JP2001004433A - Detecting device for liquid level height of cutting fluid tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the device which uses conductive cutting fluid and electrically digitaize and transmits liquid level height to an operator in real time. SOLUTION: An insulated electrode 4 is fixed to the bottom surface in a cylindrical small room 3 formed of a shield plate 2 having a small hole 2a communicating with a tank main body part at a corner part of the cutting fluid tank 1. An electrode 6 is floated on the liquid level in the small room 3. The two electrodes 4 and 6 are connected to a power source 7 and an ammeter 8 in series outside the cutting fluid tank 1 and the height of the cutting fluid is taken out as a numeral by using the variation in the current value due to the variation in the resistance accompanying a decrease in the amount of the cutting fluid between the two electrodes 4 and 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for managing the amount of cutting fluid (including grinding fluid) used in cutting and grinding in a machine tool in a cutting fluid tank.

[0002]

2. Description of the Related Art At the time of cutting by a machine tool, a cutting fluid is injected and supplied to a tool tip portion during cutting.
The first purpose is to cool to remove the heat generated during cutting. Thereby, the temperature change is reduced, and the processing accuracy is improved. In high-speed cutting recently proposed, it is particularly important to remove heat generated during cutting. Another object of the present invention is to prevent friction between the tip of the tool and the workpiece and chips, delay the progress of tool wear, and extend the life of the tool. Another object of the present invention is to flush the chips with a cutting fluid to facilitate the collection of the chips. That is, it is an important operation for the automatic machining because the tool and the attachment can be cleaned. Further, an effect of preventing oxidation by coating the cut work surface is also expected.

[0003] Each machine tool is provided with a cutting fluid tank for supplying the cutting fluid, and pumps up the cutting fluid to supply it to the tool tip. After the cutting fluid supplied to the tool tip is washed away, the cutting fluid is separated from the cutting fluid and collected in a cutting fluid tank for reuse. Since the amount of the cutting fluid in the cutting fluid tank is always collected, it does not decrease sharply. However, it cannot be completely recovered due to scattering, evaporation to the various places, and discharge attached to the chips, etc., and gradually decreases. Therefore, it is necessary to control the amount of liquid. Conventionally, the first method in which the lid of the tank is removed and the operator visually controls the liquid, or the cutting liquid tank 1 as shown in FIG.
A second method for visually controlling the liquid level gauge 102 attached to the side surface of the cutting fluid 01, or the cutting fluid tank 1 as shown in FIG.
When the float 103 floated on the liquid surface in the lower part 01 falls below a set position, the arm 104 for fixing the float
A third method using a so-called float switch has been performed in which a detector (not shown) for detecting the displacement of the sensor outputs an electric signal.

[0004]

The first problem described in the prior art is as follows.
In the second liquid level management method, the operator sometimes has to move himself to the tank installation position and perform visual observation, and if this operation is neglected, there is a possibility that the liquid may run out. When the liquid runs out, the cutting tool is overheated and breaks, and there is a problem that the work may be damaged. Further, in the third liquid level management method described in the related art, the liquid level information is not transmitted to the operator until the liquid level is below the set position, so that there is a problem that the work plan is hindered. The present invention has been made in view of the above-described problems of the related art, and has as its object to electrically digitize the liquid level in a cutting fluid tank using a conductive cutting fluid, and And a device for transmitting liquid level information in real time.

[0005]

According to a first aspect of the present invention, there is provided an apparatus for cutting a liquid to be provided in a cutting fluid tank for a machine tool using a conductive cutting fluid. A detection device, a room communicating with the inside of the tank near the bottom and having an insulated inner periphery, a fixed electrode insulated and fixed to the bottom surface in the room, and floating on a liquid surface on the fixed electrode. A floating electrode, an ammeter and a power supply are connected in series to the fixed electrode and the floating electrode to form an electric circuit, and a conductive cutting fluid flows into the tank to correspond to the liquid level of the cutting fluid. The magnitude of the internal resistance of the cutting fluid is detected as an indicated value of an ammeter.

According to the above-described apparatus, the liquid level is taken out as a current value in accordance with a change in the resistance value of the conductive cutting fluid between the electrode floating on the liquid surface and the fixed electrode. As a result, the numerical value can be displayed on the operation panel of the machine tool, and the liquid level height can be transmitted to the operator in real time by numerical values, so that the liquid level can be easily managed.

According to a second aspect of the present invention, there is provided an apparatus according to the present invention, wherein a plurality of pairs of electrodes are connected in parallel with a pair of electrodes having opposite ends instead of the fixed electrodes and the floating electrodes,
The plurality of pairs of electrodes are attached in a suspended manner, and both terminals of the plurality of pairs of electrodes are connected in series with the power supply and the ammeter.

