A kind of pumping sucker rod cold-drawing processing equipment and processing technology

Abstract

The application discloses a kind of pumping light rod cold-drawing processing equipment and processing technology, including pedestal, drawing device, head heating coil, head upsetting device, die, stress relief heating tube, the pedestal is provided with the slot for the placement and passage of pumping light rod blank, the stress relief heating tube is located outside slot and surrounds pumping light rod blank placed in slot.The application adopts multiple cold-drawing processing and surface low-temperature stress relief technical ideas, effectively solves many problems existing in one-time cold-drawing in prior art, can obtain smaller outer diameter error, lower surface roughness, better straightness pumping light rod, so that the production efficiency of pumping light rod is higher.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of pumping light rod processing, in particular to a pumping light rod cold-drawing processing equipment and processing technology. BACKGROUND

[0002] The pumping light rod is a key component of artificial lifting three-pumping equipment. Increasingly deep wells, ultra-deep wells and inclined wells, and unsatisfactory wellhead centering problems, put higher requirements on the mechanical properties of the pumping light rod. The processing process has a significant impact on the cost and mechanical properties of the pumping light rod.

[0003] The pumping light rod is usually made of steel. The size specifications and mechanical property indicators of the pumping light rod used in major domestic and foreign oilfields currently basically refer to the relevant provisions in the SY / T 5029 and API 11B standards. For example, a common uncoated CrMo steel pumping light rod often needs to go through a series of machining and heat treatment such as cold-drawing, straightening, heat treatment and upsetting, etc. to meet the requirements of the relevant standards. Due to the differences between the steel factory's steel delivery standards and the pumping light rod standards, there is a certain difference between the steel diameter size of the steel factory and the specified diameter of the pumping light rod. Therefore, steel blanks with slightly larger diameter specifications need to be ordered, and then cold-drawing processing is needed to achieve the required diameter specifications of the pumping light rod.

[0004] Generally, cold-drawing processing needs to reduce the diameter of the pumping light rod by about 1-2 mm. In order to reduce processing time, the pumping light rod blanks are mostly processed by one-time cold-drawing to size. However, this one-time cold-drawing to size has the following problems: first, due to the large processing amount, the inner surface of the cold-drawing die wears out quickly, resulting in a short service life, which leads to frequent replacement, reducing production efficiency and increasing costs; second, the rapid damage to the inner surface of the die results in a high surface roughness of the cold-drawn pumping light rod blank, especially the scratches generated during the cold-drawing process, which is not conducive to the mechanical properties of the pumping light rod in the later stage; third, due to the large internal stress after processing, the pumping light rod blank is bent and cannot directly enter the next process, so an additional straightening process is needed. In the existing cold-drawing process, the cold-drawing equipment has a simple structure, one-time cold-drawing processing leads to frequent replacement of the cold-drawing die, the surface roughness of the pumping light rod is too large and needs to be polished in the later stage, and the bending of the pumping light rod also needs an additional straightening process, which also increases costs and reduces production efficiency.

[0005] Therefore, in view of the current cold-drawing processing of pumping light rod blanks, it is necessary to develop a pumping light rod cold-drawing processing equipment and processing technology that takes into account efficient production and good mechanical properties. SUMMARY

[0006] The application aims to provide an oil pumping polished rod cold-drawing processing device and a processing technology, through functional integration design of the structure of the device, adopting multiple cold-drawing processing and convenient surface heating stress relief technical ideas, so that the outer diameter error of the oil pumping polished rod is smaller, the surface roughness is lower, the service life of the die is longer, and the additional straightening process after cold-drawing can be omitted, and the efficient production and good mechanical properties of the oil pumping polished rod are considered.

