A steel pipe hot expanding device

Abstract

The present application relates to the technical field of steel pipe processing, and discloses a steel pipe hot expanding device, which comprises a pushing device and a hot expanding machine arranged on a hot expanding assembly line, and further comprises an oil immersion device arranged between the pushing device and the hot expanding machine, wherein the oil immersion device comprises an oil pool, and a turnover mechanism is arranged in the oil pool and rotates around a group of horizontal axes; the oil pool is used for containing lubricating oil, and the length of the oil pool in the direction of the hot expanding assembly line is greater than the length of the steel pipe; the turnover mechanism is provided with a clamping mechanism used for clamping the steel pipe, so that the turnover mechanism can turn the steel pipe to opposite high and low positions; when the steel pipe is turned to the high position, the steel pipe is flush with the feeding port of the hot expanding machine, so that the pushing device can push the steel pipe into the hot expanding machine; when the steel pipe is turned to the low position, the steel pipe is immersed in the lubricating oil; the steel pipe hot expanding device is beneficial to the uniform distribution of the lubricating oil on the inner and outer surfaces of the steel pipe, reduces the abrasion of the steel pipe, the mandrel and the hot expanding die, and improves the forming quality of the steel pipe.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of steel pipe processing, in particular to a steel pipe hot expanding device. BACKGROUND

[0002] In the process of steel pipe hot expanding, the steel pipe needs to be locked by a hot expanding die in a hot expander, and then heated to a certain degree by a medium frequency heating device in the hot expander, and then a mandrel with an outer diameter not less than the inner diameter of the steel pipe is pushed through the inside of the steel pipe by a pushing device to expand the inner diameter of the steel pipe; in the steel pipe hot expanding flow line, before the steel pipe enters the hot expander, the steel pipe needs to be subjected to saponification treatment and coating of lubricating oil and other processes.

[0003] In the related prior art, in the process of coating lubricating oil on the steel pipe, the lubricating oil is generally sprayed on the steel pipe by related equipment or manually, but it is difficult to uniformly coat the inside of the steel pipe, and when the mandrel is inserted into the steel pipe, the mandrel is mostly coated with a certain amount of lubricating oil. Therefore, in the process of steel pipe hot expanding, the lubricating oil is inevitably unevenly distributed on the surface of the steel pipe, which is easy to cause wear of the steel pipe and the equipment and affect the forming quality of the steel pipe. SUMMARY

[0004] The present application aims at overcoming the shortcomings of the prior art and provides a steel pipe hot expanding device.

[0005] The technical scheme for solving the above technical problem is as follows:

[0006] A steel pipe hot expanding device comprises a pushing device and a hot expander arranged on a hot expanding flow line, and further comprises an oil immersion device arranged between the pushing device and the hot expander, wherein the oil immersion device comprises an oil pool, and a turnover mechanism is arranged in the oil pool to rotate around a group of horizontal axes.

[0007] The oil pool is used to contain lubricating oil, and the length of the oil pool in the direction of the hot expanding flow line is greater than the length of the steel pipe; the turnover mechanism is provided with a clamping mechanism for clamping the steel pipe, so that the turnover mechanism can turn the steel pipe to a relatively high position and a relatively low position; when the steel pipe is turned to the high position, the steel pipe is flush with the feeding port of the hot expander, so that the pushing device can push the steel pipe into the hot expander; when the steel pipe is turned to the low position, the steel pipe is immersed in the lubricating oil.

[0008] Further, the turnover mechanism is sequentially provided with the high position, a first middle position, the low position and a second middle position in the rotation direction, and the first middle position and the second middle position are symmetrically arranged on both sides of the line connecting the high position and the low position.

[0009] The oil pool is provided with a feeding mechanism on one side of the pusher, which is communicated with the first middle position so as to make the steel pipe enter the turnover mechanism through the first middle position.

[0010] Further, the clamping mechanism comprises a first clamping assembly and a second clamping assembly clamped on both ends of the steel pipe.

[0011] The steel pipe is arranged in the clamping cavity of the first clamping assembly, and the first clamping assembly is swingably arranged in a group of tangent planes of the turnover mechanism; the second clamping assembly comprises a fixed block and a movable block oppositely arranged in the tangent planes, and the movable block is movably arranged on the turnover mechanism relative to the fixed block; when the turnover mechanism is turned to the second middle position, the movable block is located below the fixed block, so that the steel pipe can be inclined.

