A grease application device for external threads on the end of a tubular

Abstract

This utility model discloses a grease application device for the external thread of a pipe end. Its outer sleeve contains an application drive shaft connected in sequence to a drive conversion head, a connecting sleeve with an oil inlet groove, a connecting short section with a central hole, and an application head. The application head has an oil inlet chamber with an oil application hole and an oil baffle plate fixed in the application chamber by a spring. The oil storage pipe of the electric oil gun is connected to the oil inlet of the outer sleeve through a grease delivery pipe. One end of the outer sleeve is fixed to the gun holder of the electric oil gun. This utility model uses an electric oil gun as a power source for rotary application of grease to the external thread of the pipe end, changing the manual application method and improving the structure of the application head in existing tools. It significantly improves the sealing effect and application efficiency of the downhole tubing, greatly reduces the labor intensity of manual labor, protects the environment, and improves the cleanliness and hygiene of the construction site.

Description

Technical Field

[0001] This utility model relates to the technical field of grease application tools for the external threads of pipe ends, and in particular to a grease application device for the external threads of pipe ends. Background Technology

[0002] During well workover operations in the petroleum industry, when running tubing into the well, the tubing must be connected one by one before being run into the well. Before connecting the tubing threads, thread-locking oil is applied to the outer threads of the tubing to protect the outer threads and seal the tubing string, and to prevent thread damage and leakage.

[0003] Currently, the most common method for applying thread-locking oil to the external threads of tubing is to manually apply the oil with a brush. This method is highly susceptible to human error, time-consuming, and labor-intensive, often resulting in uneven application. This can lead to some tubing threads not being properly protected, and manual application increases worker workload, reduces efficiency, and slows down the process. Uneven application can also shorten the lifespan of the tubing threads and cause tubing string leaks. Furthermore, if the oil enters the tubing during application, it can damage equipment connected to the downhole tubing string, shortening the well's production cycle, requiring frequent well workovers, increasing workover costs significantly, and reducing the well's economic efficiency.

[0004] To address the aforementioned issues, on-site staff have undertaken numerous tasks and achieved some success. Following a search, the following related technologies have been identified: 1. Patent publication number CN102688832A discloses a threaded oil application device, in which a gun cover and a housing are fitted onto an oil passage connector. A pressure cap is connected to the oil passage connector, and the right end face of the pressure cap presses against the inner shoulder of the gun cover. The gun cover presses against the left end face of the housing, and the inner shoulder of the housing presses against the outer shoulder of the oil passage connector. An oil squeezing gun is connected to the gun cover, and an oil scraper sleeve is installed on the outer end of the housing. The oil passage connector has an inner hole and a connecting hole, and the outer end of the oil passage connector has a guide head. During use, the guide head of the oil passage connector... Insert the nozzle into the oil pipe, and the scraper sleeve is fitted onto the outer wall of the oil pipe, creating a cavity between the outer shell and the oil pipe. The threads of the oil pipe are located in the cavity. After the scraper sleeve is fitted onto the outer wall of the oil pipe, operating the oil squeezing gun will fill the cavity with thread oil. When the oil squeezing gun is pulled outward, the scraper sleeve passes over the threads of the oil pipe, and the thread oil is evenly applied to the threads of the oil pipe. There is no problem of uneven application of thread oil. During the connection of the threads and during use, the threads of the oil pipe will not be damaged due to sticking or rust.

[0005] The aforementioned threaded oil coating device has the advantage that when the oil gun is pulled outward, the scraper sleeve passes over the threads of the tubing, and the threaded oil is evenly applied to the threads of the tubing. The disadvantage is that during the coating process, the tubing opening is not sealed, and the threaded oil may flow into or enter the tubing, potentially damaging equipment connected to the downhole tubing string, creating potential malfunctions in the well, and affecting subsequent normal production.

[0006] 2. Patent publication number CN114178144A discloses a device for quickly applying thread oil to internal and external pipe threads. It includes an oiling mechanism, a handle switch, a high-pressure oil injection pipe, and a pressurized oil pump. One end of the handle switch is connected to the oiling mechanism, and the other end is connected to the high-pressure oil injection pipe, which is connected to the pressurized oil pump. The device for quickly applying thread oil to internal and external pipe threads provided by the above invention can quickly complete the oiling process for internal and external pipe threads, ensuring even and complete application of the thread oil.

