JP7638533B2 - Method for controlling dust collector in blast processing device and blast processing device - Google Patents

Description

The present invention relates to a method for controlling a dust collector in a blast processing device used in processing methods such as sandblasting, shot blasting, and shot peening (collectively referred to as "blast processing" in this specification) in which blasting material made of granular material such as metals, minerals, ceramics, glass, resin, and plant seed husks is dry projected onto a workpiece, and to a blast processing device that executes the method for controlling the dust collector.

In this specification, "projecting" a projection material can include various known methods of accelerating and projecting a projection material toward a workpiece in a dry manner, such as projection carried out on a jet of compressed gas such as compressed air, projection using centrifugal force, and projection by impact.

Figure 9 shows an example of the configuration of an air blasting device that projects a blast material along with a jet of compressed air onto the workpiece.

The blast processing device 1 shown in Figure 9 is equipped with a cabinet 10 in which a blast nozzle 12 is arranged to spray blast material together with compressed air into a working space 11 provided inside, and is configured so that processing can be performed by projecting the blast material onto a workpiece (not shown) within the working space 11 of this cabinet 10.

The bottom 10a of the aforementioned cabinet 10 is formed in a hopper shape, and is configured so that the shot material projected within the working space 11 can be collected in the bottom 10a of the cabinet 10 together with crushed shot material and dust such as cutting powder generated when the workpiece is scraped by collision with the shot material.

The bottom 10a of the cabinet 10 is connected to a classifier 20 consisting of a wind-powered separator such as a cyclone via a recovery duct 13, and the classifier 20 is connected to a dust collector 30 equipped with an exhaust fan 31 via an exhaust duct 21.

Therefore, by operating the exhaust fan 31 provided on the dust collector 30 to exhaust air from inside the classifier 20, the blast material collected together with the dust at the bottom 10a of the cabinet 10 is introduced into the classifier 20 via the recovery duct 13, and the reusable blast material classified in the classifier 20 is collected in the blast material tank 22 connected to the bottom of the classifier 20.

Meanwhile, the dust separated from the reusable blast material is sucked into the dust collector 30 via the exhaust duct 21 together with the air in the classifier 20, and after the dust is removed by the dust collection filter 33 installed in the dust collector 30, the clean air is discharged outside the machine via the exhaust port 313c.

The blast material collected in this way in the blast material tank 22 is supplied again via the blast material hose 23 to the blast nozzle 12 arranged in the working space 11 of the cabinet 10, and sprayed from the blast nozzle 12 toward the workpiece (not shown), allowing the blast material to be recycled and reused.

The dust collector 30 installed in the blast processing device 1 configured as above has a dust filter 33 installed in the air flow path formed inside. Therefore, when dust adheres to the dust filter 33 and causes clogging, the amount of air passing through the dust collector 30 decreases, and the force (suction force) for sucking in the air inside the classifier 20 decreases.

When the suction power of the dust collector 30 decreases, the volume of air passing through the classifier 20, which is composed of a wind-powered separator such as a cyclone, decreases (the wind speed decreases), so the classification performance of the classifier 20 decreases and the amount of dust collected in the blast material tank 22 together with the blast material increases.

If the amount of dust and other foreign matter mixed in with the blasting material collected as reusable in this way increases, the accuracy of the blasting process carried out using the collected blasting material will decrease, making it impossible to continue blasting with a consistent level of quality.

The dust collector 30 is provided with a manual shaking lever 35 to deal with clogging of the dust filter 33. If the suction power of the dust collector 30 is reduced due to clogging of the dust filter 33, the shaking lever 35 can be operated to shake off the dust trapped in the dust filter 33, thereby restoring the airflow (suction power) passing through the dust collector 30.

However, even if the suction power of the dust collector 30 is restored by removing the dust trapped in the dust filter 33 with the shaking lever 35, the change in the airflow (suction power) passing through the dust collector 30, and therefore the airflow passing through the classifier 20, decreases over time as the dust filter 33 becomes increasingly clogged, and then is suddenly restored by operating the shaking lever 35 to shake off the dust adhering to the dust filter 33, resulting in a sawtooth change as shown in Figure 10.

