JPH0150543B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a coolant circulation system that controls the circulation of coolant when centrally managing and circulating coolant from a single coolant recovery tank to a plurality of processing machines. This relates to a control device.

(Prior Art) Conventionally, when centrally managing and circulating coolant to a plurality of processing machines, for example, a supply pump is provided in a main supply pipe that communicates each processing machine with a single coolant recovery tank. In addition to operating the pump at all times, the on-off valves installed in the branch supply pipes that branch from the main supply pipe to each processing machine are manually opened when each processing machine starts, thereby continuing to supply coolant while the processing machine is operating. On the other hand, the coolant used in each processing machine is collected into a collection tank through a collection pipe.

(Problems to be Solved by the Invention) However, in the conventional system described above, the supply pump is constantly operated to circulate the coolant, which results in high energy consumption, and there is room for improvement in terms of energy conservation. It was hot.

The present invention has been made in view of the above, and an object of the present invention is to appropriately control the operation of the above-mentioned coolant supply pump according to whether or not each processing machine is processing, thereby reducing the amount of coolant. By making it possible to efficiently supply coolant without reducing line pressure in the supply system,
The aim is to increase energy saving effects.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention includes a plurality of processing machines 1,
In a coolant circulation device that supplies coolant from a single coolant recovery tank 2 to 1,... and recovers used coolant to the recovery tank 2, the configuration of the coolant circulation system 12 is as follows:
Main supply pipe 5 leading to coolant recovery tank 2
A branch supply pipe 6 extending from the processing machine 1 to each processing machine 1, a recovery pipe 7 communicating from each processing machine 1 to a coolant recovery tank 2, and a bypass pipe 9 communicating the end of the main supply pipe 5 to the recovery pipe 7. The structure is as follows. Then, the main supply pipe 5 is connected to the bypass pipe 9.
A pressure detector 14 is provided to detect the line pressure at
Each branch supply pipe 6 is provided with an on-off valve 13 that opens and closes according to the processing timing of each corresponding processing machine 1, and the main supply pipe 5 is provided with a variable rotary pump for supplying coolant whose rotation speed can be controlled by frequency control. Set up P ₁ . Furthermore, upon receiving the detection signal from the pressure detector 14, a signal is sent to the variable rotation pump so that when the value is large, the variable rotation pump P ₁ is controlled to low rotation, and when the value is small, the variable rotation pump P ₁ is controlled to high rotation. A control means 18 for outputting to _P1 is provided.

(Function) With the above configuration, in the present invention, the on-off valve 1 of the branch supply pipe 6 corresponding to the processing machine 1 is adjusted according to the processing timing of each processing machine 1 in the processing machine group.
3 opens and closes, and the line pressure in the main supply pipe 5, which fluctuates as the on-off valve 13 opens and closes, is appropriately detected by a pressure detector 14 provided in the bypass pipe 9, and is detected from the pressure detector 14. When the control means 18 receives the detection signal, the rotation speed of the variable rotation pump _P1 is controlled in accordance with the line pressure.
That is, when the number of processing machines 1 in the above-mentioned processing state is relatively small and the line pressure is high, the variable rotary pump P1 is operated at low speed, but when the number of processing machines ₁ in processing increases and the line pressure decreases, the variable rotary pump P1 is operated at a low speed. The rotational speed of the variable rotation pump _P1 is controlled to increase, and the line pressure in the main supply pipe 5 is adjusted to be approximately constant by controlling the operation of the variable rotation pump _P1 .

In this way, the operation of the variable rotary pump is controlled at the appropriate timing depending on the number of processing machines in processing mode, allowing the required amount of coolant to be delivered to each processing machine while using less energy to drive the pump. We will be able to supply it.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings from FIG. 2 onwards.