[0007] The application discloses an oil pumping polished rod cold-drawing processing device, which adopts the following technical scheme: a base, a drawing device, a head heating coil, a head upsetting device, a die and a stress relief heating pipe are arranged, the base is provided with a slot for placing and passing the oil pumping polished rod blank, the drawing device, the head heating coil, the head upsetting device, the die and the stress relief heating pipe are collinear with the axis of the slot, the stress relief heating pipe is located outside the slot and surrounds the oil pumping polished rod blank placed in the slot, the head heating coil is located at the outlet end of the base, the head upsetting device is located on the inner side of the head heating coil, the die is located on the outer side of the head heating coil, and the drawing device is located at the outermost side of the whole base.

[0008] The drawing device is provided with a clamping head connected with the head of the oil pumping polished rod blank, and the drawing device further comprises a stepless speed regulation power device, so that the drawing device continuously and uniformly realizes the cold-drawing processing of the oil pumping polished rod blank.

[0009] The highest heating temperature of the head heating coil reaches 1300 DEG C, and the stress relief heating pipe is provided with a medium-frequency induction heating coil, and the highest heating temperature reaches 600 DEG C.

[0010] The application further discloses an oil pumping polished rod cold-drawing processing technology, which adopts the following technical scheme: after the oil pumping polished rod blank is placed in the slot, the oil pumping polished rod blank is sequentially subjected to the stress relief heating pipe, the head heating coil, the head upsetting device, and then is clamped by the drawing device and passes through the die to complete the cold-drawing processing; the cold-drawing processing of the oil pumping polished rod comprises multiple cold-drawing procedures, and the oil pumping polished rod blank is subjected to low-temperature heating stress relief treatment before the second cold-drawing procedure.

[0011] Further, the diameter reduction value of the oil pumping polished rod blank after any cold-drawing procedure is not more than 0.6 mm, and the diameter reduction value of the oil pumping polished rod blank after the first cold-drawing procedure is not more than 0.5 mm.

[0012] Further, the oil pumping polished rod cold-drawing processing technology comprises the following main steps:

[0013] (1) The sucker rod blank pre-treatment: the sucker rod blank to be cold-drawn is put into the stress heating pipe, and is put into the groove of the base of the sucker rod cold-drawing equipment, the head of the sucker rod is heated to 1000-1200°C by the head heating coil, then the heated head of the sucker rod is moved out of the head heating coil, and is upset by the head upsetting device to obtain a twisted head with a diameter less than the inner diameter of the die;

[0014] (2) The first cold-drawing of the sucker rod blank: the twisted head obtained in the above step is put into the die, and is clamped by the clamping head of the drawing device at the other end of the die, and is uniformly drawn to make the whole sucker rod pass through the die;

[0015] (3) The low-temperature heating treatment of the sucker rod blank: the sucker rod blank after the cold-drawing in the above step is subjected to the low-temperature heating treatment to remove the internal stress of the surface layer; further, the first low-temperature heating temperature range is 300-500°C, and the heating time is not more than 30 minutes;

[0016] (4) The multiple cold-drawing process of the sucker rod blank: the steps (2) and (3) are repeated until the required outer diameter of the sucker rod is obtained, and no low-temperature heating treatment is performed after the last cold-drawing.

[0017] For the same sucker rod, the treatment temperature and time of the second low-temperature heating treatment are lower than those of the first low-temperature heating treatment.

[0018] The surface hardness of the sucker rod blank after any cold-drawing process is not increased by more than 150 HV under the measurement of the micro Vickers hardness meter under the condition of 200 g load.

[0019] Compared with the prior art, the technical scheme of the sucker rod cold-drawing equipment and process has the following advantages:

[0020] Firstly, the technical scheme of the present application increases the head heating coil, the head upsetting device and the stress relieving heating pipe on the base of the existing cold-drawing equipment, which improves the cold-drawing efficiency and the performance of the sucker rod. Usually, in order to pass through the die with a smaller diameter, the end of the sucker rod needs to be twisted after heating and forging, and then is transported to the cold-drawing equipment for processing. For the sucker rod with a diameter of about 30 mm and a length of about 10 meters, the transportation is a great workload. The increase of the head heating coil and the head upsetting device in the present application makes the end clamping and twisting of the sucker rod be completed on the same cold-drawing equipment, which reduces the transportation workload; at the same time, the design of the stress relieving heating pipe makes the surface stress of the cold-drawn sucker rod blank be released in time, so that the die is not seriously worn, and the service life of the die is significantly prolonged.

