阅读说明：本技术 一种往复泵旋管接头进油通道和连接结构 (Reciprocating pump coil joint oil inlet channel and connecting structure ) 是由 黄秀芳 于 2021-11-09 设计创作，主要内容包括：本发明公开了一种往复泵旋转接头进油通道和连接结构,涉及石油工程设备领域,具体包括电机轴辅助支撑、进油管组件、进油管支撑组件、接头体支撑固定板、进油管卡组件、接头体支撑调节组件、曲轴端部、各种进油管路、各种螺栓垫圈组、接头体、滚动轴承、管接头、滚珠等,旋转接头进油通道设置在齿轮护罩的内部,固定安全可靠,不影响往复泵的外观,按照6点定位原理设计旋转接头连接结构,使旋转接头旋转部分的管接头6点定位和旋转接头固定部分的接头体的6点定位不矛盾,既能解决旋接头容易损坏的老大难问题,还可以降低旋转接头旋转部分的管接头和旋转接头固定部分的接头体的同轴度精度要求,降低旋转接头的制造成本。(The invention discloses an oil inlet channel and a connecting structure of a rotary joint of a reciprocating pump, which relate to the field of petroleum engineering equipment and particularly comprise a motor shaft auxiliary support, an oil inlet pipe assembly, an oil inlet pipe support assembly, a joint body support fixing plate, an oil inlet pipe clamp assembly, a joint body support adjusting assembly, a crankshaft end part, various oil inlet pipelines, various bolt washer sets, a joint body, a rolling bearing, a pipe joint, balls and the like, wherein the oil inlet channel of the rotary joint is arranged inside a gear shield, the fixation is safe and reliable, the appearance of the reciprocating pump is not influenced, the rotary joint connecting structure is designed according to a 6-point positioning principle, so that the 6-point positioning of the pipe joint of the rotary part of the rotary joint and the 6-point positioning of the joint body of the fixed part of the rotary joint are not contradictory, the great difficulty that the rotary joint is easy to damage can be solved, and the coaxiality precision requirements of the joint of the rotary part of the rotary joint and the pipe joint body of the fixed part of the rotary joint can be reduced, the manufacturing cost of the rotary joint is reduced.)

1. A reciprocating pump rotary joint oil inlet channel and a connecting structure are characterized in that a motor shaft auxiliary support (1), an M12 screw gasket group (2), an oil inlet pipe assembly (3), an M8 bolt gasket group (4), an oil inlet pipe support assembly (5), a joint body support fixing plate (6), an M12 bolt gasket group (7), an oil inlet pipe clamp assembly (8), a joint body vertical oil inlet upper metal pipe part (9), a joint body vertical oil inlet rubber pipe part (10), a joint body vertical oil inlet lower metal pipe part (11), a rotary joint main part (12), a joint body support adjusting assembly (13), an M10 bolt gasket group (14), a crankshaft end part (15), an M10 bolt gasket group (16), an inner hole (6.1), a joint body (12.1), a rolling bearing (12.2), a pipe joint (12.3), a connecting plate (13.1) and a ball pressing plate (13.2), the oil-out structure comprises a ball (13.3), an inner hole (13.1.1), an outer circle (13.2.1), the outer diameter of a screw thread (16.1) of M10, a junction (Y1) of oil outlet of a rack and oil inlet of an oil inlet pipe, a junction (Y2) of oil outlet of a horizontal oil pipe and oil inlet of a vertical oil pipe, a junction (Y3) of oil outlet of the vertical oil pipe and oil inlet of a connector body, a crankshaft oil inlet pipeline (Y4) and coordinate axis directions (X/Y/Z).

2. The oil feed passage and connection structure of a rotary joint of a reciprocating pump as claimed in claim 1, wherein the motor shaft auxiliary support (1) is connected to the motor bearing housing by 20M 12 bolt washer sets (2) and is a stationary base support, the oil feed pipe assembly (3) is connected to the base frame by 8M 8 bolt washer sets (4) and is fixed, the oil feed pipe support assembly (5) is connected to the base frame by 8M 8 bolt washer sets (4) and is fixed, the joint body support fixing plate (6) is connected to the motor shaft auxiliary support (1) by 6M 12 bolt washer sets (7), the oil feed pipe assembly (3) is fixed to the joint body support fixing plate (6) by the oil feed pipe clamp assembly (8), the crank shaft end portion (15) is connected to the pipe joint (12.3) in the main part portion (12) of the rotary joint by 4M 10 bolt washer sets (14), the pipe joint (12.3) rotates along with the crankshaft, the pipe joint (12.3) is connected with the joint body (12.1) through a rolling bearing (12.2), the joint body (12.1) is connected with the joint body vertical oil inlet lower metal pipe part (11), the joint body vertical oil inlet upper metal pipe part (9) is connected with the oil inlet pipe component (3), a joint body vertical oil inlet rubber pipe part (10) is arranged between the joint body vertical oil inlet upper metal pipe part (9) and the joint body vertical oil inlet lower metal pipe part (11), and all structural components are arranged inside the gear shield.