[0012] Further, a group of baffles are arranged on both ends of the oil pool in the axial direction of the turnover mechanism, and the first clamping assembly and the second clamping assembly are respectively shielded by a group of baffles during the rotation of the turnover mechanism, so as to prevent the steel pipe from sliding out of the turnover mechanism.

[0013] Further, a group of baffles are arranged on both ends of the oil pool in the axial direction of the turnover mechanism, and the first clamping assembly and the second clamping assembly are respectively shielded by a group of baffles during the rotation of the turnover mechanism, so as to prevent the steel pipe from sliding out of the turnover mechanism.

[0014] Further, the baffles on one side of the feeding mechanism are provided with a constraint assembly acting on the first clamping assembly, so as to keep the clamping cavity of the first clamping assembly horizontal when the feeding mechanism feeds.

[0015] Further, the constraint assembly comprises:

[0016] A pressing ring is movably arranged on the baffle relative to the clamping cavity, and the pressing ring is coaxially arranged with the notch corresponding to the first middle position;

[0017] An extrusion member is arranged on the rotating shaft of the turnover mechanism, and when the turnover mechanism is turned to the first middle position, the extrusion member acts on the pressing ring, so as to press the pressing ring on the end face of the clamping cavity.

[0018] Further, an oil receiving plate extending outward is arranged on the side wall of the oil pool below the second middle position.

[0019] Further, a roller way is arranged on the turnover mechanism between the first clamping assembly and the second clamping assembly, and the roller way is used for conveying the steel pipe.

[0020] Further, an oil groove is arranged in the hot expander, and the oil groove is communicated with the oil pool.

[0021] The steel pipe hot expansion device has at least the following beneficial effects:

[0022] Before the steel pipe enters the hot expander, the steel pipe is turned to the low position by the turnover mechanism, so that the steel pipe can be fully soaked in the lubricating oil in the oil pool, which is beneficial to the uniform distribution of the lubricating oil on the inner and outer surfaces of the steel pipe. In the hot expansion process, the wear of the steel pipe, the hot expansion die and the mandrel can be reduced, and the forming quality of the steel pipe can be improved.

[0023] Meanwhile, by arranging the turnover mechanism, the steel pipe can automatically separate from the liquid surface of the oil pool after adhering a proper amount of lubricating oil on the surface during the turning of the steel pipe from the low position to the high position, which reduces the waste of lubricating oil and avoids the interference of excessive lubricating oil on the subsequent hot expansion process. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a front view of the steel pipe hot expansion device in the embodiment of the present application;

[0025] Figure 2 It is a perspective view of the oil pool in the embodiment of the present application;

[0026] Figure 3 It is an axial end surface schematic view of the oil pool in the embodiment of the present application;

[0027] Figure 4 It is a local enlarged view of the first clamping assembly in the embodiment of the present application Figure 1 ;

[0028] Figure 5 It is a local enlarged view of the second clamping assembly in the embodiment of the present application;

[0029] Figure 6 It is a local enlarged view of the first clamping assembly in the embodiment of the present application Figure 2 ;

[0030] Wherein: 1 - pusher, 10 - mandrel, 2 - oil pool, 20 - baffle, 200 - notch, 21 - oil receiving plate, 3 - hot expander, 30 - oil groove, 31 - feeding port, 4 - feeding mechanism, 5 - turnover mechanism, 50 - turnover frame, 500 - rotating shaft, 501 - extrusion piece, 51 - first clamping assembly, 510 - clamping sleeve, 511 - ear plate, 512 - flared portion, 52 - second clamping assembly, 520 - fixed block, 521 - movable block, 522 - first elastic piece, 53 - roller table, 6 - steel pipe, 7 - constraint assembly, 70 - pressure ring, 71 - half ring, 72 - second elastic piece, a - high position, b - first middle position, c - low position, d - second middle position. DETAILED DESCRIPTION

[0031] The principles and characteristics of the present application are described below, and the examples are only used to explain the present application, and are not used to limit the scope of the present application.

