Deep hole grinding spindle assembly

Abstract

The utility model relates to a kind of deep hole grinding shafting devices, including installation pedestal, shell is respectively installed on installation pedestal, linear bearing between shell and bearing seat is installed, front end precision bearing assembly and rear end precision bearing assembly are assembled in bearing seat and cooperate with guide mandrel;Perforate distribution in bearing seat guide mandrel;Front end precision bearing assembly includes two first precision angular contact bearings and second precision angular contact bearings arranged back to back, rear end precision bearing assembly includes third precision angular contact bearing;Through the precision angular contact bearing support structure of front two rear one, cooperate with the ball linear bearing guidance between shell and bearing seat, and the secondary guidance design of guide seat to guide mandrel front end, effectively solve the defect that the longer the longer the rigidity is worse in traditional deep hole grinding shafting overhang.

Description

Technical Field

[0001] This utility model relates to a grinding shaft, and more particularly to a deep hole grinding shaft system device. Background Technology

[0002] Deep hole grinding is a key process in the mechanical manufacturing industry for machining long and narrow deep-hole parts (such as hydraulic valve holes and aero-engine oil pipe holes). Its core requirement is to maintain high rigidity, high speed, and low thermal deformation of the shaft system while ensuring the grinding wheel penetrates deep into the hole, in order to meet the precision and surface quality requirements of the part's inner bore. However, traditional deep hole grinding shaft systems often face multiple technical bottlenecks: when using small-diameter bearings and increasing the span to achieve deep hole feed, the excessive overhang between the grinding wheel and the support bearing leads to insufficient shaft rigidity, easily causing vibration during grinding and thus reducing the machining accuracy of the inner bore; high-speed operation causes spindle heating, which can easily lead to shaft deformation, and existing simple preload structures cannot effectively compensate for thermal deformation, resulting in a decrease in bearing precision; at the same time, grinding chips and coolant can easily penetrate into the bearing, causing component wear and shortening the shaft system's service life. These problems collectively restrict the improvement of efficiency and quality in deep hole grinding.

[0003] Existing technology includes a spindle assembly for deep hole grinding. This patent uses a combination of double-row cylindrical roller bearings and angular contact ball bearings to support the spindle, improving its radial rigidity. However, it lacks an axial sliding guide mechanism, making it difficult to adapt to the grinding requirements of holes of different depths. Furthermore, it does not mention optimized solutions for thermal deformation compensation and sealing protection. Meanwhile, there is also a deep hole internal grinding device that uses a lead screw feed mechanism to drive the grinding wheel axis along a guide rail to reach deeper into the hole. While this achieves the feeding function, it uses a common sliding guide rail with large radial clearance, failing to guarantee grinding accuracy at high speeds. Moreover, it only relies on a single dust cover for protection, leaving a high risk of chips and coolant intruding into the bearings.

[0004] In summary, while existing deep hole grinding patents offer improvements in one dimension—rigidity enhancement, feed drive, or thermal compensation—they either lack high-precision sliding guide components such as linear bearings, making it impossible to balance deep hole feed with shaft rigidity; or their thermal compensation structures are complex and poorly compatible with bearing systems; or their insufficient sealing protection leads to easy bearing wear. None of these solutions comprehensively address the core pain points of traditional deep hole grinding shaft systems. Therefore, there is an urgent need for a deep hole grinding shaft system device that is simple in structure, has sufficient rigidity, minimal thermal deformation impact, and reliable protection to fill the gaps in existing technologies. Utility Model Content

[0005] To solve the above-mentioned technical problems, the purpose of this utility model is to provide a shaft system device for deep hole grinding.

[0006] This utility model discloses a deep hole grinding shaft system device, comprising a mounting base, wherein: a housing is mounted on the mounting base, a linear bearing is mounted between the housing and a bearing seat, a front precision bearing assembly and a rear precision bearing assembly are assembled in the bearing seat and cooperate with a guide mandrel; a guide mandrel is distributed through the bearing seat; the front precision bearing assembly includes two back-to-back arranged first precision angular contact bearings and second precision angular contact bearings, the inner rings of the first precision angular contact bearings and second precision angular contact bearings are locked to the guide mandrel by first locking nuts, and their outer rings are fixed to the front end face of the bearing seat by a pressure cap; the rear precision bearing assembly includes a third precision angular contact bearing, the inner ring of the third precision angular contact bearing is locked to the guide mandrel by a second locking nut, and its outer ring rear end abuts against a spring, the other end of the spring being fixed to the rear end limiting surface of the bearing seat; a guide seat connected to the housing is sleeved on the outer side of the front end of the guide mandrel, and a sealing ring is distributed between the pressure cap and the guide mandrel.

