Vertical lathe workbench hydrostatic guideway capable of automatically controlling oil film thickness and automatic control method

Abstract

The invention relates to a vertical lathe workbench hydrostatic guideway capable of automatically controlling the thickness of an oil film and an automatic control method. The vertical lathe workbench hydrostatic guideway comprises a normal working pressure relay, a motor acceleration pressure relay, a motor acceleration and deceleration stop pressure relay, a motor deceleration pressure relay, a driving motor, a variable pump, a one-way valve, a filter and a multi-point oil distributor, the input end of the variable pump is connected to the output end of the driving motor, the multi-point oil separator is communicated with the static pressure oil cavity of the working table base through an oil way, and the device further comprises a normal working pressure relay, a motor acceleration pressure relay, a motor acceleration and deceleration stop pressure relay and a motor deceleration pressure relay. The static pressure guide rail of the workbench base can monitor whether the static pressure of the guide rail is normal or not in real time, is good in stability and easy to control, is not influenced by the unevenness of the guide rail of the workbench, is not influenced by unbalance loading of a load, and is not influenced by unstable pressure of an overflow valve for measuring the thickness by oil pressure of a system due to flow change.

Description

Technical Field

[0001] The invention relates to the field of high-speed rotary static pressure guide rails for vertical lathe worktables, and in particular to a static pressure guide rail for a vertical lathe worktable capable of automatically controlling oil film thickness and an automatic control method. Background Art

[0002] Oil film stiffness and load-bearing capacity are two main performance indicators of liquid hydrostatic guides, which directly affect the working performance of liquid hydrostatic guides. Oil film stiffness and load-bearing capacity are mainly determined by oil film thickness. Therefore, a reasonable oil supply system must be adopted to enable the liquid hydrostatic guide to have the ability to adjust the oil film thickness and keep the oil film thickness at the optimal value. The hydrostatic guide of the vertical lathe workbench adopts a constant flow method to supply oil. The oil film thickness of the vertical lathe workbench is affected by two major factors: one is the change in viscosity of the hydraulic oil at different temperatures, and the other is the load.

[0003] When the hydrostatic guide rail of the worktable is in operation, the oil film temperature rises due to the viscosity dissipation of the hydraulic oil, and the viscosity of the hydraulic oil changes greatly, causing the viscosity of the hydraulic oil to decrease significantly and affecting the thickness of the oil film. If the oil film thickness is not adjusted according to the changing temperature, performance indicators such as the oil film stiffness and load-bearing capacity will become lower, affecting the accuracy of the rotary table to a certain extent.

[0004] When the load on the workbench changes, the pressure between the guide rails will change, and the thickness of the guide rail oil film will also change. The lighter the workpiece on the workbench, the thicker the oil film and the greater the floatation of the workbench; the heavier the workpiece, the thinner the oil film and the smaller the floatation of the workbench. If the floatation of the workbench is too large, the displacement deviation is large and the processing accuracy is low; if the floatation of the workbench is too low, it may cause direct contact between the guide rails, causing guide rail grinding.

[0005] Due to the influence of the above factors, especially the viscosity of the hydraulic oil at different temperatures, the position of the workbench will change during operation, thus affecting the machining accuracy of the parts.

[0006] In order to solve the above problems, it is necessary to automatically control the change of the buoyancy of the oil film of the hydrostatic guide rail in real time, and then dynamically adjust the oil supply flow of the hydrostatic system according to the change of the buoyancy. Summary of the invention

[0007] In view of the above problems, a static pressure guide rail of a vertical lathe workbench and an automatic control method which can automatically control the oil film thickness are provided, aiming to effectively solve the problems existing in the prior art.

