CN104308561A - Static pressure guide rail oil film thickness feedback compensation device - Google Patents

Abstract

The invention discloses a static pressure guide rail oil film thickness feedback compensation device. The device comprises an oil tank 1, a metering pump 3, a large-flow multi-head pump 8 and a static pressure chamber 7, wherein the metering pump 3 is communicated with the multi-head pump 8 through a pipeline, and the multi-head pump 8 is communicated with the static pressure chamber 7. The device further comprises a grating scale 11, a programmable controller 12, a variable-frequency motor 13 and an oil liquid temperature control assembly, wherein the oil liquid temperature control assembly comprises a temperature relay 14, an electric heater 15, a freezer 16 and a motor pump set I 17, the grating scale 11 is installed on a machine tool working turntable 18, the grating scale is connected with the programmable controller through a circuit, the programmable controller is connected with the variable-frequency motor through a circuit, and the variable-frequency motor is connected with the metering pump through a coupling; the temperature relay is respectively connected with the electric heater and the motor pump set I through a circuit, and the motor pump set I is connected with the freezer through a pipeline. The static pressure guide rail oil film thickness feedback compensation device has the advantages that automatic correction or restoration to original design oil film thickness is realized, the workpiece positioning accuracy of heavy machine tools is improved, and the machining accuracy is improved.

Description

Oil film thickness of hydrostatic guide way feedback compensator

Technical field:

The present invention relates to a kind of industrial machinery fuel feeding compensation arrangement, relate in particular to the fuel feeding compensation arrangement of heavy machine tool hydrostatic slideway, specifically carry out feedback compensator for the oil film thickness change between the upper/lower guide under heavy duty machine tools Work turning table.This device all converts load, the isoparametric change of temperature to the impact of oil film thickness the single parameter of flow, segmentation or fine compensation fluid oil mass is carried out with calculating by detecting, revise oil film thickness error, improve the Workpiece fixing precision of heavy machine tool, and then improve machining accuracy.

Background technology:

The Work turning table energy easy slide of existing heavy duty machine tools and rotation are owing to arranging fueller below Work turning table, and this device can make to form one deck fluid between the upper and lower guide rail under Work turning table, and this layer of fluid thickness is called oil film.When workpiece is inserted on Work turning table, heavy load can make oil film change, and for avoiding upper and lower guide rail to produce rigid contact, fueller will carry out fuel feeding compensation to it.Along with the fast development of machinery industry, more and more higher requirement be it is also proposed to the machining accuracy of engineering goods, and basis and critical impact are played to machining accuracy in the accurate location of workpiece.In current hydrostatic slideway fueling technology, extensively adopt the fuel system of constant flow or constant voltage, thus form the rigidity oil film between upper and lower guide rail.But small change can be there is with the change of the difference of workpiece deadweight and oil temperature in the rigidity of oil film and thickness.This type of small change will affect the positioning precision (Z axis) of heavy machine tool, thus reduce the machining accuracy grade of heavy machine tool.Study discovery in practice, when the load of workbench workpiece changes, the pass of oil film thickness δ and pressure reduction p is:

${\mathrm{\δ}}_1={\mathrm{\δ}}_0/\sqrt[3]{\frac{p_1}{p_0}}---\left(1\right)$

In formula:

P ₀for two ends, the gap pressure reduction that a certain workpiece produces when workbench forms static pressure,

P ₁for two ends, the gap pressure reduction produced when same workpiece load change aftertable forms static pressure.

If p ₁=2p ₀, then have ${\mathrm{\δ}}_1={\mathrm{\δ}}_0/\sqrt[3]{\frac{p_1}{p_0}}={\mathrm{\δ}}_0/\sqrt[3]{\frac{2p_0}{p_0}}={\mathrm{\δ}}_0/\sqrt[3]{2}={\mathrm{\δ}}_0/1.26=0.79{\mathrm{\δ}}_0$

As seen from the above equation, when workpiece increases the weight of 1 times, then chinky altitude (i.e. gap floatation volume) reduces by 21%.

The general oil film thickness δ=0.06mm and 60um of heavy machine tool.If decline 21%, error amount reaches 12.6um.Such error amount is unacceptable for Precision Machining.Equally, temperature affects μ (fluid kinematic viscosity coefficient).And the change of μ also affects δ (chinky altitude).Under the double action of load and temperature affects, variable quantity (i.e. error amount) general >=12.6um in above-mentioned example, strengthens machine tool error.

