteriorates weldability. When weldment stiffness and joints When the stress is large, cracks are likely to occur. Since the chemical composition of UCrlMoV steel and Q235B carbon steel are very different, their welding is a dissimilar steel welding. To obtain a reliable welded joint under the condition of welding, there are many problems: 1. Due to the thermal conductivity of both The difference in specific heat capacity causes the melting of the two to be out of sync, and the formation of the molten pool and the poor metal bonding result in deterioration of the weld crystallization conditions, weld bead performance and poor formation. 2. The linear expansion coefficients of the two are different, resulting in different shrinkage on both sides of the weld during the cooling process after the formation of the welded joint, resulting in a complicated high stress state of the welded joint, thereby accelerating the crack generation. 3. There is a problem of weld dilution and formation of a transition layer.

In summary, it can be seen that the welding of the two different kinds of steel by the structure and welding process of the traditional welded joint can not achieve the effective welding between the two dissimilar steels, so the structure and welding process of the welded joint need to be improved. . Summary of the invention

In view of the deficiencies of the prior art, the first object of the present invention is to provide a split Spiral pile, which is welded by Q235B carbon steel pile and 12CrlMoV heat-resistant steel to the whole structure. The joint between the joints during welding is reliable, improve work efficiency, increase effective welding area and increase The weld strength after welding can achieve effective welding between the two dissimilar steels, reducing processing and production costs.

A second object of the present invention is to provide a method for welding a split type spiral pile, which can prevent cracks at the weld joint; reduce carbon diffusion; reduce intergranular corrosion, and realize Q235B carbon steel Effective welding between the pile and the 12CrlMoV heat-resistant steel drill tip.

In order to achieve the above first object, the present invention adopts the following technical solutions:

A split type spiral pile includes a tubular pile body and a conical drill tip, and the pile body is provided with a spiral blade having a spiral strip shape; the feature is: The tip includes a tip end portion and a truncated cone tail portion; the truncated cone tail portion includes a plug portion that cooperates with the inner wall surface of the pile body and a slope portion that is larger in diameter than the plug portion; the plug portion of the drill tip is inserted through the pile In the sleeve hole of the body, an annular welding groove is formed between the inclined surface of the drill tip and the open end surface of the pile body, and the axial section of the annular welding groove is a right triangle or a right angle trapezoid; the pile body It is welded with the drill tip at the annular welding groove to form a unitary structure.

The pile body is a pile made of Q235B carbon steel. The chemical composition (%) of Q235B carbon steel: C: 0.12 - 0.20, Si: < 0.30, Mn: 0.30 - 0.70, S: 0.045, P: 0.045, Cr : Permissible residual content 0.030, Ni: Permissible residual content 0.030, Cu: Permissible residual content 0.030.

The drill tip is a drill tip made of 12CrlMoV weathering steel. Chemical composition (%) of UCr lMoV weathering steel: C: 0· 07 - 0. 15 , S i : 0. 18 - 0. 37 , Μη: 0. 41 - 0. 70 , Cr : 0. 90 - 1. 20, Mo: 0. 25 - 0. 35 , V: 0. 15 - 0. 30.

One embodiment of the invention is achieved in that the cross-sectional area of the annular welding groove is greater than or equal to 8 mm ² .

One embodiment of the invention is achieved in that the end of the pile body is provided with a flange structure or a set screw structure for fixing to the outer body structure.

One embodiment of the present invention is such that the rear end portion of the pile body is provided with a curved reinforcing plate and a through hole penetrating the reinforcing plate and the pile body.

One embodiment of the invention is achieved in that the tip portion includes a breached tip of the front end and a cutting edge on both sides.

One embodiment for carrying out the invention is that the tip end portion is further provided with a circular drainage hole.

One embodiment of the invention is achieved in that the helical blade is a continuous helical blade or a segmented helical blade.