[0021] Secondly, the technical scheme of the present application adopts the technical idea of multiple cold drawing and low-temperature stress relief, which significantly improves the work hardening phenomenon caused by the cold drawing of the oil pumping polished rod, significantly prolongs the service life of the mold, and significantly improves the surface performance of the oil pumping polished rod. The cold drawing process of the prior art is processed in one step, which leads to a series of problems due to excessive processing amount. The present application adopts the technical idea of multiple cold drawing and low-temperature stress relief, which realizes the gradual reduction of the diameter of the oil pumping polished rod, and the processing stress is released in time by low-temperature stress relief after each cold drawing, which avoids the influence of excessive work hardening caused by cold drawing on the mold and the oil pumping polished rod itself, so that the oil pumping polished rod will not appear the phenomenon of jamming and local diameter mutation in the cold drawing process, which ensures higher processing quality of the oil pumping polished rod blank.

[0022] Thirdly, the technical scheme of the present application is oriented to improve the overall processing efficiency of the oil pumping polished rod, so that the oil pumping polished rod no longer needs surface polishing treatment and mechanical straightening process after cold drawing, which saves time and cost and improves production efficiency. In the prior art, the oil pumping polished rod blank needs to be cold drawn, and then a surface polishing treatment process is added to make the roughness and diameter error of the oil pumping polished rod surface meet the requirements, and a mechanical straightening process is also added to obtain the required straightness, which will bring a lot of workload and processing cost. The oil pumping polished rod obtained by the technical scheme of the present application has lower roughness, better diameter uniformity and meets the required straightness, thereby significantly improving the production efficiency and reducing the processing cost. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 Schematic diagram of the cold drawing processing equipment structure of the present application. DETAILED DESCRIPTION

[0024] Reference Figure 1The oil pumping polished rod cold-drawing processing equipment of the present application comprises a base 1, a drawing device 2, a head heating coil 3, a head upsetting device 4, a die 5, and a stress relief heating pipe 7. The base 1 is provided with a slotted opening 6 for placing and passing the oil pumping polished rod blank 9. The drawing device 2, the head heating coil 3, the head upsetting device 4, the die 5, and the stress relief heating pipe 7 are all collinear with the axis of the slotted opening 6. Therefore, the axis of the oil pumping polished rod blank 9 can be unified with the components of the equipment during the whole processing procedure, thereby ensuring better straightness. The stress relief heating pipe 7 is located outside the slotted opening 6 and surrounds the oil pumping polished rod blank 9 placed in the slotted opening 6. The stress relief heating pipe 7 can heat the surface of the oil pumping polished rod blank 9 as needed. The head heating coil 3 is located at the outlet end of the base 1, and the head upsetting device 4 is located inside the head heating coil 3. After the end of the oil pumping polished rod blank 9 is heated to the required temperature in the head heating coil 3, the end of the oil pumping polished rod blank 9 is withdrawn backward from the head heating coil 3, and the head upsetting device 4 is used to forge the end of the oil pumping polished rod blank 9 to form a twist head. The die 5 is located outside the head heating coil 3, and the drawing device 2 is located at the outermost side of the whole base 1. Under the action of the drawing device 2, the twist head passes through the inner hole of the die 5 and drives the whole oil pumping polished rod blank 9 to pass through the die 5, thereby completing one cold-drawing.

[0025] Further, the head heating coil 3 is movably arranged and can be moved out of the side of the base 1 when no heating is needed or the heating is finished. Further, the head upsetting device is also provided with an oil cooling medium, which can cool the twist head after upsetting processing when needed, thereby quickly realizing subsequent processing.

