Printer shaft parts outer circle precision grinding device

Abstract

The application relates to a precision grinding device for the outer circle of a printer shaft part, and belongs to the field of precision machining. The device comprises a base, a grinding assembly, a grinding driving assembly for driving the axial movement of the grinding assembly, two oppositely arranged end support seats and an axially movable middle support assembly. The middle support assembly comprises a middle support frame and two mounting frames arranged on the middle support frame, and the mounting frames are provided with middle support plates which can be radially expanded and contracted. The device can effectively inhibit the deformation of the slender shaft during grinding by providing dynamic following type auxiliary support near the grinding point.

Description

Technical Field

[0001] This application relates to the field of precision machining technology, and in particular to a precision grinding device for the outer diameter of printer shaft parts. Background Technology

[0002] In the field of mechanical manufacturing, shaft-type parts (such as photosensitive drum shafts and drive shafts) used in precision office equipment such as printers and copiers are mostly slender shafts with a length-to-diameter ratio (length-to-diameter ratio) typically greater than 10:1. These parts are characterized by poor rigidity and easy deformation. Such parts have extremely high requirements for dimensional accuracy, shape accuracy (such as cylindricity and straightness), and surface roughness. Their machining quality directly affects the overall machine's operational accuracy, stability, and imaging quality.

[0003] Currently, the industry generally uses a traditional cylindrical grinding machine with a "two-center" clamping method for precision external cylindrical grinding of such slender shaft parts. Specifically, the two ends of the workpiece are supported between the headstock center and the tailstock center of the machine tool, respectively, and the headstock drives its rotation, while the grinding wheel performs radial feed to complete the grinding.

[0004] This traditional "two-center" clamping method has significant technical defects. Because the middle section of a slender shaft lacks effective radial support during grinding, the combined effects of the radial grinding force of the grinding wheel, the workpiece's own weight, and the centrifugal force cause the middle section to easily experience "tool deflection," i.e., elastic bending deformation. This deformation directly leads to two serious consequences: first, at the moment of grinding, the actual cutting depth of the workpiece is less than the theoretical feed rate, making dimensional accuracy difficult to control; second, after the clamping force is removed, the workpiece recovers elastically, causing the middle section diameter to be larger than the ends, or exhibiting regular waist-shaped, saddle-shaped, or other shape errors, severely affecting the cylindricity of the part. Summary of the Invention

[0005] To address the problems existing in the above-mentioned technologies, this application provides a precision grinding device for the outer diameter of printer shaft parts.

[0006] The technical solution of the precision grinding device for the outer diameter of printer shaft parts provided in this application is as follows: A precision grinding device for the outer diameter of a printer shaft part includes a base, on which a grinding assembly is movably disposed for grinding the shaft part. The base also includes a grinding drive assembly for driving the grinding assembly to move axially along the shaft part. Two end supports are disposed on the base, facing each other and supporting the two ends of the shaft part respectively. Each end support has a rotation drive unit for driving the shaft part to rotate. A central support assembly is movably disposed on the base, and a central support drive assembly is disposed on the base for driving the central support assembly to move axially along the shaft part.

[0007] In the implementation of the above technical solution, during operation, the two ends of the printer shaft part are first placed on two opposing end supports on the base. These end supports provide stable support to both ends of the part, ensuring the accuracy of the part's mounting reference. The central support drive assembly on the base is then activated, driving the movable central support component to move along the axial direction of the shaft part to a position where bending deformation is likely to occur in the middle section (usually the midpoint of the axial direction or a point of concentrated stress), thus positioning the central support component to support the middle section of the part. Next, the grinding drive assembly on the base is activated, driving the movable grinding component to move along the axial direction of the shaft part to the outer diameter to be ground. Simultaneously, the central support component moves with the grinding component, always corresponding to the grinding position of the grinding component to synchronously support the middle section of the part. Finally, the rotary drive unit on the end supports is activated, driving the central support component to move along the axial direction of the shaft part to the outer diameter to be ground. The shaft-like parts rotate uniformly around their own axis, while the grinding assembly is activated to grind the outer diameter of the rotating shaft-like parts. During the grinding process, the grinding drive assembly can drive the grinding assembly to move along the axial direction of the shaft-like parts according to the grinding requirements. The middle support assembly moves synchronously with the grinding assembly, continuously providing stable support to the middle section of the part corresponding to the grinding area, effectively counteracting the radial grinding force generated by the grinding assembly, the part's own weight, and the rotational centrifugal force. The end support seats, in conjunction with the rotation drive unit, ensure the support stability and rotational accuracy at both ends of the part. The coordinated cooperation of all components effectively avoids the "tool deflection" phenomenon and elastic bending deformation caused by the lack of support in the middle section or the mismatch between the support position and the grinding position when grinding slender shaft parts. This effectively controls the dimensional accuracy of the parts, avoids shape errors such as waist-shaped or saddle-shaped, improves the cylindricity and surface roughness of the parts, solves the processing defects caused by the lack of middle support in traditional two-center clamping, and meets the high-precision processing requirements of slender shaft parts for printers.

[0008] Optionally, the base is provided with an end support drive assembly, which is used to drive the end support seat to move in a direction close to or away from the end of the shaft part; the end support seat is provided with an end bracket, and the rotation drive unit is used to drive the end bracket to rotate; the end bracket is provided with opposing end support plates, and the end bracket is provided with a drive unit, which is used to drive the end support plates to move in a direction close to each other to clamp the end of the shaft part.

