DE212012000270U1 - Device for complete monitoring of the secondary pressure in a hydrostatic support system - Google Patents

Abstract

A device for the complete monitoring of a secondary pressure in a hydrostatic support system, characterized in that the device contains a monitoring component, a memory and a detector, wherein: the monitoring component is introduced directly into a hydrostatic chamber of the hydrostatic support system, each hydrostatic chamber having a Monitoring component is equipped and wherein the monitoring component directly measures a pressure value in the hydrostatic chamber, the pressure value representing a secondary pressure of a throttle in the hydrostatic support system, the secondary pressure representing an output pressure; the memory stores a predetermined monitoring threshold; the detector is connected to the monitoring component and the memory, compares the pressure value measured by the monitoring component in the hydrostatic chamber with the monitoring threshold value specified in the memory, and determines, based on the comparison result, whether a warning signal is to be generated, the warning signal being used to determine a Realize warning failure and determine a warning point.

Description

THE iNVENTION field

The invention relates to a monitoring device for a hydrostatic support system, and more particularly relates to a monitoring device for detecting the secondary pressure in a hydrostatic support system.

Technical background

The hydrostatic support system is composed of an oil pump, a throttle, and some additional components (for example, a filter, a pressure sensor, an accumulator, etc.), and there are many types of restrictors: the film feedback type, the sliding feedback type However, no matter what form of throttle is used, a common requirement to be met: namely, the pressure ratio (also called throttle ratio) is 2: 1. That is, during idling, the pressure ratio β before and after the throttle opening is 2: 1. The value of the pressure ratio influences the oil film stiffness of the hydrostatic support. Hereinafter, the influence of the pressure ratio on the oil film rigidity with the film feedback type of the hydrostatic bearing will be further explained as an example. The 1A and 1B show the hydrostatic return line of the film feedback type. In 1B the hydrostatic support system consists of several pressure sensors (pressure sensor 10a . 10b . 10c . 10d in 1B ), Distributors (distributors 12a . 12b in 1B ), the hydrostatic bearing 14 , the main camp 11 and the oil pump 15 ,

If the pin is affected by a radial load F and moved downwards by a distance e, the clearance at the lower oil chamber of the bearing is reduced and the pressure P3 increases. The distance at the upper oil chamber is then increased. The pressure P1 is reduced. The pressure difference ΔP = P3 - P1 is generated between the upper and lower oil chambers. Because the oil chamber 1 and oil chamber 3 Each is connected to the upper and the lower oil chamber of a right film feedback throttle, there is also an equal pressure difference between the upper and the lower oil chamber of the right film feedback throttle. An upward force is applied to the film. The film rises, so that the upper throttle gap is reduced, and then the pressure P1 is reduced. And the lower throttle gap is increased so that the pressure P3 increases, and then the pressure difference between the oil chamber 3 and oil chamber 1 increased at the hydrostatic bearing. The pin is lifted slightly and stabilized at the new location. The stiffness of the oil film means the ability of the oil film around the journal against the load F. With regard to the hydrostatic support when the journal is affected by the radial load F, the following occurs: the smaller the distance e moved down, the larger the Stiffness of the oil film.

The magnitude of the rigidity of the oil film has a direct relation to the throttle ratio β.

From the 2 We may learn that if the pressure ratio is too great or too small, this can lead to the increased displacement of the pin. That can affect the rotational precision. Overall, the stiffness is reduced. The oil fluid is affected by temperature, and the change in viscosity can change the pressure ratio. Above all, the oil contamination (including the air mixture, the jelly from the oxidation of the oil liquid, the dirt during maintenance, etc.) can clog the throttle, so that the oil liquid can not flow well. The result is that the supports are burned.

