High-precision conical hydrostatic bearing spindle device

Abstract

The application belongs to the technical field of precision equipment manufacturing, and particularly relates to a high-precision conical hydrostatic bearing main shaft device, which comprises a main shaft, a front cover, a front throttle plate, a front shunt plate, a front bearing, a rear bearing, a sleeve, an adjusting pad, a conical sleeve, a rear shunt plate, a rear throttle plate, a locking nut and a rear cover. The main shaft comprises a journal with a conical surface, the journal is matched with the front bearing, the adjusting pad, the conical sleeve, the locking nut and the main shaft form a rotary body, the locking nut is used for fixing the adjusting pad and the conical sleeve on the main shaft, the rear bearing is sleeved on the conical sleeve, and the journal and the front bearing and the rear bearing and the conical sleeve all have lubricating gaps, lubricating oil can enter the lubricating gaps to form a pressure oil film. Compared with the prior art, the application fills the gap of the small-diameter (≤45 mm) high-precision conical hydrostatic bearing series main shaft for micro grinders, and innovatively designs a parallel plate throttle and has some innovations in the structure of the main shaft component.

Description

Technical Field

[0001] This invention relates to the field of precision equipment manufacturing technology, and more specifically, to a high-precision tapered hydrostatic bearing spindle device. Background Technology

[0002] Currently, the existing tapered hydrostatic bearing spindles used for grinding wheel spindles (grinding heads) and workpiece spindles in medium-sized grinding machines have the following disadvantages: 1. The diameter of the cone at the junction of the rotary shaft and the bearing is too large, making it unsuitable for micro internal and external cylindrical grinding machines with high rotational speeds. This is because the high rotational speed increases the surface linear velocity at the journal and the temperature rise caused by relative friction with the lubricating oil, affecting the normal operation of the grinding machine. This is especially true for high-precision micro grinding machines. In addition, its overall structure is too large to be installed on micro grinding machines. 2. Medium-sized grinding machines mostly use cylindrical hydrostatic radial bearings and disc-shaped hydrostatic thrust bearings. The thrust disc is relatively large and generates more heat. 3. Most of them use small-hole throttles or feedback throttles. However, when the oil passes through the former, it is in a turbulent state, which increases the temperature. Moreover, the small hole (hole diameter ≤ 0.5 mm) is easily blocked, causing accidents. The latter has a more complex structure and higher manufacturing cost, so it is rarely used. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a high-precision tapered hydrostatic bearing spindle device that solves the above-mentioned technical problems.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A high-precision tapered hydrostatic bearing spindle assembly includes a spindle, a front cover, a front throttle plate, a front distributor plate, a front bearing, a rear bearing, a sleeve, an adjusting shim, a tapered sleeve, a rear distributor plate, a rear throttle plate, a lock nut, and a rear cover. The front cover, front throttle plate, front splitter plate, and front bearing are all located on one side of the sleeve. The rear bearing, adjusting shim, tapered sleeve, rear splitter plate, rear throttle plate, lock nut, and rear cover are located on the other side of the sleeve. The front cover, front throttle plate, front splitter plate, front bearing, sleeve, adjusting shim, tapered sleeve, rear splitter plate, rear throttle plate, lock nut, and rear cover are all fitted onto the main shaft. The spindle includes a journal with a tapered surface, which is fitted with a front bearing. The adjusting shim, tapered sleeve, lock nut, and spindle form a rotating body. The lock nut is used to fix the adjusting shim and tapered sleeve onto the spindle, and the rear bearing is sleeved on the tapered sleeve. There are lubrication gaps between the journal and the front bearing, and between the rear bearing and the tapered sleeve, allowing lubricating oil to enter the lubrication gaps and form a pressure oil film.

[0005] Furthermore, the rear cover is provided with an oil inlet hole, and the rear throttle plate is provided with an oil outlet hole corresponding to the oil inlet hole. The sleeve is provided with an elongated hole and an oil drain hole. Both the front bearing and the rear bearing are provided with interconnected oil passages and oil cavities, and the oil cavities and lubrication gaps are correspondingly connected. Both the front and rear throttle plates are provided with an annular groove, a throttling groove, and a waist-shaped groove connected in sequence. The throttling groove is rectangular, and the inlet hole is connected to the annular groove on the rear throttle plate. Both the front and rear splitter plates are provided with a first oil distribution hole and a second oil distribution hole. The elongated hole can connect the first oil distribution hole of the front splitter plate and the first oil distribution hole of the rear splitter plate. The second oil distribution hole of the front splitter plate connects the waist-shaped hole of the front throttle plate and the oil passage of the front bearing. The second oil distribution hole of the rear splitter plate connects the waist-shaped groove of the rear throttle plate and the oil passage of the rear bearing.