[0007] The advantage of the aforementioned device is that it can apply thread-locking oil to the threads inside and outside the pipe. The disadvantage is that the pipe opening is not sealed during the application process, allowing the thread-locking oil to flow into or enter the pipe, potentially damaging equipment connected to the downhole tubing, creating potential malfunctions, and affecting subsequent well production. Furthermore, the device is bulky, and its use is inconvenient given the limited space available for modern equipment at the work site.

[0008] 3. Patent publication number CN109939904B discloses an oil pipe sealing grease application tool, which mainly solves the problems of uneven application and poor oil pipe sealing caused by the manual application of oil pipe thread sealing grease with a brush. Its features include: a grease applicator head connected to the left end of the outer cylinder; a grease applicator head sleeve covering the left end of the grease applicator head; an annular gap between the grease applicator head and the sleeve; a sealing grease channel inside the grease applicator head; a piston inside the outer cylinder; an inner sleeve inside the piston; a spring between the piston and the rear cover; and a lead screw connected to the rear cover, with its left end connected to the inner sleeve. Using this oil pipe sealing grease application tool results in a good uniformity of sealing grease application in one pass, preventing oil pipe leaks and avoiding rework.

[0009] However, the disadvantage is that the tubing opening is not sealed during the coating process, and the threaded oil may flow into or enter the tubing, which may damage the equipment connected to the downhole tubing string, leave potential faults in the oil well, and affect the normal production of the oil well in the later stage.

[0010] Therefore, the device for applying oil to the external threads of tubing, casing, or other pipe ends still needs improvement to meet the requirements of oil application to the external threads of pipe ends. Summary of the Invention

[0011] The purpose of this invention is to provide a grease application device for the external threads of pipe rods, which improves the efficiency of applying grease to the external threads of pipe rods, reduces the labor intensity of workers, prevents grease from entering the pipe rod, avoids damage to the oil pump and other equipment connected to the downhole tubing, extends the maintenance cycle of the oil pump, and improves the production efficiency of the oil well.

[0012] The technical solution of this utility model is as follows: a grease applicator for the external thread of a pipe rod, comprising an applicator head, wherein: an outer sleeve contains an applicator drive shaft, a connecting sleeve with an oil inlet groove, a connecting short section with a central hole, and the applicator head, which are sequentially connected to a transmission conversion head; the applicator head is provided with an oil inlet chamber with an oil application hole and an oil baffle plate fixed in the applicator chamber by a spring; the oil storage pipe of the electric oil gun is connected to the oil inlet of the outer sleeve through a grease delivery pipe; one end of the outer sleeve is fixed to the gun base of the electric oil gun, and the eccentric shaft at the front end of the oil gun main shaft, which is connected to the oil gun reciprocating pump connecting rod, can be inserted into the eccentric shaft mounting groove of the transmission conversion head.

[0013] Preferably, the cross-section of the transmission conversion head is T-shaped, the outer diameter of the upper body connected to the oil gun spindle is larger than the outer diameter of the lower body, and an eccentric shaft mounting groove is provided on the upper end face connected to the oil gun spindle. The width of the eccentric shaft mounting groove is larger than the width of the eccentric shaft at the front end of the oil gun spindle, and the upper end and the outer side of the groove are connected to the upper body of the transmission conversion head.

[0014] Preferably, the lower body of the transmission conversion head has an internal thread in the center hole and a screw hole in the lower body, into which a fastening screw can be installed.

[0015] Preferably, the transmission conversion head is sequentially threaded to the application transmission shaft, the connecting sleeve, the connecting short section, and the application head; the upper part of the application transmission shaft, which is threaded to the transmission conversion head, is fixed by a fastening screw in a screw hole, and a fastening nut is also connected to the outside of the application transmission shaft at the lower end of the transmission conversion head.

[0016] Preferably, the outer sleeve is provided with an assembly groove in one end of the body that is fixedly connected to the electric oil gun, and a sealing ring groove is provided in the center hole of the other end of the body and a sealing ring is installed. The oil inlet is located in the cylinder wall of the outer sleeve between the sealing rings. The grease delivery pipe is a flexible hose with one end connected to the outlet of the oil storage pipe and the other end connected to the oil nozzle installed in the oil inlet of the outer sleeve.

[0017] Preferably, the connecting sleeve is a non-uniform diameter cylindrical body with internal threads at both ends that can connect with the coating drive shaft and the connecting short section; the connecting sleeve has two or more longitudinal oil inlet grooves in the cylindrical body corresponding to the oil inlet of the outer sleeve.

