CN103909469B - A roll grinder grinding wheel spindle film section hydrostatic pressure bearing - Google Patents

Abstract

The present invention proposes a kind of grinder grinding wheel main shaft film throttling dynamic and hydrostatic bearing.Described bearing it comprise the upper static pressure chamber and lower static pressure chamber that are arranged symmetrically; Described upper static pressure chamber and lower static pressure chamber are connected with outside fuel feed hole, are connected with two-side film membrane flow controller by oil circuit; It also comprises front static pressure chamber and rear dynamic pressure cavity; Described front static pressure chamber is connected with outside fuel feed hole, is communicated with single-sided film flow controller by oil circuit.The invention solves grinder grinding wheel main shaft film throttling dynamic and hydrostatic bearing design challenges.Compare traditional capillary-compensated dynamic and hydrostatic bearing, film throttling dynamic and hydrostatic bearing has very high rigidity under the hydrostatic pressure condition started; Under main shaft High Rotation Speed hybrid condition, film throttling dynamic and hydrostatic bearing has high bearing capacity, higher stiffness and low-temperature-rise simultaneously, meets the requirement such as high efficiency, high rigidity, high accuracy of modern roll grinder development.

Description

A roll grinder grinding wheel spindle film section hydrostatic pressure bearing

technical field

The invention relates to the field of the main shaft bearing of the grinding wheel of a roll grinder, in particular to a flow static pressure bearing of a thin film section of the main shaft of the grinding wheel of a roll grinding machine.

Background technique

At present, for the dynamic and static pressure hybrid bearings of the grinding wheel spindle of the roll grinder, the capillary restrictor in the fixed throttling is mostly used. The main reason is that the capillary restrictor has the following advantages: first, it is simple to manufacture; second, the load and stiffness of the capillary throttling hydrostatic bearing have nothing to do with the viscosity and temperature rise of the lubricating oil; third, the manufacturing error of the allowable clearance of the bearing is larger, allowing The operating temperature of the bearing varies greatly. However, the designed bearing has the following problems: first, the stiffness of the oil film is not very large, so that the machining accuracy of the grinding wheel spindle cannot be improved; second, the temperature of the oil film is relatively high under the high-speed condition of the bearing, so that the bearing will have a large temperature due to uneven temperature distribution. The thermal deformation of the spindle will affect the clearance between the spindle bearings, and finally affect the machining accuracy of the machine tool.

Therefore, for the dynamic and static pressure bearings of the grinding wheel spindle of the roll grinder, can the stiffness of the bearing be increased, the precision improved, and the temperature rise and energy consumption reduced by adopting a good throttling method on the basis of ensuring the optimized bearing structure? This is the difficulty and focus that needs to be solved all the time.

The thin-film restrictor is a new type of restrictor, which has all the advantages of the capillary restrictor, that is, the clearance, bearing capacity and stiffness of the bearing are also independent of the viscosity of the oil, and are not affected by the change of the ambient temperature; in addition, Higher bearing oil film stiffness and relatively lower temperature rise and power consumption can be obtained at high speeds. However, film restrictors have been used in hydrostatic bearings with symmetrical structures in the past. There is no design precedent for hydrostatic bearings and hydrostatic bearings with asymmetric structures, and there are technical prejudices in the industry.

Contents of the invention

Aiming at the deficiencies of the prior art, the object of the present invention is to provide a thin film section hydrostatic bearing for the grinding wheel spindle of a roll grinder, in order to obtain higher bearing oil film stiffness and relatively lower temperature rise and power consumption for the hydrostatic bearing. .

In order to solve the above-mentioned technical problems, the present invention provides a roll grinder grinding wheel spindle film section hydrostatic bearing, which includes an upper static pressure chamber and a lower static pressure chamber that are opposed to each other, and is located between the upper static pressure chamber and the lower static pressure chamber. The front static pressure chamber and the rear dynamic pressure chamber are oppositely set, and the upper static pressure chamber, the lower static pressure chamber and the front static pressure chamber are all provided with communicating oil holes, and the two ports of the double-sided film restrictor are the same as the upper static pressure chamber and the upper static pressure chamber respectively. The communication oil hole of the lower static pressure chamber is connected correspondingly; the port of the single-sided film restrictor is connected with the communication oil hole of the front static pressure chamber.

