JP3979137B2 - Method and apparatus for solidifying grinding sludge - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for compressing and solidifying a grinding sludge collected together with a coolant (grinding fluid) when grinding an iron-based metal as a steelmaking raw material.
[0002]
[Prior art]
Polishing powder generated when grinding ferrous metals such as bearing steel and carburized steel (including polishing and lapping) is recovered as grinding sludge together with coolant (grinding fluid). The ground sludge is filtered to a concentrated sludge, and then pressed by a press unit using a hydraulic cylinder to become a solid (briquette). This solid material is reused as a raw material for steelmaking, for example. As shown in FIG. 3, the time change of the pressing pressure during pressing increases when the pressure increases at an accelerated rate from the start of pressing and is maintained at a predetermined maximum pressure for a predetermined time. Goes down all at once.
[0003]
[Problems to be solved by the invention]
However, in practice, it is not easy to solidify the concentrated sludge, and solidification often fails. As one of the causes, it has been found that the bubbles of air contained in the concentrated sludge are ruptured during pressurization while confined inside, and the solidification is prevented by the impact. In order to prevent such bursting, it is necessary to let air escape to the outside. However, since the abrasive powder of the quenched parts is fine, it is difficult for air to escape. Further, in the case of a coolant containing a large amount of oil, the oil film prevents air from escaping.
[0004]
In view of the conventional problems as described above, it is an object of the present invention to provide a method and an apparatus for reliably solidifying grinding sludge.
[0005]
[Means for Solving the Problems]
The present invention is a method of compressing solidified sludge containing air, which is obtained by filtering a ferrous metal grinding sludge containing coolant, wherein the air bubbles are contained inside during compression by a hydraulic cylinder. In order to prevent the air from rupturing during pressurization while being confined in the air, the air is squeezed with a press pressure at a constant pressure increase rate that is discharged from the concentrated sludge without losing the escape path (Claim 1).
In such a grinding sludge solidification method, the air contained in the concentrated sludge is discharged smoothly without losing the escape path by increasing the pressure at a constant speed.
[0006]
Further, the present invention is an apparatus for compressing and solidifying concentrated sludge containing air, which is obtained by filtering ferrous metal grinding sludge containing coolant, the press part using a hydraulic cylinder, and the press part Based on the pressure sensor that detects the press pressure during squeezing by the hydraulic pressure in the hydraulic cylinder, and based on the output of the pressure sensor, the air is discharged from the concentrated sludge during squeezing without losing the escape path Pressure control means for controlling the supply of hydraulic pressure to the hydraulic cylinder so as to achieve a speed press pressure is provided (claim 2).
[0007]
In such a grinding sludge solidifying device, the pressure control means increases the press pressure during squeezing at the above-described constant pressure increase speed based on the output of the pressure sensor. Therefore, the air contained in the concentrated sludge is discharged smoothly without losing the escape route by the constant pressure increase.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing a configuration of a grinding sludge solidifying device according to an embodiment of the present invention. In the figure, the abrasive powder generated when grinding ferrous metals such as bearing steel and carburized steel is recovered as grinding sludge together with coolant, and then filtered to become concentrated sludge 1, which is obtained by hydraulic cylinder 2 and mold 3. It is squeezed by the configured press part 4. The coolant is squeezed out by squeezing, and the concentrated sludge 1 is solidified into a cylindrical briquette.
[0009]
In the hydraulic cylinder 2, a pressure sensor 5 and an electrically controlled proportional valve 6 are connected to a port 2p1 on the side where the piston 2a is advanced. Further, the proportional valve 6 and the port 2p2 on the side for retreating the piston 2a are connected to the hydraulic pump 8 through the switching valve 7 as shown in the figure. The output signal of the pressure sensor 5 is sent to the control device 9, and the proportional valve 6 and the switching valve 7 operate in response to the control signal from the control device 9. The proportional valve 6 can change the hydraulic input / output ratio in accordance with the control signal.
The proportional valve 6 and the control device 9 constitute pressure control means for controlling the supply of hydraulic pressure to the hydraulic cylinder 2 based on the output of the pressure sensor 5.
[0010]
Next, a method for solidifying the grinding sludge with the above configuration will be described.
First, a concentrated sludge 1 obtained by filtering grinding sludge containing coolant is prepared in advance and placed in a mold 3. Next, the hydraulic pump 8 is operated, and the switching valve 7 is operated (non-excitation → excitation) by a control signal from the control device 9. As a result, the hydraulic pressure is supplied to the port 2p1 via the proportional valve 6, and the oil in the port 2p2 is returned. The hydraulic pressure loaded into the hydraulic cylinder 2 from the port 2p1 corresponds to the press pressure, and this hydraulic pressure is detected by the pressure sensor 5. The control device 9 performs feedback control of the proportional valve 6 based on the output signal of the pressure sensor 5, and controls the hydraulic pressure output from the proportional valve 6, that is, the press pressure, to change in a predetermined pattern.
