JP2023022403A - Clogging sensing device - Google Patents

Abstract

To provide a clogging sensing device that properly determines clogging of a filter.SOLUTION: A clogging sensing device 30 comprises: liquid level measuring means that measures a change in liquid level at an inside and at an outside which are communicated with each other through a filter 23 of a pump chamber 21 provided in a tank 15; and clogging determining means that determines clogging on the basis of a change with time concerning a difference in liquid level between the inside and the outside of the pump chamber 21, from a measured value obtained by the liquid level measuring means. For instance, the liquid level measuring means are level gauges 31 and 32 provided at the inside and at the outside of the pump chamber. The clogging determining means is a control device 4 that stores a clogging-sensing program for calculating liquid level on the basis of measured values from the level gauges 31 and 32 and performing determination of the clogging on the basis of the change with time in liquid level at the inside and at the outside of the pump chamber 21.SELECTED DRAWING: Figure 3

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clogging detection device that determines clogging of a filter based on changes in liquid level over time.

Machine tools use coolant to cool the machined parts and wash away chips. The coolant injected into the machining chamber flows down inside the machining chamber and is accumulated in the coolant tank, where chips and the like are removed and used repeatedly. The coolant tank is equipped with a filter such as fine mesh in the pump chamber to prevent the coolant pump from sucking in foreign matter such as chips. As the coolant deteriorates, it becomes more dirty, and the filter will be covered with chips and oil. Therefore, filters require periodic cleaning. Patent Literature 1 below discloses a clogging detection device that determines filter contamination by measuring the liquid level in two tanks sandwiching a filter.

The clogging detection device of the same document is provided with a liquid level gauge for measuring the liquid level in the dirty tank and the clean tank of the coolant tank. A suction port fitted with a filter is formed in the wall between the dirty tank and the clean tank, and the liquid level in each tank is usually the same. A liquid level differential occurs due to the limited volume passing through the filter. A conventional clogging detection device measures the state in which the liquid level difference increases due to the clogging of the filter, resulting in poor flow, and determines whether or not the coolant level is appropriate when the coolant pump is in operation. configuration is adopted.

JP 2016-43460 A

The conventional example is configured so that it can be determined that the filter is clogged when the liquid level difference exceeds a reference value. Specifically, the liquid levels of both the dirty tank and the clean tank are measured by liquid level gauges, and the liquid level difference occurring there is calculated. This liquid level difference is thought to measure the change in the liquid level that occurs when the coolant pump starts to operate, but it is not clear at what point the liquid level difference occurs, and depending on the measured value, the judgment becomes ambiguous. . Also, even if the maximum value of the liquid level difference is obtained, the result is not constant depending on the performance of the coolant pump, etc., and it is considered that the clogging state of the filter is not correctly determined. In addition, in the conventional example, the liquid level difference must be calculated while receiving data from the two liquid level gauges, which complicates the processing.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a clogging detection device that appropriately determines whether or not a filter is clogged.

The clogging detection device according to the present invention comprises liquid level measuring means for measuring a change in liquid level between the inside and the outside communicating through a filter of a pump chamber provided in a tank, and the liquid level measuring means. clogging determination means for determining clogging based on the time change of the liquid level difference between the inside and the outside of the pump chamber from the measured value obtained.

According to the above configuration, in the pump chamber provided in the tank, the coolant flows from the outside to the inside through the filter, which causes clogging of the filter. The change is measured by the liquid level measuring means, and the clogging determination means determines the state of clogging based on the time change of the liquid level difference between the inside and outside of the pump chamber from the measured value obtained by the liquid level measuring means. clogging of the filter can be determined appropriately.

1 is a side view showing an internal structure of a machine tool equipped with a clogging detection device; FIG. It is a perspective view showing a coolant tank. 1 is a simplified diagram of a first embodiment of a clogging detection device; FIG. 4 is a graph conceptually showing clogging detection processing executed by a clogging detection program. It is the figure which simplified and showed 2nd Embodiment of the clogging detection apparatus.

An embodiment of a clogging detection device according to the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing the internal structure of a machine tool equipped with the clogging detection device of this embodiment. The machine tool 1 is mounted on a movable bed 2 equipped with wheels, and is movable in the front-rear direction (Z-axis direction) along rails laid on the upper surface of the base 3 . Various driving devices such as a spindle device 5 are mounted on the movable bed 2, and a control device 4 for driving and controlling the various driving devices is mounted on the rear side of the machine body.