On the basis of optimizing the structural parameters of the dynamic and static pressure bearing of the main shaft of the grinding wheel of the roll grinder, the invention further adopts a new hybrid thin-film throttle to improve the stiffness and precision of the bearing and reduce the temperature rise and energy consumption. Structurally speaking, the film section flow static pressure bearing has three static pressure oil chambers above, below and front, and a dynamic pressure oil chamber (that is, the oil sealing surface). In view of the particularity of the bearing structure, it is obviously not suitable to use two double-sided film restrictors of traditional hydrostatic bearings, because a double-sided film restrictor must be connected to two opposing static pressure oil chambers. Considering that the bearing only has 3 static pressure oil chambers, a new hybrid film throttling method can be used for throttling, that is, a double-sided film restrictor is used for the upper and lower static pressure oil chambers; The chamber employs a single-sided membrane restrictor.

Double-sided film restrictors have two oil inlets, and are generally used in hydrostatic bearings with symmetrical structures; single-sided film restrictors have never been used in dynamic and static pressure bearings. Therefore, the design of the asymmetrical bearing structure of the present invention is extremely difficult, and hardly any technicians attempt it.

In this regard, the present invention overcomes the technical prejudice and adopts a bearing design method that is divided into blocks and then superimposed, that is, the structural parameters of the two film restrictors and the corresponding three static pressure oil chambers are firstly designed, and then the dynamic pressure is analyzed. The performance of the oil chamber, and then the performance parameters of the entire dynamic and hydrostatic bearing are calculated by the superposition method.

The specific bearing block principle in the design is: the upper and lower opposite static pressure oil chambers are the first block of the bearing, which is connected to a double-sided film restrictor; the front cavity is the second block of the bearing, and this block is connected to a single-sided film restrictor. Thin film restrictor; the dynamic pressure oil chamber is the third part of the bearing.

For the first piece of bearing, we can use MATLAB software to write the design program by referring to the general principle of double-sided thin-film flow hydrostatic bearing in the industry, and design the design parameters of the double-sided thin-film restrictor and the performance of the upper and lower hydrostatic oil chambers. parameter.

For the second piece of bearing, according to the design parameters such as the static pressure chamber in front of the bearing, combined with the single-sided thin-film throttle, use MATLAB software to write the design program to design the single-sided thin-film throttle corresponding to the front chamber (based on bearing infinite stiffness). Here, it is necessary to determine the bearing radius gap h and film thickness after the bearing is loaded , the throttling gap h _c of the film restrictor after loading, the film deformation coefficient K and other parameters; after that, the bearing capacity W of the front cavity, the flow rate Q corresponding to the front hydrostatic oil cavity, the friction power consumption N _f , Performance parameters such as pump power consumption N _p , front chamber temperature rise T, etc.,

In the second block of the bearing, the specific method for designing and determining the parameters of the front static pressure chamber and the single-sided film restrictor includes the following steps:

The front static plenum is rectangular, and the effective bearing area of the rectangular front static plenum is determined by the following method:

a. The hydraulic resistance ratio formula of the rectangular front static pressure chamber throttling through a single-sided membrane

Find the liquid resistance ratio ;

b. Calculate the effective bearing area of the rectangular front static pressure chamber :

Among them, r _c1 is the radius of the oil inlet hole of the circular table of the single-sided film restrictor, r _c2 is the radius of the circular table of the single-sided film restrictor; h ₀ is the bearing radius clearance, and h _c0 is the single-sided film throttle at the design load or no load Throttle gap; L is the length of the rectangular oil chamber, B is the width of the bearing, is the length of the axial oil seal edge, is the length of the circumferential oil seal edge of the rectangular oil cavity.

The film thickness in the single-sided film restrictor is determined by the following method:

a. by formula

Find the pressure of the front static pressure chamber under no load ; where P _s is the bearing oil supply pressure;

b. According to the infinite stiffness condition formula of single-sided film throttling in the front static pressure chamber

Deformation gives the film deformation coefficient formula:

Calculate the film deformation coefficient K, and Cc is the film control coefficient, that is, the maximum relative deformation of the film;

c. Through the calculation formula of the film thickness in the single-sided film restrictor:

Calculation of membrane thickness for single-sided membrane restrictors ;in is the elastic modulus of the film material, and m is Poisson's ratio.