In order to achieve the above second object, the present invention adopts the following technical solutions:

A method for welding split-type spiral piles is characterized in that: 1) joint butt joint: insert the plug portion of the drilled tip into the sleeve hole of the pile body, so that the inclined surface of the drilled tip Forming an annular welding groove between the portion and the open end surface of the pile body, the axial section of the annular welding groove is a right-angled triangle or a right-angled trapezoid; wherein the pile body is a pile body made of Q235B carbon steel, The tip of the drill is a drill tip made of UCr lMoV weathering steel; 2) Pre-weld cleaning: The oil and impurities on the surface of the butt-welded part of the pile and the drill tip are removed;

3) Preheating: preheating the welded part of the pile and the drill tip to 150 ~ 180 °C; Preheating is an important measure for the welding of pearlitic heat resistant steel. Preheating can slow the weld and heat affected zone. The cooling rate is beneficial to avoid the generation of hardened structure, which contributes to the escape of hydrogen in the weld zone and prevents the occurrence of weld cracks. Due to the high carbon content and alloying element content of UCrlMoV steel, the preheating temperature is selected from 150 to 180 °C;

4) Welding: The pile body and the drill tip are horizontally rotated for welding. The nickel-based welding wire ERMCrMo_3 is selected, and the manual tungsten-arc welding (TIG) is used to make the bottom. Manual arc welding

(SMAW) filling, cover surface; interlayer temperature is controlled at 180~200 °C; during the whole welding process, the interlayer temperature should be kept below the preheating temperature;

4-1) Manual tungsten argon arc welding (TIG) primer: 80% Ar and 20% He are used as shielding gas, and the control gas flow is 8 L/Min; the polarity of the power supply is: DC positive connection, current is 100A, voltage is 12V;

4-2) Manual arc welding filling: The polarity of the power supply is: DC positive connection, current is 120A, voltage is 15V;

4-3) Manual arc welding cover: The polarity of the power supply is: DC positive connection, current is 120A, voltage is 15V;

5) Post-weld heat treatment: Immediately after the welding, the insulation material is used to cover the weld and the weld near the weld zone, so that the joint is slowly cooled. Subsequently, the whole of the weldment was further heated to 760 ° C, and after being kept at a constant temperature for 30 minutes, it was cooled to room temperature. Stress-relieving heat treatment after welding can eliminate or reduce the hardened structure in the affected area, increase plasticity and toughness, and effectively reduce Welding residual stress, while facilitating the escape of diffused hydrogen, thereby reducing the tendency of cold cracking. The beneficial effects of the invention are:

1. The invention improves the structure of the welded joint, and the drilled tip is provided with a truncated cone tail; the insertion portion of the drilled tip is inserted into the sleeve hole of the pile body, so that the ground tip can be made An annular welding groove is formed between the inclined surface and the open end surface of the pile body, and the butt joint between the joints is reliable, and the working efficiency is improved; since the axial section of the annular welding groove is a right-angled triangle or a right-angled trapezoid, and the conventional Compared with the groove form, the effective welding area can be increased, the weld strength after welding can be improved, and effective welding between the two dissimilar steels can be achieved. At the same time, the present invention only requires the beveling of the tip portion of the earth-boring portion, thereby reducing the processing and production costs.

2. The present invention improves the welding process. First, the present invention preheats the welded portion of the pile body and the drill tip to 150 to 180 ° C, which can slow down the cooling rate of the weld and the heat affected zone. It is beneficial to avoid the occurrence of hardened structure, which contributes to the escape of hydrogen in the weld zone and prevents the occurrence of weld cracks. Secondly, the invention selects nickel-based welding wire ERN iCrMo-3, adopts manual tungsten argon arc welding (TIG) base, manual arc welding (SMAW) filling, cover surface, and argon-helium mixed gas GTAW bottom welding, that is, product The weld is made of 80% Ar+20%He, the arc is stabilized and soft by Ar gas, the heat of the He gas arc is large and concentrated, and the deep penetration is added to eliminate the occurrence of interlayer unfused defects in the weld welding of the dissimilar steel product. . Finally, the present invention performs post-weld heat treatment, which can eliminate or reduce the hardened structure appearing in the affected zone, increase the plasticity and toughness, effectively reduce the welding residual stress, and at the same time facilitate the diffusion of hydrogen, thereby reducing the tendency of cold cracking.

