Auxiliary heating device for expanding forming of bent pipe

Abstract

The utility model discloses an auxiliary heating device for elbow pipe expanding forming, an expanding mold with a straight line section and an expanding section with the outer diameter gradually increased and bent in an arc shape is used for elbow pipe expanding, and the auxiliary heating device is completely and annularly arranged on the expanding section and the straight line section within a certain width connected with the expanding section in a sleeving mode. The auxiliary heating device completely sleeves the expanding section and the straight section within a certain width connected with the expanding section, and performs auxiliary heating on the previously heated blank pipe again from the tail end of the straight section so as to offset the temperature drop problem existing in the process that the blank pipe is transferred to the straight section from heating equipment and penetrates through the straight section. In the whole deformation process, the blank pipe can be heated through the auxiliary heating device so as to ensure the stable heating temperature, so that the blank pipe can be quickly deformed and separated on the diameter expanding section, the forming efficiency is improved, meanwhile, at the optimal deformation temperature, the problem that internal defects are generated in the blank pipe is also avoided, and the product quality is improved. And the pipe body quality of the formed bent pipe is improved.

Description

Technical Field

[0001] This application relates to the field of pipe bending forming technology, and in particular to an auxiliary heating device for pipe bending and expanding forming. Background Technology

[0002] Pipe bending typically involves extruding a straight pipe blank through a bending die to form a bent pipe. This process is usually used when the blank pipe and the bent pipe have the same diameter. However, for large-diameter bent pipe products, a straight pipe blank of the same large diameter is required. Manufacturing large-diameter straight pipes presents significant challenges in terms of both equipment requirements, technical requirements, processing procedures, and quality control. In particular, quality control is difficult because large-diameter straight pipes are large in size and have complex structures, and even small errors can lead to product defects. Therefore, forming large-diameter bent pipes is quite challenging.

[0003] Currently, when forming large-diameter pipe bends, the following method can be used as per the instruction manual: Figure 1 The expansion mold shown has a straight section and an expansion section with a gradually increasing outer diameter and an arc-shaped bend. When forming the bend, the blank tube (straight tube structure with a diameter smaller than the forming bend) that needs to be expanded and bent is first heated to a temperature that is easy to deform. Then, it is put into the straight section and driven to the expansion section. The blank tube is driven to continue to expand and bend on the expansion section. After the blank tube is removed from the expansion section, the large-diameter bend can be formed.

[0004] During the bending and expansion deformation process of the billet tube through the expansion section, due to its metal material, there is significant resistance to its movement in the expansion section. This results in the billet tube passing through the expansion section slowly and for a long time. During this extended passage (deformation) time, the previously heated billet tube experiences a continuous temperature drop, causing the temperature to fall below the optimal deformation temperature when it is in the expansion section. This further increases the resistance to the billet tube's movement in the expansion section. At the same time, the significant driving force exerted on the billet tube after the temperature drop can also cause internal defects such as cracks, affecting the forming quality of the expanded and bent pipe. Summary of the Invention

[0005] To address the aforementioned problems, this application aims to provide an auxiliary heating device for pipe bending and expansion forming, which can heat the billet pipe throughout the entire deformation process to ensure a stable heating temperature, improve forming efficiency, and at the same time, avoid the problem of internal defects in the billet pipe under the optimal deformation temperature, thereby improving the quality of the formed bent pipe.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: an auxiliary heating device for pipe bending and expansion forming, wherein the pipe bending and expansion uses an expansion mold having a straight section and an expansion section with a gradually increasing outer diameter and an arc-shaped bend, characterized in that: the auxiliary heating device is completely encircled on the expansion section and within a certain width on the straight section connected to the expansion section.

[0007] Preferably, the auxiliary heating device is a spiral heating tube that loops around a portion of the straight section and the entire expanded diameter section.

[0008] Preferably, the pitch of the spiral heating tube gradually decreases from the straight section toward the outer end of the expanding section.