FIG. 2 shows the overall configuration of a coolant circulation control device for a group of processing machines according to an embodiment of the present invention.
1, ... are a plurality of processing machines that process workpieces, and 2 is a single coolant recovery tank that stores coolant (coolant) to be supplied to each of the processing machines 1, and the coolant recovery tank 2 is a clean tank. It consists of a tank 3 and a dirty tank 4. The plurality of processing machines 1, 1, . 6, 6, .
7a, . . . and a main pipe portion 7b which collects the branch pipe portions 7a, 7a, . . . are connected in parallel by a recovery pipe 7. In addition, the main supply pipe 5
The downstream end of the recovery pipe 7 and the upstream end of the main pipe section 7b are communicated by a bypass pipe 9 with an orifice 8 interposed therebetween, and a filter 10 is interposed between the clean tank 3 and the dirty tank 4. They are connected by a reflux pipe 11. Then,
Coolant is supplied from the clean tank 3 to each processing machine 1 through the main supply pipe 5 and each branch supply pipe 6, and a portion of it is supplied to the bypass pipe 9.
On the other hand, dirty coolant mixed with machining slag due to use in each of the processing machines 1 is collected into a dirty tank 4 through the collection pipe 7, and the machining slag is settled in the dirty tank 4. A coolant circulation system 12 is constructed in which the coolant in the dirty tank 4 is then returned to the clean tank 3 through a reflux pipe 11 while removing fine machining slag with a filter 10 along the way.

An electromagnetic on-off valve 13 consisting of an air valve is disposed in the middle of the branch supply pipe 6 branched from the main supply pipe 5 to each processing machine 1. It is connected to appropriate detection means (not shown) for detecting the state, and each branch supply pipe 6 is opened and closed by an on-off valve 13 according to the processing timing of each processing machine 1.

Furthermore, two coolant supply pumps P ₁ and P ₂ are connected in parallel to the upstream end of the main supply pipe 5, one of which is connected to the variable rotation pump P 1 whose rotation speed can be controlled by frequency control, and the other to the variable rotation pump P ₁ whose rotation speed can be controlled by frequency control. Each is set to a constant rotation pump _P2 that rotates at a constant speed.
Further, first and second filter pumps FP ₁ , FP ₂ are connected in parallel to each other in the reflux pipe 11 on the upstream side of the filter 10 , and both filter pumps FP 1 , FP ₂ are connected in parallel to each other.
The total discharge amount of FP ₂ is set larger than the total discharge amount of the two supply pumps P ₁ and P ₂ .

Further, a pressure detector 14 for detecting the line pressure in the main supply pipe 5 is disposed in the bypass pipe 9 on the upstream side of the orifice 8 . Further, 15 is a liquid level sensor that detects the liquid level of the coolant stored in the clean tank 3, and 16 is the upper and lower limit of the rotation speed of the variable rotation pump P ₁ by adjusting the frequency signal for the variable rotation pump P ₁ . A rotation speed setting device for setting a value, the pressure detector 1
4. Each output of the liquid level sensor 15 and the rotation speed setting device 16 is input to the control unit ₁₇ that controls the operation of the two supply pumps P ₁ and P ₂ and the two filter pumps FP 1 and FP ₂ . .

As shown in FIG. 3, the control unit 17 receives detection signals from the pressure detector 14 and the liquid level sensor 15, and controls the variable rotation pump P ₁ , constant rotation pump P ₂ , and both filter pumps FP ₁ , Each drive unit P _1M , P _2M , consisting of a motor etc. in FP ₂
Control circuit 18 that outputs control signals to FP _1M and FP _2M
and the output of the drive unit P _1M of the variable rotation pump P ₁ ,
In other words, the actual rotation speed of the variable rotation pump P ₁ is set by the rotation speed setting device 16.
It includes a comparison circuit 19 that compares the rotation speed of _P1 with the upper and lower limit values and outputs a comparison signal to the control circuit 18. When the detection signal value of the pressure detector 14, that is, the line pressure in the main supply pipe 5, is large, the variable rotation pump _P1 is controlled to a low rotation speed, and when it is small, the variable rotation pump _P1 is controlled to a high rotation speed. outputs a signal to the drive unit P _1M of the variable rotation pump P ₁ , and when the actual rotation speed of the variable rotation pump P ₁ reaches the upper limit set by the rotation speed setting device 16, the control circuit 18 outputs a signal to the drive unit P 1M of the variable rotation pump P 1. P ₂ and the drive parts P _2M and FP _2M of the second filter pump FP ₂
Further, when the coolant level in the clean tank 3 falls below a set value, the control circuit 18 outputs an activation signal to the drive unit FP _1M of the first filter pump FP ₁ . It is composed of

Next, the operation of the above embodiment will be explained.