[0018] Preferably, the connecting section is a non-equal diameter connecting body with external threads at both ends, which are threaded to the connecting sleeve and the applicator head respectively.

[0019] Preferably, the applicator head is a non-uniform diameter cylindrical body with its small diameter end threadedly connected to a connecting short section, and there is a tapered transition section or reinforcing ribs between the outer circles of the small diameter end and the large diameter end of the applicator head; the two ends of the spring are respectively fixed to the bottom of the applicator cavity in the applicator head and the rear end of the oil baffle.

[0020] Preferably, the oil inlet cavity of the applicator head is a clamping cavity located in the wall of the large-diameter end of the applicator head and connected to the cavity of the small-diameter end of the applicator head. The oiling holes are arranged in two or more rows longitudinally in the inner wall of the large-diameter end of the applicator head. An oil scraper is also provided in the inner wall between the longitudinally arranged oiling holes.

[0021] Preferably, the length of the cylinder without an oiling hole at the front end of the applicator head matches the length of the unthreaded portion at the root of the external threaded section of the pipe rod being applicated; the outer diameter of the oil baffle is larger than the inner diameter of the center hole at the outer end of the pipe rod being applicated, and the outer circle of the oil baffle has grooves matching the number of scraper blades.

[0022] Compared with the prior art, the significant advantage of this utility model is that this device is mainly used to apply grease or thread oil to the external threads of oil pipes, casings, and other pipe ends in the petroleum industry.

[0023] This invention uses an electric grease gun as the power source for rotary grease application to the external threads of the tubing end, changing the manual application method and improving the structure of the grease application head in existing tools. A baffle plate, fixed by a spring, is installed in the grease application chamber of the grease application head. During use, the opening of the tubing, casing, or other tubing can be blocked, preventing grease from entering the tubing or casing body during grease application. This prevents grease from entering the pump or other equipment connected to the tubing string after it has been run downhole, avoiding damage to the pump or other downhole equipment, preventing potential malfunctions, and affecting the normal production of the well later. It also avoids waste of threaded grease or oil. After application, the baffle plate returns to its original position under the action of the spring, also preventing impurities from entering the grease application chamber.

[0024] The applicator head of this device is equipped with an oil scraper, which is spaced apart from the oiling hole. This allows the grease entering the external thread at the end of the tube through the oiling hole to be further compacted and evenly applied during the rotation of the applicator head. At the same time, the oil baffle plate is provided with grooves corresponding to the number and position of the oil scrapers, which helps to straighten the oil baffle plate.

[0025] This invention truly solves the shortcomings of existing tools for applying grease to the external threads of pipe ends. It also cleverly connects the application head via a connecting section, a connecting sleeve, an application drive shaft, and a drive conversion head, and then connects it to an electric grease gun via the drive conversion head. The electric grease gun, through the drive conversion head, drives the application head to rotate and apply grease to the external threads of the pipe end, making the electric grease gun both an application tool and a tool for manipulating the rotating application head – a dual-purpose tool.

[0026] Using an electric grease gun to apply grease to the external threads of the tubing end allows for smooth and uniform 360° rotation. Combined with the scraper blade in the application head, this effectively avoids the uneven grease distribution caused by inconsistent pressure in existing application tools and traditional manual application operations. This results in grease failing to evenly cover the spiral surface of the tubing threads, significantly improving the sealing effect and application efficiency of the downhole tubing string, and greatly reducing manual labor intensity. It also prevents grease spillage, protects the environment, and improves the cleanliness and hygiene of the work site.

[0027] One set of this device has been manufactured and tested at the work site. It has been proven that the thread grease is applied evenly, has good penetration, and is highly efficient. The time required to apply grease to one pipe manually has been reduced from more than 20 seconds to just 6 seconds, saving time and effort and making it convenient and quick.

[0028] This invention significantly improves the efficiency of applying grease to the external threads of pipe rods. While preventing grease from entering the pipe rod and protecting downhole equipment, it greatly reduces the labor intensity of workers, saves thread oil, and lowers the application cost of grease. Its effect is significant and can bring good economic benefits. Attached Figure Description

[0029] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of this utility model.

[0030] Figure 2 yes Figure 1 A schematic diagram of the transmission converter.

[0031] Figure 3 yes Figure 2 Left view of the transmission converter head.

[0032] Figure 4 yes Figure 1 A schematic diagram of the structure of the applicator head.

[0033] Figure 5 yes Figure 4 A schematic diagram of the structure along the AA direction.