[0009] Preferably, the distance between the spiral heating tube and the outer circumferential surface of the straight section and the expanded diameter section gradually decreases from the straight section toward the outer end of the expanded diameter section.

[0010] The beneficial effects of this application are: the auxiliary heating device is completely encircled on the expansion section and within a certain width of the straight section where it connects to the expansion section. Starting from the tail end of the straight section, it provides secondary auxiliary heating to the previously heated billet tube to offset the temperature drop that occurs during the transfer of the billet tube from the heating equipment to the straight section and through the straight section. Throughout the deformation process, the auxiliary heating device can heat the billet tube to ensure a stable heating temperature, thereby facilitating the rapid deformation and detachment of the billet tube on the expansion section, improving forming efficiency. At the same time, under the optimal deformation temperature, it also avoids the problem of internal defects in the billet tube, improving the tube quality of the formed bent tube. Attached Figure Description

[0011] Figure 1 This diagram illustrates the process of expanding and bending a blank tube.

[0012] Figure 2 This diagram illustrates the expansion and bending deformation of the billet tube in the expansion section.

[0013] Figure 3 This is a diagram of the spiral heating tube of this application.

[0014] Figure 4 The illustration shows a portion of the spiral heating tube sleeved on the straight pipe section and the enlarged diameter section of this application.

[0015] Figure 5 A diagram showing the connecting pipe for the spiral heating tube in this application.

[0016] Figure 6 This is a physical illustration of the spiral heating tube of this application.

[0017] In the diagram: 21-overlapping pipe; 31-blank pipe; 32-formed bend pipe. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solutions of this application, the technical solutions of this application will be further described below in conjunction with the accompanying drawings and embodiments.

[0019] See attached document Figures 1-5 The diagram shows an auxiliary heating device for pipe bending and expanding. The pipe bending and expanding uses an expanding mold 1 with a straight section 11 and an expanding section 12 with a gradually increasing outer diameter and an arc-shaped bend. The specific structure of the expanding mold is as follows: Figure 1 As shown, the blank tube (straight tube structure) that needs to be expanded and bent is first heated to a temperature that facilitates deformation. Then, it is inserted onto the straight section 11 and driven to the expansion section 12. The blank tube is continued to be driven, causing it to expand and bend on the expansion section 12. After the blank tube is detached from the expansion section 12, a large-diameter bent tube can be formed. The forming process is as follows. Figure 1 As shown.

[0020] To address the temperature drop during the expansion and bending process of the billet tube, and the resulting deformation resistance and defects, this application includes an auxiliary heating device, such as... Figure 4 As shown, the auxiliary heating device completely surrounds the expansion section 12 and the straight section 11 within a certain width where it connects to the expansion section 12. This means that the auxiliary heating device reheats the previously heated billet tube starting from the tail end of the straight section 11, counteracting the temperature drop that occurs during the transfer of the billet tube from the heating device to the straight section 11 and through it. This ensures that the billet tube has the optimal deformation temperature when entering the expansion section 12, facilitating its deformation. While the billet tube is on the expansion section 12, it is heated by the auxiliary heating device throughout the entire deformation process, ensuring a stable heating temperature. This allows the billet tube to quickly complete its deformation on the expansion section 12 and detach, improving forming efficiency. Simultaneously, at the optimal deformation temperature, it avoids internal defects in the billet tube, improving the quality of the formed bent pipe.

[0021] Specifically, such as Figure 3-4 As shown, the auxiliary heating device is a spiral heating tube 2 that loops around a portion of the straight section 11 and the entire expansion section 12. This spiral heating tube 2 begins to heat the billet tube circumferentially from the end of the straight section 11, compensating for the temperature drop caused by the billet tube's movement as it enters the expansion section 12, thus facilitating rapid deformation in the expansion section 12. Similarly, the portion of the spiral heating tube 2 located on the expansion section 12 is continuously heated (temperature drop compensation) throughout the entire deformation process of the billet tube, facilitating smooth deformation of the billet tube and its smooth separation from the expansion section 12 after deformation.