[0008] The first aspect of the present invention is to provide a static pressure guide rail of a vertical lathe workbench that can automatically control the oil film thickness, including a drive motor and a variable pump, a one-way valve, a filter, and a multi-point oil separator that are sequentially connected through an oil circuit, the input end of the variable pump is connected to the output end of the drive motor, the multi-point oil separator is connected to the static pressure oil chamber of the workbench base through the oil circuit, and also includes a normal working pressure relay, a motor acceleration pressure relay, a motor acceleration / deceleration stop pressure relay, and a motor deceleration pressure relay. The input ends of the normal working pressure relay, the motor acceleration pressure relay, the motor acceleration / deceleration stop pressure relay, and the motor deceleration pressure relay are connected to the static pressure oil chamber of the workbench base, and the normal working pressure relay, the motor acceleration pressure relay, the motor acceleration / deceleration stop pressure relay, and the motor deceleration pressure relay are also electrically connected to the drive motor through a PLC.

[0009] Furthermore, the static pressure guide rail of the vertical lathe workbench also includes a solenoid valve, a first throttle and a second throttle. The first throttle and the second throttle are installed in pairs in the static pressure oil chamber of the workbench base. The A port and the B port of the solenoid valve are connected to the static pressure oil chamber of the workbench base through the first throttle and the second throttle respectively. The P port of the solenoid valve is connected to the static pressure oil chamber of the workbench base through a pipeline. The input ends of the normal working pressure relay, the motor acceleration pressure relay, the motor acceleration and deceleration stop pressure relay, and the motor deceleration pressure relay are connected to the P port of the solenoid valve and the pipeline between the static pressure oil chamber of the workbench base.

[0010] Furthermore, the static pressure guide rail of the vertical lathe workbench also includes an overflow valve, the oil inlet of the overflow valve is connected to the pipeline between the multi-point oil distributor and the filter, and the oil outlet of the overflow valve is connected to the hydraulic oil tank.

[0011] Furthermore, the static pressure guide rail of the vertical lathe workbench also includes a pressure gauge, which is installed on the pipeline between the multi-point oil separator and the filter.

[0012] Furthermore, the driving motor is a variable frequency motor or a servo motor.

[0013] Furthermore, the multi-point oil separator is one of a multi-point gear oil separator, a multi-point flow splitting motor or a gear pump group with the same flow rate.

[0014] Furthermore, the length of the first throttle is l0, and the length of the second throttle is p1 is the initial pressure of the oil chamber under the weight of the workpiece and the preload of the worktable base, and pmax is the maximum pressure of the oil chamber under the weight of the worktable and the maximum weight of the workpiece.

[0015] The second aspect of the present invention is to provide an automatic control method for the static pressure guide rail of the vertical lathe workbench capable of automatically controlling the oil film thickness, comprising:

[0016] When the pressure relay is turned on, the drive motor 1 starts to operate, and the oil enters the static pressure oil chamber of the workbench base. The pressure of the oil chamber is recorded as p1.

[0017] When the oil chamber pressure p1 drops to a certain value, the motor acceleration pressure relay is turned on, the drive motor starts to accelerate, the oil chamber pressure increases and returns to p1, the motor acceleration and deceleration stops, the pressure relay is turned on, the drive motor accelerates and stops, at this time the working pressure relay is turned on normally, and the working pressure is normal;

[0018] When the oil chamber pressure p1 rises to a certain value, the motor deceleration pressure relay is turned on, the drive motor starts to decelerate, causing the oil chamber pressure to drop and return to p1. The motor acceleration and deceleration stops, the pressure relay is turned on, and the drive motor decelerates and stops. At this time, the working pressure relay is turned on and the working pressure is normal.

[0019] The beneficial effects of the above scheme are:

[0020] The static pressure guide rail of the workbench base provided by the present invention can monitor in real time whether the static pressure of the guide rail is normal, has good stability, and is easy to control. It is not affected by the unevenness of the workbench guide rail, nor by the influence of load eccentricity, and the pressure instability of the overflow valve of the system oil pressure thickness measurement due to flow changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of the static pressure guide rail of the vertical lathe workbench provided in an embodiment of the present invention.