And the constant pressure type fueller of prior art, as shown in Figure 1, mainly be made up of fuel tank, filter I, constant displacement pump, overflow valve, filter II, choke valve, static pressure chamber, its operation principle is, from fuel tank, extract fluid by constant displacement pump and inject static pressure chamber through filter II, choke valve, realize carrying out fuel feeding between upper/lower guide.It is because fluid arrival static-pressure oil chamber will through flow controller that this fueller exists shortcoming, throttling produces the pressure loss can make system generate heat, and system pressure is adjusted by overflow valve, a large amount of overflows of overflow valve exacerbate again system heating, cause high oil temperature, work top temperature distortion is strengthened, causes the cutting precision of workpiece not easily to reach requirement.

The constant current mode fueller of prior art, as shown in Figure 2, is formed primarily of fuel tank, filter I, constant displacement pump, overflow valve, filter II, multi-head pump, static pressure chamber.Its operation principle is, extracts fluid and inject static pressure chamber by multi-head pump again after filter II, realize carrying out fluid fuel feeding between upper/lower guide by constant displacement pump from fuel tank.Constant current mode fuel feeding is relative to constant pressure type fuel feeding, although there is no Pressure Drop, temperature diminishes, but because it is always with the mode fuel feeding of constant flow, thus the continuous change of oil film thickness can not be adapted to regulate fuel delivery, modifying factor can not to bear a heavy burden change and variations in temperature and the error that causes, and then have influence on machining accuracy.

Summary of the invention:

The technical problem to be solved in the present invention is, change for the oil film thickness between the guide rail produced because of the change of the load variations on Work turning table and oil temperature that above-mentioned existing fueller exists can not accurately be revised, oil film thickness can not be made to quickly recover to the requirement of original design precision, and then have influence on the deficiency of machining accuracy or the defect of Precision Machining part.A kind of error can revised Work turning table fast and cause workpiece to be located because load variations and variations in temperature produce oil film thickness change is provided, oil film thickness between guide rail is made to return to the dimension precision requirement of setting, improve the workpiece positioning precision of heavy machine tool, and then improve the oil film thickness of hydrostatic guide way feedback compensator of machining accuracy.

Technical solution of the present invention is, provides a kind of oil film thickness of hydrostatic guide way feedback compensator with following structure.

A kind of oil film thickness of hydrostatic guide way feedback compensator, this device comprises fuel tank, constant displacement pump, large discharge multi-head pump, static pressure chamber, described constant displacement pump is communicated with large discharge multi-head pump by pipeline, the bull of described large discharge multi-head pump is communicated with multiple static pressure chamber respectively, it is characterized in that, also include grating scale displacement transducer, Programmable Logic Controller (PLC), variable-frequency motor and oil liquid temperature Control Component, described oil liquid temperature Control Component comprises temperature relay, electric heater, refrigerator, electric-motor pump group I, described grating scale displacement transducer is installed on operation turntable of machine tool, described grating scale displacement transducer is connected with Programmable Logic Controller (PLC) by circuit, described Programmable Logic Controller (PLC) and variable-frequency motor are that circuit is connected, described variable-frequency motor is connected with constant displacement pump by shaft coupling, described temperature relay is arranged on fuel tank, and described temperature relay is connected with electric heater and electric-motor pump group I respectively by circuit, and described electric-motor pump group I is connected with refrigerator by pipeline.

After adopting above structure, compared with prior art, the present invention has the following advantages:

Because oil film thickness of hydrostatic guide way feedback compensator of the present invention is on the basis of existing fuel feeding compensation arrangement, newly be provided with Oil spill detection technological means and temperature control technology means, calculated and information processing technology means by plc data, by in machine tooling process, the weight of workpiece and the isoparametric change of the temperature of fluid, oil film thickness is caused to change, by detecting and calculating load, the isoparametric change of temperature all converts the single parameter of flow to the factor of influence of oil film thickness, carry out fine compensation fluid oil mass, realize the oil film thickness of auto modification or recovery original design, improve the Workpiece fixing precision of heavy machine tool, and then raising machining accuracy.

As technique scheme supplement and perfect, the present invention also has following feature and advantage:

Described oil film thickness of hydrostatic guide way compensation arrangement, also be provided with anti-power failure compensation mechanism, described anti-power failure compensation mechanism includes electric-motor pump group II, pressure sensor, accumulator and Solenoid ball valve, the inlet pipe of described electric-motor pump group II is inserted in fuel tank, outlet is communicated with accumulator, described pressure sensor installation is put on the pipeline between electric-motor pump group and accumulator, described accumulator is communicated with static pressure chamber by pipeline, and described Solenoid ball valve is arranged on the pipeline between accumulator and static pressure chamber.The advantage of this anti-power failure compensation mechanism is, when having a power failure, due to the effect of inertia force, Work turning table still continues rotation, and oil film thickness of hydrostatic guide way compensation arrangement can not compensate to hydrostatic slideway fuel feeding owing to having a power failure, and makes oil film change that upper/lower guide can be caused to produce rigidity and rubs, at this moment, Solenoid ball valve, because of the automatic Open valve that has a power failure, makes accumulator inner fluid carry out fuel feeding in static pressure chamber, prevents upper/lower guide from producing rigidity friction and causing lathe damaged.

