CN115383473B - Preloaded hydrostatic guideway assembly applied to machine tool and machine tool - Google Patents

Abstract

The application discloses a preloaded hydrostatic guideway component applied to a machine tool and the machine tool. The preload hydrostatic guideway assembly applied to the machine tool comprises a base, a slide carriage, a restrictor and a preload mechanism. A limiting chute is arranged on the base; the slide carriage is provided with a limiting lug matched with the limiting chute, the slide carriage is slidably arranged on the base, the slide carriage is provided with a liquid storage cavity, and the side surface of the limiting lug, which is close to the limiting chute, is provided with a static pressure cavity; the restrictor is communicated with the static pressure cavity; the preload mechanism is in communication with the reservoir for delivering liquid to or from the reservoir. The preloaded hydrostatic guideway assembly can provide preload, has simple structure and is more suitable for processing and assembly.

Description

Preloaded hydrostatic guideway assembly applied to machine tool and machine tool

Technical Field

The application relates to the technical field of processing machine tools, in particular to a preloaded hydrostatic guideway assembly applied to a machine tool and the machine tool.

Background

A machine tool for machining wood, metal, or polyester materials, etc., mainly includes a machine body, a rail assembly slidably mounted on the machine body, a tool structure mounted on the machine body or the rail assembly, etc.

In order to improve the machining accuracy and the service life of the machine tool, the rail assembly is generally configured as a hydrostatic rail assembly. When the hydrostatic guideway component moves, pure liquid friction can be realized by utilizing a high-pressure oil film, and the hydrostatic guideway component has the advantages of small abrasion, high movement precision, long average fault-free time, small driving power, large bearing capacity, good vibration absorption, stable movement and the like, so that the hydrostatic guideway component is widely applied to the field of ultra-precise machining tools and is one of key parts of the ultra-precise machining tools, wherein the advantages and disadvantages of the rigidity of the hydrostatic guideway component determine the machining precision of the precise ultra-precise machining tools to a great extent.

Currently, the hydrostatic guideway assemblies in common use include an open hydrostatic guideway assembly and a closed hydrostatic guideway assembly: the open hydrostatic guideway assembly has simple structure, but the oil film pressure is only determined by load, so the oil film rigidity is lower under small load, the guideway precision is lower, and the application range is limited. Besides the load, the closed hydrostatic guideway component provides initial preload force in the upper cavity, compared with the open hydrostatic guideway component, the oil film rigidity is greatly improved, but the structure is complex, the manufacturing and the adjustment are difficult, therefore, the requirements on processing equipment are high, and the requirements on the level of assembly staff are also extremely high.

Disclosure of Invention

The application mainly aims to provide a preload hydrostatic guideway assembly applied to a machine tool and the machine tool, and the preload hydrostatic guideway assembly can provide preload and has a simple structure and is more suitable for processing and assembly.

According to one aspect of an embodiment of the present application, there is provided a preloaded hydrostatic guideway assembly for a machine tool, comprising:

the base is provided with a limiting chute;

the sliding plate is provided with a limiting lug matched with the limiting chute, the sliding plate is slidably arranged on the base, the sliding plate is provided with a liquid storage cavity, and a static pressure cavity is arranged on the side surface, close to the limiting chute, of the limiting lug;

a restrictor in communication with the hydrostatic chamber; and

and the preloading mechanism is communicated with the liquid storage cavity and used for conveying liquid to the liquid storage cavity or outputting liquid from the liquid storage cavity.

Further, the liquid storage cavity is arranged on one side, far away from the base, of the slide carriage, and the depth of the liquid storage cavity in the thickness direction of the slide carriage is unchanged.

Further, the liquid storage cavities are multiple, and the liquid storage cavities are laid on one side, away from the base, of the slide carriage side by side.

Further, the preloaded hydrostatic guideway assembly for a machine tool also includes a top cover plate disposed on top of the slide carriage to seal the liquid storage chamber.

Further, a liquid inlet and a liquid outlet are formed in the liquid storage cavity, the liquid inlet is formed in the top of the side wall of the liquid storage cavity, and the liquid outlet is formed in the bottom of the side wall of the liquid storage cavity.