3. The reciprocating pump rotary joint oil inlet passage and connection structure as claimed in claim 1, wherein a reciprocating pump pipe joint oil inlet passage is characterized in that lubricating oil flows into an oil passage inside an oil inlet pipe assembly (3) from a junction (Y1) between oil outlet of a rack and oil inlet of an oil inlet pipe, flows into an oil passage inside an upper vertical oil inlet metal pipe part (9) of a joint body from a junction (Y2) between oil outlet of a horizontal oil pipe and oil inlet of a vertical oil pipe, flows into a junction (Y3) between oil outlet of the vertical oil pipe and oil inlet of the joint body through a vertical oil inlet rubber pipe part (10) of the joint body and a lower vertical oil inlet metal pipe part (11) of the joint body, and finally flows into a crankshaft oil inlet pipeline (Y4) through an inner pipeline of the joint (12.3).

4. The oil inlet passage and connection structure of the rotary joint of the reciprocating pump as claimed in claim 1, wherein when the pipe joint (12.3) of the rotary part in the main part (12) of the rotary joint is connected with the end part (15) of the crankshaft through 4M 10 bolt washer sets (14), the very light weight joint body support adjusting assembly (13) is sleeved on the excircle of the joint body (12.1), the joint body support adjusting assembly (13) and the joint body support fixing plate (6) are fixed together through 3M 10 bolt washer sets (16), the inner hole (6.1) of the joint body support fixing plate (6) and the outer diameter (16.1) of the threads of the M10 bolt washer set (16) leave a gap, and the joint body support adjusting assembly (13) is in point contact with the excircle of the joint body (12.1) as long as the ball (13.3) is in point contact.

5. The reciprocating pump rotary joint oil feed passage and connection structure as claimed in claim 1, wherein the axis of the joint body vertical oil feed upper metal tube part (9) and the axis of the joint body vertical oil feed lower metal tube part (11) are in the same plane.

Technical Field

The invention relates to the field of petroleum engineering equipment, in particular to an oil inlet channel and a connecting structure of a rotary joint of a reciprocating pump.

Background

Two reciprocating pumps with very similar structures, namely a drilling pump and a fracturing pump, appear in the field of petroleum engineering equipment. The most similar point is that the belt transmission stage of the two-stage transmission of the belt transmission and gear transmission from the original main motor to the crankshaft is cancelled, the small gears are directly arranged at the two ends outside the supporting bearing of the motor shaft, the large gear on the end surface of the crankshaft drives the crankshaft to rotate, the reciprocating linear motion of the crosshead is changed through the connecting rod connected with the crankshaft, and finally the piston rod or plunger at the hydraulic end reciprocates to do work. The connecting rods of the two reciprocating pumps are sliding bearings, the big end of the connecting rod and the bearing of the journal of the crankshaft are connecting rod bearing bush sliding bearings, lubricating oil of the connecting rod bearing bush sliding bearings enters through the end part of the crankshaft, and as the crankshaft rotates, in order to ensure that the lubricating oil smoothly enters the rotating crankshaft, a rotating joint is needed, a rotating pipe joint is arranged in the inner cavity of the rotating joint, a channel is arranged in the pipe joint, the lubricating oil enters the channel in the crankshaft from the channel to lubricate the connecting rod bearing bush, and the pipe joint is connected with the crankshaft and rotates together; the rolling bearing is installed between the rotary joint and the joint body of the pipe joint, the joint body is provided with a threaded joint, the threaded joint is provided with an inner hole, lubricating oil provided by an oil pump of the reciprocating pump flows into the inner hole of the rotary pipe joint through the hole in the threaded joint, and the joint body, namely the threaded joint installed on the joint body, is fixed. The rotary joint has the problems that the service life of the pipe joint is short and becomes a wearing part in the field use process, the reciprocating pump stops working when the rotary joint is replaced, a large amount of lubricating oil leaked to the outside of the gear shield needs to be cleaned, expensive lubricating oil is lost, and the environment is polluted; the more serious consequence is that the reciprocating pump continues to operate without timely treatment, which can cause the occurrence of serious accidents of the reciprocating pump due to the fact that the connecting rod bearing bush lacks lubricating oil and burns the bush, and the crankshaft is damaged. Through preliminary analysis, the short-lived quality that not only is relevant with rotary joint itself of rotary joint, and to a great extent is relevant with rotary joint's connection structure, therefore analysis rotary joint connection structure why can influence the short-lived reason of rotary joint and through improving, satisfies the long reciprocating pump rotary joint oil feed passageway and the connection structure of rotary joint life and has just become the problem that awaits the opportune moment and solve.