The working parameters of the front static pressure chamber are determined by the following method:

a. According to the bearing capacity formula of the front static pressure chamber:

,

Select within the specified range and Calculate the bearing capacity of the oil cavity ;in The value is greater than or equal to 1MPa; is the bearing capacity coefficient, and its value must satisfy F _{external load X} , W ₂ is the static pressure bearing capacity of the front cavity; F _{external load X} is the external load of the bearing in X direction;

b. According to the lubricating oil flow formula of the front static pressure chamber under the design load:

The lubricating oil flow rate of the front static pressure chamber under the design external load ;in is the viscosity of lubricating oil;

c. Fore static chamber pump power consumption N _P

;

d. Friction power N _f of the rectangular front static pressure chamber:

,

Among them, n is the spindle speed, D is the inner diameter of the bearing; is the friction area of the rectangular front static pressure chamber, and its calculation formula is ;

e. Lubricating oil temperature rise T in the front static pressure chamber:

in is the total power consumption, the calculation formula is .

For the third block of the bearing, this block is a dynamic pressure chamber, that is, the oil sealing surface. When the main shaft rotates at a high speed, it will generate a strong dynamic pressure effect and generate a large dynamic pressure that can be carried. This dynamic pressure can balance the large horizontal grinding force of the main shaft of the roll grinder grinding wheel. The dynamic pressure chamber is regarded as a part of the dynamic pressure bearing, so the general dynamic pressure bearing principle in the industry can be used to analyze the performance of the dynamic pressure chamber, such as the carrying capacity of the dynamic pressure chamber, and the Fluent software programming is used to analyze the performance of the dynamic pressure sliding bearing. The force of the dynamic pressure surface and the force of the three static pressure oil chambers can be deduced from the force of the dynamic pressure surface, and then according to the force of the dynamic pressure surface, the eccentricity and eccentricity of the main shaft when rotating, the eccentricity and eccentricity The position angle is the eccentricity and deflection angle of the whole bearing, so that the performance parameters of the whole bearing can be obtained, and the temperature rise T ₃ of the dynamic pressure chamber can be obtained.

The present invention is a new type of sliding bearing, which is one of the research results of the National Science and Technology Major Project "High Efficiency and Precision Static Pressure/Dynamic and Static Pressure Spindle and Guide Rail System Research and Industrialization Technology of High-end CNC Grinding Machine" (No.: 2012ZX04002-091), which solves the problem of Difficulties in the design of hydrostatic bearings in the film section of the grinding wheel spindle of a roll grinder. Compared with the traditional capillary section hydrostatic bearing, the film section hydrostatic bearing has high stiffness under the static pressure condition of starting; at the same time, the film section hydrostatic bearing has high Excellent bearing capacity, high rigidity and low temperature rise meet the requirements of high efficiency, high rigidity and high precision in the development of modern roll grinders.

The present invention will be described in detail below in conjunction with the accompanying drawings. As a part of this specification, the principle of the present invention will be described through embodiments. Other aspects, features and advantages of the present invention will become clear at a glance through the detailed description.

Description of drawings

The drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention.

Fig. 1 is a structural schematic diagram of a roll grinder grinding wheel spindle film section hydrostatic bearing of the present invention;

Fig. 2 is a schematic diagram of bearing force of the present invention;

Fig. 3 is a structural schematic diagram of the static pressure chamber in front of the bearing in the present invention;

Fig. 4 is a structural diagram of a single-sided thin-film restrictor connected with the oil chamber in front of the bearing in the present invention.

The corresponding relationship of reference signs in Figure 1-4 is:

1-upper plenum; 2-lower plenum; 3-front plenum;

4-Rear dynamic pressure chamber; 5-Double-sided film restrictor; 6-Single-sided film restrictor.

detailed description

It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and examples. For the convenience of description, if the words "up", "down", "left" and "right" appear in the following, it only means that the directions of up, down, left and right are consistent with the drawings themselves, and do not limit the structure.

As shown in Figure 1-2, a roll grinder grinding wheel spindle film section fluid static pressure bearing includes an upper static pressure chamber 1 and a lower static pressure chamber 2 arranged symmetrically; the upper static pressure chamber 1 and the lower static pressure chamber The chamber 2 is connected with an external oil inlet hole, and is connected with the double-sided film restrictor 5 through an oil circuit; it also includes a front static pressure chamber 3 and a rear dynamic pressure chamber 4; the front static pressure chamber 3 is connected with an external oil inlet hole , communicate with the single-sided diaphragm restrictor 6 through the oil passage. The centers of the upper static pressure chamber 1 and the lower static pressure chamber 2 are located on the vertical line of the bearing.