Further, the preload mechanism includes:

the liquid storage device comprises a liquid storage device, a liquid inlet, a liquid outlet and a liquid outlet, wherein the liquid storage device is used for loading liquid, the liquid inlet is communicated with the liquid storage device through a first pipeline, and the liquid outlet is communicated with the liquid storage device through a second pipeline;

a first hydraulic pump disposed on the first conduit;

the first control valve is arranged on the first pipeline and is positioned between the first hydraulic pump and the liquid inlet so as to control the on-off of the first pipeline; and

the second control valve is arranged on the second pipeline to control the on-off of the second pipeline.

Further, the preloading mechanism further comprises a liquid cooler which is communicated with the liquid storage device to cool liquid in the liquid storage device.

Further, a first filter and a first pressure gauge are arranged on the first pipeline, and the first filter and the first pressure gauge are both arranged between the first hydraulic pump and the first control valve.

Further, the limit protruding block is a V-shaped block, a plurality of static pressure cavities are formed in two side wall surfaces of the V-shaped block, and each static pressure cavity is communicated with the restrictor.

On the other hand, the application also provides a machine tool which is a milling machine tool or a polishing machine tool, and the machine tool comprises the preloaded hydrostatic guideway assembly.

Compared with the prior art, the technical scheme of the application has at least the following technical effects:

because the slide carriage of the hydrostatic guideway assembly is provided with the liquid storage cavity, the hydrostatic guideway assembly is connected with the liquid storage cavity through the preloading mechanism in the actual use process, and then liquid can be conveyed to the liquid storage cavity. That is, the present application can apply a predetermined load to the carriage by providing the liquid storage chamber and the preload mechanism.

When the hydrostatic guideway assembly is actually used, a preset load can be applied to the slide carriage before the hydrostatic guideway assembly starts to work, and after a workpiece and other structures are installed on the slide carriage, an oil film gap between the slide carriage and a base is relatively stable, so that the rigidity of the hydrostatic guideway assembly can be improved, and the hydrostatic guideway assembly can be widely applied to ultra-precise machine tools instead of open hydrostatic guideway and closed hydrostatic guideway. Meanwhile, the liquid storage cavity is only required to be processed on the slide carriage and the corresponding preloading mechanism is provided for conveying and extracting the liquid, so that the liquid storage device is simple in structure and convenient to process and assemble.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:

FIG. 1 is a schematic illustration of the base, carriage and top deck portions of a preloaded hydrostatic rail assembly according to an embodiment of the present application;

FIG. 2 is a schematic illustration of the configuration of a carriage in a preloaded hydrostatic guideway assembly according to an embodiment of the present disclosure;

FIG. 3 is a diagram illustrating the connection of various structures of a preloaded hydrostatic guideway assembly according to an embodiment of the present application.

Wherein the above figures include the following reference numerals:

10. a base; 11. limiting sliding grooves; 20. a slide carriage; 21. a limit bump; 22. a liquid storage cavity; 221. a liquid inlet; 222. a liquid outlet; 23. a static pressure cavity; 30. a throttle; 40. a preload mechanism; 41. a reservoir; 42. a first pipe; 43. a second pipe; 44. a first hydraulic pump; 45. a first control valve; 46. a second control valve; 47. a liquid cooling machine; 48. a first filter; 49. a first pressure gauge; 410. a first overflow valve; 50. a top cover plate; 60. an oil tank; 70. a second filter; 80. a second hydraulic pump; 90. a third filter; 100. a second overflow valve; 110. and a second pressure gauge.

Detailed Description

It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The application will be described in detail below with reference to the drawings in connection with embodiments.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present application. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.

The relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application unless it is specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective parts shown in the drawings are not drawn in actual scale for convenience of description. Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but should be considered part of the authorization specification where appropriate. In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.

Referring to fig. 1-3, a preloaded hydrostatic rail assembly, hereinafter hydrostatic rail assembly, for use in a machine tool is provided in accordance with an embodiment of the present application. The hydrostatic rail assembly is particularly suitable for use in milling or polishing machines and includes a base 10, a carriage 20, a restrictor 30, and a preload mechanism 40.