[0006] Furthermore, both the front and rear bearings include tapered bores, with the larger diameter side of the tapered bore facing outwards and the smaller diameter side facing inwards.

[0007] Furthermore, there can be 3-6 elongated holes, throttling grooves, waist-shaped grooves, first oil distribution holes, second oil distribution holes, and oil cavities, with the throttling grooves and waist-shaped grooves arranged in a ring.

[0008] Furthermore, both the front and rear covers are threadedly connected to the main shaft.

[0009] Furthermore, this device can be applied to internal and external grinding machines as well as lathes.

[0010] By adopting the above technical solution, the beneficial effects of the present invention are as follows: 1. This invention fills a gap in the micro-grinding machine market by introducing a series of high-precision tapered hydrostatic bearing spindles with small diameter (≤45mm). It features an innovative parallel plate throttle design and structural innovations in the spindle components. This design allows for adjustments to the dimensions of the shaft and bearing journal or the front and rear ends of the spindle, without altering the overall structure, to meet the requirements of different micro-grinding machines. This facilitates the development of a series of products and creates conditions for assembly line processing. 2. Because the outer surface of the spindle journal and the inner surface of the front bearing are completely separated by a layer of pressure oil film, forming pure fluid lubrication, the surfaces of the journal and the bearing hole (tapered hole) do not come into direct contact, and there is no wear during operation; thus, its service life is greatly extended, and it can be maintained for a long time without maintenance. 3. Due to the presence of the pressure oil film, the manufacturing precision of the journal and bearing bore can be maintained for a long time, thus ensuring that the rotational precision of the spindle remains unchanged. 4. Due to the presence of the oil film, the required drive power is small, and the spindle rotates smoothly; 5. Due to the presence of the pressure oil film, it can compensate for the manufacturing errors of the journal and bearing hole. For example, when the roundness error of the journal and bearing hole is 3μm, the rotation accuracy can be around 1μm when they are assembled and driven to rotate. This is a prominent advantage of the hydrostatic bearing spindle, and therefore it is extremely beneficial for obtaining high-precision rotation characteristics. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention.

[0012] Figure 2 This is a schematic diagram of the exploded structure according to an embodiment of the present invention.

[0013] Figure 3 This is a side view of an embodiment of the present invention.

[0014] Figure 4 This is a schematic cross-sectional view of section AA in an embodiment of the present invention.

[0015] Figure 5 This is a cross-sectional structural diagram of an embodiment of the present invention.

[0016] Figure 6 This is a schematic cross-sectional view of section BB in an embodiment of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0019] like Figure 1 As shown, the high-precision tapered hydrostatic bearing spindle assembly includes a spindle 1, a front cover 2, a front throttle plate 3, a front distributor plate 4, a front bearing 5-1, a rear bearing 5-2, a sleeve 6, an adjusting shim 7, a tapered sleeve 8, a rear distributor plate 9, a rear throttle plate 10, a lock nut 11, and a rear cover 12. These components are installed as follows: The front bearing 5-1 and the rear bearing 5-2 are of the same size, have an inner tapered bore, and have four oil chambers 501. They are installed in corresponding holes at the front and rear of the sleeve. The main shaft 1 with a single conical journal is inserted from the front of the sleeve 6, so that the outer tapered surface of the main shaft 1 is against the tapered bore of the front bearing 5-1. The adjusting shim 7 is inserted from the rear end of the main shaft 1 and abuts against the end face of the journal corresponding to the inner bore of the adjusting shim 7. The tapered sleeve 8 is also inserted from the rear end of the main shaft 1 and is close to the right end face of the adjusting shim 7, with the outer tapered surface of the tapered sleeve 8 abutting against the tapered bore of the rear bearing 5-2. Two locking nuts 11 are inserted from... The rear end of the spindle 1 is inserted and screwed onto the external thread of the spindle 1 in sequence, and is close to the right end face of the adjusting shim 7. At this point, the adjusting shim 7, the tapered sleeve 8, and the locking nut 11 are assembled with the spindle 1 into a rotating body with a conical journal. The front bearing 5-1 and the rear bearing 5-2 are arranged in reverse (i.e., the large end of the tapered surface faces outward and the small end faces inward) and are installed in the holes at both ends of the sleeve 6. The journal of the spindle 1 is integrated with the shaft. The tapered sleeve 8 is fixed to the spindle 1 by the adjusting shim 7 and two locking nuts 11. The ideal oil film clearance can be obtained by matching the thickness of the adjusting shim 7. The front oil distributor plate 4 is fitted onto the spindle 1 from the front end and enters the larger hole at the front end of the sleeve 6, close to the common end face formed by the large hole and the left side of the front bearing 5-1. Then, the front throttle plate 3 is installed and close to the left end face of the front oil distributor plate 4. Next, the front cover 2 is also installed from the front end of the spindle 1 into the large hole of the sleeve 6 and close to the left end face of the front throttle plate 3. Then, the internal hexagon screw with washers is screwed through the through holes of the front cover 2, the front throttle plate 3, and the front oil distributor plate 4 into the threaded hole of the sleeve 6, fixing the front cover 2, the front throttle plate 3, and the front oil distributor plate 4 in the hole of the sleeve 6. As described above, the rear oil distributor plate 9, the rear throttle plate 10, and the rear cover 12 are then installed into the large hole at the rear end of the sleeve 6 and fixed with internal hexagon screws. At this point, the assembly of the high-precision tapered hydrostatic bearing spindle component of the micro grinder is completed.