The main shaft device 5 is provided with a main shaft chuck 11 for a rotatable main shaft, and rotates a gripped work W by a spindle motor. The machine tool 1 has a turret device 6 in which a plurality of tools are attached to a tool rest 12 . The turret device 6 selects a tool to be used for machining from a plurality of attached tools by turning indexing of the tool post 12 . The machine tool 1 moves the turret device 6 in the Z-axis direction, which is the longitudinal direction of the machine body, and in the X-axis direction, which is the vertical direction of the machine body, in order to move the tool to the machining position for the workpiece. An X-axis drive 8 is provided.

In such a machine tool 1 , the workpiece W is gripped by the spindle chuck 11 by delivery with an automatic workpiece transfer machine (not shown), and is rotated by driving the spindle device 5 . In the turret device 6, a tool to be used for machining the work W is selected by turning indexing. By driving the Z-axis driving device 7 and the X-axis driving device 8, the tool moves in the machining axis direction together with the turret device 6, and the workpiece W is machined in a predetermined manner. After machining the work W, the machined work W is replaced with a new work W in the spindle chuck 11, and the work W is repeatedly machined automatically.

In the machine tool 1, an inlet to a coolant tank 15 is formed at the bottom of a machining chamber 10 for machining, and chips and the like generated by machining the workpiece W are accumulated in the coolant tank 15. Since the coolant tank 15 has a built-in chip conveyor, chips are carried to the rear of the machine body and discharged and collected in an external collection box. The machine tool 1 also uses working fluids such as coolant for lubrication and washing away chips, and compressed air for cleaning and operating actuators. In particular, since the coolant is jetted inside the processing chamber 10, it flows down into the coolant tank 15 together with chips and the like.

The machine tool 1 is configured so that the coolant can be used repeatedly. However, the coolant accumulated in the coolant tank 15 cannot be used as it is because it contains chips and the like. Therefore, foreign matter is removed from the coolant through a filter while it is sent to the coolant pump 16, and the regenerated coolant flows through the coolant pipe 17 by the coolant pump 16 and is sent to the processing chamber 10 again.

FIG. 2 is a perspective view showing the coolant tank 15. FIG. A chip conveyor 18 is incorporated in the coolant tank 15 as indicated by a dashed line. The chip conveyor 18 is formed with an inlet 181 that opens at the bottom of the processing chamber 10 , and chips and coolant enter through the inlet 181 and are stored in the storage tank of the chip conveyor 18 . By driving the chip conveyor 18, only chips are carried out of the machine and then collected.

The storage tank of the chip conveyor 18 is formed with an outflow port closed with fine hole punching metal or the like, and the coolant flowing out from the outflow port is stored in the coolant tank 15 . The machine tool 1 is provided with a coolant device that filters the used coolant and feeds it into the machining chamber 10 repeatedly. In the coolant device, a pump chamber 21 surrounded by side walls 22 is formed at a corner within a coolant tank 15, and a coolant pump 16 is installed therein. A suction port is formed in a side wall 22 of the pump chamber 21, and a mesh plate 23 is fitted therein as a filter.

The coolant in the coolant tank 15 is driven by the coolant pump 16 to flow into the pump chamber 21 , and the mesh plate 23 removes chips and lubricating oil contained in the coolant. Such a mesh plate 23 needs to be periodically cleaned because clogging occurs due to adhering chips and the like. However, in the compact machine tool 1, the position of the mesh plate 23 is located in the narrow base 3, and other adjacent machine tools are close to each other, so clogging cannot be easily confirmed. . Therefore, the machine tool 1 is provided with a clogging detection device for notifying the cleaning time of the mesh plate 23 .

FIG. 3 is a diagram showing a simplified first embodiment of the clogging detection device. In the clogging detection device 30 of the present embodiment, liquid level gauges 31 and 32 are installed inside and outside the pump chamber 21 in the coolant tank 15, and the liquid level gauges 31 and 32 store a clogging detection program. It is connected to the control device 4 . FIG. 4 is a graph conceptually showing the clogging detection process executed by the clogging detection program. The liquid level gauges 31 and 32 of the present embodiment may be of a float type, an electrode type, an ultrasonic type, a capacitance type, or the like, as long as they can measure the liquid level.

