Planetary roller reciprocating type hollow oil cooling lead screw and working method thereof

Abstract

The invention discloses a planetary roller reciprocating type hollow oil cooling lead screw device and a working method thereof, and belongs to the technical field of mechanical transmission. The device comprises a planetary screw rod, a nut assembly, a plurality of planetary pin rollers, a retainer, a gland and an oil cooling assembly. A hollow oil cooling hole is formed in the planetary screw rod, and an external thread of the hollow oil cooling hole is meshed with an external thread of the planetary roller; the planetary pin roller is rotatably mounted in the mounting groove of the retainer, and an external thread of the planetary pin roller is meshed with an internal thread of the nut assembly; the retainer is fixed in the nut assembly through glands at the two ends; the oil cooling assembly comprises an oil injection connector communicated with the hollow oil cooling hole. The invention has the advantages that the planetary roller line contact transmission is adopted, and compared with the traditional ball point contact mode, the bearing capacity, the transmission precision and the transmission speed are higher; active cooling is achieved through the hollow oil cooling hole and the oil injection connector, thermal deformation is effectively restrained, and the service life is prolonged; and the structure is compact and reliable, and is suitable for high-precision, high-load and high-speed transmission occasions.

Description

Technical Field

[0001] This invention relates to a planetary roller reciprocating hollow oil-cooled lead screw and its working method, belonging to the field of mechanical transmission technology. Background Technology

[0002] Currently, planetary ball screws are commonly used as rotary-linear motion conversion mechanisms in high-precision and high-load transmission applications such as precision machinery, industrial automation, aerospace, and heavy equipment. They achieve transmission through the rolling of balls between the screw and nut. However, because the contact between the balls and the screw and nut is point-to-point, the following inherent drawbacks arise: Insufficient transmission accuracy and stability: The point contact method leads to contact stress concentration, which is prone to elastic deformation and vibration under high speed or variable load conditions, making it difficult to meet the requirements of high-precision equipment for smooth motion and positioning accuracy. Limited transmission speed: The small bearing area of ​​point contact makes it prone to slippage and severe temperature rise during high-speed operation, which restricts the improvement of transmission speed. Low load capacity: The point contact bearing form limits its axial and radial loads, making it unsuitable for high-load applications such as large equipment and heavy-duty robots; No built-in cooling system: Existing planetary ball screws generally do not integrate an effective cooling structure. During long-term high-speed operation, the screw temperature rises significantly due to friction, leading to thermal deformation and lubrication failure, which seriously affects transmission accuracy and service life.

[0003] Therefore, there is an urgent need for a new type of ball screw structure that features line contact transmission, high rigidity, high speed, high load capacity, and an integrated effective cooling system to solve the common technical problems in the industry. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a planetary roller reciprocating hollow oil-cooled lead screw. The technical solution of this invention is as follows: A planetary roller reciprocating hollow oil-cooled lead screw device includes: Planetary screw (4), with hollow oil cooling holes (5) provided axially inside the planetary screw (4); The nut assembly is coaxially sleeved outside the planetary screw (4) and can reciprocate linearly along its axis; Multiple planetary rollers (1) are arranged circumferentially between the planetary lead screw (4) and the nut assembly; The retainer (3) is fixedly disposed in the nut assembly and has several planetary roller mounting grooves in the circumferential direction; Pressure caps (7), two pressure caps (7) are respectively disposed at both ends of the axial direction of the retainer (3) and are fixedly connected to the nut assembly for axially pressing and fixing the retainer (3); The oil cooling assembly includes an oil injection connector (6) mounted on the planetary screw (4), the oil injection connector (6) being connected to the hollow oil cooling hole (5); The planetary rollers (1) are rotatably mounted in the planetary roller mounting slots of the cage (3) in a one-to-one correspondence. The external threads of the planetary rollers (1) mesh with the external threads of the planetary screw (4), and the external threads of the planetary rollers (1) mesh with the internal threads of the nut assembly. When the planetary screw (4) rotates, the planetary rollers (1) are driven to rotate in the mounting slots of the cage (3) through the meshing of the planetary rollers (1) and the planetary screw (4). Then, through the meshing of the planetary rollers (1) and the nut assembly, the nut assembly is driven to make linear reciprocating motion along the axis of the planetary screw (4).

[0005] The nut assembly includes a flange nut (2), which forms a receiving cavity with the planetary screw (4), and the cage (3), the planetary roller (1) and the gland (7) are all located in the receiving cavity.