In the past, the pressure gauges and pressure sensors were only installed at the inlet of the pressure oil in the throttle, this is often called the primary control method. Regular maintenance is the only means of guaranteeing the safety of the hydrostatic system. For example, changing the fluid, changing the filter pack, cleaning the throttle, cleaning the pipes, checking the stiffness of the oil film, etc. The disadvantages are: long downtime, heavy operation, and heavy responsibility.

Due to the existence of objective factors, there is always the possibility that the choke becomes clogged. The conventional primary pressure control method can not fully protect the support elements. When an alarm is signaled, the internal components of the system have already been damaged. The safety of the hydrostatic bearing system can only be guaranteed by the measures of regular production interruption and maintenance.

Summary of the invention

The purpose of the present invention is to provide a device for the complete monitoring of the secondary pressure in the hydrostatic support system, which fully and timely monitor the pressure change of the hydrostatic support system, and can promptly and effectively cause an early warning.

As a solution, the invention discloses a device for the complete monitoring of the secondary pressure with a monitoring component, a memory, and a detector, having the following features:
the monitoring component is introduced directly into the hydrostatic chamber of the hydrostatic support system, and measures the pressure value in the hydrostatic chamber directly;
the memory stores a predetermined monitoring threshold;
the detector is connected to the monitoring component and the memory, compares the measured pressure value in the hydrostatic chamber with the predetermined monitoring threshold value, and after the comparison result determines whether a warning signal is to be generated.

According to one embodiment of the device for complete monitoring of the secondary pressure in the hydrostatic support system, the pressure monitoring device includes:
a warning device connected to the detector, receiving the warning signal from the detector and reporting the alarm.

According to one embodiment of the device for complete monitoring of the secondary pressure in the hydrostatic support system, the pressure monitoring device includes:
a screen connected to the detector which receives and displays the warning signal from the detector.

According to one embodiment of the device for complete monitoring of the secondary pressure in the hydrostatic support system, the monitoring component includes a digital pressure sensor.

In contrast to the prior art, the invention has the following advantages: the solution of the invention connects the monitoring component to the hydrostatic chamber in the hydrostatic support system, directly measures the pressure information in the hydrostatic chamber, and compares the pressure information with a predetermined monitoring threshold, so that the alarm signal is given in time , and can be shown on the screen by PLC programming to monitor the pressure in a timely manner. Comparing the invention with the prior art, the pressure change in the hydrostatic support system can be completely and timely monitored, and the early warning can be reported in a timely and effective manner. The monitoring function of the hydrostatic support system is being disseminated to provide a guarantee of the safety of the hydrostatic support system in an effective manner. The apparatus of the invention is simple, easy to use, and the apparatus of the invention can with great applicability permit pressure monitoring of a variety of hydrostatic assist systems.

Description of the figures

1A and 1B Fig. 10 are schematic diagrams of the film return hydrostatic return line in the film feedback type hydrostatic support system.

2 is the graphical representation of relationship of hydrostatic return line of the film feedback.

3 Figure 3 is the structural illustration of one example of a complete, secondary pressure monitor in the hydrostatic support system.

4 Figure 3 is the flowchart of one example of a method for fully monitoring the secondary pressure in the hydrostatic support system.

5 Figure 4 is an illustration of the use of the device to fully monitor the secondary pressure of the hydrostatic support system in the film feedback type hydrostatic support system.

6 is the relationship representation between the displacement and the pressure ratio when the throttle is stuffed.

7 is a graph of the value between the displacement and the pressure ratio when the load leads to the reduction of the chamber pressure.

8th is a schematic diagram of the disposable analog pressure reduction line.

Embodiment of the invention

In the following, the present invention will be further explained with reference to figures and examples.

Embodiments of the device for complete monitoring of the secondary pressure in the hydrostatic support system.

3 shows the structure of an embodiment of a device for complete monitoring of the secondary pressure in the hydrostatic support system. Please look 3 , The monitoring device of the embodiment has a monitoring component 20 , a store 21 , a detector 22 , an alarm 23 (Optional), and a screen 24 (Optional).