The clogging detection process of the present embodiment focuses on the fact that the clogging state of the filter appears as a temporal change in the liquid level (liquid level) between the inside and outside of the pump chamber 21 . Graph A shown in FIG. 4 shows changes over time in the liquid level inside the pump chamber 21 measured by the liquid level gauge 31, and graphs B and C show the liquid level outside the pump chamber 21 measured by the liquid level gauge 32. is shown. In particular, graph B shows a case where the clogging of the mesh plate 23 is permissible, and graph C shows a case where the clogging of the mesh plate 23 has deteriorated to such an extent that cleaning is required. Such changes in the liquid level are obtained by transmitting the measured values obtained by the liquid level gauges 31 and 32 to the control device 4 .

When the coolant pump 16 is driven, the coolant in the coolant tank 15 is sucked in, so that the level of the coolant drops to a certain extent. Inside the pump chamber 21 where the coolant is directly sucked by the coolant pump 16, as shown in graph A, the liquid level changes from t1 to t4. Outside the pump chamber 21, the liquid level also changes as shown in graphs B and C in the same manner. However, the flow of the coolant outside the pump chamber 21 is blocked by the side wall 22 until it is sucked into the coolant pump 16, and the mesh plate 23 at the suction port also resists. It changes so as to lag behind the liquid level.

In particular, changes in the liquid level outside the pump chamber 21 are affected by the state of clogging of the mesh plate 23 . In the state of the mesh plate 23 shown in graph B, the time t5 until the liquid level stabilizes when the coolant pump 16 sucks in is delayed by T5 from the time t2 of the pump chamber 21 . In the state of the mesh plate 23 shown in graph C, the time t6 at which the liquid level is stabilized is further delayed to T6. Therefore, let tn be the time for the liquid level to stabilize in the coolant tank 15 outside the pump chamber 21 during suction by the coolant pump 16, and when the time Tn taken from t2 to tn exceeds a certain time (threshold), It is determined that the mesh plate 23 is in a clogged state requiring cleaning. The term "stabilized liquid level" refers to a state in which changes in the liquid level are kept within a certain range (the same shall apply hereinafter).

The clogging detection program is started when the coolant pump 16 starts driving, and the liquid level is calculated based on the measured values from the liquid level gauges 31 and 32, and the inside and outside of the pump chamber 21 as shown in FIG. Liquid level change data is created according to the passage of time. Then, the difference between the corresponding times tn and t2 (for example, T5 or T6) is obtained as a determination value from the liquid level change data, and clogging is determined by comparison with a preset threshold value. If the determination value exceeds the threshold value, it is determined that the mesh plate 23 needs cleaning due to clogging, and the monitor 25 on the front of the machine body displays that effect.

Therefore, the clogging detector 30 of the present embodiment uses the liquid level gauges 31 and 32 as in the conventional example to measure the liquid levels inside and outside the pump chamber 21, but the mesh plate By using the liquid level change data indicating the influence of the flow of coolant passing through 23 as a judgment material, the state of clogging of mesh plate 23 can be judged appropriately. In the machine tool 1 of the present embodiment, the pump chamber 21 is present in the narrow base 3, and although it is difficult to visually determine the state of clogging, the monitor 25 indicates an appropriate cleaning timing for the mesh plate 23. can be displayed on the screen, greatly reducing the labor of workers.

By the way, in the first embodiment, the liquid level change data based on time is created from the measured values of the liquid level gauges 31 and 32, but it is preferable to make the determination by a simpler process. FIG. 5 is a simplified diagram of a second embodiment of the clogging detection device. The state of clogging in the mesh plate 23 can also be grasped as a temporal change in the liquid level difference between the inside and outside of the pump chamber 21 . In the clogging detection device 40 of the present embodiment, a seesaw base 43 connecting floats 41 and 42 floating in the coolant tank 15 inside and outside the pump chamber 21 is provided with an inclination sensor 45 for measuring the inclination thereof. and connected to the control device 4 .