[0007] Furthermore, in the aforementioned deep hole grinding shaft system device, the inner ring of the linear bearing is precisely fitted with the outer wall of the bearing housing, and its outer ring is precisely fitted with the inner wall of the housing; the linear bearing is a ball linear bearing, allowing the bearing housing to slide with high precision along the axial direction of the housing.

[0008] Furthermore, in the aforementioned deep hole grinding shaft system device, the rear end of the guide mandrel is connected to a drive bushing via a thermal interference fit, and its front end has a threaded hole for fixing the grinding wheel.

[0009] Furthermore, in the aforementioned deep hole grinding shaft system, the first precision angular contact bearing, the second precision angular contact bearing, and the third precision angular contact bearing are all angular contact ball bearings, and the first precision angular contact bearing and the second precision angular contact bearing are arranged back to back.

[0010] Furthermore, in the aforementioned deep hole grinding shaft system device, the spring is a cylindrical helical compression spring, and the preload of the spring is adjusted by a spring seat to compensate for the temperature rise deformation of the guide spindle.

[0011] Furthermore, in the aforementioned deep hole grinding shaft system device, the sealing ring is a rubber sealing ring, and a sealing gasket is provided between the pressure cap and the bearing seat to prevent chips and coolant from entering the interior of the bearing seat.

[0012] Furthermore, in the aforementioned deep hole grinding shaft system device, the guide seat is an annular metal part, which is fixed to the housing by a plurality of first screws, and a rotation and sliding clearance is left between its inner wall and the guide spindle to achieve secondary guidance.

[0013] Furthermore, in the aforementioned deep hole grinding shaft system device, the mounting base has several mounting holes, and the housing is fixed to the mounting base by several second screws.

[0014] Furthermore, in the aforementioned deep hole grinding shaft system device, the pressure cap is fixed to the front end face of the bearing seat by a plurality of third screws, and the pressure cap is an annular metal pressure cap.

[0015] Furthermore, in the aforementioned deep hole grinding shaft system device, the bearing seat is a cylindrical metal seat, and its inner wall is provided with steps for positioning the first precision angular contact bearing, the second precision angular contact bearing, and the third precision angular contact bearing.

[0016] By means of the above solution, this utility model has at least the following advantages: 1. By employing a precision angular contact bearing support structure with two front and one rear bearing, combined with ball linear bearing guidance between the housing and bearing seat, and a secondary guiding design of the guide seat for the front end of the guide spindle, the defect of decreasing rigidity with longer shaft overhang in traditional deep hole grinding is effectively solved. Radial runout during high-speed rotation of the guide spindle is significantly suppressed, ensuring the parallelism between the grinding wheel and the inner wall of the deep hole, ultimately improving the dimensional accuracy and surface quality of grinding slender deep holes.

[0017] 2. The design of the rear cylindrical helical compression spring, combined with the spring seat and adjusting shims, allows for flexible adjustment of the spring preload, compensating in real time for temperature rise deformation caused by the high-speed rotation of the guide spindle and preventing the bearing from being "locked up" due to spindle elongation. Simultaneously, the drive shaft sleeve separates the drive end from the shaft system, blocking the direct transmission of motor temperature rise to the guide spindle and precision bearing assembly. This dual design reduces the interference of thermal deformation on shaft system accuracy, ensuring long-term stable operation of the device.

[0018] 3. Through the synergistic action of the rubber sealing ring between the gland and the guide spindle, and the sealing gasket between the gland and the bearing housing, a double sealing structure is formed, which can effectively prevent the chips and coolant generated during the grinding process from entering the interior of the bearing housing, avoiding wear of the precision bearing components, maintaining the long-term accuracy of the bearing, and extending the service life of the entire shaft system.

[0019] 4. The evenly distributed mounting holes pre-drilled in the mounting base facilitate quick fixing to external grinding equipment; the annular step on the inner wall of the bearing housing can directly position each precision bearing, reducing assembly positioning errors. The combination of the spring seat and the copper adjusting shims facilitates adjustment of the spring preload, adapting to the thermal compensation requirements under different working conditions. The threaded hole at the front end of the guide spindle can flexibly adapt to the mounting interface of commonly used grinding wheels. The overall structural design takes into account both ease of assembly and adaptability to different scenarios, enhancing the practical value of the device.

[0020] The above description is only an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, the preferred embodiments of this utility model are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the shaft system device for deep hole grinding.

[0022] The meanings of the labels in the figures are as follows.

[0023] Detailed Implementation The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this utility model, but are not intended to limit its scope.