Wherein, the base 10 is provided with a limit chute 11; a limiting lug 21 matched with the limiting chute 11 is arranged on the slide carriage 20, the slide carriage 20 is slidably arranged on the base 10, a liquid storage cavity 22 is arranged on the slide carriage 20, and a static pressure cavity 23 is arranged on the side surface, close to the limiting chute 11, of the limiting lug 21; restrictor 30 communicates with hydrostatic cavity 23; the preload mechanism 40 communicates with the reservoir 22 for delivering liquid to the reservoir 22 or for delivering liquid from within the reservoir 22.

Because the carriage 20 of the hydrostatic rail assembly of this embodiment is provided with the fluid storage chamber 22, during actual use, the fluid storage chamber 22 is connected to the fluid storage chamber 40 by the preloading mechanism 40, so that fluid can be supplied to the fluid storage chamber 22. That is, the present application can apply a predetermined load to the carriage 20 by providing the reservoir 22 and the preload mechanism 40.

When the hydrostatic guideway assembly is actually used, a preset load can be applied to the slide carriage 20 before the hydrostatic guideway begins to work, and after a workpiece and other structures are installed on the slide carriage 20, an oil film gap between the slide carriage 20 and the base 10 is relatively stable, so that the rigidity of the hydrostatic guideway assembly in the embodiment can be improved, and the hydrostatic guideway assembly can be widely applied to ultra-precise machine tools instead of open hydrostatic guideway and closed hydrostatic guideway. Meanwhile, the application only needs to process the liquid storage cavity 22 on the slide carriage 20 and be provided with the corresponding preloading mechanism 40 for conveying and extracting the liquid, and the application has simple structure and is convenient to process and assemble.

Specifically, the base 10 in this embodiment is a plate-shaped structure, the limit sliding grooves 11 are disposed on the upper surface of the base 10, and the limit sliding grooves 11 may be one, two or more, and specifically, the design and selection are performed according to actual use and limit requirements, and in this embodiment, the situation when the limit sliding grooves 11 are disposed in two is shown in fig. 1. Correspondingly, one, two or more than two limit protrusions 21 may be provided on the slide carriage 20, and in this embodiment, the case where two limit protrusions 21 are shown in fig. 1 is shown. Through the cooperation of the two limiting lugs 21 and the two limiting sliding grooves 11, the slide carriage 20 can be effectively limited and supported.

Further, the slide carriage 20 in this embodiment is generally a rectangular plate structure, and the limit bump 21 is a V-shaped block disposed at the bottom of the slide carriage 20, which is understood to refer to a V-shaped block structure when viewed from the side, as can be seen in fig. 1. The two side wall surfaces (i.e., the left and right side surfaces in fig. 1) of the V-shaped block are each provided with a plurality of hydrostatic chambers 23, and each hydrostatic chamber 23 communicates with the throttle 30. It will be appreciated that the restrictor 30 in this embodiment is an integrated structure, each hydrostatic cavity 23 is in communication with the restrictor 30, and by virtue of the restrictor 30, the pressure and flow of the oil entering the hydrostatic cavity 23 can be regulated, so that the rigidity of the hydrostatic guideway assembly in this embodiment can be further ensured.

Alternatively, the liquid storage chamber 22 in the present embodiment is disposed on a side of the slide carriage 20 away from the base 10, and the depth of the liquid storage chamber 22 in the thickness direction of the slide carriage 20 is unchanged. That is, the depth of each portion of the liquid storage chamber 22 in the thickness direction of the slide carriage 20 is kept constant, and the bottom surface of the liquid storage chamber 22 is a plane. Through making the depth of liquid storage chamber 22 in carriage 20 thickness direction unchanged, after carrying liquid to liquid storage chamber 22 in, the load that liquid was exerted to each part of the bottom surface of liquid storage chamber 22 is equal, can prevent carriage 20 receives too big load and take place the skew in a certain position, is more suitable for guaranteeing the rigidity of hydrostatic guideway subassembly in this embodiment, can effectively improve the machining precision and the life of lathe.

Alternatively, there may be one or more liquid storage chambers 22, and in this embodiment, it is preferable to provide a plurality of liquid storage chambers 22, where the plurality of liquid storage chambers 22 are laid side by side on the side of the slide carriage 20 away from the base 10. Illustratively, the liquid storage chambers 22 in the present embodiment may be provided as two, three, four, or more than four. Fig. 2 of the present embodiment shows the case where the liquid storage chambers 22 are six. Through setting up liquid storage chamber 22 to a plurality ofly, in the in-service use's in-process, can carry liquid in order to apply predetermined load to different positions of carriage 20 according to the assembly and the processing condition in each position of carriage 20 in order to the carriage 20, so, can guarantee carriage 20 upper surface's planarization, can improve the machining precision of work piece.