When each processing machine 1 enters the processing state by carrying in a workpiece, the on-off valve 13 corresponding to the processing machine 1 opens and the workpiece is fed under pressure to the processing machine 1 by one or both of the supply pumps P ₁ and P ₂ . Coolant is supplied via the main supply pipe 5 and each branch supply pipe 6. Further, the dirty coolant used in each processing machine 1 is collected into a dirty tank 4 through a collection pipe 7, and after the processing slag is settled and removed in the dirty tank 4, one or both of the filter pumps FP ₁ and FP ₂ are used. The waste is refluxed to the cree tank 3 via the reflux pipe 11, during which fine machining slag is removed by the filter 10.

In that case, the control operation for the two supply pumps P ₁ and P ₂ will be explained along the flow chart shown in FIG. 4. In step S ₁ after the start, the control circuit ₁₈ controls the variable rotation pump P In the next step _S2 , the line pressure in the main supply pipe 5 is checked based on the detection signal of the pressure detector 14, and then in step _S3 it is determined whether or not the line pressure is low. This judgment is YES if pressure = small
When , move to step S ₄ ,
Increase the frequency signal output to _P1 to
After increasing the rotational speed of _P1 , the process moves to step _S7 .
On the other hand, the judgment in step _S3 above is NO if pressure ≠ small.
When this happens, the process moves to step _S5 to determine whether or not the line pressure is large, and when this judgment is NO (pressure≠high), the process returns to step _S2 and performs the subsequent steps _S3 ,
Repeat S ₄ ,... Further, if the judgment in step _S5 is YES that the pressure is large, the process moves to step _S6 , where the frequency signal output to the variable rotation pump _P1 is lowered to reduce the rotational speed of the pump _P1 , and then the process proceeds to step _S7 . Move to.

In this step _S7 , the rotation speed of the variable rotation pump _P1 is detected, and in the next step _S8 , it is determined whether or not the rotation speed has reached the upper limit set by the rotation speed setting device 16. If the judgment is NO, return to step _S2 and perform subsequent steps _S3 ,
Repeat S ₄ ,... On the other hand, if the determination is YES, the process moves to step _S9 , where an operating signal is output to the constant rotation pump _P2 to operate the pump _P2 , and at the same time, at step _S10 , the rotation speed of the variable rotation pump _P1 is set as described above. Hold at upper limit and then step
By determining whether or not T ₁ hour has elapsed in S ₁₁ and repeating steps S ₁₀ and S ₁₁ until T ₁ hour has elapsed, the upper limit value of the rotation speed of variable rotation pump P ₁ is maintained for T ₁ hour. let

After this T ₁ hour has elapsed, the process moves to step _S12 , where the upper limit value of the rotation speed of the variable rotation pump _P1 is released, and then, in step _S13 , the rotation speed of the variable rotation pump _P1 is set to the lower limit. It is determined whether or not the value has been reached, and if the determination is NO, the above steps S ₂ , S ₃ , . . . are repeated. On the other hand, the judgment
If YES, the process moves to step _S14 , where it is determined whether the rotational speed of the variable rotation pump _P1 has remained at the set lower limit value for _T2 hours, and if this determination is NO, the process returns to step _S2 . If the determination in step _S14 is YES, the process moves to step _S15 , where detection of the line pressure by the pressure detector 14 is canceled, and then, in step _S16 , the variable rotation pump _P1
At the same time as raising the rotation speed of the pump P1 to the set upper limit value, in step _S17 , the rotation speed of the pump _P1 is maintained at the set upper limit value, and in subsequent step _S18 , it is determined whether or not ₃ hours T have elapsed. Repeat steps S ₁₇ and S ₁₈ until T ₃ hours have elapsed, and then
The upper limit value of the rotation speed of P ₁ is maintained for T ₃ hours.
Then, when the determination becomes YES after _T3 hours have elapsed, the process moves to step _S19 , where the pressure detection cancellation performed in step _S15 is reset, and the holding of the upper limit value of the rotation speed of the variable rotation pump _P1 is canceled. In step _S20 , the operation signal outputted from the control circuit 18 to the constant rotation pump _P2 is cut to stop the operation of the constant rotation pump _P2 , and then the process returns to the original step _S2 to perform the subsequent steps. Repeat S ₃ , S ₄ , etc.