Disclosure of Invention

The invention aims to provide an oil inlet channel and a connecting structure of a rotary joint of a reciprocating pump.

The technical scheme of the invention is as follows:

1. finding the cause of short life of rotary joint

The inner cavity of the rotary joint is provided with a rotary pipe joint, a passage is arranged in the pipe joint, lubricating oil enters the passage in the crankshaft from the passage to lubricate a connecting rod bearing bush, and the pipe joint is connected with the crankshaft through a connecting part and rotates together; the rolling bearing is arranged between the pipe joint and the joint body, the joint body is provided with a threaded joint, the threaded joint is provided with an inner hole, lubricating oil provided by an oil pump of the reciprocating pump flows into the inner hole of the pipe joint through the hole in the threaded joint, and the joint body and the threaded joint arranged on the joint body are fixed. When the pipe joint and the joint body of the rotary joint do not work, the coaxiality error of the inner holes of the pipe joint and the joint body is very small, the service life of a rolling bearing in the rotary joint is very long, when the rotary joint is damaged, the coaxiality error of the inner holes of the pipe joint and the joint body is increased, the joint body is fixed, the pipe joint is forcibly rotated by a crankshaft through a connecting part, when the misalignment error between the fixed part and the rotating part increases and exceeds the clearance allowed by the inner ring and the outer ring of the rolling bearing, the pipe joint or the joint body is forced to change the position, the weak one of the pipe joint and the joint body is the connecting part of the pipe joint and the crankshaft, and the pipe joint only needs to change the connecting part of the pipe joint and the crankshaft when the position is changed, so that only the connecting part between the pipe joint and the crankshaft is damaged because the rigidity of the crankshaft is very good.

The reason why the inner hole axiality of coupling and joint body can increase by the mistake when rotary joint during operation, analysis reason rotary joint's connection structure is unreasonable causes.

The coaxiality of the connection between the pipe joint and the crankshaft is well guaranteed, but the fixed connection of the joint body is an overlooked link, and the fixed connection of the joint body is commonly used in the prior art and comprises the following two methods:

(1) the joint body is not separately designed and fixedly connected, and is connected with a threaded joint on the joint body by a threaded joint of an oil inlet pipe, the pipe joint is of an extending beam structure, although the rolling bearing is arranged between the pipe joint and the joint body, friction force still exists between the rolling bearing, and the friction force acting on the rolling bearing can cause the joint body, the threaded joint on the joint body and the oil inlet pipeline to generate a rotating trend, because the oil inlet pipe is connected with the fixed part together and can not rotate, only the swing can be generated, the pipe joint of the overhanging beam structure can be bent, meanwhile, the oil inlet pipe has gravity, so that the axis of an inner hole of the joint body can be inclined after the threaded joint of the oil inlet pipe is connected with the threaded joint on the joint body, the bending deformation of the pipe joint is further increased, and the pipe joint after the bending deformation rotates, so that the connecting part between the pipe joint and the crankshaft is damaged.

(2) The connector body has designed fixed connection, and the outside that connects the body all generally adopts the excircle structure, and the hole that adopts fixed part to connect the body connection to the connector body and connect the body excircle cooperation and compress tightly the connector body, original design, fixed part's hole and the connector body hole guarantee the axiality very difficultly, and such fixed and compress tightly the connector body has just caused connector body hole and coupling coaxiality error.