[0032] Referring to Figure 1 , the embodiment of the present application discloses a steel pipe 6 hot expanding device, which comprises a pushing machine 1 and a hot expander 3 arranged on a hot expanding production line, wherein the core rod 10 in the pushing machine 1 is opposite to the feeding port 31 of the hot expander 3, and the core rod 10 can push the steel pipe 6 into the hot expander 3 for diameter expansion under the hydraulic drive in the hot expanding process; wherein the pushing machine 1 and the hot expander 3 are common equipment for expanding the diameter of the steel pipe 6, and the specific structure and principle thereof will not be described here.

[0033] Referring to Figure 1 , the oil immersion equipment is further arranged between the pushing machine 1 and the hot expander 3, and the oil immersion equipment comprises an oil pool 2, the oil pool 2 is used for containing lubricating oil, and the length of the oil pool 2 in the direction of the hot expanding production line is greater than the length of the steel pipe 6, and the oil pool 2 is provided with a turnover mechanism 5 which can be turned around a horizontal axis.

[0034] The turnover mechanism 5 is provided with a clamping mechanism for clamping the steel pipe 6, the clamping mechanism comprises a first clamping assembly 51 for clamping the first end of the steel pipe 6 and a second clamping assembly 52 for clamping the second end of the steel pipe 6, and when the steel pipe 6 is clamped and fixed on the turnover mechanism 5, the steel pipe 6 can be entirely immersed in the lubricating oil by the turning of the turnover mechanism 5, so that the inner and outer surfaces of the steel pipe 6 are uniformly adhered with the lubricating oil.

[0035] Referring to Figure 3 , the turnover mechanism 5 can turn the steel pipe 6 to a relatively high position a and a low position c, the high position a refers to the upper side of the oil pool 2, and the low position c refers to the oil inside the lower side of the oil pool 2; wherein when the steel pipe 6 is turned to the high position a, the steel pipe 6 is flush with the feeding port 31 of the hot expander 3, at this time, the core rod 10 can push the steel pipe 6 to insert into the hot expander 3 for hot expansion; when the steel pipe 6 is turned to the low position c, the steel pipe 6 is immersed in the lubricating oil.

[0036] Referring to Figure 2 , the turnover mechanism 5 is provided with a rotating shaft 500, the two ends of the rotating shaft 500 are rotatably installed on the wall surface of the oil pool 2, therefore, in the embodiment, the rotating axis of the turnover mechanism 5 is the axis of the rotating shaft 500, one end of the rotating shaft 500 is connected with a driving motor set (not shown) located outside the oil pool 2, the driving motor set adopts a servo motor technology, can accurately close-loop control the turning angle of the turnover mechanism 5, the turnover mechanism 5 comprises a turnover frame 50 installed on the rotating shaft 500, and the first clamping assembly 51 and the second clamping assembly 52 are both installed on the turnover frame 50.

[0037] In addition, the turnover mechanism 5 is provided with a plurality of oil spraying nozzles 4 arranged on the turnover frame 50, the oil spraying nozzles 4 are used for spraying the lubricating oil on the surface of the steel pipe 6 when the steel pipe 6 is turned to the low position c. Figure 3The high position a, the first middle position b, the low position c and the second middle position d are sequentially arranged in the counterclockwise rotation direction shown in the figure, the first middle position b and the second middle position d are symmetrically arranged on both sides of the line connecting the high position a and the low position c, and the interval between any two adjacent positions of the high position a, the first middle position b, the low position c and the second middle position d is 90°.

[0038] Referring to Figure 1 The oil pool 2 is also provided with a feeding mechanism 4 on the outer side close to the pushing mechanism 1, wherein the feeding mechanism 4 is communicated with the first middle position b shown in the figure, that is, when the feeding mechanism 4 feeds through the conveying roller, the turnover mechanism 5 needs to be turned to the first middle position b, and the steel pipe 6 can enter the turnover mechanism 5 at the first middle position b. Figure 3

[0039] Among them, Figure 4 The state of the first clamping assembly 51 when the turnover mechanism 5 is in the high position a or the low position c is shown, the first clamping assembly 51 includes a clamping sleeve 510 with an inner diameter slightly larger than the outer diameter of the steel pipe 6, the steel pipe 6 is arranged in the clamping sleeve 510, and a set of ear plates 511 is arranged on both sides of the clamping sleeve 510, the two sets of ear plates 511 are provided with arc-shaped holes, and the arc-shaped holes on the two sets of ear plates 511 are located on the same circular ring with the clamping sleeve 510 as the center, and the turnover frame 50 is provided with a sliding block inserted in the two sets of arc-shaped holes, so that, Figure 4 At this time, the first clamping assembly 51 shown can swing within a certain angle range in the plane around a vertical shaft perpendicular to the steel pipe 6.