[0022] In the attached figure: 1. driving motor; 2. variable pump; 3. non-return valve; 4. filter; 5. pressure gauge; 6. overflow valve; 7. multi-point oil distributor; 8. normal working pressure relay; 9. motor acceleration pressure relay; 10. motor acceleration, deceleration and stop pressure relay; 11. motor deceleration pressure relay; 12. solenoid valve; 13. first throttle; 14. second throttle. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0026] like Figure 1 As shown, the static pressure guide rail of the vertical lathe workbench which can automatically control the oil film thickness provided in the embodiment of the present invention comprises a driving motor 1, a normal working pressure relay 8, a motor acceleration pressure relay 9, a motor acceleration / deceleration stop pressure relay 10, a motor deceleration pressure relay 11 and a variable pump 2, a one-way valve 3, a filter 4, and a multi-point oil separator 7 which are sequentially connected through an oil circuit, wherein the input end of the variable pump 2 is connected to the output end of the driving motor 1, the multi-point oil separator 7 is connected to the static pressure oil chamber of the workbench base through the oil circuit, the input ends of the normal working pressure relay 8, the motor acceleration pressure relay 9, the motor acceleration / deceleration stop pressure relay 10, and the motor deceleration pressure relay 11 are connected to the static pressure oil chamber of the workbench base, and the output ends of the normal working pressure relay 8, the motor acceleration pressure relay 9, the motor acceleration / deceleration stop pressure relay 10, and the motor deceleration pressure relay 11 are also electrically connected to the driving motor 1 through a PLC.

[0027] Under the above structure, when the pressure relay 8 is turned on, the driving motor 1 (a variable frequency motor or a servo motor can be selected) drives the variable pump 2 to run, and the hydraulic oil flows into the filter 4 through the one-way valve 3, and is pressed into the multi-point oil separator 7 (a multi-point gear oil separator, a multi-point flow separation motor or a gear pump group with the same flow rate can be selected) after fine filtration. The multi-point oil separator 7 discharges an equal amount of hydraulic oil into each oil chamber of the hydrostatic guide rail. It should be noted that, based on this technical solution, a pressure gauge 5 can be added to the oil circuit to display the system pressure of the hydrostatic guide rail hydraulic system of the workbench; at the same time, an overflow valve 6 can be added to the oil circuit to be used as a safety valve in the oil circuit.

[0028] Under the above structure, when the drive motor 1 operates normally and the oil enters the static pressure oil chamber of the workbench base, the flow rate through the static pressure guide rail oil chamber of the workbench base is Q0.

[0029]

[0030] In formula (1), p1 is the oil chamber pressure (MPa); h0 is the oil seal surface gap between the moving object and the fixed object (cm); L is the support length (cm); l is the oil chamber length (cm); B is the support width (cm); b is the oil chamber width (cm); μ is the dynamic viscosity of the lubricating oil (MPa·S).

[0031] When the temperature rises, the μ value decreases (dynamic viscosity μ is inversely proportional to temperature); at the same time, when the flow rate Q0 is constant, it can be seen from the above formula that the oil chamber pressure p1 also decreases (the remainder in the formula is the design constant). In this case, when the oil chamber pressure p1 drops to a certain value, the motor acceleration pressure relay 9 is turned on, and the drive motor 1 starts to accelerate, so that the oil chamber pressure increases and returns to p1, and the motor acceleration and deceleration stop pressure relay 10 is turned on, and the drive motor 1 accelerates and stops. At this time, the normal working pressure relay 8 is turned on and the working pressure is normal; when the oil chamber pressure p1 rises to a certain value, the motor deceleration pressure relay 11 is turned on, and the drive motor 1 starts to decelerate, so that the oil chamber pressure drops and returns to p1, and the motor acceleration and deceleration stop pressure relay 10 is turned on, and the drive motor 1 decelerates and stops. At this time, the normal working pressure relay 8 is turned on and the working pressure is normal, thereby adjusting the oil film thickness according to the changing temperature, which affects the accuracy of the rotary table to a certain extent.