As a result, restoring the airflow (suction force) by operating the shaking lever 35 does not have the effect of stabilizing the airflow (suction force) of the dust collector 30, and therefore does not have the effect of stabilizing the classification performance of the classifier 20.

As such, the classification performance of the classifier 20 installed in the blast processing device 1 decreases with the decrease in the suction power of the dust collector 30 due to clogging of the dust collection filter 33 installed in the dust collector 30, so there is a demand for a blast processing device equipped with a dust collector 30 that can always suck in a constant amount of air from inside the classifier 20 without being affected by clogging of the dust collection filter 33.

Although not an invention related to a dust collector for a blast processing machine, Patent Document 1, which is listed below, proposes that in a ceiling cassette type air conditioner incorporating a HEPA filter (High-Efficiency Particulate Air Filter), in order to prevent a change in air volume due to clogging of the HEPA filter, the pressure on the primary and secondary sides of the HEPA filter is measured, the increase in pressure loss ΔPt from the initial state is calculated, and based on the calculated increase in pressure loss ΔPt, the torque of the fan motor installed in the dust collector is increased to increase and compensate for the decrease in the air volume passing through the HEPA filter (Claim 1, Claim 2, Paragraphs [0019]-[0020], Figure 1 of Patent Document 1).

Japanese Patent Application Publication No. 11-169634

The air conditioner described in Patent Document 1 introduced earlier detects the pressure loss caused by the HEPA filter, and compensates for the decrease in air volume caused by the increase ΔPt in the detected pressure loss relative to the initial pressure loss value by increasing the torque of the fan motor, making it possible to maintain a constant volume of air passing through the air conditioner even as the HEPA filter becomes clogged.

Therefore, if the fan motor 312 of the exhaust fan 31 provided in the dust collector 30 of the blast processing device 1 described with reference to Figure 9 is controlled to increase the torque in response to the increase in pressure loss ΔPt obtained by measuring the pressure on the primary and secondary sides of the dust collection filter 33, following the example of Patent Document 1, the amount of air passing through the dust collection filter 33 can be maintained constant, and the amount of air passing through the classifier 20 can also be maintained constant, stabilizing the classification performance of the classifier 20.

However, when controlling the dust collector 30 installed in the blast processing device 1 using the method described in Patent Document 1, the following problems may occur.

The flow rate Q (m ³ /s) of a fluid can be expressed as the product (Q=AV) of the area A (m ² ) of the flow path through which the fluid passes and the flow velocity V (m/s) of the fluid.
Here, the velocity of the fluid V (m/s) is given by Bernoulli's theorem as follows:
V=(2q/ρ) ^1/2 ...(Formula 1)
q is dynamic pressure (Pa), ρ is fluid density (kg/cm ³ ).
It is.
Therefore, the flow rate Q of the fluid (m ³ /s) is
Q=AV=A(2q/ρ) ^1/2 ...(Formula 2)
It becomes.

From the above equation 2, if the area A ( ^m2 ) of the flow path through which the fluid passes is constant and the density of the fluid is constant, the change in the fluid flow rate Q ( ^m3 /s) can be calculated based on the change in dynamic pressure q (Pa).

However, when trying to measure the volume of air passing through the dust collecting filter 33 installed in the dust collector 30 following the method described in Patent Document 1, even if the pressure difference (dynamic pressure) between the primary and secondary sides of the dust collecting filter 33 and the density of the fluid (air) are known, the air volume cannot be calculated unless the flow path area A ( ^m2 ), i.e., the total area of the filter openings, is known.

The total area of the openings of the dust collection filter 33 (flow path area A) not only has a unique initial value depending on various conditions such as the grade, manufacturer, and size of the filter used, but also changes over time as the dust collection filter 33 becomes clogged, making it difficult to measure.

Therefore, in order to obtain the required air volume increase ΔFu (air volume decrease due to pressure loss increase) by calculation based on the pressure loss increase Δpt that increases over time according to the method of the cited document 1, and to obtain the torque increase of the fan motor that will obtain this air volume increase ΔFu, it is necessary to conduct experiments in advance to measure the initial pressure loss value and passing air volume for each combination of dust collector 30 and dust collection filter 33, and to measure how the pressure loss changes in response to the decrease in air volume when dust is collected and the air volume is reduced, and to obtain the relational equation between the pressure loss increase ΔPt and the corresponding air volume increase ΔFu (paragraph [0019] of Patent Document 1).