In summary, the present invention improves the structure and welding process of the welded joint, It can prevent the occurrence of cracks at the weld; reduce the diffusion of carbon; reduce the intergranular corrosion, and achieve effective welding between the Q235B carbon steel pile and the 12Cr lMoV heat-resistant steel drill tip. The joint has a breaking strength of 735. The mechanical properties of the weld joint area are better than that of the base metal. The microstructure observation shows that the joint structure is dense and the grain size is small. The SEM observation of the joint fracture shows that the fracture zone is large and deep, showing ductile fracture characteristics. See defects such as inclusions, pores and microcracks. At the same time, the invention also has the reliability of the butt joint between the joints during welding, improves the working efficiency, increases the effective welding area, improves the weld strength after welding, and reduces the advantages of processing and production costs. DRAWINGS

1 is a schematic structural view of a split type spiral pile of the present invention.

Fig. 2 is a schematic view showing the structure of the pile body and the drill tip of the utility model in a welded connection manner.

Figure 3 is a partial enlarged view of the weld A in Figure 2. detailed description

Specific embodiment:

The present invention will be further described with reference to the accompanying drawings and specific embodiments. Referring to Figures 1 - 3, the split type spiral pile according to the embodiment includes a tubular pile 2 and a conical ground provided separately. a tip 1 , an outer surface of the tubular body 201 of the pile 2 is sleeved with a spiral blade 202 in the form of a spiral strip; the drill tip 1 includes a tip end portion 102 and a truncated cone tail portion 101; The trapezoidal tail portion 101 includes a mating surface with the inner wall surface of the pile body 2. The insertion portion 101a and the inclined surface portion 101b having a diameter larger than the insertion portion; the insertion portion 101a of the earth-drilling tip is inserted into the socket hole of the pile body 2, so that the slope portion 101b of the earth-boring tip 1 is An annular welding groove 3 is formed between the open end faces 203 of the pile body 2, and the axial section of the annular welding groove 3 is a right-angled triangle or a right-angled trapezoid; the pile body and the grounding tip are welded at the annular welding groove Into the overall structure.

In this embodiment:

The pile body 2 is a pile body made of Q235B carbon steel. The chemical composition (%) of Q235B carbon steel: C: 0.12 ~ 0.20, Si: < 0.30, Mn: 0.30 ~ 0.70, S: < 0.045, P: 0.045 , Cr: Allowable residual content of 0.030, Ni: Allowable residual content of 0.030, Cu: Allowable residual content of 0.030.

The drill tip 1 is a drill tip made of 12CrlMoV weathering steel. The chemical composition (%) of UCrlMoV weathering steel: C: 0.07-0.15, Si: 0.18 - 0.37, Mn: 0.41 - 0.70, Cr: 0.90 - 1.20, Mo: 0.25 - 0.35, V: 0.15 - 0.30.

The cross-sectional area of the annular welding groove 3 is greater than or equal to 8 mm ² . The end of the pile 2 is provided with a flange structure or a set bolt structure 204 for fixing to the outer body structure. The rear end portion of the pile body is provided with an arc-shaped reinforcing plate and a through hole penetrating the reinforcing plate and the pile body. The tip portion includes a breached tip of the front end and a cutting edge on both sides. The tip end portion 102 is further provided with a circular drain hole 102a. The spiral blade is a continuous spiral blade or a segmented spiral blade.

A welding method for a split spiral pile is carried out as follows:

1) joint butt joint: insert the plug portion of the drilled tip into the sleeve hole of the pile body, so that an annular welding groove is formed between the inclined surface of the drill tip and the open end surface of the pile body, the ring The axial section of the welding groove is a right-angled triangle or a right-angled trapezoid; wherein the pile body is a pile body made of Q235B carbon steel material, and the drill tip is a drill tip made of 12CrlMoV weathering steel material;

2) Pre-weld cleaning: The oil and impurities on the surface of the butt-welded part of the pile and the ground tip are removed;

5) Post-weld heat treatment: Immediately after the welding, the insulation material is used for the weld and close The weld zone is covered and insulated to slowly cool the joint. Then, the weldment is heated to the whole

After cooling at 760 °C for 30 minutes, cool to room temperature. Stress-relieving heat treatment after welding can eliminate or reduce the hardened structure in the affected zone, increase the plasticity and toughness, effectively reduce the welding residual stress, and at the same time facilitate the diffusion of hydrogen, thus reducing the tendency of cold cracking.