Further, each liquid storage cavity 22 in the present embodiment is provided with a liquid inlet 221 and a liquid outlet 222, where the liquid inlet 221 is located at the top of the side wall of the liquid storage cavity 22, i.e. the highest position of the liquid storage cavity 22, and the liquid outlet 222 is located at the bottom of the side wall of the liquid storage cavity 22, i.e. the lowest position of the liquid storage cavity 22, so as to facilitate filling and discharging of the liquid in the liquid storage cavity 22. The liquid in this embodiment may be oil, water or another fluid medium, and is not particularly limited in the present application as long as it is another medium that can be filled into the liquid storage chamber 22 to preload the slide carriage 20.

To seal the fluid storage chamber 22, the hydrostatic rail assembly of this embodiment also includes a top cover plate 50, the top cover plate 50 being disposed on top of the carriage 20 so that the fluid storage chamber 22 can be sealed. Optionally, a sealing ring or the like may be further disposed between the top cover 50 and the slide carriage 20 to further improve the sealing performance of the liquid storage chamber 22.

As shown again in fig. 1 to 3, the preload mechanism 40 in the present embodiment includes a reservoir 41, a first hydraulic pump 44, a first control valve 45, and a second control valve 46. Wherein, the liquid storage 41 is used for loading liquid, the liquid inlet 221 is communicated with the liquid storage 41 through the first pipeline 42, and the liquid outlet 222 is communicated with the liquid storage 41 through the second pipeline 43; the first hydraulic pump 44 is disposed on the first pipe 42 to facilitate pumping the liquid in the liquid reservoir 41 to the first pipe 42; the first control valve 45 is disposed on the first pipeline 42 and located between the first hydraulic pump 44 and the liquid inlet 221 to control on-off of the first pipeline 42; the second control valve 46 is provided on the second pipe 43 to control on-off of the second pipe 43. Alternatively, the first control valve 45 and the second control valve 46 in the present embodiment are both electromagnetic directional valves. Through the cooperative control action of the first hydraulic pump 44, the first control valve 45 and the second control valve 46, liquid is conveniently input into or discharged out of the liquid storage cavity 22, and the hydraulic pump is simple in structure and convenient to assemble and disassemble.

Further, the first pipeline 42 is provided with a first filter 48 and a first pressure gauge 49, the first filter 48 and the first pressure gauge 49 are both arranged between the first hydraulic pump 44 and the first control valve 45, liquid entering the liquid storage cavity 22 is convenient to filter under the action of the first filter 48, and the pressure of the liquid entering the liquid storage cavity 22 is convenient to monitor under the action of the first pressure gauge 49.

Further, the preloading device 40 further includes a first overflow valve 410, the liquid inlet end of the first overflow valve 410 is connected to the first pipe 42, the liquid outlet end is communicated with the liquid reservoir 41, and the connection position between the liquid inlet end of the first overflow valve 410 and the first pipe 42 is located between the first filter 48 and the first hydraulic pump 44, and by the action of the first overflow valve 410, the working stability of the preloading device 40 can be improved.

Further, the preload mechanism 40 further includes a liquid cooler 47, and the liquid cooler 47 communicates with the reservoir 41 to cool the liquid in the reservoir 41. The liquid is cooled to a set temperature of 20 ℃ by a liquid cooler 47 in the liquid storage 41 (which can be adjusted according to actual conditions), and then is pressurized by a first hydraulic pump 44 and enters the corresponding liquid storage cavity 22 on the slide carriage 20 from a liquid inlet 221 through a first control valve 45. The cooling fluid in the reservoir 22 is returned to the reservoir 41 through the outlet 222 via the second control valve 46.

In use, the amount of coolant in reservoir 22 is regulated by controlling the opening and closing times and the opening and closing states of first and second control valves 45 and 46 to apply a desired preload force to the hydrostatic rail assembly, causing the hydrostatic rail assembly to form a variable adjustment preload hydrostatic rail.