The monitoring component 20 and the memory 21 are each with the detector 22 connected. The output from the detector 22 is always with the alarm 23 and the screen 24 connected.

The main components of the hydrostatic support system are the oil pump, the throttle and the auxiliary component, etc. The monitoring component 20 is introduced directly into the hydrostatic chamber of the hydrostatic support system, and directly measures the pressure value in the hydrostatic chamber. In this case, the pressure value refers to the secondary pressure, and the secondary pressure means the output pressure of the throttle. The monitoring component 20 may be a pressure sensor, for. B. a digital pressure sensor. In the store 21 a predetermined monitoring threshold is stored. The measured pressure value in the hydrostatic chamber is in the detector 22 compared with the predetermined monitoring threshold. After the comparison result, it is determined whether a warning signal is generated.

When the alarm device 23 the warning signal from the detector 22 receives, z. B. an audible alarm. When the screen 24 the warning signal from the detector 22 then the screen alerts 24 ,

The hydrostatic support system is very sensitive to the participation of the elasticity (more specifically, from the throttle to the hydrostatic chamber) because it can reduce the power of the hydrostatic support. These components include: pressure gauge, hose, accumulator and some pressure sensors that do not meet the requirement of the system. When using these components in the secondary section, it should be noted that in the pressure sensor, the deformation of the spring can badly affect the response speed of the signal feedback, namely, can slow down the response speed of the signal feedback.

Here, the difference between constant load and changing load should be considered. For the constant load: the absorption amount of the spring can go to stability in a very short time by compensating the oil flow, namely, the wearer can have new place in a very short time, so that the movement precision is still normal.

But the situation of the changing load is different: The carrier moves at a certain distance under short-term heavy load. As the inverted hydrostatic chamber is increased, the spring absorbs energy, resulting in a slower increase in feedback pressure. The longer the time interval, the slower the response speed and the worse the stiffness of the oil film.

5 Figure 11 shows a representation of the use of the device to fully monitor the secondary pressure of the hydrostatic support system in the film feedback type hydrostatic support system. The traditional monitoring method is a primary monitoring method whereby due to blockage of the throttle, the bearings can be burned. Therefore, the monitoring request can not be met only with the primary monitoring. As the 5 shows, a complete secondary pressure monitoring is attached to the hydrostatic bearing of the workhead and the tailstock.

The hydrostatic bearing system in the 5 has a back warehouse 31 , a feedback movie 32 , a front end of the main shaft 33 , a front camp 34 , a throttle 35 , a rear end of the main shaft 36 , a hydrostatic chamber 37 , and a throttle area 38 , where P0 is the input from the primary pressure, P1 ~ P8 are the secondary pressure measuring points, SD1 ~ SD8 are pressure sensors. On the clamping head and tailstock, there are a total of 16 hydrostatic chambers. Each chamber has a pressure sensor as a monitoring component. In this state of full monitoring, when the pressure in one of the chambers drops, the alarm can be signaled and the location shown on the screen in time by PLC control.

When determining the monitoring threshold set in memory, two questions must be considered: one question is: if the throttle is stuffed, the pressure reduction in the hydrostatic chamber can lead in time to the signal alarm; the other question is: the pressure reduction of the hydrostatic chamber in the same direction can lead to a signal alarm in case of overload, but under normal load the pressure reduction of the hydrostatic chamber in the same direction can not lead to a signal alarm.

β

– das Druckverhältnis

ΔP

– der sekundäre Druck

P

– der primäre Druck

The following is the determination of the monitoring threshold. If the throttle opening of the throttle is blocked, normal measurement can not be guaranteed. The pressure in the hydrostatic chamber is lowered sharply. The pressure difference between the primary pressure and the secondary pressure is very high. Then, the pressure ratio β may exceed the normal range, and the displacement of the support body is increased until damage due to the collision of supports. According to the 6 the transmission point of the signal can be determined. β = P / ΔP in which:

β

- the pressure ratio

.DELTA.P

- the secondary pressure

P

- the primary pressure

The throttle is always blocked and the secondary pressure is always lowered so that the transmission value is taken as the lower limit of the secondary pressure, namely ΔPmin = P / βmax

ΔP min is the minimum value of the secondary pressure in the system. If the value is less than this minimum value, the bearing is likely to be damaged.