[0009] In the implementation of the above technical solution, during operation, the end support drive assembly on the base is first activated. This assembly drives the two end support seats to move towards both ends of the shaft-like part until they reach a position suitable for the length of the shaft-like part, preparing for end support. Subsequently, the drive units on the two end support seats are activated, driving the opposing end support plates on their respective end supports to move towards each other until the two end support plates stably clamp both ends of the shaft-like part, achieving precise support of both ends of the shaft-like part. Positioning and clamping; next, the rotary drive unit is activated, driving the end supports to rotate. The end supports drive the clamped shaft parts to rotate synchronously around their own axes, providing stable rotational power for the grinding operation. When the grinding assembly grinds the middle section of the shaft part, the middle support plate of the middle support assembly provides stable support for the middle section of the part, and both end supports maintain a clamping and supporting state to ensure the overall stability of the part. When grinding reaches one end of the shaft part, one end support is switched to continue supporting the other end of the part, while the middle support plate of the middle support assembly... Auxiliary support ensures the part remains stable at the grinding end, preventing deformation caused by unilateral support. Simultaneously, the end support drive assembly drives the end support frame at the grinding end to retract away from the end of the shaft-like part, causing the end support plate on the end support frame to move away from the grinding end, avoiding obstruction of the grinding area and ensuring sufficient and precise grinding of the end, completely eliminating grinding dead zones. Throughout the entire process, the end support drive assembly, end support base, end support frame, rotary drive unit, drive unit, and end support plate work together in concert, combining with the central... The auxiliary support of the support plate not only achieves stable clamping and rotational drive of the shaft parts, ensuring the rotational accuracy of the parts and the stability during the grinding process, but also ensures that the ends of the shaft parts can be precisely ground through the yielding function of the end support bracket to be ground, in conjunction with the synergistic effect of the single end support bracket and the auxiliary support of the middle support plate. At the same time, the clamping and adjustment function of the end support plate is adapted to the ends of shaft parts of different diameters, improving the adaptability and practicality of the end support, further enhancing the precision grinding effect of the entire device, and ensuring that the dimensional accuracy and surface quality of the end and middle sections of the parts are consistent.

[0010] Optionally, the central support assembly includes a central support frame movably disposed on the base, and the central support drive assembly is used to drive the central support frame to move axially along the shaft-like part; the central support frame is provided with two mounting brackets, which are arranged opposite to each other, and a grinding space for accommodating the grinding assembly is formed between the two mounting brackets; the mounting brackets are provided with opposing central support plates, and the mounting brackets are provided with telescopic parts, which are used to drive the central support plates to move in a direction close to the shaft-like part until they abut against the shaft-like part.

[0011] In the implementation of the above technical solution, when grinding shaft-like parts using the device, the two ends of the shaft-like parts are first supported by two end support seats, so that the shaft-like parts can be stably supported as a whole. The telescopic parts on the two mounting brackets move to move the middle support plate in the direction close to the shaft-like parts. After the relatively arranged middle support plates move to abut against the shaft-like parts, the two sides of the shaft-like parts are symmetrically radially clamped and supported. At this time, the grinding assembly is located in the grinding space. The grinding assembly operates to grind the shaft-like parts, and the grinding drive assembly drives the grinding assembly to move along the axial direction of the shaft-like parts. During this process, the middle support assembly drives the middle support frame to move along the axial direction of the shaft-like parts, and the two mounting brackets move accordingly. As the grinding assembly moves, the telescopic section maintains the contact between the central support plate and the shaft-like parts. The two opposing central support plates provide symmetrical and stable radial support from both sides of the shaft-like parts, effectively counteracting the grinding force, the weight of the parts themselves, and the centrifugal force of rotation. The coordinated operation of all structures further enhances the stability and precision of the central support, effectively suppressing bending deformation and "tool deflection" in the middle section of slender shafts. At the same time, the setting of the grinding space ensures smooth grinding operations. The adjustability of the telescopic section adapts to printer shaft-like parts of different diameters, significantly improving the adaptability and practicality of the central support assembly, further strengthening the precision grinding support effect on slender shaft-like parts, and ensuring machining accuracy and surface quality.

[0012] Optionally, the mounting bracket has a clearance opening for inserting the shaft-like parts, and the middle support plate and the end support plate are staggered.

[0013] In the implementation of the above technical solution, during workpiece loading and unloading, the workpiece can be horizontally or inclinedly inserted into or removed directly from the side into the grinding space between the two opposing mounting brackets through the clearance opening on the mounting bracket, without having to laboriously insert it from the axial end of the device. This achieves quick and convenient workpiece clamping. During grinding, the telescopic part drives the middle support plate to extend, abutting against the workpiece and providing support. Simultaneously, because the middle support plate and the end support plate are staggered in the circumferential direction, i.e., their contact positions are offset in the circumferential direction of the workpiece, the circumferential surface of the workpiece at any axial position receives the combined action of two sets of support systems (end clamping and middle auxiliary support) from different angles that do not interfere with each other. This staggered layout avoids the overlap of support points on the workpiece surface, optimizes the constraint force distribution along the circumferential direction of the workpiece, and effectively prevents over-positioning and local stress concentration caused by support. Thus, while providing sufficient support, it minimizes the additional deformation of the workpiece caused by clamping and support, laying a stable benchmark for high-precision grinding.

[0014] Optionally, the central support plate on one of the mounting brackets is configured as a grinding plate, the telescopic part is used to drive the grinding plate to move in a direction close to the shaft part, and the grinding plate has an abrasive layer on the side facing the shaft part.

[0015] In the implementation of the above technical solution, the grinding assembly performs grinding operations between two mounting brackets. This results in two states on the shaft-like parts: the parts on either side of the grinding assembly are either ground or unground. The part in the ground-complete state is positioned opposite the grinding plate. Under the action of the telescopic part, the grinding plate moves towards the shaft-like part until the abrasive layer comes into contact with it. In this state, the workpiece continues to rotate under the drive of the end support. Through the rotation of the workpiece, the abrasive layer simultaneously grinds the outer surface of the ground part, effectively removing residual microburrs, grinding marks, and unevenness. Throughout the entire process, the grinding plate, telescopic part, mounting brackets, and abrasive layer work together, with the telescopic part providing stable contact for the grinding plate. The abrasive layer adheres tightly and with uniform pressure to the part surface. The abrasive layer itself achieves efficient grinding, eliminating the need for additional independent grinding equipment. Surface grinding can be completed simultaneously with the grinding operation, simplifying the processing steps and significantly improving efficiency. Simultaneously, the grinding effect of the abrasive layer effectively optimizes the surface roughness of the part's outer diameter, making the surface smoother and preventing burrs or rough textures from affecting subsequent assembly accuracy and performance. This further ensures the precision machining quality of printer shaft parts. Furthermore, the grinding plate, as a central support plate, combines support and grinding functions. While providing stable support for the middle section of the part and preventing deformation during rotation, it simultaneously improves surface quality, precisely meeting the high-precision, high-surface-quality machining requirements of printer shaft parts.

[0016] Optionally, the grinding plate is provided with an adsorption component, and the grinding plate has an adsorption port facing the shaft part. The adsorption port is connected to the adsorption component through a built-in air channel.