As a result of performing the above control, the main supply pipe 5
The characteristics of the line pressure fluctuation, the rotational speed change of the variable rotation pump _P1 , and the operating state of the constant rotation pump _P2 are shown in FIG. In other words, the number of processing machines in processing state is relatively small, and the above line pressure is, for example, 1.75Kg/cm 2 and 1.75Kg/cm ² respectively.
In a state within the setting range of 1.25 Kg/cm ² , only the variable rotation pump P ₁ is controlled in rotation speed based on the frequency adjusted by the control circuit 18. In other words,
When the line pressure in the main supply pipe 5 fluctuates due to an increase or decrease in the number of machining machines in the machining state, the output frequency from the control circuit 18 to the variable rotation pump _P1 changes up or down to compensate for the pressure fluctuation.
When the line pressure is balanced within the set range, the output frequency is also balanced. Through such control, the line pressure is kept almost constant at a reference value within the set range.

From this state of constant pressure control, the number of operations of the processing machine 1 increases significantly at the point indicated by point _A in the figure, and the line pressure reaches the lower limit of the set range, and in addition, the control circuit When the output frequency of the variable rotation pump P 18 increases and the rotation speed of the variable rotation pump P ₁ reaches the upper limit set by the rotation speed setting device 16, the rotation speed of the variable rotation pump P ₁ is forcibly increased for T ₁ time. The pump _P1 is operated at a constant speed while being maintained at the above upper limit value, and then returns to the original constant pressure control. Further, at the same time as the constant speed operation of the variable rotation pump P ₁ starts, the control circuit 18 starts the operation of the constant rotation pump P ₂ .

At this time, when the rotation speed of the variable rotation pump P ₁ reaches the set upper limit value, the pump P ₁ is operated at a constant speed at the upper limit value for T ₁ hours, so that the constant rotation pump P ₂
Coupled with the start of constant speed operation, the line pressure can be rapidly increased, and the lower limit state can be quickly escaped.

On the other hand, conversely, the number of operations of the processing machine 1 decreases significantly at the point shown at point _A2 in the figure, and the line pressure increases, and the output frequency of the control circuit 18 decreases and the variable rotation pump P When the rotation speed of ₁ reaches the set lower limit value, the pump rotation speed will reach the lower limit value.
After confirming that it has lasted for only ₂ hours, that is, that the rotation speed is not hunting, the rotation speed control (constant pressure control) for the variable rotation pump P ₁ is forcibly stopped, and the rotation speed control (constant pressure control) for the variable rotation pump P ₁ is forcibly stopped. is controlled and operated according to a predetermined control pattern. i.e. variable rotary pump P ₁
When the rotation speed reaches the set lower limit value, the rotation speed is held at the lower limit value for T ₂ hours, and then increases to the set upper limit value and is held at the upper limit value for T ₃ hours. After such forced control, the constant pressure control is restarted, and the constant speed operation of the constant rotation pump _P2 is stopped.

At that time, when the lower limit of the rotation speed of the variable rotation pump P ₁ is reached, the rotation speed is temporarily changed to the set upper limit T ₃
Since the operation of the constant rotation pump P ₂ is stopped after holding the constant rotation pump P ₂ for a certain period of time, it is possible to avoid a sudden drop in line pressure due to the operation stop of the constant rotation pump P 2. can be stably supplied. In addition, in FIG. 5, the pressure change when the line pressure is not controlled is shown by a broken line.

On the other hand, the above two filter pumps FP ₁ ,
Regarding the control operation for FP ₂ , when the coolant level in the clean tank 3 drops below a predetermined value, the liquid level sensor 15 detects this.
sends an output signal to the control circuit 18, and as a result of the operation of the control circuit 18, the first filter pump FP ₁ is operated, and the coolant in the dirty tank 4 is filtered by the filter 10 and flows back into the clean tank 3. When the coolant level in the filter rises, the operation of the first filter pump FP ₁ is stopped.