[0026] The drawing device 2 is provided with a clamping head, which is connected with the head of the oil pumping polished rod blank and can clamp the twist head of the head of the oil pumping polished rod blank. The drawing device 2 further comprises a stepless speed regulation power device, so that the drawing device continuously and uniformly realizes the cold-drawing processing of the oil pumping polished rod blank.

[0027] The maximum heating temperature of the head heating coil reaches 1300°C, which can meet the heating requirements of different steel oil pumping polished rods. The head heating coil is connected with a medium frequency power supply. The stress relief heating pipe is provided with a medium frequency induction heating coil 8 inside, and the maximum heating temperature reaches 600°C, which can meet the temperature requirements of stress relief of different steel oil pumping polished rods. The stress relief heating pipe mainly releases the internal stress of the work-hardened layer of the oil pumping polished rod blank by low-temperature heating treatment. The head heating coil and the stress relief heating pipe are separately controlled by their respective power supplies and can be opened and closed as needed.

[0028] The oil pumping polished rod cold-drawing process of the present application is as follows: after the oil pumping polished rod blank is placed in the slot, it is sequentially subjected to stress relief heating pipe, head heating coil, head upsetting device processing, and then is clamped by the drawing device to pass through the die to complete the cold-drawing process; before the oil pumping polished rod blank is placed in the slot, it is subjected to pickling to remove rust and scale; before the first cold-drawing process of the oil pumping polished rod blank, it does not need to be heated in the stress relief heating pipe.

[0029] Different from the one-time cold-drawing process of the prior art, the cold-drawing process of the oil pumping polished rod of the present application includes multiple cold-drawing processes, and the oil pumping polished rod blank is subjected to low-temperature heating stress relief treatment before the second cold-drawing process. The present application adopts the technical idea of multiple cold-drawing and low-temperature heating stress relief, realizes the gradual reduction of the diameter of the oil pumping polished rod, avoids the influence of single over-hardening on the die and the oil pumping polished rod itself, and obtains good processing effect of uniform diameter and straightness of the rod body. At the same time, since each cold-drawing process is a diameter reduction process of the oil pumping polished rod blank, there is obvious plastic deformation on the surface of the oil pumping polished rod, which causes the concentration of internal stress on the surface layer and the increase of surface hardness. Therefore, before the next cold-drawing process, low-temperature heating stress relief treatment is adopted, which makes the next cold-drawing process easier, avoids the accumulation of internal stress, and also avoids excessive concentration of internal stress on the die, prolongs the service life of the die, reduces the production cost, and reduces the adverse effect of frequent replacement of the die on the production efficiency.

[0030] Further, the diameter reduction value of the oil pumping polished rod blank after each cold-drawing process is not more than 0.6 mm. The diameter reduction value of the oil pumping polished rod blank after the first cold-drawing process is not more than 0.5 mm. The above limitation of the maximum diameter reduction value of the oil pumping polished rod blank in each cold-drawing process makes the work hardening caused by cold-drawing be in a relatively small degree, which is beneficial to the effective release of internal stress caused by cold-drawing by low-temperature heating stress relief treatment.

[0031] The oil pumping polished rod cold-drawing process of the present application comprises the following steps:

[0032] (1) Oil pumping polished rod blank pretreatment: the oil pumping polished rod blank 9 to be cold-drawn is passed through the stress relief heating pipe 7, is placed in the slot 6 of the oil pumping polished rod cold-drawing equipment base 1, the head of the oil pumping polished rod blank 9 is inserted into the head heating coil 3 and is heated to 1000-1200°C, then the heated head of the oil pumping polished rod is removed from the head heating coil, and the head upsetting device 4 is used for upsetting to obtain a twisted head with a diameter smaller than the inner diameter of the die 5;

[0033] (2) First cold drawing of the sucker rod blank: The twist obtained in the previous step is inserted into the mold 5, and the clamping head of the drawing device 2 is used to clamp it at the other end of the mold 5, and the drawing process is carried out at a uniform speed so that the entire sucker rod passes through the mold 5.