[0017] In the implementation of the above technical solution, the adsorption component is activated simultaneously when the abrasive layer contacts the outer surface of the workpiece and begins to perform the support and micro-grinding functions. Negative pressure (vacuum adsorption force) is generated through the adsorption port on the grinding plate facing the workpiece. This negative pressure acts directly on the tiny gap area between the grinding plate and the outer surface of the workpiece through the adsorption port, forming a continuous, concentrated local adsorption flow. This adsorption flow plays multiple key roles during operation: First, it powerfully removes the extremely fine abrasive chips, detached abrasive particles, and dust generated by the grinding plate during grinding, preventing them from remaining between the abrasive layer and the workpiece, thereby avoiding scratches on the processed surface due to "secondary grinding" and maintaining the sharpness and effectiveness of the abrasive layer itself; Second, it enhances the "lifting" effect on the workpiece surface, providing radial support while further stabilizing the radial position of the workpiece during grinding / polishing through negative pressure adsorption, especially helping to suppress micro-vibrations in thin-walled or small-diameter shaft sections; Third, it improves the heat dissipation conditions in the grinding area, accelerating heat dissipation. By integrating the triple functions of "mechanical support + abrasive grinding + negative pressure cleaning / stabilization", this solution significantly improves the surface quality consistency, process stability and cleanliness of in-situ grinding operations, providing an effective environmental control means for achieving ultra-precision machining.

[0018] Optionally, the grinding plate has an adsorption layer on the side facing the shaft part, the abrasive layer is located between the grinding assembly and the adsorption layer, the grinding plate has a liquid inlet, and the grinding plate is provided with a liquid delivery assembly for delivering coolant to the liquid inlet.

[0019] In the implementation of the above technical solution, the abrasive layer is disposed between the grinding component and the adsorption layer, thereby enabling the grinding plate to move towards the shaft-like parts until the abrasive layer comes into contact with the part corresponding to the completed grinding state of the shaft-like parts. This part will first contact the abrasive layer and then release from the adsorption layer. As the shaft-like parts continue to rotate and contact the abrasive layer, the abrasive layer performs grinding on the shaft-like parts. During the process of the central support drive component driving the central support frame to move with the grinding component, the ground part will contact the adsorption layer. During this process, the liquid delivery component is activated to continuously deliver coolant to the liquid delivery port opened on the grinding plate. After the coolant flows out through the liquid delivery port, the adsorption layer, with its own porous or fibrous structure, effectively adsorbs, retains, and diffuses the coolant flowing out of the liquid delivery port along the circumference and axial direction of the workpiece, quickly forming a uniform, continuous, and durable coolant covering film on the surface of the workpiece. The coolant significantly extends the effective residence time on the surface of high-temperature workpieces through the retention and slow release effect of the adsorption layer, achieving efficient and deep heat removal from grinding / polishing. This effectively suppresses the overall thermal deformation and local residual stress concentration of the workpiece, which is crucial for ensuring the dimensional stability and shape accuracy of slender shaft parts.

[0020] Optionally, the grinding plate is provided with an elastic separation layer, which is located between the adsorption layer and the abrasive layer.

[0021] In the implementation of the above technical solution, the shaft part rotates under the drive of the rotary drive unit, and the grinding assembly grinds the outer diameter of the part. Simultaneously, the abrasive layer polishes the surface of the ground part with the help of the part's rotation. At the same time, the fluid delivery assembly starts synchronously with the grinding plate, delivering coolant to the delivery port through the delivery pipe. The coolant enters the porous adsorption layer through the delivery port and is uniformly wetted and coated onto the ground and polished surface of the shaft part. Its core function is to cool and de-temperature the ground and polished shaft part. During this process, the elastic separation layer works in conjunction with the abrasive layer and the porous adsorption layer, utilizing its own elastic properties to adapt to the curvature of the outer diameter surface of the shaft part. This ensures that the independent grinding function of the abrasive layer is not affected, nor is the adsorption of coolant by the porous adsorption layer hindered. Uniform diffusion and an elastic separator layer form a physical barrier, preventing the coolant infiltrated in the porous adsorption layer from penetrating into the abrasive layer. This avoids coolant contact with the abrasive layer, which could lead to decreased grinding performance and accelerated wear of the abrasive layer. In addition, the elastic separator layer can accommodate minor vibrations during part rotation, helping to improve the stability of abrasive layer grinding and the uniformity of cooling in the porous adsorption layer. Throughout the entire process, the elastic separator layer, abrasive layer, porous adsorption layer, fluid delivery assembly, and fluid inlet work together to ensure that the coolant only cools shaft-type parts without interfering with abrasive layer grinding. This further enhances the structural stability and service life of the device, ensuring the synergistic effect of precision grinding and cooling, and meeting the high-precision, high-surface-quality processing requirements of printer shaft-type parts.

[0022] Optionally, the grinding plate has a liquid delivery chamber, the liquid delivery port is connected to the liquid delivery chamber, the liquid delivery assembly is used to deliver coolant to the liquid delivery chamber, and the elastic dividing layer has a leakage hole at one end facing the shaft part, the leakage hole is connected to the liquid delivery chamber.

[0023] In the implementation of the above technical solution, during the process of the grinding plate supporting, grinding, and cooling the shaft parts, the liquid supply assembly supplies coolant to the liquid delivery chamber inside the grinding plate, maintaining a stable liquid source in the chamber. The coolant then flows through two paths: the main path flows out through the liquid delivery port, is fully absorbed by the outer loose and porous adsorption layer, and is used for macroscopic cooling and cleaning; the key auxiliary path seeps out in a controlled, minute amount through the leakage holes opened on the more dense elastic separation layer. Due to the high porosity and good permeability of the adsorption layer, and the dense matrix of the elastic separation layer, even with a small number of leakage holes, its overall permeation resistance is still much higher than that of the adsorption layer. This causes the coolant from the liquid delivery chamber to mainly flow towards and fill the highly permeable adsorption layer under pressure, with only a very small portion able to seep out directionally through the precisely defined leakage holes. This process achieves intelligent fluid distribution based on differences in material permeability: on the one hand, the dense, elastic separator effectively prevents large-scale penetration of coolant into the inner abrasive layer, protecting the dryness and efficiency of the abrasive layer; on the other hand, the pre-designed leakage holes, while ensuring the overall separation function, create an adjustable, low-flow coolant seepage channel, precisely guiding a small amount of coolant to the friction interface between the elastic separator and the workpiece (or outer layer), forming a lubricating film to reduce wear. Thus, this structure, while ensuring that the main body of coolant is utilized by the adsorption layer and effectively "separates" the abrasive layer, cleverly solves the lubrication problem of the elastic separator's own working interface, achieving a balance between isolation, lubrication, and long service life.