The test piece is welded according to the above welding process. After the test piece has passed the visual inspection, magnetic particle inspection and X-ray flaw detection, the mechanical property test sample and the metallographic test sample are taken out on the test piece for inspection. The test results are shown in Tables 1 and 2.

Table 1 Mechanical properties of joints

Table 2 Metallographic organization

The results show that the tensile fracture zone occurs on the side of the parent metal, and the joint has a high breaking strength.

7 35 MPa , the mechanical properties of the weld joint area are better than that of the base metal; the metallographic observation shows that the joint structure is dense and the grain is fine; the SEM observation of the joint fracture shows that the fracture zone is large and deep, showing ductile fracture characteristics, joint No defects such as inclusions, pores and microcracks were observed.

Various other changes and modifications may be made by those skilled in the art in light of the above-described technical solutions and modifications, and all such changes and modifications are intended to fall within the scope of the appended claims.

Claims

Claim

A split type spiral pile comprising a tubular pile body and a conical drill tip, wherein the pile body is surrounded by a spiral blade having a spiral strip shape; The drill tip includes a tip end portion and a truncated cone tail portion; the truncated cone tail portion includes a plug portion mated with the inner wall surface of the pile body and a slope portion having a diameter larger than the plug portion; the plug portion of the drill point is interspersed Forming an annular welding groove between the inclined surface of the drill tip and the open end surface of the pile body in the sleeve hole of the pile body, the axial section of the annular welding groove is a right triangle or a right angle trapezoid; The pile body and the drill tip are welded to form a unitary structure at the annular welding groove.

The split type spiral pile according to claim 1, wherein the pile body is a pile body made of Q235B carbon steel.

3. A split type spiral pile according to claim 1, wherein: the grounding tip is a grounding tip made of UCr lMoV weathering steel.

4. A split type spiral pile according to claim 1, wherein: the cross-sectional area of the annular welding groove is greater than or equal to 8 mm ² .

A split type spiral pile according to claim 1, wherein: the end of the pile body is provided with a flange structure or a fixed bolt structure for fixing to the outer main body structure.

The split spiral pile according to claim 1, wherein: the rear end portion of the pile body is provided with an arc-shaped reinforcing plate and a through hole penetrating the reinforcing plate and the pile body.

7. A split-type spiral pile according to claim 1, wherein: said tip portion includes a breached tip of the front end and a cutting edge on both sides.

8. A split spiral pile according to claim 1, wherein: said tip portion is further provided with a circular drain hole.

9. A split type spiral pile according to claim 1, wherein: said spiral blade is a continuous spiral blade or a segmented spiral blade.

A method of welding a split type spiral pile according to any one of claims 1 to 4, characterized in that the following steps are carried out:

1) joint butt joint: insert the plug portion of the drilled tip into the sleeve hole of the pile body, so as to form an annular welding groove between the inclined surface of the drill tip and the open end surface of the pile body, the ring welding The axial section of the groove is a right-angled triangle or a right-angled trapezoid; wherein the pile body is a pile body made of Q235B carbon steel material, and the drill tip is a drill tip made of 12Cr lMoV weathering steel material;

3) Preheating: Preheat the welded part of the pile and the drill tip to 150 ~ 180 °C;

4) Welding: The pile body and the drill tip are horizontally rotated for welding, and the nickel-based welding wire ERN iCrMo-3 is selected, which is made by manual tungsten argon arc welding, manual arc welding filling and capping; interlayer temperature control At 180 ~ 200 °C ;

4-1) Manual tungsten argon arc welding primer: 80% Ar and 20% He are used as shielding gas, and the control gas flow is 8 L/Min; the polarity of the power supply is: DC positive connection, The current is 100A and the voltage is 12V.

4-3) Manual arc welding cover: The polarity of the power supply is: DC positive connection, current is 120A, voltage is 15V; 5) Post-weld heat treatment: Immediately after the welding, the insulation and the near-weld area are covered with insulation material to make the joint cool slowly. Then, the whole weldment is heated to 760 °C, and the temperature is kept for 30 minutes. To room temperature.