Further, the hydrostatic rail assembly in this embodiment is further provided with a tank 60, a second filter 70, a second hydraulic pump 80, a third filter 90, a second relief valve 100, and a second pressure gauge 110. The connection relationship among the oil tank 60, the second filter 70, the second hydraulic pump 80, the third filter 90, the second relief valve 100 and the second pressure gauge 110 is shown in fig. 3, and in fig. 3, the oil in the oil tank 60 may be filtered by the second filter 70 and then pumped to the restrictor 30 by the second hydraulic pump 80. The third filter 90 and the second pressure gauge 110 are disposed between the second filter 70 and the restrictor 30, so that the oil can be filtered again and the pressure can be detected, and the two ends of the second overflow valve 100 are respectively connected with the oil tank 60, the second hydraulic pump 80 and the restrictor 30 through pipelines, so that the working stability of the hydraulic oil path can be further improved.

The structure of hydrostatic rail assemblies incorporating the present application may be known:

before the hydrostatic guideway assembly starts to work, the liquid cooling machine 47 and the first hydraulic pump 44 are started first, at this time, the first control valve 45 at the liquid inlet 221 is controlled by the main machine of the machine tool, the second control valve 46 at the liquid outlet 222 side is temporarily in a closed state, and cooling liquid is injected into the liquid storage cavity 22 until the gravity of the cooling liquid injected into the liquid storage cavity 22 reaches the pre-loading force required by the initially designed hydrostatic guideway, at this time, the second control valve 46 at the liquid outlet 222 side is started, the cooling liquid is in circulation, and simultaneously, the slide carriage 20 is cooled.

When the hydrostatic guideway assembly is in a working state, a workpiece is additionally arranged on the slide carriage 20, and the pressure on the slide carriage 20 is unevenly distributed due to the different quality and the different positions during processing, so that the oil film gap between each hydrostatic cavity 23 and the base 10 is affected by the action of the parts on the hydrostatic cavity 23. At this time, the host machine can read the pressure of each hydrostatic cavity 23, and the amount of cooling oil in the liquid storage cavities 22 at the upper ends of different hydrostatic cavities 23 is regulated, so that the pressure of each hydrostatic cavity 23 is homogenized, the consistency of the oil film gap between the slide carriage 20 and the base 10 can be ensured, the surface flatness of the slide carriage 20 can be ensured, and the processing quality of a workpiece can be ensured.

The amount of initial cooling oil in the reservoir 22 is calculated to provide a preload force, and the hydrostatic chamber 23 is calculated to provide a load force, oil pressure, etc.

By adjusting the amount of cooling oil in reservoir 22, the hydrostatic rail assembly may be maintained in an optimal state of stiffness while also increasing the mass range of the hydrostatic rail pair carrying the workpiece.

On the other hand, the embodiment of the application also discloses a machine tool, which can be a milling machine tool or a polishing machine tool, and the machine tool comprises the preloaded hydrostatic guideway assembly in the embodiment, so that the machine tool in the embodiment comprises all technical effects of the preloaded hydrostatic guideway assembly, and the technical effects of the preloaded hydrostatic guideway assembly are described in detail in the foregoing, and are not repeated here.

From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

1. the application provides a preload force for the hydrostatic guideway assembly by controlling the amount of the cooling liquid filled in the liquid storage cavity, can improve the rigidity of the guideway, and can replace open hydrostatic guideway and closed hydrostatic guideway to be widely applied to ultra-precision machine tools.

2. According to the application, the liquid storage cavity is arranged on the slide carriage, so that the volume space can be reasonably utilized.

3. According to the application, the liquid storage cavity cooling liquid circulation mechanism is added on the slide carriage, so that the slide carriage can be cooled, the slide carriage can be kept at constant temperature all the time in the part processing process, and the processing error caused by temperature change is avoided.

4. When a workpiece is additionally arranged on the slide carriage, the host machine can read the pressure of each static pressure cavity through the pressure sensor, the pressure of each static pressure cavity can be homogenized through adjusting the quantity of cooling liquid in liquid storage cavities at the upper ends of different static pressure cavities, the consistency of the integral oil film gap between the slide carriage and the base is ensured, the surface flatness of the slide carriage can be further ensured, and finally the purpose of ensuring the processing quality of the workpiece is achieved.