[0024] Optionally, the central support plate on one of the mounting brackets is configured as a cooling plate, the telescopic part is used to drive the cooling plate to move in a direction close to the shaft part until it abuts against the shaft part, the cooling plate has an air supply cavity, the cooling plate is provided with an air supply part for supplying cooling air to the air supply cavity, the cooling plate has an air outlet communicating with the air supply cavity, and the air outlet is directed towards the shaft part.

[0025] In the implementation of the above technical solution, the grinding assembly is located between two mounting brackets to perform grinding operations. As a result, the corresponding parts on both sides of the grinding assembly on the shaft part will have two states: grinding completed and ungrinded. The part corresponding to the grinding completed state is configured to face the cooling plate. Under the action of the telescopic part, the cooling plate moves in the direction close to the shaft part until it comes into contact with the surface of the ground shaft part. While the plate body of the cooling plate provides the necessary physical support, the air supply part on the mounting bracket is activated, continuously pressing the cooling air into the air supply cavity opened inside the cooling plate. After the cooling air is evenly distributed in the air supply cavity, it is concentrated and sprayed out from the air outlet opened on the plate and directed towards the workpiece, forming one or more streams of cooling air that are close to the surface of the workpiece, directional and covering the grinding area. This process innovatively integrates "contact rigid support" and "non-contact forced air cooling" into a single functional component. While the cooling plate retains its core function of physically stabilizing the workpiece and suppressing vibration, its contact interface with the workpiece becomes the most effective guide and constraint structure for the cooling airflow. This allows the high-speed airflow to form an efficient airflow layer close to the workpiece surface, achieving highly efficient "fitted" heat dissipation at the grinding point. This integrated design maximizes the removal of grinding heat, significantly reducing the risk of localized temperature rise and thermal deformation in the workpiece's grinding zone.

[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. By setting a central support component that can move axially and follow the grinding components in conjunction, synchronous and stable dynamic support is provided for the middle section of slender shaft parts near the grinding point, effectively counteracting grinding force, gravity and centrifugal force, fundamentally suppressing the "tool deflection" phenomenon and bending deformation, and significantly improving the dimensional accuracy, cylindricity and surface quality of the parts. 2. By configuring at least one central support plate as a multi-functional plate (such as a grinding plate or a cooling plate), it integrates surface treatment (grinding, deburring) or process control (cooling, cleaning, lubrication) functions while undertaking radial support functions. This achieves process integration and functional composite, simplifies process steps, and improves overall processing efficiency and quality while ensuring processing accuracy. 3. In the grinding plate, the "adsorption layer + coolant" structure achieves efficient, uniform, and long-lasting post-cooling of the workpiece surface after grinding / polishing, effectively controlling the thermal deformation of the workpiece; furthermore, the "elastic separation layer" effectively isolates the coolant from the abrasive layer, protecting the performance of the abrasive; and even further, the "drainage hole" design provides a small amount of lubrication to the interface between the elastic separation layer and the workpiece while achieving physical separation, solving its own wear problem, extending the component's lifespan, and forming a synergistic composite cooling and interface management system. Attached Figure Description

[0027] Figure 1This is a schematic diagram of the overall structure of a precision grinding device for the outer diameter of a printer shaft part according to Embodiment 1 of this application; Figure 2 This is a top view of Embodiment 1 of this application; Figure 3 This is a partial side view of Embodiment 1 of this application; Figure 4 yes Figure 1 An enlarged schematic diagram of part A in the middle; Figure 5 yes Figure 1 Enlarged schematic diagram of part B; Figure 6 This is a schematic diagram of the cooperation between the mounting frame and the central support frame in Embodiment 1 of this application; Figure 7 yes Figure 6 An enlarged schematic diagram of section C; Figure 8 This is a cross-sectional schematic diagram of the grinding plate in Embodiment 1 of this application; Figure 9 This is a cross-sectional schematic diagram of the cooling plate in Embodiment 2 of this application.

[0028] Explanation of reference numerals in the attached drawings: 1. Base; 2. Shaft-type parts; 3. Grinding assembly; 301. Grinding motor; 302. Grinding cutter; 4. Grinding drive assembly; 401. First lead screw; 402. First motor; 5. End support seat; 6. Rotary drive unit; 601. Rotary motor; 7. Middle support assembly; 701. Middle support frame; 702. Mounting bracket; 8. Middle support drive assembly; 801. Second lead screw; 802. Second motor; 9. End support drive assembly; 901. Hydraulic rod; 10. End support frame; 11. End support plate; 12. Drive unit; 1201. Bidirectional lead screw; 1202. Bidirectional drive motor; 13. Clearance opening; 14. Grinding space; 15. Middle support plate; 16. Telescopic part; 1601. Third telescopic rod; 17. 18. Grinding plate; 19. Abrasive layer; 10. Adsorption assembly; 1901. Vacuum pump; 20. Adsorption port; 21. Internal air passage; 22. Adsorption layer; 23. Liquid delivery port; 24. Infusion assembly; 2401. Infusion tank; 2402. Infusion pump; 25. Elastic dividing layer; 26. Liquid delivery chamber; 27. Leakage hole; 28. Cooling plate; 29. ​​Air supply chamber; 30. Air supply section; 3001. Blower; 31. Air outlet; 3101. First air outlet; 3102. Second air outlet; 32. First guide groove; 33. First telescopic rod; 34. Second telescopic rod; 35. Grinding seat; 36. Mating seat; 37. Fixing seat; 38. Second guide groove; 39. Adsorption chamber; 40. Second T-shaped insert; 41. Second T-shaped slot; 42. Liquid dispensing chamber; 44. Ball bearing. Detailed Implementation

[0029] The following combination Figures 1-9 This application will be described in further detail. Example 1

[0030] Embodiment 1 of this application discloses a precision grinding apparatus for the outer diameter of printer shaft parts. (Refer to...) Figures 1-8 The precision grinding device for the outer diameter of a printer shaft part includes a base 1, on which a grinding assembly 3 is movably mounted. The grinding assembly 3 is used to grind the shaft part 2. A grinding drive assembly 4 is provided on the base 1 to drive the grinding assembly 3 to move along the axial direction of the shaft part 2. Two end supports 5 are provided on the base 1. The two end supports 5 are arranged opposite each other and are used to support the two ends of the shaft part 2 respectively. A rotation drive part 6 is provided on the end supports 5 to drive the shaft part 2 to rotate. A middle support assembly 7 is movably mounted on the base 1. A middle support drive assembly 8 is provided on the base 1 to drive the middle support assembly 7 to move along the axial direction of the shaft part 2.