Moreover, such a relationship can only be measured by actually causing the dust collection filter to become clogged, for example by operating the blasting device to collect dust in the dust collection filter 33, and this measurement takes a long time.

In addition, in the method of Patent Document 1, the amount of air passing through the dust collection filter 33 is increased by controlling the torque of the fan motor, so it is necessary to determine in advance by experiment the relationship between the total air volume Fut, taking into account the required increase in air volume ΔF, and the torque of the fan motor (paragraph [0020] of Patent Document 1). This not only requires a great deal of effort in the preparation for control, but also complicates the control because of the increased amount of calculation processing that must be performed during control.

Moreover, in the method described in Patent Document 1, even if the same dust collector 30 is used, if the dust collection filter 33 attached to the dust collector 30 is replaced with one of a different grade or manufacturer, for example, and this causes changes in the relationship between the initial values of pressure loss and passing air volume, the increase in pressure loss ΔPt, and the required increase in air volume ΔF, it is necessary to experimentally re-acquire each of the above data each time the dust collection filter 33 is replaced, and it is also necessary to reconfigure the relational equations and control program.

Furthermore, while the control method described in Patent Document 1 can compensate for the reduction in the amount of air passing through due to clogging of the dust collection filter 33, it cannot deal with reductions in the amount of air passing through due to other causes (for example, reductions in the amount of air passing through due to narrowing of the flow path caused by the adhesion of projection material or dust to the inner walls of the collection duct or exhaust duct).

The present invention has been made in consideration of the above-mentioned shortcomings of the prior art, and aims to provide a method for controlling a dust collector in a blast processing device, which not only maintains the classifier's classification performance constant by maintaining the dust collector's airflow rate, and therefore the classifier's airflow rate, constant in a relatively simple manner, but also maintains the airflow rate constant without resetting the relational equation or rearranging the control program, even if the dust collector is replaced with a different grade filter, causing fluctuations in the pressure loss of the dust collector, the initial value of the airflow rate, or the relationship between the pressure loss and the airflow rate, without resetting the relational equation or rearranging the control program, and further prevents not only a decrease in airflow due to clogging of the dust collector, but also a general decrease in airflow rate caused by the adhesion of projectiles or dust to the inner walls of the collection duct or exhaust duct, or narrowing of the flow path caused by the dust collector or its primary side, etc.

Below, the means for solving the problem are described together with the reference symbols used in the description of the embodiment of the invention. These reference symbols are intended to clarify the correspondence between the description of the claims and the description of the embodiment of the invention, and needless to say, are not used in a restrictive manner in interpreting the technical scope of the present invention.

In order to achieve the above object, the control method of the dust collector 30 in the blast processing apparatus 1 of the present invention is as follows:
A blast processing device 1 includes a cabinet 10 having a working space 11, a classifier 20 consisting of an air sorter which introduces and classifies blast material blasted in the cabinet 10 and collected together with dust, a blast material tank 22 which stores the reusable blast material classified by the classifier 20, and a dust collector 30 equipped with a fan 311 which sucks in and exhausts air from within the classifier 20, and which collects reusable blast material in the blast material tank 22 by air sorting using an air flow generated within the classifier 20 by suction using the dust collector 30,
The fan 311 is provided in a secondary side flow passage 36 of the dust collection filter 33 of the dust collector 30, and the secondary side flow passage 36 is opened to the atmosphere on the secondary side of the fan 311,
A pressure difference ΔP ₁ between the pressure in the space 38 in the secondary flow passage 36 between the dust collecting filter 33 and the fan 311 and atmospheric pressure is detected, and an air volume control is performed to control the rotation speed of the fan 311 so that the passing air volume Q of the dust collector 30 grasped based on the detected pressure difference ΔP ₁ approaches a preset target air volume Q _{0 ;}
A pressure difference across the front and rear of the dust collecting filter 33 that may cause damage to the dust collecting filter 33 is measured in advance as a withstand pressure limit pressure difference ΔP _fmax ,
The rotation speed (including stopping ₎ of the fan 311 is controlled so that a measured value of a pressure difference ΔP1 between the pressure in the space 38 in the secondary side flow path 36 between the dust collecting filter 33 and the fan 311 and atmospheric pressure becomes less than a numerical value set as the withstand limit pressure difference ΔPfmax ₍ claim 1 ).