In Figure 2, F dynamic pressure X is the X-direction force of the bearing dynamic pressure chamber; F dynamic pressure Y is the Y-direction force of the bearing dynamic pressure chamber; W ₁ is the bearing capacity of the upper and lower static pressure oil chambers; W ₂ is the front Cavity static pressure bearing capacity.

The specific block principle in the bearing design is: the upper and lower static pressure chambers 1 and 2 are the first block of the bearing, and this block is connected with a double-sided film restrictor 5; the front static pressure chamber 3 is the second block of the bearing, and the The block is connected with a single-sided film restrictor 6; the rear dynamic pressure oil chamber 4 is the third block of the bearing.

For the second block of the bearing, according to the design parameters of the front oil chamber of the bearing (the diameter of the main shaft d, the length of the oil chamber L, the design radius gap between the main shaft and the front oil chamber h ₀ , the length of the axial oil sealing edge b ₁ ; the length of the circumferential oil sealing edge , the effective bearing area of the front oil chamber ). Combined with the single-sided thin-film throttle on the front oil chamber of the hydrostatic bearing. Use MATLAB software to write the design program to design the single-sided thin-film restrictor corresponding to the front cavity (based on the infinite stiffness of the bearing), including the thickness of the thin film , film deformation coefficient K and other parameters; after that, the performance parameters such as the bearing capacity W of the front chamber, the flow rate Q corresponding to the front hydrostatic oil chamber, friction power consumption N _f , pump power consumption N _p , and temperature rise T of the front chamber should be calculated. value.

The structure of the single-sided film restrictor is shown in Figure 4, where r _c - the radius of the working range of the circular table, r _c1 - the radius of the oil inlet hole of the circular table, r _c2 - the radius of the circular table, --membrane thickness. h _c0 is the throttling gap of the single-sided film restrictor at the design load (or no-load).

The specific design steps and design formula of the second block of bearing are as follows:

1 The liquid resistance ratio formula of the rectangular front oil cavity with single-sided membrane throttling: ;Effective bearing area of rectangular front oil chamber: , L is the length of the rectangular oil chamber, B is the width of the bearing, is the length of the axial oil seal edge, is the length of the circumferential oil seal edge of the rectangular oil cavity, and the structure of the rectangular front oil cavity is shown in Figure 3.

2 Oil pressure inside the front oil chamber when no load , P _s —— bearing oil supply pressure, from which the pressure of the front oil chamber under no-load can be obtained .

3 According to the infinite rigidity condition of the single-sided film throttling of the front oil cavity: ; From this, the film deformation coefficient K can be obtained: , h _{c0 ——Single} -sided film restrictor throttle gap at design load (or no load).

4 Thickness of film in single-sided film restrictor: , ——Elastic modulus of the film material, m——Poisson's ratio; from this, the film thickness of the single-sided film restrictor is calculated .

5 The bearing capacity formula of the front oil chamber: , generally select the bearing oil inlet pressure MPa; where is the bearing capacity coefficient; here Take a value to obtain the bearing capacity of the oil chamber . Course selection must satisfy F _{external load X} , so you can choose within the allowable range Value, W ₂ is the static pressure bearing capacity of the front cavity; F _{external load X} is the external load of the bearing in X direction.

6 Lubricating oil flow in front oil chamber under design load: , - lubricating oil viscosity. From this, the lubricating oil flow rate of the front oil chamber under the design external load is obtained .

7 Pump power consumption: , from which the power consumption of the front oil chamber pump is obtained .

8 Friction power consumption : Friction area of rectangular front oil chamber: ;The friction power of the rectangular front oil chamber is: , n——Spindle speed, D is the inner diameter of the bearing;

9 Lubricating oil temperature rise T in the front oil chamber: temperature rise , total power consumption .

In the simulation experiment below, the performance of the dynamic and static pressure hybrid bearing of the grinding wheel spindle of the roll grinder is compared through analysis and calculation under the capillary throttling and film throttling. ; The capillary throttling roll grinder grinding wheel spindle design adopts the traditional method and uses the Fluent software to analyze the dynamic and static pressure hybrid bearing. Known: bearing external load F _X =11736N; F _Y =2455.7N. Bearing oil supply pressure 2MPa, lubricating oil dynamic viscosity Pa.s, spindle speed 1200r/min. The bearing diameter and length are both 120mm, and the bearing diameter clearance is 0.06mm.