[0024] like Figure 1 The deep hole grinding shaft system includes a mounting base 8, which is unique in that: the mounting base 8 can be made of 45# steel, milled into shape, and has several mounting holes evenly distributed along its length for fixing to external grinding equipment. Simultaneously, the housing 3 is fixed to the mounting base 8 by several second screws. These second screws can be hexagonal socket head cap screws, and tightening them ensures no relative wobbling between the housing 3 and the mounting base 8, providing a stable support foundation for the entire device.

[0025] The housing 3 used in this invention has a cylindrical structure and can be made of 20CrMnTi alloy steel pipe with a wall thickness of 8mm. Its interior forms a cavity to accommodate the bearing housing 6 and the linear bearing 7. The bearing housing 6 is a cylindrical metal seat with three annular steps on its inner wall. These three steps are used to position the outer rings of the first precision angular contact bearing 9, the second precision angular contact bearing 10, and the third precision angular contact bearing 4, respectively. Furthermore, the axial spacing of the steps is designed according to the thickness of the corresponding bearings to ensure that the outer rings of the bearings fit tightly against the step surfaces after assembly, preventing axial movement.

[0026] In a preferred embodiment of this invention, a linear bearing 7 is installed between the housing 3 and the bearing seat 6. This linear bearing 7 is a ball linear bearing, and a conventional commercially available model can be selected. Its core function is to allow the bearing seat 6 to slide with high precision along the axial direction of the housing 3, while simultaneously providing radial support to ensure rigidity. Furthermore, the inner ring of the linear bearing 7 and the outer wall of the bearing seat 6 employ a precision transition fit, as does the outer ring and the inner wall of the housing 3. This fit not only prevents jamming during the sliding of the bearing seat 6 but also controls the radial clearance to a minimum, ensuring no radial offset during the sliding process of the bearing seat 6 and providing stable guidance for subsequent deep hole grinding by the grinding wheel.

[0027] During actual assembly, lithium-based grease can be applied to the ball circulation channel of the linear bearing 7 to reduce the sliding friction coefficient, reduce wear between the linear bearing 7 and the bearing seat 6 and the housing 3, and extend the overall service life of the device.

[0028] Furthermore, the guide mandrel 1 used in this invention can be made of alloy structural steel and is precision ground. Its outer cylindricity is controlled to a high precision to ensure coaxiality during high-speed rotation. Simultaneously, the guide mandrel 1 is distributed throughout the bearing housing 6, with a front precision bearing assembly and a rear precision bearing assembly respectively mounted at its front and rear ends, forming a "two-front-one-rear" support structure suitable for high-speed grinding requirements.

[0029] In practical implementation, the front-end precision bearing assembly includes two back-to-back arranged first precision angular contact bearings 9 and second precision angular contact bearings 10, both of which are angular contact ball bearings. The back-to-back arrangement means that the outer rings of the two bearings face each other. This arrangement can form a large support span, which can simultaneously withstand radial loads and axial overturning moments, and avoid radial runout when the guide spindle 1 rotates at high speed.

[0030] During assembly, the inner ring of the second precision angular contact bearing 10 is first heat-fitted onto the step at the front end of the guide spindle 1. After cooling, the inner ring will fit tightly against the guide spindle 1. Then, the inner ring of the first precision angular contact bearing 9 is installed tightly against the inner ring of the second precision angular contact bearing 10, ensuring no gap between the two bearing inner rings. Finally, the first locking nut 11 is used to lock the inner rings of both bearings to the guide spindle 1. The first locking nut 11 can be a fine-thread locking nut with an anti-loosening washer. After tightening, it prevents relative sliding between the inner ring and the spindle when the guide spindle 1 rotates at high speed, achieving rigid preload and ensuring the rigidity of the front-end support.

[0031] During assembly, the outer rings of the first precision angular contact bearing 9 and the second precision angular contact bearing 10 are fixed by a pressure cap 12. The pressure cap 12 is an annular metal pressure cap, made of 304 stainless steel with a thickness of 10mm. A small gap is left between its inner diameter and the outer circle of the guide spindle 1 to ensure unimpeded rotation of the guide spindle 1. Its outer diameter mates with the inner hole at the front end of the bearing housing 6. The pressure cap 12 is fixed to the front end face of the bearing housing 6 by several third screws, which can be countersunk hexagonal screws, evenly distributed along the circumference of the pressure cap 12. After tightening, the rear end of the pressure cap 12 presses tightly against the front end face of the outer ring of the first precision angular contact bearing 9, firmly fixing the outer rings of the two bearings to the corresponding steps on the inner wall of the bearing housing 6.