[0040] Among them, Figure 5 The state of the second clamping assembly 52 when the turnover mechanism 5 is in the high position a or the low position c is shown, the second clamping assembly 52 includes a fixed block 520 and a movable block 521 arranged oppositely in the plane, the fixed block 520 is fixedly arranged on the turnover frame 50, and the movable block 521 is movably arranged on the turnover mechanism 5 relative to the fixed block 520, that is, the interval between the movable block 521 and the fixed block 520 is variable, and a clamping cavity for clamping the steel pipe 6 is formed between the fixed block 520 and the movable block 521.

[0041] Among them, referring to Figure 5 The movable block 521 is slidingly installed on the turnover frame 50, and a plurality of first elastic members 522 are arranged between the turnover frame 50 and the movable block 521 to push the movable block 521 to gather towards the fixed block 520.

[0042] In fact, from the perspective of the rotation arc formed by the turnover mechanism 5 around the rotation shaft 500, the swinging of the first clamping assembly 51 and the movement of the movable block 521 in the second clamping assembly 52 can be regarded as being carried out in a group of tangent planes of the rotation arc.

[0043] Specifically, the turnover mechanism 5 is in the Figure 2 ​In the first intermediate position b, the first clamping assembly 51 can swing around a set of horizontal axes perpendicular to the axis of the steel pipe 6, at this time, the moving block 521 in the second clamping assembly 52 is above the fixed block 520, the moving block 521 can move up and down within a certain range, thus, the swing of the first clamping assembly 51 and the moving block 521 in the second clamping assembly 52 are both within a set of vertical tangent planes of the aforementioned rotary circular arc.

[0044] With reference to Figure 2 On the axial direction of the turnover mechanism 5, a set of baffles 20 are arranged at both ends of the oil pool 2.

[0045] Thus, on the axial direction of the turnover mechanism 5, the first clamping assembly 51 and the second clamping assembly 52 are each blocked by a set of baffles 20, the steel pipe 6 is arranged between the first clamping assembly 51 and the second clamping assembly 52, during the rotation of the turnover mechanism 5, due to the limiting of the baffles 20, the steel pipe 6 can be prevented from sliding out of the turnover mechanism 5.

[0046] With reference to Figure 2 And Figure 3 On the two sets of baffles 20, there are also notches 200 corresponding to the high position a and the first intermediate position b; thus, when the turnover mechanism 5 is turned to the first intermediate position b, the steel pipe 6 conveyed by the feeding mechanism 4 can be inserted into the clamping mechanism along the notches 200, when the turnover mechanism 5 is turned to the high position a, the mandrel 10 can be inserted into the steel pipe 6 through the notches 200 on the side of the high position a, and the steel pipe 6 can be pushed into the hot expander 3.

[0047] Thus, with reference to Figure 2 The turnover frame 50 is provided with a roller bed 53 arranged between the first clamping assembly 51 and the second clamping assembly 52, that is, the roller bed 53 is arranged below the steel pipe 6 and on the side close to the rotation shaft 500; when the turnover mechanism 5 is turned to the first intermediate position c, the steel pipe 6 is conveyed by the feeding mechanism 4 into the clamping cavity of the first clamping assembly 51, through manual pushing or hydraulic driving, the other end of the steel pipe 6 can be inserted into the second clamping assembly 52.

[0048] When the turnover mechanism 5 is turned to the low position c in the counterclockwise direction in Figure 3 Since the fixed block 520 in the second clamping assembly 52 is always below the moving block 521, during the process, the fixed block 520 in the second clamping assembly 52 supports the second end of the steel pipe 6, the first clamping assembly 51 and the second clamping assembly 52 can stably clamp the steel pipe 6, and the steel pipe 6 will not tilt.