[0034] In the diagram: 1. Electric oil gun, 1-1. Oil storage pipe, 1-2. Oil gun spindle, 1-3. Oil gun reciprocating pump connecting rod, 1-3. Transmission conversion head, 2. Eccentric shaft mounting groove, 2-1. Screw hole, 2-2. Application transmission shaft, 3. Outer sleeve, 4. Sealing ring, 4-1. Grease delivery pipe, 5. Connecting sleeve, 6. Connecting short section, 7. Application head, 8. Application head oil inlet chamber, 8-1. Scraper, 8-2. Oil baffle, 8-3. Application hole, 8-4. Spring, 8-5. Detailed Implementation

[0035] The accompanying drawings are for reference and illustration only and are not intended to limit the scope of protection of this utility model. The technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0036] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0037] In the description of this utility model, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, in the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0038] See Figures 1-5A grease applicator for externally threaded pipe ends includes an applicator head 8, wherein: an outer sleeve 4 houses an applicator drive shaft 3, a connecting sleeve 6 with an oil inlet groove, a connecting short section 7 with a central hole, and the applicator head 8, which are sequentially connected to a transmission conversion head 2; the applicator head 8 has an oil inlet chamber 8-1 with an oil application hole 8-4 and an oil baffle plate 8-3 fixed in the applicator chamber by a spring 8-5; the oil storage pipe 1-1 of the electric oil gun 1 is connected to the oil inlet of the outer sleeve 4 through a grease delivery pipe 5; one end of the outer sleeve 4 is fixed to the gun base of the electric oil gun 1, and the eccentric shaft at the front end of the oil gun main shaft 1-2, which is connected to the oil gun reciprocating pump connecting rod 1-3, can be inserted into the eccentric shaft mounting groove 2-1 of the transmission conversion head 2.

[0039] In this utility model, the applicator head 8 is equipped with an oil baffle plate 8-3 installed in the applicator cavity via a spring 8-5. When applying grease to the external threads at the end of the tubing, the applicator head 8 is first placed over the external threads at the end of the tubing and pushed against the root of the external thread section. At this time, the oil baffle plate 8-3 installed in the applicator cavity of the applicator head 8 can block the opening of the tubing, casing, or other tubing, preventing grease from entering the tubing, casing, or other tubing body from the opening during the grease application process. This also prevents grease in the tubing or casing after it is connected to the well from entering the pump or other equipment connected in the tubing string, effectively avoiding damage to the pump or other downhole equipment, potential malfunctions, and problems that affect the normal production of the well in the later stages. At the same time, it also avoids the waste of threaded oil or grease.

[0040] This invention truly solves the defects of existing tools for applying grease to the external threads of pipe ends, and at the same time cleverly connects the application head 8 through the connecting short section 7, the connecting sleeve 6, the application drive shaft 3 and the drive conversion head 2, and connects it to the electric oil gun 1 through the drive conversion head 2.

[0041] This invention involves inserting the eccentric shaft of the oil gun 1, with the oil gun main shaft 1-2 and the oil gun reciprocating pump connecting rod 1-3 mounted at its front end, into the eccentric shaft mounting groove 2-1 of the transmission conversion head 2. Driven by the oil gun main shaft 1-2 and the reciprocating motion of the oil gun reciprocating pump connecting rod 1-3, the grease in the oil storage pipe 1-1 enters the oil inlet chamber 8-1 of the application head 8 through the grease delivery pipe 5, the oil inlet groove of the connecting sleeve 6, and the central hole of the connecting short section 7, and then enters the application chamber through the application hole 8-4. While supplying grease to the application head 8, the electric oil gun 1 simultaneously drives the transmission conversion head 2 and its connected components to rotate together with the application head 8. The electric oil gun 1, through the transmission conversion head 2, drives the application head 8 to rotate and apply grease to the external thread at the end of the tube rod, thus making the electric oil gun 1 both an oil injection tool and a tool for manipulating the rotation of the application head 8—a dual-purpose tool. The electric oil gun 1 can be purchased commercially.

[0042] This utility model is easy to use and significantly improves the efficiency of applying grease to the external threads of pipe ends. While preventing grease from entering the pipe and protecting downhole equipment, it greatly reduces the labor intensity of workers, saves grease and thread oil, and reduces the application cost of grease. Its use effect is significant and can bring good economic benefits.