[0031] Reference Figures 1-8 A first guide groove 32 is provided on the base 1 along the axial direction of the shaft part 2. The grinding drive assembly 4 includes a first lead screw 401 and a first motor 402. The first lead screw 401 is disposed in the first guide groove 32 and is rotatably connected to the base 1. The first motor 402 is mounted on the base 1. The output shaft of the first motor 402 is coaxially and fixedly connected to the first lead screw 401. A grinding seat 35 is fixedly connected to the lead screw nut of the first lead screw 401. The rotation of the output shaft of the first motor 402 can drive the first lead screw 401 to rotate. The rotation of the first lead screw 401 drives the grinding seat 35 to move along the axial direction of the shaft part 2. A first, electrically controlled telescopic rod 33 is vertically mounted on the top of the grinding base 35. The fixed end of the first telescopic rod 33 is fixedly connected to the grinding base 35, and the movable section of the first telescopic rod 33 is fixedly connected to a mating seat 36. A second, electrically controlled telescopic rod 34 is horizontally mounted on the mating seat 36. The fixed end of the second telescopic rod 34 is fixedly connected to the mating seat 36, and the movable end of the second telescopic rod 34 is fixedly connected to a fixing seat 37. The grinding assembly 3 includes a grinding motor 301 mounted on the fixing seat 37, and a grinding cutter 302 is fixedly connected to the output shaft of the grinding motor 301. The grinding motor 301 drives the grinding cutter 302 to rotate, and the grinding cutter 302 contacts the outer cylindrical surface of the shaft-like part 2 to perform grinding operations. The combined action of the first telescopic rod 33 and the second telescopic rod 34 can improve the flexibility and applicability of the grinding operation.

[0032] Reference Figures 1-8An end support drive assembly 9 is provided on the base 1. The end support drive assembly 9 is used to drive the end support seat 5 to move in a direction close to or away from the end of the shaft part 2. An end support frame 10 is provided on the end support seat 5. A rotation drive unit 6 is used to drive the end support frame 10 to rotate. Opposite end support plates 11 are provided on the end support frame 10. A drive unit 12 is provided on the end support frame 10. The drive unit 12 is used to drive the end support plates 11 to move in a direction close to each other to clamp the end of the shaft part 2.

[0033] Reference Figures 1-8 The base 1 has an axial mounting groove along the shaft part 2. The end support drive assembly 9 includes a hydraulic rod 901 disposed in the mounting groove. The movable end of the hydraulic rod 901 is horizontally positioned and fixedly connected to the end support seat 5. The movement of the movable end of the hydraulic rod 901 drives the end support seat 5 to move. The rotary drive unit 6 includes a rotary motor 601 mounted and fixed on the end support seat 5. The output shaft of the rotary motor 601 is coaxially fixedly connected to the central axis of the end support 10. The rotation of the output shaft of the rotary motor 601 drives the end support 10 to rotate.

[0034] Reference Figures 1-8 The end support 10 is arranged in a disc shape. The drive unit 12 includes a bidirectional lead screw 1201 arranged radially on the end support 10. The bidirectional lead screw 1201 is rotatably connected to the end support 10. A bidirectional drive motor 1202 for driving the bidirectional lead screw 1201 to rotate is installed and fixed on the end support 10. The output shaft of the bidirectional drive motor 1202 is coaxially fixedly connected to the bidirectional lead screw 1201. The oppositely arranged end support plates 11 are respectively fixedly connected to the two lead screw nuts of the bidirectional lead screw 1201. The cross-section of the end of the end support plate 11 away from the shaft part 2 is planar and abuts against the support surface of the end support 10, thereby preventing the end support plate 11 from rotating on the end support 10. The bidirectional lead screw 1201 is driven to rotate by the rotation of the output shaft of the bidirectional drive motor 1202. The oppositely arranged end support plates 11 can thus slide in the direction of approaching or moving away from each other.

[0035] Reference Figures 1-8 In this embodiment of the application, in order to achieve a more stable clamping and fixing of the shaft part 2, each end support 10 is provided with two sets of end support plates 11. Each set of end support plates 11 includes two oppositely arranged end support plates 11. Each set of end support plates 11 is driven by a corresponding bidirectional lead screw 1201 and a bidirectional drive motor 1202 to slide closer or further away from each other.

[0036] Reference Figures 1-8The central support assembly 7 includes a central support frame 701 movably mounted on the base 1. The central support drive assembly 8 is used to drive the central support frame 701 to move axially along the shaft part 2. The central support frame 701 is provided with two mounting brackets 702, which are arranged opposite to each other. A grinding space 14 is formed between the two mounting brackets 702 to accommodate the grinding motor 301 and the grinding tool 302. The mounting brackets 702 are provided with clearance openings 13 for the shaft part 2 to be placed. The mounting brackets 702 are provided with opposing central support plates 15. The central support plates 15 are provided with rolling balls 44 that can contact the outer circular surface of the shaft part 2. The central support plates 15 and the end support plates 11 are staggered. The mounting brackets 702 are provided with telescopic parts 16, which are used to drive the central support plates 15 to move in a direction close to the shaft part 2 until they abut against the shaft part 2.

[0037] Reference Figures 1-8 A second guide groove 38 is provided on the base 1 along the axial direction of the shaft part 2. The middle support drive assembly 8 includes a second lead screw 801 and a second motor 802. The second lead screw 801 is disposed in the second guide groove 38 and is rotatably connected to the base 1. The second motor 802 is mounted on the base 1. The output shaft of the second motor 802 is coaxially and fixedly connected to the second lead screw 801. The lead screw nut of the second lead screw 801 is fixedly connected to the middle support frame 701. The rotation of the output shaft of the second motor 802 can drive the second lead screw 801 to rotate. The rotation of the second lead screw 801 drives the middle support frame 701 to move along the axial direction of the shaft part 2.