The following explains how to determine the monitoring threshold in reducing the pressure in the hydrostatic chamber due to the load.

There is the normal and abnormal load. The normal load is the load which the oil film of the hydrostatic support system can support and which does not result in a substantial change in the pressure ΔP in the hydrostatic chamber. In contrast, the overload.

Due to the load force F, the gap of the oil seal in the hydrostatic chamber is increased. Then the pressure will drop. If the pressure reduction exceeds a certain value, the monitoring device will immediately report an alarm. The determination of the signal transmission can be made only by the test on the system, since corresponding data from the respective systems are different.

Example: 5 shows the test data of the fixed hydrostatic bearing value at the clamping head and tailstock in CNC crankshaft grinding machine. test condition Radial load (N) The pressure in the hydrostatic chamber in the same direction as the load (bar) The pressure in the hydrostatic chamber in the opposite direction as the load (bar) The displacement of the axis (μ) turn on 0 19 19 0 Turn off 0 0 0 30 Normal machining / 17 21 / Static 1000 16 22 4 Static 3000 13 23 10 Static 5000 10 24 20

For the main shaft, the amount of displacement is an indicator that can judge the pivoting precision. The 5 shows the crankshaft, with relative higher precision. At the normal processing load, the pressure difference of the hydrostatic chamber in the same or opposite direction is 4 bar. According to the above table, the amount of displacement is less than 3 μ. With the requirement of the roundness of the workpiece, the main shaft allows the maximum displacement of 10 μ for the clamping head and tailstock. Then the pressure ΔPmin in the hydrostatic chamber in the same direction is 13 bar. Therefore the value should be ≥ 13 bar to guarantee the operating accuracy.

By the above mentioned methods one can get two ΔPmin values, namely 11.3 bar and 13 bar. To further explore their relationship, we identify a value that satisfies the system's requirement with an imaging method. Please refer 7 , The pressure ratio β is at the left vertical axis. The normal range is between 1.5 and 3. By calculating, the value range of ΔP can be 11.3 ~ 22.7 (bar). In the right vertical axis is the displacement of the carrier e. Through the test we get: if the displacement is 10 μ, then the pressure in the hydrostatic chamber is reduced from 19 bar to 13 bar. Since the precision requirement of the workpiece requires a maximum value of 10 μ, 13 bar can guarantee the minimum accuracy.

13 bar is currently between 11.3 and 22.7. It can meet the accuracy requirements, and also meet the requirements of the normal pressure ratio.

If the throttle is blocked, the pressure on the carrier is reduced. If the pressure is reduced up to 13 bar, the relay can report the alarm immediately and switch off the machines. If the load is more than 3000 N, the pressure of the hydrostatic chamber in the same direction is also reduced to 13 bar. The relay can also report the alarm and switch off the machines. This method protects the supports from damage, guarantees the movement accuracy of the support body, and also guarantees the safety of other mechanical components. In this sense, there is another method for overload protection.

Before setting the transmission value of the pressure sensors, the secondary pressure must be reduced to the alarm point. This can be realized by the simulation of the pressure reduction and operated in the form of individual adjustment.

In the 8th becomes the special tool 400 shown, consisting of a relief valve with a small flow, the pressure gauge and the oil tank. The special tool is connected by a quick coupling with the oil passage of the secondary pressure in the system. The relief valve is set according to the pressure value on the pressure gauge so that the pressure of the simulated transmission can be obtained. After setting the corresponding relay, it is only necessary to remove the quick coupling. The number is the same as the number of hydrostatic chambers.