[0034] (3) Low-temperature heating treatment of sucker rod blank: The sucker rod blank 9 after cold drawing in the previous step is subjected to low-temperature heating treatment using stress-relief heating tube 7 to remove the internal stress on the surface; furthermore, the initial low-temperature heating temperature range is 300-500°C, and the heating time does not exceed 30 minutes.

[0035] (4) Multiple cold drawing processes for the sucker rod blank: Repeat steps (2) and (3) until the desired sucker rod is obtained.

[0036] The outer diameter of the oiled rod is not subjected to low-temperature heating treatment after the last cold drawing process.

[0037] For the same sucker rod, starting from the second low-temperature heating treatment, both the treatment temperature and time are lower than those of the first low-temperature heating treatment.

[0038] The surface hardness of the sucker rod blank after any cold drawing process shall not exceed 150 HV, measured by a micro Vickers hardness tester under a 200 g load.

[0039] Taking the cold drawing process of a common 30CrMo sucker rod blank as an example, the diameter of the steel mill is 30 mm, and the final size of the sucker rod is 28.6 mm. The diameter of the sucker rod blank needs to be reduced by 1.4 mm through the cold drawing process.

[0040] The main steps of the cold drawing process for the oil sucker rod of this invention are described below:

[0041] (1) Pretreatment of sucker rod blank: The 30CrMo sucker rod blank is treated with pickling to remove rust and oxide scale; the sucker rod blank to be cold drawn is passed through the stress relief heating tube and placed into the slot of the base of the sucker rod cold drawing equipment. The head of the sucker rod is inserted into the head heating coil and heated to about 1100°C. Then the heated sucker rod head is removed from the head heating coil and upset using the head upset forging device to obtain a twisted head with a diameter not exceeding 26 mm.

[0042] (2) The first cold-drawing processing of the sucker rod blank: install the die with an inner diameter of 29.6 mm, insert the twist head obtained in the previous step into the die, and clamp the twist head at the other end of the die by using the clamping head of the drawing device, and then draw the sucker rod blank at a uniform speed by using the hydraulic or stepless motor to drive the drawing device, so that the sucker rod blank can pass through the die at a uniform speed; the surface hardness of the sucker rod blank is increased by no more than 100 HV after the first cold-drawing process, which is measured by using the micro Vickers hardness tester under the condition of a load of 200 g;

[0043] (3) Low-temperature heating treatment of the sucker rod blank: start the power supply of the stress relief heating pipe, and perform 30-minute 350°C low-temperature heating treatment on the sucker rod blank after the cold-drawing process in the previous step, so as to remove the internal stress of the surface layer; during the heating process, the sucker rod blank in the stress relief heating pipe is in a slow rotating state, so that the heating is more uniform;

[0044] (4) Multiple cold-drawing processing procedure stacking of the sucker rod blank: repeat steps (2) and (3) twice, respectively replace the die with an inner diameter of 29 mm and an inner diameter of 28.6 mm, and measure the surface hardness of the sucker rod blank after the second cold-drawing process by using the micro Vickers hardness tester under the condition of a load of 200 g, and the surface hardness of the sucker rod blank is increased by 90 HV; the second low-temperature heating treatment of the sucker rod blank adopts a process parameter of 20-minute 300°C, and the outer diameter of the sucker rod is 28.6 mm after the third cold-drawing, and the low-temperature heating treatment is not performed after the third cold-drawing, and the subsequent quenching and tempering heat treatment of the sucker rod can be combined. The surface hardness of the sucker rod blank after the third cold-drawing process is increased by 70 HV, which is measured by using the micro Vickers hardness tester under the condition of a load of 200 g.

[0045] After the stacking of the above three cold-drawing processes, the surface roughness of the 30CrMo sucker rod blank obtained is not more than 1.6 microns, the straightness of the sucker rod blank meets the requirements of the sucker rod standard, and the subsequent straightening treatment is not required, and the sucker rod can directly meet the mechanical property requirements of the relevant standards after the quenching and tempering treatment.