[0049] When the steel pipe 6 is immersed in the lubricating oil at the low position c, the moving block 521 in the second clamping assembly 52 will be below the fixed block 520 during the process of turning the steel pipe 6 counterclockwise from the low position c to the second middle position d, at this time, the steel pipe 6 is supported by the moving block 521, and the moving block 521 will slide down slightly after the first elastic member 522 is extruded, at the same time, the first clamping assembly 51 can swing, therefore, the second end of the steel pipe 6 will be slightly tilted downward at this time, and the lubricating oil remaining in the steel pipe 6 can be discharged.

[0050] At the same time, during the process of turning the steel pipe 6 from the low position c to the second middle position d, and turning the steel pipe 6 from the second middle position d to the high position a, the steel pipe 6 will not slide out of the turning mechanism 5 due to the limiting constraint of the two sets of baffles 20, even if the steel pipe 6 is tilted.

[0051] When the steel pipe 6 is turned to the high position a, the fixed block 520 and the moving block 521 in the second clamping assembly 52 are located in the same plane, and the first elastic member 522 can push the moving block 521 to gather towards the fixed block 520.

[0052] When the steel pipe 6 immersed in the lubricating oil is turned to the high position a, the steel pipe 6 is pushed into the hot expander 3 by the mandrel 10 for hot expansion, at this time, since the roller 53 is arranged on the turning frame 50, the steel pipe 6 can be conveniently pushed into the hot expander 3.

[0053] After the hot expansion is completed, the mandrel 10 is withdrawn Figure 1 to the initial state shown, and then the turning mechanism 5 is turned to the first middle position b for loading operation.

[0054] It is easy to understand that since the first clamping assembly 51 is swingably installed on the turning frame 50, when loading at the first middle position b, the clamping cavities in the first clamping assembly 51 can be tilted at both ends, which makes it difficult for the steel pipe 6 on the loading mechanism 4 to be accurately inserted into the first clamping assembly 51.

[0055] To solve the above problems, in one embodiment, referring to Figure 6 a constraint assembly 7 acting on the first clamping assembly 51 is arranged on the baffle 20 close to the loading mechanism 4, so that the clamping cavities of the first clamping assembly 51 remain horizontal when the loading mechanism 4 is loaded.

[0056] The constraint assembly 7 includes a pressing ring 70, a half ring 71, a second elastic member 72 and an extrusion member 501.

[0057] In which, referring to Figure 6The pressing ring 70 is arranged on the baffle 20 in a reciprocating manner relative to the clamping cavity of the first clamping assembly 51, and the pressing ring 70 is coaxially arranged with the notch 200 corresponding to the first middle position b. The half ring 71 is arranged on the other side of the baffle 20, and the half ring 71 is connected with the pressing ring 70 through a pin provided on the baffle 20. The second elastic member 72 is sleeved on the pin, and the second elastic member 72 is located on the side of the baffle 20 where the half ring 71 is arranged.

[0058] With reference to Figure 6 The extrusion member 501 is arranged on the rotating shaft 500 on the side of the baffle 20. The extrusion member 501 has a protruding extrusion surface on the side facing the baffle 20, and the two sides of the extrusion surface are transition inclined surfaces.

[0059] In a natural state, under the driving of the second elastic member 72, the pressing ring 70 is away from the first clamping assembly 51, and the first clamping assembly 51 can freely swing. When the turnover mechanism 5 is turned to the first middle position b, the extrusion member 501 changes from the transition surface contacting the half ring 71 to the extrusion surface contacting the half ring 71, and the extrusion member 501 pushes the half ring 71 and the pressing ring 70 to move towards the first clamping assembly 51, and when the pressing ring 70 abuts against the end surface of the clamping cavity of the first clamping assembly 51, the clamping cavity can be kept horizontal.

[0060] In some embodiments, with reference to Figure 4 The first clamping assembly 51 further has a flared portion 512 on the end surface facing the same side of the baffle 20. The inner diameter of the flared portion 512 is larger than the inner diameter of the clamping cavity, which can further improve the convenience of inserting the steel pipe 6.