According to the above-mentioned apparatus, a plurality of pairs of electrodes are connected in parallel and arranged in a suspended state without using a fixed electrode or a floating electrode. A current value corresponding to the height can be indicated. Further, the electrode can be easily removed from the cutting fluid tank, and the electrode can be easily cleaned.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing a cutting fluid tank and a liquid level detecting device according to a first embodiment of the present invention.

A cutting fluid tank (hereinafter referred to as a tank) 1 is filled with a highly conductive cutting fluid (including a grinding fluid) mainly composed of cutting water. Normally used cutting fluid is collected in the tank 1 for reuse, and the collected cutting fluid contains foreign matter such as cutting chips. The liquid surface is wavy due to the flow of the liquid into the tank. Therefore, a cylindrical small chamber 3 is provided by the shielding plate 2 at the tank corner farthest from the inflow portion of the collected cutting fluid and farthest from the cutting fluid suction port by the pump. The shield plate 2 is provided on the bottom surface 1 of the tank 1 to prevent the liquid level from fluctuating due to the movement of the liquid in the tank 1 and the inflow of foreign matter on the liquid level.
A cutting hole in the tank 1 is communicated with the cutting fluid in the small chamber 3 by piercing the lateral hole 2a slightly above the position a. Therefore, the liquid level in the small room 3 is always the same as the liquid level in the tank 1. If a net or a filter is attached to the lateral hole 2a, it is possible to further prevent the inflow of foreign matter in the liquid.

An inner peripheral surface of the cylindrical small room 3 is entirely covered with an insulating coating, and an electrode 4 is fixed on the bottom surface of the small room 3 in an insulated state. Then, the lead wire 5 of the electrode 4 is led out of the tank 1 while being insulated from the bottom surface 1a of the tank 1. The floating electrode 6 is floated on the liquid surface in the small room 3 in a float shape. The fixed electrode 4 and the floating electrode 6 are the tank 1
A closed circuit is formed by a series connection with a DC power supply 7 and an ammeter 8 as a power supply outside the device and a conductive cutting fluid.

A variable resistor 9 is connected in series to this closed circuit, and the variable resistor 9 is adjusted so that the ammeter 8 indicates a minimum value when the cutting fluid level is at the highest position. Since the entire inner peripheral surface of the cylindrical small room 3 is covered with the insulating film, the current value may be abnormal even if the floating electrode 6 comes into contact with the wall surface of the cylindrical small room 3 due to the fluctuation of the liquid level. There is no. The surfaces of the electrodes 4 and 6 are preferably made of chromium plating or stainless steel having corrosion resistance. When the power source 7 is a battery, the switch 10 can be inserted into the circuit to cut the circuit appropriately in order to reduce consumption. Further, when an AC power supply is used as the power supply, the voltage may be reduced by a transformer (not shown) and the AC may be converted to DC by a rectifier (not shown). In this case, a circuit breaking switch is unnecessary in the electric circuit, and the current value of the ammeter 8 can be continuously monitored.

[Operation] When the tank 1 is initially filled with the cutting fluid, the level of the cutting fluid is at the highest position, and the floating electrode 6 is also at the highest position. The fixed electrode 4 and the floating electrode 6 are in the most distant state. Since the cutting fluid is conductive, a current flows between the fixed electrode 4 and the floating electrode 6. At this time, the internal resistance value between the electrodes of the cutting fluid becomes maximum, and the current value of the ammeter 8 shows the minimum value. Therefore, adjustment is performed by the variable resistor 9 so that the ammeter 8 indicates the minimum value of the scale. If the variable resistor 9 is initially set, there is no need to adjust thereafter.

Next, when cutting is performed for a long time, the cutting fluid gradually decreases due to scattering, evaporation, adhesion to chips, etc., and the liquid level in the tank 1 falls. Then, the floating electrode 6 descends as the liquid level descends, and the distance from the fixed electrode 4 decreases. At this time, the internal resistance value of the cutting fluid between the electrodes also gradually decreases, and the current value indicated by the ammeter 8 gradually increases. When this is applied to an equation, if the voltage of the power supply 7 is E, the current value indicated by the ammeter 8 is I, the internal resistance between the electrodes of the cutting fluid is R, and the set resistance value of the variable resistor 9 is rx,

(Equation 1) Here, the voltage of the power supply 7 is constant, and is constant without being changed after the setting resistance value rx of the variable resistor 9 is set. Therefore, when the floating electrode 6 moves down, the distance between the electrodes becomes short and the internal resistance R of the cutting fluid decreases, the current value I indicated on the ammeter 8 increases. By displaying the current value indicated by the ammeter 8 on the operation panel of the machine tool, the operator can recognize the liquid level of the cutting fluid in real time as a numerical value called the current value. If the cutting fluid is determined, it is necessary to grasp the data based on the experimental result of actually measuring the resistance value depending on the liquid level.