[0043] Based on the above embodiment one, the present invention also has the following embodiments: In a preferred embodiment, the transmission conversion head 2 has a T-shaped cross-section. The outer diameter of the upper body connected to the oil gun spindle 1-2 is larger than the outer diameter of the lower body. An eccentric shaft mounting groove 2-1 is provided on the upper end face connected to the oil gun spindle 1-2. The width of the eccentric shaft mounting groove 2-1 is larger than the width of the eccentric shaft at the front end of the oil gun spindle 1-2, and the upper end and the outer side of the groove are connected to the upper body of the transmission conversion head 2.

[0044] In a preferred embodiment, the lower body of the transmission conversion head 2 has an internal thread in its central hole and a screw hole 2-2 in its lower body, into which a fastening screw can be inserted to strengthen the connection with the coating transmission shaft 3.

[0045] In a preferred embodiment: the transmission conversion head 2 is sequentially threaded to the application transmission shaft 3, the connecting sleeve 6, the connecting short section 7, and the application head 8; the upper part of the application transmission shaft 3, which is threaded to the transmission conversion head 2, is fixed by a fastening screw in the screw hole 2-2, and a fastening nut is also connected to the outside of the application transmission shaft 3 at the lower end of the transmission conversion head 2. Fastening screws and fastening nuts are used to prevent the transmission conversion head 2 from disengaging from the application transmission shaft 3.

[0046] In a preferred embodiment: the outer sleeve 4, which is fixedly connected to the electric oil gun 1, has an assembly groove in one end of its main body, and a sealing ring groove with a sealing ring 4-1 installed in the center hole of the other end of its main body. The oil inlet is located in the cylinder wall of the outer sleeve 4 between the sealing rings 4-1. The grease delivery pipe 5 is a flexible hose, with one end connected to the outlet of the oil storage pipe 1-1 and the other end connected to the oil nozzle installed in the oil inlet of the outer sleeve 4. The assembly groove in the outer sleeve 4 facilitates the connection and disassembly between the transmission conversion head 2 and the application transmission shaft 3.

[0047] In a preferred embodiment: the connecting sleeve 6 is a non-uniform diameter cylindrical body with internal threads at both ends that can connect to the coating drive shaft 3 and the connecting short section 7; the connecting sleeve 6 has two or more longitudinal oil inlet grooves in the cylindrical body corresponding to the oil inlet of the outer sleeve 4. The grease transported through the grease conveying pipe 5 enters the connecting sleeve 6 through these oil inlet grooves.

[0048] In a preferred embodiment, the connecting section 7 is a non-equal diameter connector with external threads at both ends, which are threaded to the connecting sleeve 6 and the applicator head 8, respectively.

[0049] In a preferred embodiment: the applicator head 8 is a non-uniform diameter cylindrical body with its small diameter end threadedly connected to the connecting short section 7. There is a tapered transition section or reinforcing ribs between the outer circles of the small diameter end and the large diameter end of the applicator head 8 to increase the strength of the applicator head 8. The two ends of the spring 8-5 are respectively fixed to the bottom of the applicator cavity in the applicator head 8 and the rear end of the oil baffle 8-3. After the grease is applied to the external thread of the pipe end, the oil baffle 8-3 is reset under the action of the spring 8-5, which can also keep impurities from entering the applicator cavity of the applicator head 8.

[0050] In a preferred embodiment, the oil inlet cavity 8-1 of the applicator head is a clamped cavity located in the wall of the large-diameter end of the applicator head 8 and communicating with the cavity of the small-diameter end. Two or more rows of oiling holes 8-4 are arranged longitudinally within the inner wall of the large-diameter end of the applicator head 8. An oil scraper 8-2 is also provided within the inner wall between the longitudinally arranged oiling holes 8-4. The oil scraper 8-2 is spaced apart from the oiling holes 8-4, allowing the grease entering the external thread at the end of the tube from the oiling holes 8-4 to be further compacted and evenly applied during the rotation of the applicator head 8.

[0051] In a preferred embodiment: the length of the cylinder of the applicator head 8 without the applicator hole 8-4 matches the length of the unthreaded portion at the root of the threaded section of the pipe end to be applicated; the outer diameter of the baffle plate 8-3 is larger than the inner diameter of the center hole at the outer end of the pipe to be applicated, and the outer circumference of the baffle plate 8-3 has grooves matching the number of scraper blades 8-2. Under the action of the spring 8-5, the baffle plate 8-3 can retract and extend along the scraper blades 8-2, thus straightening the baffle plate 8-3.