Through analysis, the reason that the service life of the rotary joint is short is that the coaxiality error between the pipe joint and the joint body is large due to the fact that the joint body is unreasonable in connecting structure when the rotary joint works.

2. The solution of the invention is:

after finding the reason, through a reciprocating pump rotary joint oil inlet channel and a connecting structure, the connecting structure can ensure that the original coaxiality of the pipe joint and the inner hole of the joint body cannot be damaged, and when the pipe joint rotates together with the crankshaft, a connecting part between the pipe joint and the crankshaft cannot be damaged. The concrete measures are

1) The joint body needs to be positioned and fixed, the contact of the inner hole of a fixed part for positioning the joint body and the excircle of the joint body is a steel ball, the steel ball is in point contact with the joint body, the coaxiality of the axis of the inner hole of the joint body and the axis of the pipe joint cannot be damaged, the fixing force of the joint body does not need to be too large, the fixing force only needs to be larger than the friction force of a rolling bearing between the joint body and the pipe joint, and the coaxiality of the axis of the inner hole of the joint body and the axis of the pipe joint cannot be damaged after the fixing;

2) the gravity of the oil inlet pipe connected with the joint body and the threaded joint on the oil inlet pipe is not applied to the joint body, and the pipe on the joint body bears the gravity;

3) the axis of the threaded joint of the oil inlet pipe and the axis of the threaded joint of the joint body are in the same plane, a part of rubber flexible connecting pipe is arranged in the middle of the oil inlet pipe, and the coaxiality of the axis of the inner hole of the joint body and the axis of the pipe joint cannot be damaged after the two threaded joints are connected.

Drawings

FIG. 1 is a perspective view of an oil inlet passage and connection structure of a rotary joint of a reciprocating pump;

FIG. 2-a front view of a reciprocating pump rotary union oil inlet passage and connection structure;

FIG. 3-section A-A of FIG. 2;

FIG. 4-section B-B of FIG. 2;

FIG. 5-the cross-sectional view D-D of FIG. 3;

FIG. 6-E of FIG. 3 are enlarged partial views;

fig. 7-fig. 6 are partial H enlarged views.

The reference numerals are as follows

1-motor shaft auxiliary support, 2-M12 screw washer group, 3-oil inlet pipe assembly, 4-M8 bolt washer group, 5-oil inlet pipe support assembly, 6-joint body support fixing plate, 7-M12 bolt washer group, 8-oil inlet pipe clamp assembly, 9-joint body vertical oil inlet upper metal pipe part, 10-joint body vertical oil inlet rubber pipe part, 11-joint body vertical oil inlet lower metal pipe part, 12-rotary joint main part, 13-joint body support adjusting assembly, 14-M10 bolt washer group, 15-crankshaft end part, 16-M10 bolt washer group, 6.1-inner hole, 12.1-joint body, 12.2-rolling bearing, 12.3-pipe joint, 13.1-connecting plate, 13.2-ball pressing plate, 13.3-ball pressing plate, 13.1.1-inner hole, 13.2.1-outer circle, 16.1-M10 thread outer diameter, Y1-junction of oil outlet of machine frame and oil inlet pipe, Y2-junction of oil outlet of horizontal oil pipe and oil inlet of vertical oil pipe, Y3-junction of oil outlet of vertical oil pipe and oil inlet of connector body, Y4-crankshaft oil inlet pipeline, X/Y/Z-coordinate axis direction.

Detailed Description

The invention is further described with reference to the following figures and detailed description.

The embodiments of the present invention are not limited to the following examples, and various changes made without departing from the spirit of the present invention are within the scope of the present invention.

The embodiment of the invention takes a reciprocating pump above 2200hp as an example, and because the oil inlet channels and the connecting structures of the pipe joints at two ends of the reciprocating pump are the same, only the oil inlet channel and the connecting structure of the pipe joint at one side are described.