Accompanying drawing illustrates:

Fig. 1 is the constant pressure type fueller operation principle schematic diagram of prior art;

Fig. 2 is the constant current mode fueller operation principle schematic diagram of prior art;

Fig. 3 is oil film thickness of hydrostatic guide way feedback compensator fundamental diagram of the present invention;

Fig. 4 is Work turning table in oil film thickness of hydrostatic guide way feedback compensator of the present invention and static pressure cavity configuration schematic diagram;

Fig. 5 is the static pressure chamber schematic diagram in oil film thickness of hydrostatic guide way feedback compensator of the present invention.

Shown in figure: 1 fuel tank, 2, filter I, 3, constant displacement pump, 4, overflow valve, 5, filter II, 6, choke valve, 7, static pressure chamber, 8, multi-head pump, 9, coarse filter, 10 fine filters, 11, grating scale displacement transducer, 12, Programmable Logic Controller, 13, variable-frequency motor, 14, temperature relay, 15, electric heater, 16, refrigerator, 17, electric-motor pump group I, 18, Work turning table, 19, electric-motor pump group II, 20, pressure sensor, 21, accumulator, 22, Solenoid ball valve, 23, oil return pipe, 24, vehicle body.

Detailed description of the invention:

Below in conjunction with the drawings and specific embodiments, the invention will be further described:

Fig. 1 is the constant pressure type fueller operation principle schematic diagram of prior art, this device is mainly made up of fuel tank 1, filter I2, constant displacement pump 3, overflow valve 4, filter II5, choke valve 6, static pressure chamber 7, its operation principle is, from fuel tank 1, extract fluid by constant displacement pump 3 and inject static pressure chamber 7 through filter II5, choke valve 6, realize carrying out fuel feeding between upper/lower guide.

Fig. 2 is the constant current mode fueller operation principle schematic diagram of prior art; This device is formed primarily of fuel tank 1, filter I2, constant displacement pump 3, overflow valve 4, filter II5, multi-head pump 8, static pressure chamber 7.Its operation principle is, extracts fluid inject static pressure chamber 7 by multi-head pump 8 again by constant displacement pump 3 from fuel tank 1 after filter II5, realizes carrying out fuel feeding between upper/lower guide.

Fig. 3, Fig. 4 and Fig. 5 schematic diagram, comparatively clearly show the structural relation of oil film thickness of hydrostatic guide way feedback compensator of the present invention.This device is formed primarily of two parts, and one is that oil film thickness detects and quantitative fuel feeding bucking-out system, and two is ensure that oil liquid temperature remains on the oil liquid temperature Control Component of a certain range of set value.Oil film thickness detection and quantitatively fuel feeding bucking-out system are primarily of fuel tank 1, constant displacement pump 3, coarse filter 9, fine filter 10, large discharge multi-head pump 8, static pressure chamber 7, and grating scale displacement transducer 11, Programmable Logic Controller (PLC) 12, variable-frequency motor 13 and oil liquid temperature Control Component assemble.The entrance point of constant displacement pump 3 is inserted in fuel tank 1, and the port of export is by pipeline and be communicated with large discharge multi-head pump 8 after fine filter 10 through coarse filter 9, the multi-head pump that large discharge multi-head pump 8 can select an import eight to export; The bull of large discharge multi-head pump 8 respectively be arranged on static pressure chamber 7 on fuselage 24 and be communicated with, the number of units of large discharge multi-head pump 8 arrange answer the static pressure chamber 7 on bed piece 24 number configure.Grating scale displacement transducer 11 includes vertical chi, read head, and vertical chi is arranged on the slide plate of Work turning table 18, and read head is fixed on lathe bed 24, makes read head be installed on the below of vertical chi as far as possible.The selection of its mounting means must be noted that to avoid chip, cutting fluid and fluid splash down direction, misread to avoid affecting read head.Grating scale displacement transducer is connected with Programmable Logic Controller (PLC) 12 by circuit, and Programmable Logic Controller (PLC) 12 is with variable-frequency motor 13 for circuit is connected, and variable-frequency motor 13 is connected with constant displacement pump 3 by shaft coupling.Quantitative fuel feeding compensation program software is installed in Programmable Logic Controller (PLC) 12.Following formula is satisfied with in the establishment of this software program:

$\mathrm{\δ}=\sqrt[3]{\frac{12/q_w{u}_0{e}^{-\mathrm{\λ}(t-t_0)}}{\mathrm{\ΔpB}}}---\left(2\right)$

We know, hydrostatic slideway oil film is easily subject to the combined influence of load, temperature and pressure, and in general, in hydrostatic slideway, its pressure is far smaller than 20MPa, therefore the impact of pressure is ignored.Formula 2 is the comprehensive mathematical model of oil film thickness and flow, temperature.