[0020] The device of this invention is a high-precision hydrostatic bearing spindle for a micro grinder. It is a device that completely separates the rotating spindle from the sliding bearing surface (oil chamber 501) by setting pressure oil, forming a pure fluid lubrication state. There is no friction between the journal and the bearing metal surface when the spindle is running, so it is an excellent slewing bearing.

[0021] like Figure 2As shown, the front oil distribution plate 4 and the rear oil distribution plate 9 installed in the inner hole of the sleeve 6 are both disc-shaped. On the same side of each of them, there is a first oil distribution hole 401 to distribute pressurized oil. On the same circumference of each of them, there are four second oil distribution holes 402 evenly distributed to complete the delivery of pressurized oil after throttling into the four corresponding oil chambers 501 of the front bearing 5-1 and the rear bearing 5-2. The front section plate 3 and the rear throttling plate 10 installed axially in the inner hole of the sleeve 6 are also disc-shaped. On one side of each of their end faces, there is an annular groove 301, four evenly distributed rectangular shallow throttling grooves 302 connected to the annular groove 301, and four shorter waist grooves 303 connected to the throttling grooves 302. The four waist grooves 303 of each correspond to the four second oil distribution holes 402 on the front oil distribution plate and the rear oil distribution plate, so that the throttled pressurized oil can be injected into the four oil chambers 501 of the front bearing 5-1 and the rear bearing 5-2. The front and rear throttling plates with rectangular shallow grooves are a new type of parallel plate throttling device, which is the first of its kind in hydrostatic support throttling devices; Pressurized oil enters through the inlet hole 1201 at the oil pipe joint on one side of the rear cover 10, passes through the oil delivery hole 1001, the annular groove 301, and the first oil distribution hole 401, and then enters the elongated hole 601 of the sleeve 6. Pressurized oil from the front end of the elongated hole 601 passes through the oil delivery hole 1001 on the rear side of the front oil distribution plate 3 and enters the annular groove 301 of the front throttling plate 3. From the annular groove 301, it flows to four radially evenly distributed throttling grooves 302. The throttling grooves 302 are rectangular shallow grooves that can throttle and generate pressure drop; they are parallel plate throttling devices. The oil with pressure drop enters four waist-shaped grooves, and then enters the four second oil distribution holes 4 corresponding to the waist grooves 303 of the front oil distribution plate 4 and the front throttling device 3. 02. The oil then flows through the four oil passages 502 of the front bearing 5-1 and finally enters the four oil chambers 501 of the front bearing 5-1, thus completing the oil supply route at the front end. Before the pressurized oil entering from the rear cover 12 passes through the rear oil distribution plate 9 and the rear throttle plate 10 and enters the long hole 601 of the sleeve 6, the pressurized oil has also entered the annular groove 301 of the rear throttle plate 10. Then, it flows from the annular groove 301 to the four radially evenly distributed rectangular shallow grooves. Similar to the front end, the oil with pressure drop passes through the four waist-shaped grooves, the four second oil distribution holes 402 of the rear oil distribution plate 9, and the four oil passages 502 on the end face of the rear bearing 5, and finally enters the four oil chambers 501 of the bearing 5, thus completing the oil supply route at the rear end.

[0022] The pressure oil film formed by the lubricating oil with pressure drop on the surfaces of the bearing (excluding the oil cavity 501, respectively called the circumferential oil-blocking surface and the axial oil-blocking surface) and the tapered surface of the spindle 1, after adjustment by the adjusting shim 7, completely separates the inner tapered surface of the bearing and the outer tapered surface of the spindle, forming a pure fluid lubrication state. This oil film has a predetermined load-bearing capacity and oil film stiffness (i.e., the ability to resist changes in external load), which are important design parameters to ensure the normal operation of the spindle.