[0038] Reference Figures 1-8 The telescopic part 16 includes a third telescopic rod 1601 disposed inside the mounting frame 702. The third telescopic rod 1601 is arranged radially along the shaft part 2. The fixed end of the third telescopic rod 1601 is fixedly connected to the mounting frame 702, and the movable end of the third telescopic rod 1601 is fixedly connected to the central support plate 15. Through the telescopic movement of the movable end of the third telescopic rod 1601, the central support plate 15 can be driven to move radially along the shaft part 2. The central support plate 15 can thus move closer to the shaft part 2 until it abuts against the outer circular surface of the shaft part 2.

[0039] Reference Figures 1-8 In this embodiment of the application, in order to achieve a more stable clamping and fixing of the shaft part 2, each mounting bracket 702 is provided with two sets of central support plates 15. Each set of central support plates 15 includes two central support plates 15 arranged opposite to each other. Each central support plate 15 is driven by the corresponding third telescopic rod 1601 to slide in the direction close to or away from the shaft part 2.

[0040] Reference Figures 1-8One of the mounting brackets 702 has a central support plate 15 configured as a grinding plate 17. A third telescopic rod 1601 on the mounting bracket 702 is used to drive the grinding plate 17 to move in the direction close to the shaft part 2. The grinding plate 17 has an abrasive layer 18 on the side facing the shaft part 2. A first T-shaped insert (not shown in the figure) is fixed on the abrasive layer 18. A first T-shaped slot (not shown in the figure) is opened on the grinding plate 17 for the first T-shaped insert to be inserted. The abrasive layer 18 is installed by plugging and connecting, which facilitates the disassembly and replacement of the abrasive layer 18.

[0041] Reference Figures 1-8 The grinding plate 17 is provided with an adsorption component 19, and the grinding plate 17 has an adsorption port 20 facing the shaft part 2. The adsorption port 20 and the adsorption component 19 are connected through the built-in air passage 21.

[0042] Reference Figures 1-8 The adsorption assembly 19 includes an air extractor 1901 embedded in the grinding plate 17 (the grinding plate 17 has a cavity for installing the air extractor 1901, which is detachably installed in the cavity). The grinding plate 17 has an adsorption cavity 39. An internal air passage 21 is opened in the grinding plate 17 and communicates with the adsorption cavity 39. The other end of the internal air passage 21 is connected to the air extraction port of the air extractor 1901. The adsorption port 20 is connected to the adsorption cavity 39. The operation of the air extractor 1901 forms an adsorption flow from the adsorption port 20 to the adsorption cavity 39 and then to the internal air passage 21. The adsorption flow removes the extremely fine abrasives, detached abrasive particles and dust generated by the grinding plate 17 during the grinding process, preventing them from being retained between the abrasive layer 18 and the workpiece, thereby avoiding scratches on the processed surface due to "secondary grinding".

[0043] Reference Figures 1-8 The grinding plate 17 has an adsorption layer 22 on the side facing the shaft part 2. A second T-shaped insert 40 is fixed on the adsorption layer 22. The grinding plate 17 has a second T-shaped slot 41 for the second T-shaped insert 40 to be inserted. The adsorption layer 22 is installed by the plug-in connection, which facilitates the disassembly and replacement of the adsorption layer 22. The abrasive layer 18 is located between the grinding assembly 3 and the adsorption layer 22. The grinding plate 17 has a liquid inlet 23 and a liquid delivery assembly 24 is provided on the grinding plate 17. The liquid delivery assembly 24 is used to deliver coolant to the liquid inlet 23.

[0044] Reference Figures 1-8The infusion assembly 24 includes an infusion tank 2401 embedded in a grinding plate 17 (the grinding plate 17 has a cavity for installing the infusion tank 2401, which is detachably installed in this cavity). An infusion pump 2402 is installed inside the infusion tank 2401, and the inlet end of the infusion pump 2402 communicates with the internal space of the infusion tank 2401. A dispensing chamber 42 is provided in the grinding plate 17, and the outlet end of the infusion pump 2402 communicates with the internal space of the dispensing chamber 42. The operation of the infusion pump 2402 can deliver the coolant in the infusion tank 2401 to the dispensing chamber 42. In the process, the outlet and inlet of the infusion pump 2402 are equipped with control valves for controlling the on / off of the corresponding end; the grinding plate 17 has multiple liquid delivery ports 23, which are all connected to the liquid distribution chamber 42. The coolant in the liquid distribution chamber 42 is delivered to the adsorption layer 22 through the liquid delivery ports 23. The adsorption layer 22 adsorbs the coolant. With its own porous or fibrous structure, the adsorption layer 22 effectively adsorbs, retains and diffuses the coolant flowing out of the liquid delivery ports 23 along the circumference and axial direction of the workpiece, and quickly forms a uniform, continuous and durable coolant covering film on the surface of the workpiece.

[0045] Reference Figures 1-8 The grinding plate 17 is provided with an elastic partition layer, which is located between the adsorption layer 22 and the abrasive layer 18. The grinding plate 17 is provided with a liquid delivery chamber 26, and the liquid delivery port 23 is connected to the liquid delivery chamber 26. The liquid delivery chamber 26 is connected to the liquid distribution chamber 42. The elastic partition layer 25 is provided with a leakage hole 27 at one end facing the shaft part 2, and the leakage hole 27 is connected to the liquid delivery chamber 26.

[0046] Reference Figures 1-8 The elastic separator layer is made of a dense elastic material with a porosity of less than 10% (such as high-density polyurethane, fluororubber, etc.). Multiple micropores are perforated on its working surface facing the shaft parts, serving as leakage holes. The total flow cross-sectional area of ​​these micropores is much smaller than the total flow cross-sectional area of ​​all the liquid inlets. During operation, the pump delivers coolant to the distribution chamber, and then distributes it through the delivery chamber. Because the adsorption layer is a high-porosity material with low permeability resistance, most of the coolant is rapidly absorbed and diffused through the liquid inlets, providing uniform cooling and cleaning to the workpiece. Simultaneously, due to the dense material and small total flow area of ​​the micropores in the elastic separator layer, only a small amount of coolant can slowly seep out under pressure through the micropores, forming an extremely thin lubricating film between the elastic separator layer and the workpiece (or outer layer). This effectively isolates the large amount of coolant in the adsorption layer from penetrating the inner abrasive layer, protecting the abrasive performance, and cleverly solves the lubrication and friction reduction problems at the working interface of the elastic separator layer itself, extending its service life.