[0032] Meanwhile, the rear-end precision bearing assembly selected in this utility model includes a third precision angular contact bearing 4, which is also an angular contact ball bearing, suitable for the smaller load requirements at the rear end. The inner ring of the third precision angular contact bearing 4 and the step at the rear end of the guide spindle 1 adopt a transition fit, and are locked to the guide spindle 1 by a second locking nut 2. The second locking nut 2 is a fine-tooth locking nut with a locking washer. After tightening, it can ensure that the inner ring and the guide spindle 1 rotate synchronously. Furthermore, the rear end of the outer ring of the third precision angular contact bearing 4 abuts against a spring 5. The spring 5 is a cylindrical helical compression spring, which can be made of spring steel with a wire diameter of 3mm, an outer diameter of 20mm, and a free length of 30mm. The other end of the spring 5 is fixed to the rear end limiting surface of the bearing seat 6. Moreover, in order to adjust the preload of the spring 5, a spring seat is provided between the spring 5 and the rear end limiting surface of the bearing seat 6. By adding or removing copper adjusting shims between the spring seat and the limiting surface, the compression of the spring 5 can be changed. This design can effectively compensate for the temperature rise deformation of the guide spindle 1 during high-speed rotation. When the guide spindle 1 elongates due to heat, the spring 5 will be further compressed to prevent the outer ring of the third precision angular contact bearing 4 from being jammed by the spindle, thus ensuring the stability of the rear support.

[0033] Looking further, a guide seat 14, a ring-shaped metal component, is fitted onto the outer side of the front end of the guide spindle 1. It is fixed to the housing 3 by multiple first screws, which are hexagonal socket head cap screws evenly distributed along the circumference of the guide seat 14. A clearance for rotation and sliding is provided between the inner wall of the guide seat 14 and the guide spindle 1. This clearance ensures unimpeded high-speed rotation of the guide spindle 1 and provides secondary guidance to the front end of the guide spindle 1 when the bearing seat 6 drives it to slide axially, suppressing radial runout and ensuring the parallelism between the grinding wheel and the inner wall of the deep hole, thus improving grinding accuracy.

[0034] Furthermore, a sealing ring 13 is distributed between the pressure cap 12 and the guide spindle 1. The sealing ring 13 is a rubber sealing ring, made of nitrile rubber, a material commonly used in existing technology. This sealing ring can "scrape" the coolant and chips generated during grinding back to the grinding area when the guide spindle 1 rotates, preventing them from entering the bearing housing 6. Simultaneously, a sealing gasket is provided between the pressure cap 12 and the bearing housing 6. Under the clamping force of the third screw, the sealing gasket undergoes elastic deformation, filling the microscopic gap between the pressure cap 12 and the front end face of the bearing housing 6, further preventing chips and coolant from intruding into the bearing housing 6, protecting the internal precision bearing components from wear, and maintaining the bearing's accuracy.

[0035] Considering the needs of subsequent drive connections, a drive bushing is connected to the rear end of the guide spindle 1 via a thermal interference fit. The drive bushing is preferably made of 45# steel, with an interference fit of 0.02-0.04mm between its inner diameter and the guide spindle 1. The rear end of the drive bushing is used to connect to an external drive end (such as a motor output shaft), transmitting power to the guide spindle 1 through the drive bushing to achieve high-speed rotation of the guide spindle 1. This separate arrangement of the drive end and shaft system avoids direct transmission of motor temperature rise to the guide spindle 1 and precision bearing assembly, reducing the impact of thermal deformation on accuracy. Simultaneously, a threaded hole for fixing a grinding wheel is provided at the front end of the guide spindle 1. The specifications of the threaded hole are designed according to the mounting interface of commonly used grinding wheels. The grinding wheel is connected and fixed to the threaded hole at the front end of the guide spindle 1 via an internal threaded flange, ensuring that the grinding wheel can rotate synchronously with the guide spindle 1, enabling deep hole grinding operations.

[0036] The working principle of this utility model is as follows: In use, the external drive end drives the guide spindle 1 to rotate at high speed through the drive bushing. The grinding wheel at the front end of the guide spindle 1 rotates synchronously with it, generating grinding power. At the same time, the external feed mechanism (such as the axial feed system of the machine tool) pushes the bearing seat 6. Under the guidance of the linear bearing 7, the bearing seat 6 slides forward along the axial direction of the housing 3, driving the guide spindle 1 and the grinding wheel to penetrate into the slender deep hole and complete the grinding feed.