$\mathrm{\δ}=\sqrt[3]{\frac{12/q_w{u}_0{e}^{-\mathrm{\λ}(t-t_0)}}{\mathrm{\ΔpB}}}---\left(2\right)$

Q _wflow (the cm of-unit width ³/ s); δ-chinky altitude (i.e. oil film thickness) (cm);

/-gap length (cm); Pressure reduction (the p at Δ p-two ends _a); B-gap unit width (cm).

U ₀-pressure is 1 atmospheric pressure, and temperature is t ₀time viscosity (pa.s); Temperature (DEG C) after t-work; t ₀-initial temperature, (DEG C); The viscosity-temperature coefficient of λ-oil pressure.

For concrete lathe, l, u ₀, λ, t, t ₀, B, Δ P be known quantity, therefore formula 2 is rewritten as: $\mathrm{\δ}=\sqrt[3]{\frac{12/q_w{u}_0{e}^{-\mathrm{\λ}(t-t_0)}}{\mathrm{\ΔpB}}}=a.\sqrt[3]{q_w}---\left(3\right)$

As can be seen from formula 3, the simple relation of oil film thickness and flow, changes into the impact of load, temperature the impact of single parameter flow, and different lathes is that coefficient is different, and this is just for PLC programming is had laid a good foundation.

Oil film thickness detects and the course of work of quantitative fuel feeding bucking-out system is, carry out measurement by the oil film thickness between grating scale displacement transducer 11 pairs of upper/lower guides to detect, data measurement detected by the displacement transducer in grating scale displacement transducer 11 or information transmission are to Programmable Logic Controller (PLC) 12, the data that Programmable Logic Controller (PLC) 12 inputs displacement transducer according to the program software loaded in advance or information calculate or process, namely current oil film thickness and the difference setting original oil film thickness is contrasted by PLC, pass through program computation, draw required flow, signal instruction input variable-frequency motor 13 is converted to by auxiliary reclay, variable-frequency motor 13 is adjusted frequency according to signal, constant displacement pump 3 fuel feeding oil mass is changed, fluid is supplied large discharge multi-head pump 8 by constant displacement pump 3, large discharge multi-head pump 8 will not have again liquid to supply static-pressure oil chamber 7, modifying factor is born a heavy burden change and variations in temperature and the error that causes, heavy machine tool oil film thickness of hydrostatic guide way is made to reach the dimension precision requirement of setting, improve the positioning precision of heavy machine tool, and then raising machining accuracy.

Oil liquid temperature Control Component comprises temperature relay 14, electric heater 15, refrigerator 16, electric-motor pump group I17.Temperature relay 14 is arranged on fuel tank 1, and temperature relay 14 is connected with electric heater 15 and electric-motor pump group I17 respectively by circuit, and electric-motor pump group I17 is connected with refrigerator 16 by pipeline.

When oil temperature changes, when temperature relay 14 records oil temperature in fuel tank lower than a certain setting value, fluid in temperature relay 14 instruction electric heater 15 pairs of fuel tanks 1 heats, and when oil liquid temperature rises to a certain setting value, electric heater 15 stops heating; And when temperature relay 14 records oil temperature in fuel tank higher than a certain setting value, temperature relay 14 command motor pump group I17 works, in electric-motor pump group I17, oil pump is lowered the temperature in fuel tank inner fluid suction refrigerator 16, fluid after cooling is back to fuel tank, when temperature relay 14 oil temperature recorded in fuel tank 1 rises to a certain setting value, temperature relay 14 command motor pump group I17 quits work.

The major function of oil liquid temperature Control Component ensures that oil temperature remains in a certain range of set value, prevents from, because of high oil temperature or too low and make oil film thickness produce larger change, controlling oil temperature in certain limit, greatly can reducing the excursion of oil film thickness.