When the coolant pump 16 starts to be driven, there is a period of time when the liquid levels inside and outside the pump chamber 21 are different, as shown in FIG. For example, the worse the clogging of the mesh plate 23, the worse the flow, and it takes time until the liquid levels inside and outside the pump chamber 21 stabilize. For example, in the case of graph B, the liquid level is stabilized at time t5, but in the case of graph C, it takes time until t6. Therefore, the clogging detection device 40 has a clogging detection program that determines whether or not the time for which the measured value of the tilt sensor 45 is tilted by a predetermined angle (reference angle) or more exceeds a predetermined time (reference time). stored in

The clogging detection program is started when the coolant pump 16 is started, and the inclination due to the liquid level difference is confirmed based on the measurement value from the inclination sensor 45 . When the coolant pump 16 is driven, the coolant is sucked in and the liquid level inside the pump chamber 21 drops, and the liquid level outside drops with a delay. Therefore, since the heights of the floats 41 and 42 are different depending on the respective liquid levels, the seesaw base 43 is tilted. The measured value from the tilt sensor 45 is transmitted to the control device 4, and the control device 4 determines whether or not the measured angle is greater than or equal to the reference angle.

If the angle measured by the tilt sensor 45 is equal to or less than the reference angle, it is determined that the degree of clogging of the mesh plate 23 is low. On the other hand, if the measured angle is greater than or equal to the reference angle, the duration of that state is counted. If the time is equal to or shorter than the reference time, it is determined that the degree of clogging of the mesh plate 23 is low. On the other hand, when the measured angle continues to be equal to or greater than the reference angle for the reference time or longer, it is determined that the mesh plate 23 needs to be cleaned due to clogging, and the monitor 25 on the front of the machine body indicates this fact.

Therefore, the clogging detection device 40 uses the time change of the liquid level difference indicating the effect of the flow of coolant passing through the mesh plate 23 as a judgment material, and based on the measurement value of the tilt sensor 45, the clogging detection device 40 detects clogging from the duration of the measurement angle based on the measurement value. is determined, the clogging state can be appropriately determined. In addition, the clogging detection program of the present embodiment, which determines by measuring the time for which the measured value of the tilt sensor 45 is tilted by a certain angle or more, is simpler than the processing of the clogging detection program in the first embodiment. . Also in this embodiment, the cleaning time of the mesh plate 23 is appropriately displayed on the monitor 25, and the labor of the operator can be greatly reduced.

Although one embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made without departing from the scope of the invention.
For example, in the above embodiment, the pump chamber 21 in the coolant tank 15 of the machine tool 1 has been described as an example, but the present invention is not limited to this.
Moreover, although the mesh plate 23 was described as an example of the filter, any filter structure may be used.

DESCRIPTION OF SYMBOLS 1... Machine tool 3... Base 4... Control device 15... Coolant tank 16... Coolant pump 18... Chip conveyor 21... Pump chamber 22... Side wall 23... Mesh plate 30... Clogging detector 31, 32... Liquid level gauge 40... Eyes Clogging detection device 41, 42... Float 43... Seesaw table 45... Inclination sensor

Claims (4)

liquid level measuring means for measuring a change in liquid level between the inside and the outside communicating through a filter in a pump chamber provided in the tank;
clogging determining means for determining clogging based on the time change of the liquid level difference between the inside and the outside of the pump chamber from the measured value obtained by the liquid level measuring means;
A clogging detection device having a The liquid level determination means is a liquid level gauge provided inside and outside the pump chamber, and the clogging determination means calculates the liquid level based on the measured value from the liquid level gauge, 2. The clogging detection device according to claim 1, wherein the control device stores a clogging detection program for judging clogging based on the time change of the liquid level inside and outside the chamber. The clogging detection program creates liquid level change data that changes over time between the inside and outside of the pump chamber, and the time difference until the liquid level stabilizes exceeds a preset threshold. 3. The clogging detection device according to claim 2, wherein it is determined that the filter needs to be cleaned due to clogging. The liquid level determination means is a tilt sensor provided on a seesaw table having floats floating on the inside and outside of the pump chamber, and the clogging determination means determines that the measured value of the tilt sensor is tilted by a certain angle or more. 2. The clogging detection device according to claim 1, wherein the control device stores a clogging detection program for judging clogging depending on whether or not the time of stay exceeds a reference value.

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