[0037] During the grinding process, the first precision angular contact bearing 9 and the second precision angular contact bearing 10, arranged back-to-back at the front end, provide strong rigid support to prevent radial runout when the guide spindle 1 rotates at high speed. The third precision angular contact bearing 4 at the rear end, in conjunction with the preload of the spring 5, can withstand the remaining load and compensate for the temperature rise deformation of the guide spindle 1, preventing the bearing from seizing. The guide seat 14 provides secondary guidance for the front end of the guide spindle 1, further suppressing radial movement. The linear bearing 7 provides high-precision guidance for the sliding of the bearing seat 6, while ensuring the rigidity of the shaft system during overhang.

[0038] The sealing ring 13 and the sealing gasket work together to prevent chips and coolant from entering the bearing housing 6, protecting the precision bearing assembly; the stable connection between the mounting base 8 and the housing 3 ensures that the entire device remains displacement under grinding vibration. Through the synergy of these structures, this device can achieve high-precision grinding of long and deep holes, while improving grinding efficiency and surface quality.

[0039] Furthermore, the directions or positional relationships described in this utility model are based on the directions or positional relationships shown in the accompanying drawings. They are only for the purpose of facilitating the description of this utility model and simplifying the description, and are not intended to indicate or imply that the device or structure referred to must have a specific orientation, or to operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0040] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A deep hole grinding shaft system device, comprising a mounting base (8), characterized in that: The mounting base (8) is respectively equipped with a housing (3), a linear bearing (7) installed between the housing (3) and the bearing seat (6), a front precision bearing assembly and a rear precision bearing assembly assembled in the bearing seat (6) and cooperating with the guide spindle (1); and a guide spindle (1) that runs through the bearing seat (6). The front precision bearing assembly includes two back-to-back arranged first precision angular contact bearings (9) and second precision angular contact bearings (10). The inner rings of the first precision angular contact bearings (9) and the second precision angular contact bearings (10) are locked to the guide spindle (1) by a first locking nut (11), and their outer rings are fixed to the front end face of the bearing seat (6) by a pressure cap (12). The rear precision bearing assembly includes a third precision angular contact bearing (4), the inner ring of which is locked to the guide spindle (1) by a second locking nut (2), and a spring (5) abuts the rear end of its outer ring. The other end of the spring (5) is fixed to the rear end limiting surface of the bearing seat (6). The guide mandrel (1) is fitted with a guide seat (14) connected to the housing (3) on the outer side of the front end, and a sealing ring (13) is distributed between the pressure cap (12) and the guide mandrel (1).

2. The deep hole grinding shaft system device according to claim 1, characterized in that: The inner ring of the linear bearing (7) is precisely fitted with the outer wall of the bearing seat (6), and its outer ring is precisely fitted with the inner wall of the housing (3); the linear bearing (7) is a ball linear bearing, which allows the bearing seat (6) to slide with high precision along the axial direction of the housing (3).

3. The deep hole grinding shaft system device according to claim 1, characterized in that: The rear end of the guide mandrel (1) is connected to a drive shaft sleeve by a thermal interference fit, and its front end has a threaded hole for fixing the grinding wheel.

4. The deep hole grinding shaft system device according to claim 1, characterized in that: The first precision angular contact bearing (9), the second precision angular contact bearing (10) and the third precision angular contact bearing (4) are all angular contact ball bearings, and the first precision angular contact bearing (9) and the second precision angular contact bearing (10) are arranged back to back.

5. The deep hole grinding shaft system device according to claim 1, characterized in that: The spring (5) is a cylindrical helical compression spring. The preload of the spring (5) is adjusted by the spring seat to compensate for the temperature rise deformation of the guide spindle (1).

6. The deep hole grinding shaft system device according to claim 1, characterized in that: The sealing ring (13) is a rubber sealing ring, and a sealing gasket is provided between the pressure cap (12) and the bearing seat (6) to prevent chips and coolant from entering the interior of the bearing seat (6).

7. The deep hole grinding shaft system device according to claim 1, characterized in that: The guide seat (14) is an annular metal part, which is fixed to the housing (3) by a plurality of first screws. There is a rotation and sliding gap between its inner wall and the guide spindle (1) to achieve secondary guidance.

8. The deep hole grinding shaft system device according to claim 1, characterized in that: The mounting base (8) has several mounting holes, and the housing (3) is fixed to the mounting base (8) by several second screws.

9. The deep hole grinding shaft system device according to claim 1, characterized in that: The pressure cap (12) is fixed to the front end face of the bearing seat (6) by a number of third screws. The pressure cap (12) is an annular metal pressure cap.

10. The deep hole grinding shaft system device according to claim 1, characterized in that: The bearing housing (6) is a cylindrical metal housing with steps on its inner wall for positioning the first precision angular contact bearing (9), the second precision angular contact bearing (10) and the third precision angular contact bearing (4).

Images