Also be provided with anti-power failure compensation mechanism in addition, described anti-power failure compensation mechanism includes electric-motor pump group II19, pressure sensor 20, accumulator 21 and Solenoid ball valve 22.The inlet pipe of electric-motor pump group II19 is inserted in fuel tank 1, outlet is communicated with accumulator 21, pressure sensor 20 installation is put on the pipeline between electric-motor pump group II19 and accumulator 21, accumulator 21 is communicated with static pressure chamber 7 by pipeline, Solenoid ball valve 22 is arranged on the pipeline between accumulator 21 and static pressure chamber 7, and the pipeline between electric-motor pump group II19 and accumulator 21 is also provided with coarse filtration valve 9 and overflow valve.

The operation principle of anti-power failure compensation mechanism is, when having a power failure suddenly, due to the effect of inertia force, Work turning table still continues rotation, and oil film thickness of hydrostatic guide way compensation arrangement can not compensate to hydrostatic slideway fuel feeding owing to having a power failure, and makes oil film change that diction upper/lower guide can be caused to produce rigidity and rubs, at this moment, Solenoid ball valve, because of the automatic Open valve that has a power failure, makes accumulator inner fluid carry out fuel feeding compensation in static pressure chamber, prevents upper/lower guide from producing rigidity friction and causing lathe damaged.And when after incoming call, Solenoid ball valve, because of incoming call automatic-closing valve, stops accumulator to static pressure chamber fuel feeding.During owing to having a power failure, the fluid in accumulator makes the pressure in its accumulator reduce to fuel feeding in static pressure chamber, and pressure sensor will be taken out temperature and enter in accumulator by command motor pump group II in fuel tank.Pressure sensor ensures that in accumulator, oil pressure remains in the scope of certain setting value.Make accumulator can keep certain oil pressure and at any time because of power failure to fuel feeding in static pressure chamber.

Claims (3)

1. an oil film thickness of hydrostatic guide way feedback compensator, this device comprises fuel tank (1), constant displacement pump (3), large discharge multi-head pump (8), static pressure chamber (7), described constant displacement pump (3) is communicated with large discharge multi-head pump (8) by pipeline, the bull of described large discharge multi-head pump (8) is communicated with multiple static pressure chamber (7) respectively, it is characterized in that, also include grating scale displacement transducer (11), Programmable Logic Controller (12), variable-frequency motor (13) and oil liquid temperature Control Component, described oil liquid temperature Control Component comprises temperature relay (14), electric heater (15), refrigerator (16), electric-motor pump group I (17), described grating scale displacement transducer (11) is arranged on operation turntable of machine tool (18), described grating scale displacement transducer (11) is connected with Programmable Logic Controller (12) by circuit, described Programmable Logic Controller (12) with variable-frequency motor (13) for circuit is connected, described variable-frequency motor (13) is connected with constant displacement pump (3) by shaft coupling, described temperature relay (14) is installed and is put on fuel tank (1), described temperature relay (14) is connected with electric heater (15) and electric-motor pump group I (17) respectively by circuit, and described electric-motor pump group I (17) is connected with refrigerator (16) by pipeline.

2. oil film thickness of hydrostatic guide way feedback compensator as claimed in claim 1, it is characterized in that: be also provided with anti-power failure compensation mechanism, described anti-power failure compensation mechanism includes electric-motor pump group II (19), pressure sensor (20), accumulator (21) and Solenoid ball valve (22), the inlet pipe of described electric-motor pump group II (19) is inserted in fuel tank (1), outlet is communicated with accumulator (21), described pressure sensor (20) installation is put on the pipeline between electric-motor pump group II (19) and accumulator (21), described accumulator (21) is communicated with static pressure chamber (7) by pipeline, described Solenoid ball valve (22) is arranged on the pipeline between accumulator (21) and static pressure chamber (7).

3. oil film thickness of hydrostatic guide way feedback compensator as claimed in claim 1, is characterized in that: be provided with quantitative fuel feeding compensation program software in described Programmable Logic Controller (12), following formula is satisfied with in the establishment of this software program:

$\mathrm{\δ}=3\sqrt{\frac{{12\mathrm{lq}}_w{u}_o{e}^{-\mathrm{\λ}(l-l_0)}}{\mathrm{\ΔpB}}}$

Q _wflow (the cm of-unit width ³/ s); δ-chinky altitude (i.e. oil film thickness) (cm);

L-gap length (cm); Pressure reduction (the p at Δ p-two ends _a); B-gap unit width (cm).

U ₀-pressure is 1 atmospheric pressure, and temperature is t ₀time viscosity (pa.s); Temperature (DEG C) after t-work; t ₀-initial temperature, (DEG C); The viscosity-temperature coefficient of λ-oil pressure.