The results of bearing performance simulation analysis are shown in Table 1.

It can be seen from Table 1 that the temperature rise of the lubricating oil in each part of the bearing when the capillary throttling is used for the dynamic and static pressure hybrid bearing of the grinding wheel spindle of the roll grinder is obviously higher than that of the thin film throttling, and the friction power consumption is much larger, which shows that the thin film throttling is adopted. When throttling, the bearing reduces temperature rise and power consumption very significantly. At the same time, the large external load of the bearing means high carrying capacity. The rigidity of the dynamic and static pressure hybrid bearing of the grinding wheel spindle of the roll grinder with film throttling is higher than that of the capillary throttling, which shows that the dynamic and static pressure hybrid bearing of the roll grinder grinding wheel spindle is under the condition of lower oil supply pressure (small oil pump power) when the thin film throttling is adopted With high rigidity, the precision of natural grinding will also be improved. The invention has strong practicability.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (4)

1. A roll grinder grinding wheel spindle film section flow hydrostatic bearing, including the opposite upper static pressure chamber (1) and lower static pressure chamber (2), and the upper static pressure chamber (1) and the lower static pressure chamber ( Between 2), the front static pressure chamber (3) and the rear dynamic pressure chamber (4) are set oppositely, and the upper static pressure chamber (1), the lower static pressure chamber (2) and the front static pressure chamber (3) are all equipped with The connecting oil hole is characterized in that: the two ports of the double-sided diaphragm restrictor (5) are respectively connected with the communicating oil holes of the upper static pressure chamber (1) and the lower static pressure chamber (2); the single-sided diaphragm restrictor The port of (6) communicates with the communicating oil hole of the front static pressure chamber (3). 2. According to claim 1, the hydrostatic bearing of the film section of the grinding wheel spindle of the roll grinder is characterized in that the front static pressure chamber (3) is rectangular, and the effective bearing area of the rectangular front static pressure chamber is determined by the following method: a. The hydraulic resistance ratio formula of the rectangular front static pressure chamber throttling through a single-sided membrane Find the liquid resistance ratio ; b. Calculate the effective bearing area of the rectangular front static pressure chamber : Among them, r _c1 is the radius of the oil inlet hole of the circular table of the single-sided film restrictor, r _c2 is the radius of the circular table of the single-sided film restrictor; h ₀ is the bearing radius clearance, and h _c0 is the single-sided film throttle at the design load or no load Throttle gap; L is the length of the rectangular oil chamber, B is the width of the bearing, is the length of the axial oil seal edge, is the length of the circumferential oil seal edge of the rectangular oil cavity. 3. According to claim 2, the film section hydrostatic bearing of the grinding wheel spindle of the roll grinder is characterized in that, the thickness of the film in the single-sided film throttle (6) is determined by the following method: a. by formula Calculate the pressure of the front static pressure chamber (3) under no load ; where P _s is the bearing oil supply pressure; b. According to the infinite stiffness condition formula of single-sided film throttling in the front static pressure cavity Deformation gives the film deformation coefficient formula: Calculate the film deformation coefficient K, and Cc is the film control coefficient, that is, the maximum relative deformation of the film; c. Through the calculation formula of the film thickness in the single-sided film restrictor: Calculation of membrane thickness for single-sided membrane restrictors ;in is the elastic modulus of the film material, and m is Poisson's ratio. 4. According to claim 2, the hydrostatic bearing of the film section of the grinding wheel spindle of the roll grinder is characterized in that, the working parameters of the front static pressure chamber (3) are determined by the following method: a. According to the bearing capacity formula of the front static pressure chamber: , Select within the specified range and Calculate the bearing capacity of the oil cavity ;in The value is greater than or equal to 1MPa; is the bearing capacity coefficient, and its value must satisfy F _{external load X} , W ₂ is the static pressure bearing capacity of the front cavity; F _{external load X} is the external load of the bearing in X direction; b. According to the lubricating oil flow formula of the front static pressure chamber under the design load: The lubricating oil flow rate of the front static pressure chamber under the design external load ;in is the viscosity of lubricating oil; c. Fore static chamber pump power consumption N _P ; d. Friction power N _f of the rectangular front static pressure chamber: , Among them, n is the spindle speed, D is the inner diameter of the bearing; is the friction area of the rectangular front static pressure chamber, and its calculation formula is ; e. Lubricating oil temperature rise T in the front static pressure chamber: in is the total power consumption, the calculation formula is .