[0061] With reference to Figure 2 In some embodiments, an oil receiving plate 21 extending outward is arranged on the side wall of the oil pool 2 below the second middle position d, which can guide the lubricating oil discharged from the inclined steel pipe 6 into the oil pool 2.

[0062] With reference to Figure 1 In some embodiments, an oil groove 30 is further arranged in the hot expander 3, which is in communication with the oil pool 2, and can guide the filtered lubricating oil in the hot expansion process into the oil pool 2.

[0063] The terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0064] In the present application, unless otherwise explicitly specified and limited, a first feature is "on" or "under" a second feature can mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "over", "above" and "on top of" the second feature can mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature. The first feature "under", "below" and "underneath" the second feature can mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is horizontally lower than the second feature.

[0065] Although the embodiments of the present application have been shown and described above, it is to be understood that the above-described embodiments are exemplary only, and are not to be construed as limiting the present application, and that changes, modifications, substitutions and variations can be made thereto by those skilled in the art without departing from the scope of the present application.

Claims

1. A steel pipe hot expanding apparatus comprising a pusher and a hot expander provided on a hot expanding line, characterized in that, The oil immersion device is arranged between the pushing device and the hot expanding device, and comprises an oil pool and a turnover mechanism arranged in the oil pool and rotating around a group of horizontal axes. The oil pool is used to contain lubricating oil, and the length of the oil pool in the direction of the hot expanding line is greater than the length of the steel pipe. The turnover mechanism is provided with a clamping mechanism for clamping the steel pipe, so that the turnover mechanism can turn the steel pipe to opposite high and low positions. When the steel pipe is turned to the high position, the steel pipe is flush with the feeding port of the hot expanding device, so that the pushing device can push the steel pipe into the hot expanding device. When the steel pipe is turned to the low position, the steel pipe is immersed in the lubricating oil. The turnover mechanism is sequentially provided with the high position, a first middle position, the low position and a second middle position in the rotation direction. The oil pool is provided with a feeding mechanism on the side close to the pushing device.

2. The steel pipe hot expanding apparatus according to claim 1, characterized by The clamping mechanism comprises a first clamping assembly and a second clamping assembly clamped on both ends of the steel pipe.

3. The steel pipe hot expanding apparatus according to claim 2, wherein The steel pipe is arranged in the clamping cavity of the first clamping assembly, and the first clamping assembly is swingably arranged in a group of tangent planes of the turnover mechanism.

4. The steel pipe hot expanding apparatus according to claim 3, wherein The second clamping assembly comprises a fixed block and a movable block arranged opposite to each other in the tangent planes.

5. The apparatus according to claim 4, wherein The turnover mechanism comprises a turnover frame, the fixed block is fixedly arranged on the turnover frame, and the movable block is movably arranged on the turnover frame relative to the fixed block. A plurality of first elastic members are arranged between the turnover frame and the movable block to push the movable block to gather towards the fixed block. When the turnover mechanism is turned to the second middle position, the movable block is located below the fixed block, so that the steel pipe can be inclined.

6. The steel pipe hot expanding apparatus as set forth in claim 1, characterized by In the axial direction of the turnover mechanism, a group of baffles are arranged at both ends of the oil pool.

7. The steel pipe hot expanding apparatus as set forth in claim 1, characterized by In the rotation process of the turnover mechanism, the first clamping assembly and the second clamping assembly are each blocked by a group of baffles to prevent the steel pipe from sliding out of the turnover mechanism. Two groups of baffles are each provided with a notch corresponding to the high position and the first middle position. A restraint assembly acting on the first clamping assembly is arranged on the baffle close to the feeding mechanism to keep the clamping cavity of the first clamping assembly horizontal when the feeding mechanism feeds. The restraint assembly comprises: A compression ring is reciprocally arranged on the baffle relative to the clamping cavity, and the compression ring is coaxially arranged with the notch corresponding to the first middle position. An extrusion member is arranged on the rotating shaft of the turnover mechanism. An oil receiving plate extending outward is arranged on the sidewall of the oil pool below the second middle position. A roller way is arranged between the first clamping assembly and the second clamping assembly on the turnover mechanism, and the roller way is used to convey the steel pipe.

8. The steel pipe hot expanding apparatus as set forth in claim 1, characterized by The heat expander is further provided with an oil groove in communication with the oil pool.

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