[0046] The cold-drawing processing equipment and processing technology of the sucker rod can effectively solve the many problems existing in the one-time cold-drawing in the prior art by using the multiple cold-drawing processing and surface low-temperature stress relief technology, and can obtain a sucker rod with smaller outer diameter error, lower surface roughness and better straightness, so that the production efficiency of the sucker rod is higher.

Claims

1. A cold-drawing process for sucker rod, characterized in that, The cold-drawing equipment for sucker rod comprises a base, a drawing device, a head heating coil, a head upsetting device, a die, and a stress relief heating tube, the base is provided with a slot for placing and passing through the sucker rod blank, the drawing device, the head heating coil, the head upsetting device, the die, and the stress relief heating tube are all collinear with the axis of the slot, the stress relief heating tube is located outside the slot and surrounds the sucker rod blank placed in the slot, the head heating coil is located at the outlet end of the base, the head upsetting device is located inside the head heating coil, the die is located outside the head heating coil, and the drawing device is located at the outermost side of the whole base; After the sucker rod blank is placed in the slot, it is processed by the stress relief heating tube, the head heating coil, and the head upsetting device in sequence, and then it is drawn through the die under the clamping action of the drawing device to complete the cold-drawing process; the cold-drawing process of the sucker rod comprises the superposition of multiple cold-drawing procedures, and the sucker rod blank is subjected to low-temperature heating and stress relief treatment before the second cold-drawing procedure; The diameter reduction of the sucker rod blank after any cold-drawing procedure is not more than 0.6 mm; The surface hardness of the sucker rod blank after any cold-drawing procedure is increased by not more than 150 HV, which is measured by a micro Vickers hardness tester under a load of 200 g; The cold-drawing process for sucker rod specifically comprises the following main steps: (1) Pre-treatment of the sucker rod blank: the sucker rod blank to be cold-drawn is passed through the stress relief heating tube and placed in the slot of the base of the cold-drawing equipment for sucker rod, the head of the sucker rod is inserted into the head heating coil and heated to 1000-1200°C, then the heated head of the sucker rod is removed from the head heating coil, and the head upsetting device is used for upsetting to obtain a twisted head with a diameter smaller than the inner diameter of the die; (2) First cold-drawing of the sucker rod blank: the twisted head obtained in the previous step is inserted into the die, the clamping head of the drawing device at the other end of the die is used for clamping, and uniform speed drawing is performed so that the whole sucker rod blank passes through the die; (3) Low-temperature heating treatment of the sucker rod blank: the sucker rod blank after the cold-drawing in the previous step is subjected to low-temperature heating treatment by the stress relief heating tube to remove the internal stress of the surface layer; the first low-temperature heating temperature is 300-500°C, and the heating time is not more than 30 minutes; for the same sucker rod, the treatment temperature and time are lower than those of the first low-temperature heating treatment from the second low-temperature heating treatment; (4) Superposition of multiple cold-drawing procedures for the sucker rod blank: steps (2) and (3) are repeated until the required outer diameter of the sucker rod is obtained, and no low-temperature heating treatment is performed after the last cold-drawing.

2. The cold-drawing process of sucker rod as claimed in claim 1, characterized in that, The drawing device is provided with a clamping head connected to the head of the sucker rod blank, and further comprises a stepless speed regulation power device to realize continuous and uniform speed cold-drawing of the sucker rod blank.

3. The cold-drawing process of sucker rod as claimed in claim 1, wherein, The maximum heating temperature of the head heating coil reaches 1300°C, and the stress relief heating tube is provided with a medium-frequency induction heating coil with a maximum heating temperature of 600°C.

4. The cold-drawing process of sucker rod as claimed in claim 1, wherein, The diameter reduction of the oil-free polished rod blank after the first cold-drawing process is not more than 0.5 mm. The diameter reduction of the oil-free polished rod blank after the first cold-drawing process is not more than 0.5 mm.

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