Spatially relative terms, such as "above … …," "above … …," "upper surface at … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial location relative to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "over" other devices or structures would then be oriented "below" or "beneath" the other devices or structures. Thus, the exemplary term "above … …" may include both orientations of "above … …" and "below … …". The device may also be positioned in other different ways (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

In addition, the terms "first", "second", etc. are used to define the components, and are only for convenience of distinguishing the corresponding components, and the terms have no special meaning unless otherwise stated, and therefore should not be construed as limiting the scope of the present application.

The above is only a preferred embodiment of the present application, and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (7)

1. A preloaded hydrostatic guideway assembly for a machine tool, comprising:

the base (10) is provided with a limiting chute (11);

the sliding plate comprises a sliding plate (20), wherein a limiting lug (21) matched with the limiting chute (11) is arranged on the sliding plate (20), the sliding plate (20) is slidably arranged on the base (10), a liquid storage cavity (22) is arranged on the sliding plate (20), and a static pressure cavity (23) is arranged on the side surface, close to the limiting chute (11), of the limiting lug (21);

the throttle device comprises a throttle device (30), wherein the throttle device (30) is communicated with a static pressure cavity (23), a liquid storage cavity (22) is arranged on one side, far away from a base (10), of a slide carriage (20), the depth of the liquid storage cavity (22) in the thickness direction of the slide carriage (20) is unchanged, a plurality of liquid inlets (221) and liquid outlets (222) are formed in the liquid storage cavity (22), the liquid storage cavities (22) are arranged on one side, far away from the base (10), of the slide carriage (20) side by side, and the pressure of each static pressure cavity (23) is homogenized by adjusting the quantity of cooling oil in the liquid storage cavity (22) at the upper end of the static pressure cavity (23);

the liquid storage device comprises a preloading mechanism (40), wherein the preloading mechanism (40) is communicated with a liquid storage cavity (22) for conveying liquid to the liquid storage cavity (22) or outputting the liquid from the liquid storage cavity (22), the preloading mechanism (40) comprises a liquid storage device (41) and a liquid cooling machine (47), the liquid storage device (41) is used for loading the liquid, a liquid inlet (221) is communicated with the liquid storage device (41) through a first pipeline (42), a liquid outlet (222) is communicated with the liquid storage device (41) through a second pipeline (43), and the liquid cooling machine (47) is communicated with the liquid storage device (41) for cooling the liquid in the liquid storage device (41).

2. The preloaded hydrostatic rail assembly for a machine tool of claim 1, further comprising a top cover plate (50), said top cover plate (50) being disposed on top of said slide carriage (20) to seal said reservoir (22).

3. The preloaded hydrostatic rail assembly for a machine tool of claim 1, wherein said liquid inlet (221) is located at the top of the side wall of said liquid storage chamber (22), and said liquid outlet (222) is located at the bottom of the side wall of said liquid storage chamber (22).

4. A preloaded hydrostatic rail assembly for a machine tool as claimed in claim 3, wherein said preloading organ (40) further comprises:

a first hydraulic pump (44), the first hydraulic pump (44) being arranged on the first conduit (42);

the first control valve (45) is arranged on the first pipeline (42) and is positioned between the first hydraulic pump (44) and the liquid inlet (221) so as to control the on-off of the first pipeline (42); and

and the second control valve (46) is arranged on the second pipeline (43) to control the on-off of the second pipeline (43).

5. The preloaded hydrostatic guideway assembly for a machine tool according to claim 4, characterized in that a first filter (48) and a first pressure gauge (49) are provided on the first pipe (42), the first filter (48) and the first pressure gauge (49) being both provided between the first hydraulic pump (44) and the first control valve (45).

6. Preloaded hydrostatic rail assembly for a machine tool according to any one of claims 1 to 5, characterized in that the limit projection (21) is a V-shaped block, on both side wall surfaces of which a plurality of said hydrostatic pockets (23) are provided, each said hydrostatic pocket (23) being in communication with the restrictor (30).

7. A machine tool which is a milling machine or a grinding and polishing machine, characterized in that it comprises a preloaded hydrostatic guideway assembly according to any one of claims 1 to 6.