[0006] The nut assembly includes a flat key (9), a nut (10), and an adjusting washer (11). The adjusting washer (11) is embedded in the middle of the nut (10), and the flat key (9) is installed on the nut (10) outside the adjusting washer (11).

[0007] The number of external threads on the planetary screw (4) is different from the number of internal threads on the planetary roller (1).

[0008] The external thread of the planetary screw (4) is a 3-start thread, and the internal thread of the planetary roller (1) is a 5-start thread.

[0009] The number of oil injection connectors (6) is one, which is connected to one end of the planetary screw (4).

[0010] There are two oil injection connectors (6), which are respectively connected to the two ends of the planetary screw (4).

[0011] The outer peripheral surface of the pressure cap (7) mates with the inner wall of the nut assembly.

[0012] A method for operating a planetary roller reciprocating hollow oil-cooled lead screw device, characterized by comprising the following steps: S1. Power input and primary meshing transmission: An external rotating power source drives the planetary screw (4) to rotate around its own axis; the external thread of the planetary screw (4) meshes with the internal thread of the planetary roller (1) to transmit the rotational motion to the planetary roller (1) and drive it to generate a rotational tendency.

[0013] S2. Constrained movement and secondary engagement of planetary rollers: The planetary roller (1) rotates around its own axis in the planetary roller mounting groove of the cage (3); at the same time, the external thread of the planetary roller (1) engages with the internal thread of the nut assembly; the cage (3) is axially pressed and fixed in the nut assembly by the pressure caps (7) at both ends, so that the revolution tendency of the planetary roller (1) is constrained when it rotates.

[0014] S3, Linear Motion Output: Under the constraint conditions of step S2, the rotational motion of the planetary screw (4) is converted into an axial thrust on the nut assembly through two-stage thread engagement, namely the planetary screw and planetary roller, and the planetary roller and nut assembly, driving the nut assembly to make precise linear reciprocating motion along the axis of the planetary screw (4), thereby realizing the conversion from rotational motion to linear motion.

[0015] S4. High-speed transmission and active cooling: By setting the planetary screw (4) and the planetary roller (1) to have different numbers of thread heads, high-speed linear transmission is achieved; at the same time, during the operation of the device or during the operation interval, cooling medium is injected into the hollow oil cooling hole (5) inside the planetary screw (4) through the oil injection joint (6) of the oil cooling component to directly cool the high-speed rotating planetary screw (4) to suppress thermal deformation and maintain transmission accuracy and stability.

[0016] When the nut assembly is the flange nut (2), the entire device is installed to the external equipment through its external flange structure; when the nut assembly is a structure including a flat key (9), a nut (10) and an adjusting washer (11), the circumferential positioning and torque transmission with the external component are achieved through the flat key (9), and the transmission clearance can be adjusted through the adjusting washer (11). The advantages of this invention are: 1. Using planetary rollers as the transmission medium, a line contact is formed between the internal thread of the nut assembly and the external thread of the planetary screw. Compared with the point contact of traditional ball screws, the contact area is significantly increased, which greatly enhances the transmission rigidity, load-bearing capacity and impact resistance. At the same time, the movement is smoother and the transmission accuracy is higher, which can meet the requirements of high-precision equipment.

[0017] 2. Through the design of multi-start planetary thread pair (preferably the planetary screw has 3-start threads and the planetary roller has 5-start threads), the linear movement speed of the nut assembly is faster and the transmission rate is higher at the same speed, which meets the requirements of high-speed transmission.

[0018] 3. A hollow oil cooling hole is axially installed inside the planetary screw, and an external oil injection connector is connected to form an oil cooling assembly. Cooling oil can be injected through this channel to directly and effectively cool the screw that generates high temperatures during high-speed operation, thereby suppressing thermal deformation and maintaining the constant temperature and stability of the transmission system. This not only ensures transmission accuracy but also significantly extends the service life of the entire screw assembly.

[0019] 4. The axial position of the cage and planetary rollers is fixed by the end caps, ensuring a stable structure. The adjusting washers facilitate adjustment of the axial clearance or preload of the nut assembly, helping to maintain transmission accuracy over the long term and reducing manufacturing and assembly difficulties. This invention provides two specific nut assembly embodiments (including flange-type nuts or flat key adjustment structures), which can be flexibly selected according to different installation and load requirements, and have a wide range of applications.