In addition, when the constant rotation pump P ₂ is operated, that is, when the line pressure in the main supply pipe 5 is greatly reduced and a large amount of coolant is forced from the clean tank 3 to each processing machine 1, the constant rotation pump
The second filter pump FP ₂ is operated in synchronization with the operation of P ₂ , and coolant is replenished from _the dirty tank 4 into the clean tank 3 by the operation of the second filter pump FP 2 .

At that time, since the total discharge amount of both filter pumps FP ₁ and FP ₂ is set larger than the total discharge amount of both supply pumps P ₁ and P ₂ , all pumps P ₁ ,
Even when P ₂ , FP ₁ , and FP ₂ are in operation, there is no shortage of coolant in the clean tank 3, and coolant can be stably circulated and supplied to each processing machine 1.

Therefore, in this embodiment, the line pressure in the main supply pipe 5, which fluctuates as the number of operations of the processing machine 1 increases or decreases, is detected, and the variable rotary pump is adjusted so that the line pressure becomes approximately constant. The rotation speed of variable rotation pump P ₁ is controlled, and when the rotation speed of variable rotation pump P ₁ reaches the set upper limit due to a significant increase in the operating speed of processing machine 1, constant rotation pump P ₂ is operated. It is possible to supply coolant to each processing machine 1 in a timely and efficient manner according to the operation of each processing machine 1 without reducing the energy efficiency, and to reduce the operating rate of the supply pumps P ₁ and P ₂ to increase the energy saving effect. Can be done.

In addition, since the first filter pump FP ₁ is operated in a limited manner when the coolant level in the clean tank 3 drops, and the second filter pump FP ₂ is operated in a limited manner when the constant rotation pump P ₂ is operated, both filters are operated in a limited manner. The operating rates of pumps FP ₁ and FP ₂ can also be reduced, and thus the energy saving effect can be further enhanced.

(Effects of the Invention) As explained above, according to the present invention, changes in the number of processing machines in a processing machine group during processing can be accurately detected by pressure changes in the bypass pipe provided at the end of the main supply pipe. By controlling the rotation speed of the variable rotary pump in a timely manner, coolant can be efficiently supplied without reducing the line pressure in the coolant supply system to the processing machine. This can enhance the energy saving effect.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the configuration of the present invention. 2 to 5 show embodiments of the present invention;
Figure 3 is a detailed diagram of the control unit, Figure 4 is a control flowchart, and Figure 5 is a variable rotation pump and line pressure that changes according to the increase or decrease in the number of operations of the processing machine. It is an explanatory view showing each characteristic of the number of rotations of , and the operating state of a constant rotation pump. 1... Processing machine, 2... Coolant recovery tank, 5... Main supply pipe, 6... Branch supply pipe, 7
... Recovery pipe, 9 ... Bypass pipe, 12 ... Coolant circulation system, 13 ... Solenoid on-off valve, P ₁ ... Variable rotation pump, 14 ... Pressure detector, 18 ... Control circuit.

Claims (1)

[Claims] 1. Coolant is supplied to multiple processing machines from a single coolant recovery tank, and the used coolant is recovered to the recovery tank, and each processing machine is supplied with coolant from the main supply pipe leading to the coolant recovery tank. A coolant circulation system including an extending branch supply pipe, a recovery pipe leading from each processing machine to a coolant recovery tank, and a bypass pipe communicating an end of the main supply pipe to the recovery pipe, and a coolant circulation system provided in the bypass pipe. a pressure detector installed in each branch supply pipe, which opens and closes according to the processing timing of each processing machine; and a variable rotation valve installed in the main supply pipe, for supplying coolant whose rotation speed can be controlled. Control that receives the detection signal from the pump and the pressure detector and outputs a signal to the variable rotation pump so that when the value is large, the variable rotation pump is controlled to low rotation, and when the value is small, the variable rotation pump is controlled to high rotation. A coolant circulation control device for a group of processing machines, characterized in that it has means.