[0047] In this embodiment, the abrasive layer 18 preferably uses a resin-bonded cubic boron nitride abrasive. Specific parameters are as follows: the abrasive is cubic boron nitride micropowder with a particle size of approximately 20 μm (W20), and the binder is heat-resistant phenolic resin. This combination ensures that the abrasive layer has sufficient cutting power while also possessing good elasticity and self-sharpening properties, effectively removing micro-burrs and vibration marks after grinding, and achieving excellent surface finish. The abrasive layer 18 is a flat plate that adheres to the base surface of the grinding plate 17, with a thickness of approximately 5 mm. To facilitate convenient replacement after wear, a metal substrate is bonded to the back of the abrasive layer 18 using high-strength epoxy resin adhesive. This metal substrate is fixedly connected to a first T-shaped insert. During installation, the first T-shaped insert is slid into the slot and locked, achieving rapid, precise positioning and reliable fixation of the abrasive layer 18. Disassembly is performed by reversing the operation, greatly improving maintenance efficiency and ensuring the accuracy of repeated installations.

[0048] In another alternative embodiment, the abrasive layer 18 can also be a strip or sheet-shaped flexible abrasive, such as diamond abrasive paper with adhesive backing or a polishing film with a polyester fiber substrate. It is directly attached to the working surface of the grinding plate 17 by adhesive backing. This solution is lower in cost, extremely convenient to replace, and suitable for applications with extremely high surface requirements where the abrasive layer is a rapidly consumable item.

[0049] The adsorption layer 22 on the grinding plate 17 is the core thermal management medium layer. In this embodiment, the adsorption layer 22 is made of open-cell polyurethane foam material. Its key structural parameters are: porosity 70%-85%, average pore size 100-200 micrometers, and thickness of approximately 3 mm. This high-porosity, interconnected three-dimensional mesh structure gives it excellent capillary adsorption effect and liquid retention capacity, enabling it to rapidly and massively absorb and uniformly store the coolant flowing from the liquid inlet 23 throughout the entire material. During operation, the adsorption layer 22 is fully wetted by the coolant, and its surface contacts the rotating shaft part 2. Through capillary action, the coolant is continuously and uniformly "pumped" to the entire workpiece contact area, forming a stable, fully covered liquid film, achieving efficient and long-lasting evaporative cooling and cleaning. For easy replacement and cleaning, the adsorption layer 22 also adopts a detachable design: a second T-shaped insert is fixed on its back, which cooperates with the second T-shaped slot on the grinding plate 17 for installation.

[0050] In another high-performance embodiment, the adsorption layer 22 can be made of porous alumina ceramic sheet. It is manufactured using a powder sintering process, with a porosity controllable between 40% and 60% and a uniform pore size distribution. The ceramic adsorption layer possesses extremely high wear resistance, heat resistance, and chemical stability, resulting in an extremely long service life. Its rigid structure also helps maintain the flatness of the support interface. It is fixed to the grinding plate 17 by high-temperature resistant silicone adhesive or mechanical snap-fit.

[0051] The implementation principle of the precision grinding device for the outer diameter of a printer shaft part in Embodiment 1 of this application is as follows: During operation, the two ends of the printer shaft part 2 are first placed on two opposing end support seats 5 on the base 1. The two end support seats 5 provide stable support for the two ends of the part, ensuring the accuracy of the part's installation reference. The middle support drive assembly 8 on the base 1 is activated, which drives the movable middle support assembly 7 to move along the axial direction of the shaft part 2 to the position where the middle section of the part is prone to bending deformation (usually the midpoint of the axial direction of the part or the point of force concentration), thus completing the positioning of the middle support assembly 7 to support the middle section of the part. Next, the grinding drive assembly 4 on the base 1 is activated, which drives the movable grinding assembly 3 to move along the axial direction of the shaft part 2 to the outer diameter position to be ground. At the same time, the middle support assembly 7 moves together with the grinding assembly 3, always corresponding to the grinding position of the grinding assembly 3 to synchronously support the middle section of the part. After that, the rotation of the end support seats 5 is activated. The drive unit 6 drives the shaft part 2 to rotate at a constant speed around its own axis. At the same time, the grinding assembly 3 is activated to perform grinding operations on the outer circle of the rotating shaft part 2. During the grinding process, the grinding drive assembly 4 can drive the grinding assembly 3 to move along the axial direction of the shaft part 2 according to the grinding requirements. The middle support assembly 7 moves synchronously with the grinding assembly 3, continuously providing stable support to the middle section of the part corresponding to the grinding area, effectively offsetting the radial grinding force generated by the grinding assembly 3, the part's own weight, and the rotational centrifugal force. The end support seat 5, in conjunction with the rotary drive unit 6, ensures the support stability and rotational accuracy at both ends of the part. The coordinated cooperation of all components effectively avoids the "tool deflection" phenomenon and elastic bending deformation caused by the lack of support in the middle section or the mismatch between the support position and the grinding position when grinding slender shaft parts. This effectively controls the dimensional accuracy of the part, avoids shape errors such as waist drum shape and saddle shape, improves the cylindricity and surface roughness of the part, solves the processing defects caused by the lack of middle section support in traditional two-center clamping, and meets the high-precision processing requirements of the printer for slender shaft parts 2. Example 2

[0052] The difference between Example 2 and Example 1 is that: (Refer to...) Figure 9 One of the mounting brackets 702 has a central support plate 15 configured as a cooling plate 28. A third telescopic rod 1601 on the mounting bracket 702 is used to drive the cooling plate 28 to move in a direction close to the shaft part 2 until it comes into contact with the shaft part 2. The cooling plate 28 has an air supply cavity 29 and an air supply part 30 for supplying cooling air to the air supply cavity 29. The cooling plate 28 has an air outlet 31 that communicates with the air supply cavity 29 and the air outlet 31 is directed toward the shaft part 2.

[0053] The air supply section 30 includes a blower 3001 embedded in the cooling plate 28 (the cooling plate 28 has a cavity for installing an exhaust fan 1901, and the blower 3001 is detachably installed in this cavity), and the delivery port of the blower 3001 is connected to the air supply chamber 29; the air outlet 31 includes a first air outlet 3101 and a second air outlet 3102 connected to the air supply chamber 29, the first air outlet 3101 is arranged radially along the shaft part 2, the second air outlet 3102 is inclined to the first air outlet 3101, and the second air outlet 3102 is inclined towards the axial direction of the shaft part 2 in the direction close to the end of the shaft part 2.