[0023] When the spindle is working, due to the throttling devices (front and rear throttling plates), the throttling fluid resistance is fixed, and the pressurized oil will not flow back. Taking the spindle journal as an example of being subjected to an external force from directly above, the center of the journal relative to the center of the bearing hole will be displaced downward along the direction of the force. The oil film in the lower chamber decreases and the fluid resistance increases; the oil film in the upper chamber increases and the fluid resistance decreases. As a result, the pressure in the lower chamber increases and the pressure in the upper chamber decreases. The instantaneous pressure difference between the upper and lower chambers acts to resist the external load, allowing the spindle center to return to a certain distance upward and continue normal operation.

[0024] The front and rear covers can be machined with left-hand and right-hand shallow threads in their inner holes according to the direction of spindle rotation, which serve as a seal and allow the lubricating oil to flow inward. The oil is collected through the annular groove 301, the throttling groove 302, the waist-shaped groove, and the elongated hole 601 and discharged from the oil drain hole below the sleeve. The front and rear covers also serve to press and fix the oil distribution plate and the throttling plate.

[0025] In addition to being used to produce miniature high-precision internal and external cylindrical grinding machines and to modify various miniature ordinary internal and external cylindrical grinding machines to improve their machining accuracy, this invention can also replace the spindle of various miniature benchtop machines such as instrument lathes. It can be used to design high-precision products and develop new series, or to modify existing equipment to improve its machining accuracy.

[0026] The overall structure of the device of this invention can be slightly modified according to the different requirements of micro-grinding machines, and can become a series of high-precision conical hydrostatic bearing spindles for micro-grinding machines, providing innovative products for production lines and automated production.

[0027] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any ordinary changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-precision tapered hydrostatic bearing spindle assembly, characterized in that, Includes main shaft, front cover, front throttle plate, front splitter plate, front bearing, rear bearing, sleeve, adjusting shim, tapered sleeve, rear splitter plate, rear throttle plate, lock nut and rear cover; The front cover, front throttle plate, front splitter plate, and front bearing are disposed on one side of the sleeve, and the rear bearing, adjusting shim, tapered sleeve, rear splitter plate, rear throttle plate, lock nut, and rear cover are disposed on the other side of the sleeve. The front cover, front throttle plate, front splitter plate, front bearing, sleeve, adjusting shim, tapered sleeve, rear splitter plate, rear throttle plate, lock nut, and rear cover are all sleeved on the main shaft. The main shaft includes a journal with a conical surface, which is adapted to the front bearing. The adjusting shim, the tapered sleeve, the locking nut, and the main shaft form a rotating body. The locking nut is used to fix the adjusting shim and the tapered sleeve on the main shaft. The rear bearing is sleeved on the tapered sleeve. Lubrication gaps are formed between the journal and the front bearing, and between the rear bearing and the tapered sleeve. The rear cover is provided with an oil inlet hole, the rear throttle plate is provided with an oil delivery hole corresponding to the oil inlet hole, the sleeve is provided with an elongated hole, and the front bearing and the rear bearing are respectively provided with interconnected oil passages and oil chambers, and the oil chambers are connected to the corresponding lubrication gaps. The front throttle plate and the rear throttle plate are each provided with an annular groove, a throttle groove and a waist-shaped groove connected in sequence on one side of their end faces. The throttle groove is connected to the annular groove and the corresponding waist-shaped groove, respectively. The throttle groove is a rectangular shallow groove opened on the end face of the throttle plate. Both the front and rear splitter plates are provided with a first oil distribution hole and a second oil distribution hole. The elongated hole of the sleeve connects the first oil distribution holes of the front and rear splitter plates. The second oil distribution holes on the front and rear splitter plates correspond to the waist-shaped grooves on the corresponding throttling plates, and are connected to the corresponding oil chambers through the oil passages of the front and rear bearings, respectively. This allows the pressurized oil to generate a pressure drop after passing through the rectangular shallow groove throttling groove and be supplied to the oil chambers of the front and rear bearings, forming a pressurized oil film in the lubrication gap. The thickness of the adjusting shim is used to determine the axial mounting position of the tapered sleeve relative to the spindle, so as to set the lubrication clearance between the rear bearing and the tapered sleeve.

2. The high-precision tapered hydrostatic bearing spindle device according to claim 1, characterized in that, Both the front and rear bearings include tapered holes, with the larger diameter side of the tapered hole facing outwards and the smaller diameter side facing inwards.

3. The high-precision tapered hydrostatic bearing spindle device according to claim 2, characterized in that, Each of the following components can be provided in 3-6 forms: elongated orifice, throttling groove, waist-shaped groove, first oil distribution hole, second oil distribution hole, and oil cavity. The throttling groove and waist-shaped groove are arranged in a ring.

4. A high-precision tapered hydrostatic bearing spindle assembly according to claim 1 or 3, characterized in that, Both the front cover and the rear cover are threadedly connected to the main shaft.

5. The high-precision tapered hydrostatic bearing spindle device according to claim 4, characterized in that, This device can be applied to internal and external grinding machines as well as lathes.

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