[0022] As the outer diameter of the expansion section 12 gradually increases to achieve the expansion forming of the billet tube, the deformation of the billet tube gradually increases during its movement along the expansion section 12. This means the pipe diameter increases and the wall thickness decreases, leading to an increased rate of temperature drop in the billet tube. Therefore, to compensate for the gradually increasing deformation of the billet tube, heating (temperature drop compensation) is required. Figure 3-4 As shown, the pitch of the spiral heating tube 2 gradually decreases from the straight section 11 toward the outer end of the expanded diameter section 12. This structure causes the heating area of ​​the spiral heating tube 2 on the blank tube to gradually increase, thereby improving the heating and heat treatment effect on the blank tube and compensating for the temperature drop of the blank tube with a larger heating area, so as to solve the problem of excessive temperature drop caused by the gradual increase of deformation of the blank tube.

[0023] To further improve the understanding of the deformation impact caused by the increased temperature drop in the billet tube under increased deformation conditions, such as... Figure 3-4 As shown, the distance between the spiral heating tube 2 and the outer circumference of the straight section 11 and the expanded diameter section 12 gradually decreases from the straight section 11 toward the outer end of the expanded diameter section 12. This structure makes the spiral heating tube 2 closer to the surface of the billet tube when the deformation of the billet tube is greater, thereby enabling rapid temperature transfer, improving the heating efficiency of the billet tube, and allowing the billet tube to heat up quickly to reach the optimal deformation temperature.

[0024] Because the spiral heating tube 2 bends synchronously with the expanding section 12, the pitch of the outer side of the spiral heating tube 2 is greater than the pitch of the inner side, such as... Figure 3-4 The state shown results in a large area remaining between adjacent single heating tubes, affecting the heating effect on the billet tube. Therefore, to solve this problem, as follows... Figure 5 As shown, preferably, an overlapping pipe 21 is provided in a larger retention area, which is used to fill the larger retention space of the spiral heating pipe 2 to ensure the heating effect and deformation effect of the billet pipe at the expansion section 12.

[0025] The principle of this application is as follows: a spiral heating tube 12 is partially sleeved on the expansion section 12 and the straight section 11 of the expansion mold 1. When expanding and bending the blank tube, the blank tube is first heated to a temperature that is easy to deform, and then it is sleeved on the straight section 11 and driven to the expansion section 12. The spiral heating tube 2 heats the blank tube, solving the problem of temperature drop of the blank tube. Then the blank tube is driven to expand and bend on the expansion section 12. After the blank tube is detached from the expansion section 12, it can be expanded to form a large-diameter bent tube.

[0026] The foregoing has shown and described the basic principles, main features, and advantages of this application. Various changes and modifications may be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims.

Claims

1. An auxiliary heating device for forming a bent pipe with an enlarged diameter, wherein the pipe enlargement uses an enlargement mold (1) having a straight section (11) and an enlargement section (12) with a gradually increasing outer diameter and an arc-shaped bend, characterized in that: The auxiliary heating device is completely encircled on the expanded diameter section (12) and on the straight section (11) within a certain width where it connects with the expanded diameter section (12); The auxiliary heating device is a spiral heating tube (2) that is looped around a portion of the straight section (11) and the entire expanded section (12); The pitch of the spiral heating tube (2) gradually decreases from the straight section (11) toward the outer end of the expanded diameter section (12); The distance between the spiral heating tube (2) and the outer circumference of the straight section (11) and the expanded diameter section (12) gradually decreases from the straight section (11) toward the outer end of the expanded diameter section (12); The pitch of the outer side of the spiral heating tube (2) is greater than that of the inner side, and a retention area is formed between adjacent single heating tubes. A connecting pipe (21) is provided in the retention area.

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