[0054] The implementation principle of Example 2 is as follows: The grinding assembly 3 is located between two mounting brackets 702 to perform grinding operations, thereby causing the corresponding parts on both sides of the grinding assembly 3 on the shaft part 2 to present two states: grinding completed and ungrinded. The part corresponding to the grinding completed state is configured to face the cooling plate 28. Under the action of the telescopic part 16, the cooling plate 28 moves in the direction close to the shaft part 2 until it comes into contact with the surface of the ground shaft part 2. While the plate body of the cooling plate 28 provides the necessary physical support, the air supply part 30 on the mounting bracket 702 is activated, continuously pressing the cooling air into the air supply cavity 29 opened inside the cooling plate 28. After the cooling air is evenly distributed in the air supply cavity 29, it is concentratedly sprayed out from the air outlet 31 opened on the plate and directed towards the workpiece, forming one or more streams of cooling airflow that are close to the surface of the workpiece, directional and covering the grinding area. This work process creatively integrates "contact rigid support" and "non-contact forced air cooling" into a single functional component. The core function of the cooling plate 28—physically stabilizing the workpiece and suppressing vibration—remains unchanged. Its contact interface with the workpiece becomes the most effective guide and constraint structure for the cooling airflow, allowing high-speed airflow to form an efficient airflow layer close to the workpiece surface. This achieves highly efficient "fitted" heat dissipation at the grinding point. This integrated design maximizes the removal of grinding heat, significantly reducing the risk of localized temperature rise and thermal deformation in the workpiece's grinding zone.

[0055] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A precision grinding device for the outer diameter of printer shaft parts, characterized in that: The system includes a base (1), on which a grinding assembly (3) is movably disposed, the grinding assembly (3) being used to grind shaft-like parts (2), and a grinding drive assembly (4) being disposed on the base (1) for driving the grinding assembly (3) to move along the axial direction of the shaft-like parts (2); two end support seats (5) are disposed on the base (1), the two end support seats (5) being disposed opposite to each other and respectively used to support the two ends of the shaft-like parts (2), and a rotation drive part (6) being disposed on the end support seats (5) for driving the shaft-like parts (2) to rotate; a middle support assembly (7) is movably disposed on the base (1), and a middle support drive assembly (8) being disposed on the base (1) for driving the middle support assembly (7) to move along the axial direction of the shaft-like parts (2).

2. The precision grinding device for the outer diameter of printer shaft parts according to claim 1, characterized in that: An end support drive assembly (9) is provided on the base (1), which is used to drive the end support seat (5) to move in a direction close to or away from the end of the shaft part (2); an end support frame (10) is provided on the end support seat (5), and a rotation drive unit (6) is used to drive the end support frame (10) to rotate; an opposing end support plate (11) is provided on the end support frame (10), and a drive unit (12) is provided on the end support frame (10), which is used to drive the end support plate (11) to move in a direction close to each other to clamp the end of the shaft part (2).

3. The precision grinding device for the outer diameter of printer shaft parts according to claim 1, characterized in that: The central support assembly (7) includes a central support frame (701) movably disposed on the base (1), and the central support drive assembly (8) is used to drive the central support frame (701) to move along the axial direction of the shaft part (2); the central support frame (701) is provided with two mounting brackets (702), the two mounting brackets (702) are arranged opposite to each other, and a grinding space (14) for accommodating the grinding assembly (3) is formed between the two mounting brackets (702); the mounting brackets (702) are provided with opposing central support plates (15), and the mounting brackets (702) are provided with telescopic parts (16), the telescopic parts (16) are used to drive the central support plates (15) to move in a direction close to the shaft part (2) until they abut against the shaft part (2).

4. The precision grinding device for the outer diameter of printer shaft parts according to claim 3, characterized in that: The mounting bracket (702) has a clearance opening (13) for the shaft part (2) to be placed in, and the middle support plate (15) and the end support plate (11) are staggered.

5. A precision grinding device for the outer diameter of printer shaft parts according to claim 3, characterized in that: One of the mounting brackets (702) has a central support plate (15) configured as a grinding plate (17), and the telescopic part (16) is used to drive the grinding plate (17) to move in a direction close to the shaft part (2). The grinding plate (17) has an abrasive layer (18) on the side facing the shaft part (2).

6. The precision grinding device for the outer diameter of printer shaft parts according to claim 5, characterized in that: The grinding plate (17) is provided with an adsorption component (19), and the grinding plate (17) has an adsorption port (20) facing the shaft part (2). The adsorption port (20) and the adsorption component (19) are connected through a built-in air passage (21).

7. A precision grinding device for the outer diameter of printer shaft parts according to claim 5, characterized in that: The grinding plate (17) has an adsorption layer (22) on the side facing the shaft part (2), the abrasive layer (18) is located between the grinding assembly (3) and the adsorption layer (22), the grinding plate (17) has a liquid inlet (23), and the grinding plate (17) has a liquid delivery assembly (24) for delivering coolant to the liquid inlet (23).

8. A precision grinding device for the outer diameter of printer shaft parts according to claim 7, characterized in that: An elastic separation layer is provided on the grinding plate (17), and the elastic separation layer is located between the adsorption layer (22) and the abrasive layer (18).

9. A precision grinding device for the outer diameter of printer shaft parts according to claim 8, characterized in that: The grinding plate (17) has a liquid delivery chamber (26), the liquid delivery port (23) is connected to the liquid delivery chamber (26), the liquid delivery assembly (24) is used to deliver coolant to the liquid delivery chamber (26), and the elastic dividing layer (25) has a leakage hole (27) at one end facing the shaft part (2), the leakage hole (27) is connected to the liquid delivery chamber (26).

10. A precision grinding device for the outer diameter of printer shaft parts according to claim 3, characterized in that: One of the mounting brackets (702) has a central support plate (15) configured as a cooling plate (28). The telescopic part (16) is used to drive the cooling plate (28) to move in a direction close to the shaft part (2) until it abuts against the shaft part (2). The cooling plate (28) has an air supply cavity (29). The cooling plate (28) is provided with an air supply part (30) for supplying cooling air to the air supply cavity (29). The cooling plate (28) has an air outlet (31) communicating with the air supply cavity (29). The air outlet (31) is directed towards the shaft part (2).

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