[0011]
FIG. 2 is a graph showing temporal changes in press pressure and cylinder stroke by the hydraulic cylinder 2. In the figure, at time t1 when the piston 2a moves forward and comes into contact with the concentrated sludge 1, the piston 2a temporarily stops, and the press pressure starts to increase from time t2 when the play is absorbed. At this time, if the hydraulic pressure is simply continued to be supplied to the port 2p1 (that is, if the predetermined set pressure is supplied without providing the control device 9 and the proportional valve 6), the press pressure is a constant speed as indicated by the broken line. The controller 9 increases in an accelerating manner instead of (gradient), but the control device 9 takes into account the output of the pressure sensor 5 so as to avoid such a situation so that the rising speed of the press pressure is substantially constant. To control.
Thus, the press pressure rises at a constant speed having the same inclination as the tangential line at the time t2 of the acceleration rising curve when the control is not performed as indicated by the broken line in FIG. At time t3 when the press pressure reaches a predetermined set pressure (for example, 10 to 15 Mpa), the hydraulic pressure is stopped and held until time t4, and then a control signal is sent from the control device 9 to the switching valve 7 to switch the switching valve 7 Is returned to a non-excited state, and the piston 2a is moved backward. At the time t5 when the piston 2a has fully retracted, the pressing process ends.
[0012]
As a result of raising the press pressure at a constant speed as described above, the concentrated sludge 1 was solidified dramatically more reliably than before. This is considered to be because the air (bubbles) contained in the concentrated sludge 1 was discharged smoothly without losing the escape route due to the constant pressure increase. That is, in the case of an acceleration rising curve when no control is performed, when air is about to escape to the outside in a state where a considerable pressure has already been applied at the end of the press, This is considered to be because there is no such problem at a constant speed.
[0013]
The optimum constant speed varies depending on the type of sludge. Therefore, various sludges can be solidified reliably by selecting the optimum constant speed. However, it is considered that a constant speed exceeding the acceleration rising curve when the control is not performed is not preferable because it is not sufficient in terms of air escape.
[0014]
【The invention's effect】
The present invention configured as described above has the following effects.
According to the solidification method of the grinding sludge according to claim 1, the air contained in the concentrated sludge is smoothly discharged without losing the escape path by the constant pressure increase, and the air bubbles remain trapped inside. Since it is prevented from rupturing at the time of pressurization, the concentrated sludge is solidified significantly more reliably than before.
[0015]
According to the grinding sludge solidifying device of claim 2 , based on the output of the pressure sensor, the pressure control means at a constant pressure increase speed at which the press pressure during the compression is discharged from the concentrated sludge without losing the escape path. By increasing the pressure, the air contained in the concentrated sludge is discharged smoothly without losing the escape path due to the constant pressure increase, preventing air bubbles from being ruptured during pressurization while being trapped inside. Is done. Therefore, the concentrated sludge is solidified dramatically more reliably than before.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a grinding sludge solidifying device according to an embodiment of the present invention.
FIG. 2 is a graph showing temporal changes in press pressure and cylinder stroke by the hydraulic cylinder in the apparatus of FIG. 1;
FIG. 3 is a graph showing a temporal change in pressure in a conventional pressing process for solidifying grinding sludge.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Concentrated sludge 2 Hydraulic cylinder 3 Die 4 Press part 5 Pressure sensor 6 Proportional valve 8 Hydraulic pump

Claims (2)

A method of filtering and solidifying concentrated sludge containing air, which is obtained by filtering a ferrous metal grinding sludge containing coolant,
In order to prevent the air bubbles from being ruptured during pressurization while being squeezed inside during the squeezing by a hydraulic cylinder , the air is discharged at a constant pressurization speed from the concentrated sludge without losing the escape path. A method for solidifying grinding sludge characterized by squeezing. An apparatus for compressing and solidifying concentrated sludge containing air, which is obtained by filtering a ferrous metal grinding sludge containing coolant,
A press part by a hydraulic cylinder;
A pressure sensor for detecting the press pressure during the squeezing by the press unit by a hydraulic pressure that is put in a hydraulic cylinder;
Based on the output of the pressure sensor, the air is discharged from the concentrated sludge without losing the escape path to prevent the bubbles of air from being entrapped and ruptured during pressurization during compression. An apparatus for solidifying grinding sludge, comprising pressure control means for controlling the supply of hydraulic pressure to the hydraulic cylinder so as to obtain a press pressure at a pressure increase speed.

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