FIG. 2 is an explanatory view showing a cutting fluid tank and a liquid level detecting device according to a second embodiment of the present invention. The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

In a small room 3 similar to that shown in FIG. 1, two electrode mounting plates 11 and 12 made of a conductive material are held by insulating supports 13 and 13 in a state where they face each other. , 17 so as to hang from above. A plurality of pairs of electrodes 14 and 15 which are opposed to and protrude from the two electrode mounting plates 11 and 12 and have a slight gap between the tips are mounted at an equal pitch. Then, the two electrode mounting plates 11 and 12, the support 13, and each electrode 14
The detector 16 is constituted by 15. The shape of each electrode can be appropriately used, such as a sphere or a rod. In order to impart corrosion resistance to the surfaces of the electrode mounting plate and the electrodes, it is necessary to consider using, for example, chrome plating or stainless steel.

A lead wire is provided on each of the two electrode mounting plates 11 and 12, and a power supply 7, an ammeter 8, and a variable resistor 9 are connected in series between the two lead wires. When the conductive cutting fluid is filled in the tank 1, all the pairs of the plurality of electrodes are immersed in the cutting fluid. The current value indicated by the total 8 changes. When this is applied to an equation, the voltage of the power source 7 is E, the current value indicated by the ammeter 8 is I, the internal resistance value of the cutting fluid between one electrode pair is r, and the number of electrode pairs immersed in the cutting fluid is n, assuming that the set resistance value of the variable resistor 9 is rx,

(Equation 2) Becomes That is, as the number of electrode pairs immersed in the cutting fluid decreases, the value of the current value I also decreases.

In each of the above embodiments, numerical values such as a current value and a voltage value indicating a liquid level are displayed on a control operation panel of a machine tool, and information is transmitted to an operator in real time. However, it is also possible to provide an AD converter in the control operation panel, convert analog information such as current value and voltage value into digital information and display the digital information on the operation panel. Further, in each of the above embodiments, the electrode is provided in the small room provided with the shielding plate in the tank, but the small room may be separate as long as it communicates with the tank at the bottom, or the cutting fluid / chip If it is not affected, it may be provided in the tank as it is. Further, in order to cope with a change in conductivity caused by a change in concentration due to the evaporation of the cutting fluid, a means for measuring and correcting the concentration may be added.

[0020]

Since the apparatus according to the present invention is constructed as described above, the following effects can be obtained.

According to a first aspect of the present invention, the liquid surface height is represented by a current value in accordance with a change in the resistance value of the conductive cutting fluid between the electrode suspended on the liquid surface and the fixed electrode. Since it can be taken out, it is possible to display the numerical value on the operation panel of the machine tool, and it is possible to transmit the liquid level to the operator as numerical information in real time, making it easier to manage the liquid level Was.

In the apparatus according to the second aspect, since a plurality of pairs of electrodes are connected in parallel and arranged in a suspended state, there is little adhesion of foreign matter on the electrodes, and the current value corresponding to the liquid level is accurately indicated. Can be done. Further, the electrode can be easily removed from the cutting fluid tank, and the electrode can be easily cleaned.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory view showing a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a conventional technique.

FIG. 4 is an explanatory diagram showing another conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cutting fluid tank 1a Bottom surface 2 Shield plate 2a Small hole 3 Small room 4 Fixed electrode 6 Floating electrode 14, 15 electrode 7 Power supply 8 Ammeter

Claims (2)

[Claims] 1. A liquid level detecting device provided in a cutting fluid tank for a machine tool using a conductive cutting fluid, comprising: a chamber which communicates with the inside of the tank and near a bottom thereof, and which has an insulated inner periphery; A fixed electrode insulated and fixed on the bottom of the room, a floating electrode floating on the liquid surface on the fixed electrode, and an ammeter and a power supply connected in series to the fixed electrode and the floating electrode. An electric circuit was formed to allow the conductive cutting fluid to flow into the tank and detect the magnitude of the internal resistance of the cutting fluid corresponding to the liquid level of the cutting fluid as the indicated value of the ammeter. Characteristic liquid level detector for cutting fluid tank. 2. In place of the fixed electrode and the floating electrode, a plurality of pairs of electrodes are connected in parallel with the tip portions facing each other in a vertical direction, and the plurality of pairs of electrodes are attached in a hanging manner.
2. The liquid level detecting device for a cutting fluid tank according to claim 1, wherein both terminals of the plurality of pairs of electrodes are connected in series with the power supply and the ammeter. 3.