[0052] The embodiments described above are merely typical examples, but the present invention is not limited to these embodiments. Those skilled in the art can make modifications without departing from the spirit and teachings of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the inventive spirit and concept of the present invention should be included within the protection scope of the present invention. Therefore, the protection scope is not limited to the above description.

Claims

1. A grease applicator for the external thread of a pipe rod end, comprising an applicator head, characterized in that, The outer sleeve contains an applicator drive shaft connected in sequence to the transmission conversion head, a connecting sleeve with an oil inlet groove, a connecting short section with a center hole, and an applicator head. The applicator head has an oil inlet chamber with an oiling hole and an oil baffle plate fixed in the applicator chamber by a spring. The oil storage pipe of the electric oil gun is connected to the oil inlet of the outer sleeve through a grease delivery pipe. One end of the outer sleeve is fixed to the gun base of the electric oil gun, and the eccentric shaft at the front end of the oil gun spindle, which is connected to the oil gun reciprocating pump connecting rod, can be inserted into the eccentric shaft mounting groove of the transmission conversion head.

2. The grease application device for the external thread of a pipe rod end as described in claim 1, characterized in that, The transmission conversion head has a T-shaped cross-section. The outer diameter of the upper body connected to the oil gun spindle is larger than the outer diameter of the lower body. An eccentric shaft mounting groove is provided on the upper end face connected to the oil gun spindle. The width of the eccentric shaft mounting groove is larger than the width of the eccentric shaft at the front end of the oil gun spindle, and the upper end and the outer side of the groove are connected to the upper body of the transmission conversion head.

3. The grease application device for the external thread of a pipe end as described in claim 2, characterized in that, The lower body of the transmission conversion head has an internal thread in its central hole and a screw hole in its lower body, into which a fastening screw can be installed.

4. The grease application device for the external thread of a pipe end as described in claim 3, characterized in that, The transmission conversion head is sequentially threaded to the application transmission shaft, the connecting sleeve, the connecting short section, and the application head; the upper part of the application transmission shaft, which is threaded to the transmission conversion head, is fixed by a fastening screw in the screw hole, and a fastening nut is also connected to the outside of the application transmission shaft at the lower end of the transmission conversion head.

5. The grease application device for the external thread of a pipe end as described in claim 1, characterized in that, The outer sleeve is fixedly connected to the electric oil gun. One end of the body has an assembly groove, and the other end of the body has a sealing ring groove in the center hole and is fitted with a sealing ring. The oil inlet is located in the cylinder wall of the outer sleeve between the sealing rings. The grease delivery pipe is a flexible hose with one end connected to the outlet of the oil storage pipe and the other end connected to the oil nozzle installed in the oil inlet of the outer sleeve.

6. The grease application device for the external thread of a pipe end as described in claim 5, characterized in that, The connecting sleeve is a non-uniform diameter cylindrical body with internal threads on the inner circles of both ends that can connect with the coating drive shaft and the connecting short section; the connecting sleeve has two or more longitudinal oil inlet grooves in the cylinder corresponding to the oil inlet of the outer sleeve.

7. The grease application device for the external thread of a pipe end as described in claim 4, characterized in that, The connecting section is a non-equal diameter connector with external threads at both ends, which are threaded to the connecting sleeve and the applicator head, respectively.

8. The grease application device for the external thread of a pipe end as described in claim 7, characterized in that, The applicator head is a non-uniform diameter cylindrical body with its small diameter end threaded to a connecting short section. There is a tapered transition section or reinforcing ribs between the outer circles of the small diameter end and the large diameter end of the applicator head. The two ends of the spring are respectively fixed to the bottom of the applicator cavity in the applicator head and the rear end of the oil baffle.

9. A grease applicator for the external thread of a pipe end as described in claim 8, characterized in that, The oil inlet cavity of the applicator head is a clamping cavity set in the tube wall of the large diameter end of the applicator head and connected to the tube cavity of the small diameter end. The oiling holes are arranged in two or more rows in the inner tube wall of the large diameter end of the applicator head, and an oil scraper is also provided in the inner tube wall between the longitudinally arranged oiling holes.

10. The grease application device for the external thread of a pipe end as described in claim 9, characterized in that, The length of the cylinder without an oiling hole at the front end of the applicator head matches the length of the unthreaded portion at the root of the external thread section of the pipe rod being applicated; the outer diameter of the oil baffle is larger than the inner diameter of the center hole at the outer end of the pipe rod being applicated, and the outer circle of the oil baffle has grooves matching the number of scraper blades.

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