[0032] Based on the above technical solution, further, Figure 1 As shown, in order to realize automatic control of the oil film thickness when the weight of the workpiece on the workbench changes, a solenoid valve 12, a plurality of first throttles 13 and a plurality of second throttles 14 may be further provided in the static pressure guide rail of the vertical lathe workbench. The first throttle 13 and the second throttle 14 have the same diameter and are respectively installed in the static pressure oil chamber of the workbench base in a one-to-one correspondence. The inlet of the first throttle 13 is connected to the A port of the solenoid valve 12 through a pipeline, and the inlet of the second throttle 14 is connected to the B port of the solenoid valve 12 through a pipeline. The A port and the B port of the solenoid valve 12 are respectively connected to the static pressure oil chamber of the workbench base through the first throttle 13 and the second throttle 14, and the T port of the solenoid valve 12 is connected to the oil tank. Under this structure, the normally working pressure relay 8, the motor acceleration pressure relay 9, the motor acceleration / deceleration stop pressure relay 10, and the motor deceleration pressure relay 11 can be connected to the static pressure oil chamber of the workbench base through the solenoid valve 12. Specifically, the P port of the solenoid valve 12 is connected to the static pressure oil chamber of the workbench base through a pipeline, and the input ends of the normally working pressure relay 8, the motor acceleration pressure relay 9, the motor acceleration / deceleration stop pressure relay 10, and the motor deceleration pressure relay 11 are connected to the P port of the solenoid valve 12 and the pipeline between the static pressure oil chamber of the workbench base.

[0033] Under the above structure, the flow rate through the throttle is Q1.

[0034]

[0035] In formula (2), d0 is the diameter of the throttle (cm); l0 is the length of the throttle (cm); p0 is the pressure of the oil chamber under the action of the moving parts (MPa); μ is the dynamic viscosity of the lubricating oil (MPa·S).

[0036] When the workbench is loaded with workpieces and the hydrostatic guide rails of the vertical lathe workbench are operating normally, formula (1) is equal to formula (2). It can be seen that when the oil pressure p1 changes, in order to ensure that the oil film thickness h0 remains unchanged, the length of the throttle must change accordingly. Specifically, in order to stably control the oil film thickness, the length of the first throttle 13 is l0, and the length of the second throttle 14 is l0 / n. P1 is the initial pressure of the oil chamber under the weight of the workpiece and the preload of the workbench base, and pmax is the maximum pressure of the oil chamber under the weight of the workbench and the maximum weight of the workpiece. When the weight of the workpiece changes, in order to make the oil film thickness of the static pressure guide rail of the workbench base change less or remain unchanged, the two-speed throttle is automatically controlled by the solenoid valve 12. Take the use of the second throttle 14 as an example (at this time, the oil chamber reaches the maximum pressure pmax), when the weight of the workpiece increases, the pressure in the oil chamber of the workbench base increases, the oil film thickness decreases, the pressure P0 in formula (2) decreases, and the throttle length becomes smaller. At this time, the acceleration pressure relay 9 in the oil circuit is turned on, the frequency conversion motor 1 starts, and drives the variable pump 2 to start filling the oil circuit, the flow rate increases, and the oil film thickness in the oil chamber of the workbench base returns to the original value.

[0037] The two-speed throttle in the present invention is used to control the oil film thickness within a certain pressure range. The two-speed throttle is specifically automatically controlled and selected by the solenoid valve 12 .

[0038] In the present invention, the normally working pressure relay 8, the motor acceleration pressure relay 9, the motor acceleration / deceleration stop pressure relay 10, and the motor deceleration pressure relay 11 are all pressure relays.