[0020] 5. The planetary rollers operate in an orderly manner under the constraint of the cage, resulting in uniform wear. The cooling system reduces the thermal load on critical components, improving reliability. The external oil filling connector facilitates connection to an external cooling circulation system and enables convenient maintenance. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the main structure of the first embodiment of the present invention.

[0022] Figure 2 yes Figure 1 A sectional view.

[0023] Figure 3 This is a schematic diagram of the main structure of the second embodiment of the present invention.

[0024] Figure 4 yes Figure 3 A sectional view. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer as a result. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0026] See Figures 1 to 4This invention relates to a planetary roller reciprocating hollow oil-cooled screw device, comprising: a planetary screw 4, wherein a hollow oil-cooling hole 5 is provided axially inside the planetary screw 4; a nut assembly, coaxially sleeved on the outside of the planetary screw 4, and capable of linear reciprocating motion along its axis; a plurality of planetary rollers 1, circumferentially disposed between the planetary screw 4 and the nut assembly; a retainer 3, which is fixedly disposed inside the nut assembly and has several planetary roller mounting grooves in its circumferential direction; pressure caps 7, two of which are respectively disposed at the axial ends of the retainer 3 and fixedly connected to the nut assembly for axially pressing and fixing the retainer 3; and an oil-cooling assembly, including mounting... The oil injection connector 6 on the planetary screw 4 is connected to the hollow oil cooling hole 5. The planetary rollers 1 are rotatably mounted in the planetary roller mounting slots of the cage 3, with their external threads engaging with the external threads of the planetary screw 4 and the internal threads of the nut assembly. When the planetary screw 4 rotates, the engagement between the planetary rollers 1 and the planetary screw 4 drives the planetary rollers 1 to rotate within the mounting slots of the cage 3. Furthermore, the engagement between the planetary rollers 1 and the nut assembly drives the nut assembly to reciprocate linearly along the axis of the planetary screw 4.

[0027] The external thread of the planetary roller 1 simultaneously engages with the external thread of the planetary screw 4 and the internal thread of the nut assembly, forming a line contact transmission pair. Compared with the point contact of ball screws in the prior art, this greatly increases the contact area and load-bearing capacity, resulting in smoother transmission and higher rigidity, thereby significantly improving transmission accuracy, impact resistance, and overall service life.

[0028] By axially opening hollow oil cooling holes 5 inside the planetary lead screw 4 and connecting them to external oil injection joints 6 to form an oil cooling assembly, direct and efficient cooling of the lead screw body can be achieved. This structure can effectively dissipate the frictional heat generated during high-speed operation, suppress thermal deformation of the lead screw, and stabilize the temperature field of the transmission system, thereby maintaining constant transmission accuracy and high efficiency under high-speed and heavy-load conditions.

[0029] The retainer 3 is firmly axially pressed and fixed within the nut assembly by the end caps 7, providing a precise and stable running track for the planetary roller 1. This integrated encapsulation structure is not only compact and rigid, ensuring the reliability and consistency of the transmission process, but also houses the main moving parts inside the nut assembly. The external interface (oil filling connector) is simple, facilitating installation, sealing, and maintenance.

[0030] like Figure 1 and Figure 2As shown, the nut assembly includes a flange nut 2, which forms a receiving cavity with the planetary screw 4. The cage 3, the planetary rollers 1, and the gland 7 are all located within this receiving cavity. The flange nut 2 constitutes a complete and enclosed transmission unit housing, integrating and encapsulating all internal transmission components, such as the cage 3, planetary rollers 1, and gland 7, within the receiving cavity formed by it and the planetary screw 4. Its external flange structure is a standard interface, allowing for direct rigid connection and fixation to the equipment base or actuator without the need for additional connecting components or complex assembly. like Figure 3 and Figure 4 As shown, the nut assembly includes a flat key 9, a nut 10, and an adjusting washer 11. The adjusting washer 11 is embedded in the middle of the nut 10, and the flat key 9 is mounted on the nut 10 outside the adjusting washer 11. The adjusting washer 11 embedded in the middle of the nut 10 allows for convenient fine-tuning of the axial clearance or preload of the transmission system to maintain high transmission accuracy over a long period. Simultaneously, the externally located flat key 9 structure ensures reliable connection and torque transmission between the nut assembly and the external actuator or support structure, preventing relative rotation and achieving a balance between adjustable accuracy and stable connection.