Referring to fig. 1 to 7, the oil inlet passage and connection structure of a rotary joint of a reciprocating pump in this embodiment includes an auxiliary support 1 for a motor shaft, an M12 screw washer set 2, an oil inlet pipe assembly 3, an M8 bolt washer set 4, an oil inlet pipe support assembly 5, a joint body support fixing plate 6, an M12 bolt washer set 7, an oil inlet pipe clamp assembly 8, an upper vertical oil inlet metal pipe portion 9 of a joint body, a rubber vertical oil inlet pipe portion 10 of a joint body, a lower vertical oil inlet metal pipe portion 11 of a joint body, a main part portion 12 of a rotary joint, a joint body support adjusting assembly 13, an M10 bolt washer set 14, a crankshaft end portion 15, an M10 bolt washer set 16, an inner hole 6.1, a joint body 12.1, a rolling bearing 12.2, a rolling bearing 12.3, a connecting plate 13.1, a ball pressing plate 13.2, a ball 13.3, an inner hole 13.1.1, an outer circle 13.2.1, a threaded outer diameter 16.1 of M10, a Y1 at a junction of a machine frame oil outlet and an oil inlet pipe and a junction Y2 at a junction of a horizontal oil outlet and a vertical oil pipe, the junction Y3 between the oil outlet of the vertical oil pipe and the oil inlet of the joint body, the oil inlet pipeline Y4 of the crankshaft, and the X/Y/Z coordinate axis direction.

Referring to fig. 1, 2, 3 and 6, 20M 12 bolt washer sets 2 are used to connect the motor shaft auxiliary support 1 with the motor bearing seat (not shown) to form a stationary base support, 8M 8 bolt washer sets 4 are used to connect the oil inlet pipe assembly 3 with the base frame (not shown) to form a stationary base support, 8M 8 bolt washer sets 4 are used to connect the oil inlet pipe support assembly 5 with the base frame to form a stationary base support, 6M 12 bolt washer sets 7 are used to connect the joint body support fixing plate 6 with the motor shaft auxiliary support 1, 8 oil inlet pipe clamp sets are used to fix the oil inlet pipe assembly 3 with the joint body support fixing plate 6, the fixing position of the oil inlet pipe assembly 3 is reliable, the crankshaft is rotating during operation, the crankshaft end 15 and the pipe joint 12.3 in the main part 12 of the rotary joint are connected by 4M 10 bolt washer sets 14, the pipe joint 12.3 rotates along with the crankshaft, the pipe joint 12.3 is connected with the joint body 12.1 through the rolling bearing 12.2 and is a boundary line between rotation and fixation, the part connected with the inner ring of the bearing is rotation, the part connected with the outer ring of the bearing is not movement, the joint body 12.1 is connected with the joint body vertical oil inlet lower metal pipe part 11, the joint body vertical oil inlet upper metal pipe part 9 is connected with the oil inlet pipe assembly 3, the joint body vertical oil inlet rubber pipe part 10 is arranged between the joint body vertical oil inlet upper metal pipe part 9 and the joint body vertical oil inlet lower metal pipe part 11, all the structures are arranged in the gear shield, the fixation is safe and reliable, and the appearance of the reciprocating pump is not influenced.

Referring to fig. 4, 5 and 3, in the oil inlet passage of the rotary joint of the reciprocating pump, lubricating oil flows into an oil passage inside the oil inlet pipe assembly 3 from a Y1 at the junction between the oil outlet of the frame and the oil inlet of the oil inlet pipe, flows into an oil passage inside the upper vertical oil inlet metal pipe part 9 of the joint body from a Y2 at the junction between the oil outlet of the horizontal oil pipe and the oil inlet of the vertical oil pipe, then flows into a Y3 at the junction between the oil outlet of the vertical oil pipe and the oil inlet of the joint body through the rubber vertical oil inlet pipe part 10 of the joint body and the lower vertical oil inlet metal pipe part 11 of the joint body, and finally flows into the oil inlet pipeline Y4 of the crankshaft through an inner pipeline of the joint 12.3, and the oil inlet passage of the rotary joint is arranged inside the gear shield.

Referring to fig. 2, 3, 6 and 7, in the main component part 12 of the rotary joint, the pipe joint 12.3 of the rotary part is connected with the end 15 of the crankshaft through 4M 10 bolt washer sets 14, 5 degrees of freedom of the space of the pipe joint 12.3 are limited, that is, the freedom of movement of the pipe joint 12.3 along the X-axis, the Y-axis and the Z-axis is limited, the freedom of rotation around the X-axis and the Y-axis is limited, only the pipe joint 12.3 is allowed to rotate around the Z-axis, the joint body 12.1 is connected with the pipe joint 12.3 through 2 rolling bearings 12.2, wherein the outer ring of the joint body 12.1 and the outer ring of the rolling bearing 12.2 are connected in an interference fit manner, the 2 rolling bearings 12.2 limit the freedom of movement of the joint body 12.1 along the X-axis, the Y-axis and the Z-axis, the freedom of rotation around the X-axis and the Y-axis is limited, the rotation of the joint body 12.1 is limited by the fixing structure of the joint 12.1 and the rolling bearing 12.2 The body 12.1 conflicts with each other, so the way to prolong the service life of the pipe joint 12.3 is to solve the problem that the joint body 12.1 is fixed reasonably and cannot conflict with the joint body 12.1 limited by 2 rolling bearings 12.2.