This procedure is accurate, convenient, and can be done without changing the primary pressure at the throttle. Of course, this is not the only option. It is also possible to do according to the individual method as long as the purpose can be achieved.

In a normal hydrostatic system there is a primary pressure monitor and a pressure differential monitor on the filter. The goal is to avoid interrupting the oil supply to the system and lacking flow volume.

Since the number of monitors in the hydrostatic chamber is relatively large, the signal sources are also increased. In an ordinary device, one only needs to connect all the signal contacts in the electrical control circuit in series. If a program control device or CNC is available, the position of the pressure signal at standstill can also be displayed on the screen by PLC program. This brings great convenience to the repairs.

For the system with original contact points at the relay, one only needs to connect all signal contacts with original contact points in series.

The embodiment of the method for complete monitoring of the secondary pressure in the hydrostatic support system

Due to the above-mentioned device for the complete monitoring of the secondary pressure in the hydrostatic support system, this invention also provides a monitoring method that can be realized by the device. Please see the 4 , The detailed description of the individual steps for the method according to the invention is made in the following.

Step S10: The monitoring component, which is introduced directly into the hydrostatic chamber of the hydrostatic support system, directly measures the pressure value of the hydrostatic chamber.

The monitoring component may be a pressure sensor.

Step S12: Compare the measured pressure value with a predetermined monitoring threshold.

Step S14: After the comparison result, determine whether to generate a warning signal.

Step S16: Receive an early warning signal and report an alarm.

This step is an optional step. The alarm includes an audible alarm and a display alarm.

The device by which the method is implemented is already described in the above example and is no longer explained.

The above examples are offered so that those skilled in the art can realize and use the present invention. The technicians in the field may make various changes and variations to the invention without departing from the teachings of the present invention. Therefore, the present invention is not limited to the above examples and can achieve the maximum scope of protection of claims.

Claims (5)

A device for fully monitoring a secondary pressure in a hydrostatic support system, characterized in that the device includes a monitoring component, a memory and a detector, wherein: the monitoring component is introduced directly into a hydrostatic chamber of the hydrostatic support system, each hydrostatic chamber having a Monitoring component is provided and wherein the monitoring component directly measures a pressure value in the hydrostatic chamber, wherein the pressure value represents a secondary pressure of a throttle in the hydrostatic support system, wherein the secondary pressure represents an outlet pressure; the memory stores a predetermined monitoring threshold; the detector is connected to the monitoring component and the memory, compares the pressure value measured in the hydrostatic chamber by the monitoring component with the monitoring threshold value stored in the memory, and after the comparison result determines whether a warning signal is to be generated, wherein the warning signal is used to generate a warning signal Failure to realize warning and determine a warning point. The device for the complete monitoring of a secondary pressure in a hydrostatic support system according to claim 1, characterized in that two questions must be taken into account when determining the monitoring threshold value set in the memory: a question is: when the throttle is stuffed, the pressure reduction in the hydrostatic Bring the chamber in time for the signal alarm; Another question is whether the pressure reduction of the hydrostatic chamber in the same direction can lead to the signal alarm because of the overload, but the pressure reduction of the hydrostatic chamber in the same direction due to the normal load can not lead to a signal alarm. The apparatus for fully monitoring a secondary pressure in a hydrostatic support system according to claim 1, characterized in that the apparatus further comprises: a warning device connected to the detector and receiving the warning signal sent by the detector and signaling an alarm. The apparatus for fully monitoring a secondary pressure in a hydrostatic support system according to claim 1, characterized in that the apparatus further comprises: a screen connected to the detector and receiving the warning signal sent from the detector and indicating the warning signal and the warning location. The device for fully monitoring a secondary pressure in a hydrostatic support system according to claim 1, characterized in that the monitoring component includes a digital pressure sensor.

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