[0031] The number of external thread starts of the planetary screw 4 is different from the number of internal thread starts of the planetary roller 1. The external thread of the planetary screw 4 has 3 starts, while the internal thread of the planetary roller 1 has 5 starts. By setting the number of external thread starts of the planetary screw 4 and the number of internal thread starts of the planetary roller 1 to be different (e.g., 3 starts and 5 starts), the nut assembly can be driven to produce a larger axial displacement per unit number of rotations of the planetary screw, thereby significantly improving the linear motion speed (i.e., transmission ratio) of the transmission system and meeting the core efficiency requirement of high-speed transmission equipment.

[0032] The number of oil injection connectors 6 is one, which is connected to one end of the planetary screw 4.

[0033] Two oil injection connectors 6 are provided, each connected to one end of the planetary screw 4. The outer circumferential surface of the gland 7 mates with the inner wall of the nut assembly. By providing oil injection connectors 6 at one or both ends of the hollow oil cooling hole 5, efficient injection and circulation of cooling oil can be achieved. This structure can directly and actively remove the frictional heat generated by the planetary screw 4 during high-speed operation, effectively suppressing its thermal expansion and deformation, thereby ensuring long-term stable transmission accuracy and significantly extending the service life of the device.

[0034] This invention also relates to a working method of the aforementioned planetary roller reciprocating hollow oil-cooled screw device, characterized by comprising the following steps: S1. Power input and primary meshing transmission: An external rotary power source drives the planetary screw 4 to rotate around its own axis; the external thread of the planetary screw 4 meshes with the internal thread of the planetary roller 1, transmitting the rotational motion to the planetary roller 1 and driving it to generate a rotational tendency.

[0035] S2. Constrained movement and secondary engagement of planetary rollers: The planetary roller 1 rotates around its own axis in the planetary roller mounting groove of the cage 3; at the same time, the external thread of the planetary roller 1 engages with the internal thread of the nut assembly; the cage 3 is axially pressed and fixed in the nut assembly by the pressure caps 7 at both ends, so that the revolution tendency of the planetary roller 1 is constrained when it rotates.

[0036] S3. Linear motion output: Under the constraints of step S2, the rotational motion of the planetary screw 4 is converted into an axial thrust on the nut assembly through two-stage thread engagement, namely the planetary screw and planetary rollers, and the planetary rollers and nut assembly. This drives the nut assembly to make precise linear reciprocating motion along the axis of the planetary screw 4, thereby realizing the conversion from rotational motion to linear motion.

[0037] S4. High-speed transmission and active cooling: By setting the planetary screw 4 and the planetary roller 1 to have different numbers of thread turns, high-speed linear transmission is achieved; at the same time, during the operation of the device or during the operation interval, cooling medium is injected into the hollow oil cooling hole 5 inside the planetary screw 4 through the oil injection joint 6 of the oil cooling component to directly cool the high-speed rotating planetary screw 4, so as to suppress thermal deformation and maintain transmission accuracy and stability.

[0038] When the nut assembly is the flange nut 2, the entire device is installed to the external equipment through its external flange structure; when the nut assembly is a structure including a flat key 9, a nut 10 and an adjusting washer 11, the flat key 9 realizes circumferential positioning and torque transmission with the external component, and the transmission clearance can be adjusted by adjusting the adjusting washer 11.

[0039] Whether Figure 1-2 The flange nut 2 shown in the embodiment is still... Figure 3-4 The embodiment shown, which includes a flat key 9, a nut 10, and an adjusting washer 11, follows the same internal transmission principle as described above. The main difference lies in the connection and adjustment method between the nut assembly and the external equipment: the former is directly installed via a flange, resulting in high structural integration; the latter transmits torque via a flat key and allows for fine adjustment of the axial clearance via the adjusting washer to adapt to different application scenarios and precision requirements.

[0040] In summary, this invention achieves superior transmission performance with high precision, high speed, high load, and low thermal deformation through a transmission path of "planetary screw rotation, driving planetary roller rotation, and converting into linear motion of the nut assembly," combined with line contact threaded pairs, multi-start thread design, and built-in oil cooling channels.