Referring to fig. 6 and 7, in detail, after the pipe joint 12.3 of the rotary part in the main part 12 of the rotary joint is connected with the end part 15 of the crankshaft through 4M 10 bolt washer sets 14, the very light weight joint body support adjusting assembly 13 (the connecting plate 13.1 and the ball pressure plate 13.2 of the joint body support adjusting assembly 13 are both made of aluminum with very small density and the total weight is 0.88 kg) is sleeved on the excircle of the joint body 12.1, the joint body support adjusting assembly 13 and the joint body support fixing plate 6 are fixed together through 3M 10 bolt washer sets 16, a gap is left between the inner hole 6.1 of the joint body support fixing plate 6 and the outer diameter 16.1 of the M10 bolt washer set 16, the matching condition of the joint body support adjusting assembly 13 and the joint body 12.1 is not disturbed, only the ball 13.3 of the joint body support adjusting assembly 13 is in a point contact state with the excircle of the joint body 12.1, and the structure of the fixed joint body 12.1 limits the joint body 12.1 from point contact along the axis X, The freedom of movement along the Y axis is not contradictory to the freedom of movement along the X axis and the Y axis of the 2 rolling bearings 12.2 limiting the joint body 12.1, the freedom of movement along the Z axis of the joint body 12.1 is still limited by the 2 rolling bearings 12.2, if the outer circle of the joint body 12.1 is not coaxial with the outer circles of the 2 rolling bearings 12.2, the freedom of rotation about the Z axis of the joint body 12.1 can be limited by the joint body support adjustment assembly 13, the remaining condition is that the freedom of rotation about the X axis and the Y axis of the joint body 12.1 is limited, the influence factor of the freedom of rotation about the X axis and the Y axis of the joint body 12.1 is the weight of the oil inlet pipe of the joint body, if the weight of the oil inlet pipe of the joint body is below, or in the horizontal direction, the joint body 12.1 is subjected to a bending moment of rotation about the X axis or the Y axis, the structure arranges the oil inlet pipe of the joint body above, the weight of the oil inlet pipe perpendicular to be borne by the oil inlet pipe assembly 3, the joint body 12.1 is not subjected to a bending moment rotating around the X axis or the Y axis, the freedom degree of the joint body 12.1 rotating around the X axis or the Y axis is still controlled by 2 rolling bearings 12.2, and through careful analysis, the joint body 12.1 is fixed reasonably and is not contradictory to the limitation of 2 rolling bearings 12.2.

Referring to fig. 2, fig. 3, fig. 4 and fig. 5, the axes of the upper metal tube part 9 with vertical oil feeding of the joint body and the lower metal tube part 11 with vertical oil feeding of the joint body are in the same plane, and a flexible connecting tube 10 with vertical oil feeding of the joint body is arranged between the upper metal tube part 9 with vertical oil feeding of the joint body and the lower metal tube part 11 with vertical oil feeding of the joint body, so that the coaxiality of the inner hole axis of the joint body and the tube joint axis cannot be damaged after the lower metal tube part 11 with vertical oil feeding of the joint body is connected with the rotary joint.

The rotary joint connecting structure is designed according to a 6-point positioning principle, so that 6-point positioning of the pipe joint 12.3 of the rotary joint rotary part and 6-point positioning of the joint body 12.1 of the rotary joint fixing part are not contradictory, the old and difficult problem that the pipe joint 12.3 is easy to damage can be solved, the coaxiality precision requirement of the pipe joint 12.3 of the rotary joint rotary part and the joint body 12.1 of the rotary joint fixing part can be reduced, and the manufacturing cost of the rotary joint is reduced.

The above detailed description of the embodiments of the present invention is provided in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art, and these changes are within the protection of the present invention and also within the protection scope of the present invention.