[0039] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A static pressure guide rail for a vertical lathe workbench capable of automatically controlling the thickness of an oil film, comprising a drive motor and a variable pump, a one-way valve, a filter, and a multi-point oil distributor connected in sequence through an oil circuit, wherein the input end of the variable pump is connected to the output end of the drive motor, and the multi-point oil distributor is connected to the static pressure oil chamber of the workbench base through an oil circuit, characterized in that: It also includes a normal working pressure relay, a motor acceleration pressure relay, a motor acceleration / deceleration stop pressure relay, and a motor deceleration pressure relay. The input ends of the normal working pressure relay, the motor acceleration pressure relay, the motor acceleration / deceleration stop pressure relay, and the motor deceleration pressure relay are connected to the static pressure oil chamber of the workbench base. The normal working pressure relay, the motor acceleration pressure relay, the motor acceleration / deceleration stop pressure relay, and the motor deceleration pressure relay are also electrically connected to the drive motor through the PLC.

2. The static pressure guide rail of a vertical lathe workbench capable of automatically controlling the oil film thickness according to claim 1 is characterized in that: The static pressure guide rail of the vertical lathe workbench also includes a solenoid valve, a first throttle and a second throttle. The first throttle and the second throttle are installed in pairs in the static pressure oil chamber of the workbench base. The A port and the B port of the solenoid valve are connected to the static pressure oil chamber of the workbench base through the first throttle and the second throttle respectively. The P port of the solenoid valve is connected to the static pressure oil chamber of the workbench base through a pipeline. The input ends of the normal working pressure relay, the motor acceleration pressure relay, the motor acceleration and deceleration stop pressure relay, and the motor deceleration pressure relay are connected to the P port of the solenoid valve and the pipeline between the static pressure oil chamber of the workbench base.

3. The static pressure guide rail of a vertical lathe workbench capable of automatically controlling the oil film thickness according to claim 1 or 2, characterized in that: The static pressure guide rail of the vertical lathe workbench also includes an overflow valve, the oil inlet of the overflow valve is connected to the pipeline between the multi-point oil distributor and the filter, and the oil outlet of the overflow valve is connected to the hydraulic oil tank.

4. The static pressure guide rail of a vertical lathe workbench capable of automatically controlling the oil film thickness according to claim 1 or 2, characterized in that: The static pressure guide rail of the vertical lathe workbench also includes a pressure gauge, which is installed on the pipeline between the multi-point oil separator and the filter.

5. The static pressure guide rail of a vertical lathe workbench capable of automatically controlling the oil film thickness according to claim 1 or 2, characterized in that: The driving motor is a variable frequency motor or a servo motor.

6. The static pressure guide rail of a vertical lathe workbench capable of automatically controlling the oil film thickness according to claim 1 or 2, characterized in that: The multi-point oil separator is one of a multi-point gear oil separator, a multi-point flow splitting motor or a gear pump group with the same flow rate.

7. The static pressure guide rail of a vertical lathe workbench capable of automatically controlling the oil film thickness according to claim 2 is characterized in that: The length of the first throttle is l0, and the length of the second throttle is p1 is the initial pressure of the oil chamber under the weight of the workpiece and the preload of the worktable base, and pmax is the maximum pressure of the oil chamber under the weight of the worktable and the maximum weight of the workpiece.

8. An automatic control method for a static pressure guide rail of a vertical lathe workbench capable of automatically controlling the oil film thickness, characterized in that: The automatic control of the static pressure guide rail of the vertical lathe workbench capable of automatically controlling the oil film thickness as claimed in any one of claims 1 to 7 comprises: When the pressure relay is turned on, the drive motor 1 starts to operate, and the oil enters the static pressure oil chamber of the workbench base. The pressure of the oil chamber is recorded as p1. When the oil chamber pressure p1 drops to a certain value, the motor acceleration pressure relay is turned on, the drive motor starts to accelerate, the oil chamber pressure increases and returns to p1, the motor acceleration and deceleration stops, the pressure relay is turned on, the drive motor accelerates and stops, at this time the working pressure relay is turned on normally, and the working pressure is normal; When the oil chamber pressure p1 rises to a certain value, the motor deceleration pressure relay is turned on, and the drive motor starts to decelerate, causing the oil chamber pressure to drop and return to p1. The motor acceleration and deceleration stops, and the pressure relay is turned on, driving the motor to decelerate and stop. At this time, the working pressure relay is turned on normally and the working pressure is normal.

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