[0041] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A planetary roller reciprocating hollow oil-cooled lead screw device, characterized in that, include: Planetary screw (4), with hollow oil cooling holes (5) provided axially inside the planetary screw (4); The nut assembly is coaxially sleeved outside the planetary screw (4) and can reciprocate linearly along its axis; Multiple planetary rollers (1) are arranged circumferentially between the planetary lead screw (4) and the nut assembly; The retainer (3) is fixedly disposed in the nut assembly and has several planetary roller mounting grooves in the circumferential direction; Pressure caps (7), two pressure caps (7) are respectively disposed at both ends of the axial direction of the retainer (3) and are fixedly connected to the nut assembly for axially pressing and fixing the retainer (3); The oil cooling assembly includes an oil injection connector (6) mounted on the planetary screw (4), the oil injection connector (6) being connected to the hollow oil cooling hole (5); The planetary rollers (1) are rotatably mounted in the planetary roller mounting slots of the cage (3) in a one-to-one correspondence. The external threads of the planetary rollers (1) mesh with the external threads of the planetary screw (4), and the external threads of the planetary rollers (1) mesh with the internal threads of the nut assembly. When the planetary screw (4) rotates, the planetary rollers (1) are driven to rotate in the mounting slots of the cage (3) through the meshing of the planetary rollers (1) and the planetary screw (4). Then, through the meshing of the planetary rollers (1) and the nut assembly, the nut assembly is driven to make linear reciprocating motion along the axis of the planetary screw (4).

2. The planetary roller reciprocating hollow oil-cooled lead screw device according to claim 1, characterized in that, The nut assembly includes a flange nut (2), which forms a receiving cavity with the planetary screw (4), and the cage (3), the planetary roller (1) and the gland (7) are all located in the receiving cavity.

3. The planetary roller reciprocating hollow oil-cooled lead screw device according to claim 1, characterized in that, The nut assembly includes a flat key (9), a nut (10), and an adjusting washer (11). The adjusting washer (11) is embedded in the middle of the nut (10), and the flat key (9) is installed on the nut (10) outside the adjusting washer (11).

4. The planetary roller reciprocating hollow oil-cooled lead screw device according to claim 2 or 3, characterized in that, The number of external threads on the planetary screw (4) is different from the number of internal threads on the planetary roller (1).

5. The planetary roller reciprocating hollow oil-cooled lead screw device according to claim 4, characterized in that, The external thread of the planetary screw (4) is a 3-start thread, and the internal thread of the planetary roller (1) is a 5-start thread.

6. The planetary roller reciprocating hollow oil-cooled lead screw device according to claim 5, characterized in that, The number of oil injection connectors (6) is one, which is connected to one end of the planetary screw (4).

7. The planetary roller reciprocating hollow oil-cooled lead screw device according to claim 6, characterized in that, There are two oil injection connectors (6), which are respectively connected to the two ends of the planetary screw (4).

8. The planetary roller reciprocating hollow oil-cooled lead screw device according to claim 7, characterized in that, The outer peripheral surface of the pressure cap (7) mates with the inner wall of the nut assembly.

9. A method for operating a planetary roller reciprocating hollow oil-cooled screw device according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1, Power input and primary meshing transmission: An external rotating power source drives the planetary screw (4) to rotate around its own axis; the external thread of the planetary screw (4) meshes with the internal thread of the planetary roller (1) to transmit the rotational motion to the planetary roller (1) and drive it to generate a rotational tendency; S2, Constrained movement and secondary engagement of planetary rollers: The planetary roller (1) rotates around its own axis in the planetary roller mounting groove of the cage (3); at the same time, the external thread of the planetary roller (1) engages with the internal thread of the nut assembly; the cage (3) is axially pressed and fixed in the nut assembly by the pressure caps (7) at both ends, so that the revolution tendency of the planetary roller (1) is constrained when it rotates. S3, Linear motion output: Under the constraint of step S2, the rotational motion of the planetary screw (4) is converted into an axial thrust on the nut assembly through two-stage thread engagement, namely the planetary screw and planetary roller, and the planetary roller and nut assembly, driving the nut assembly to make precise linear reciprocating motion along the axis of the planetary screw (4), thereby realizing the conversion from rotational motion to linear motion. S4. High-speed transmission and active cooling: By setting the planetary screw (4) and the planetary roller (1) to have different numbers of thread heads, high-speed linear transmission is achieved; at the same time, during the operation of the device or during the operation interval, cooling medium is injected into the hollow oil cooling hole (5) inside the planetary screw (4) through the oil injection joint (6) of the oil cooling component to directly cool the high-speed rotating planetary screw (4) to suppress thermal deformation and maintain transmission accuracy and stability.

10. The working method according to claim 9, characterized in that, When the nut assembly is the flange nut (2), the entire device is installed to the external equipment through its external flange structure; when the nut assembly is a structure including a flat key (9), a nut (10) and an adjusting washer (11), the circumferential positioning and torque transmission with the external component are achieved through the flat key (9), and the transmission clearance can be adjusted through the adjusting washer (11).

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