In the above-mentioned method for controlling the dust collector 30 ,
The flow rate Q of the air passing through the dust collector 30 is calculated based on a predetermined relational expression (e.g., Q=f(ΔP ₁ , Inv)) from the pressure difference ΔP ₁ between the detected pressure in the space 38 and atmospheric pressure and the rotation speed of the fan 311 at the time of detection of the pressure difference ΔP ₁ (in this embodiment, the output Inv of the inverter corresponding to the rotation speed);
The air volume control may be executed to control the rotation speed of the fan 311 so as to bring the calculated passing air volume Q closer to the target air volume _Q0 .

In any of the above configurations, the air volume passing through the dust collector 30 that can cause the mesh of the dust collection filter 33 to expand at the beginning of use is set as a limit air volume _Qmax ,
It is preferable to control the rotation speed (including stopping) of the fan 311 so that the passing air volume Q is less than the limit air volume Q _max (claim 3 ).

Furthermore,
When the rotation speed of the fan 311 reaches a predetermined upper limit rotation speed, the fan 311 may be stopped in an emergency (claim 4 ).

In addition, the blast processing device 1 of the present invention is
A blast processing device 1 has a cabinet 10 with a working space 11, a classifier 20 consisting of an air sorter that introduces and classifies blast material blasted in the cabinet 10 and collected together with dust, a blast material tank 22 that stores the reusable blast material classified by the classifier 20, and a dust collector 30 equipped with a fan 311 that sucks in and exhausts air from within the classifier 20, and the reusable blast material is collected in the blast material tank 22 by air sorting using an air flow generated in the classifier 20 by suction using the dust collector 30,
The fan 311 is provided in a secondary side flow passage 36 of the dust collection filter 33 of the dust collector 30, and the secondary side flow passage 36 is opened to the atmosphere on the secondary side of the fan 311,
a pressure detection means for detecting a pressure difference _ΔP between the pressure in the space in the secondary flow passage between the dust collecting filter and the fan and atmospheric pressure ;
a control device 60 for controlling the rotation speed of the fan 311 so as to bring the passing air volume Q of the dust collector 30, which is grasped based on the differential pressure ΔP ₁ detected by the pressure detection means 50 , closer to a preset target air volume Q _0;
The control device 60 includes:
A pressure difference across the front and rear of the dust collecting filter 33 that may cause damage to the dust collecting filter 33 is stored as a withstand pressure limit pressure difference ΔP _fmax ,
The rotation speed (including stopping ₎ of the fan 311 is controlled so that the measured value of the differential pressure ΔP1 between the pressure in the space 38 in the secondary side flow path 36 between the dust collecting filter 33 and the fan 311 and atmospheric pressure becomes less than the value set as the pressure resistance limit pressure difference ΔPfmax ₍ Claim 5 ) .

In the blast processing device 1 having the above configuration ,
The control device 60 may be configured to calculate the passing air volume Q of the dust collector 30 based on a preset relational equation (e.g., Q = f ( _ΔP1 , Inv)) from the pressure difference ΔP1 from the atmospheric pressure detected by the pressure sensor ₅₁ and the rotational speed of the fan 311 at the time of detection of the pressure difference _ΔP1 (in this embodiment, the inverter output Inv corresponding to the rotational speed), and to execute the air volume control by controlling the rotational speed of the fan 311 so as to bring the calculated passing air volume Q close to the target air volume _Q0 (claim 5 ).

In both of the above blast processing devices 1,
The control device 60 includes:
The air volume passing through the dust collector 30 that can cause the mesh of the dust collection filter 33 to expand at the beginning of use is stored as a limit air volume Q _max ,
The rotation speed of the fan 311 (including stopping the fan) may be controlled so that the passing air volume Q becomes less than the limit air volume _Qmax (claim 7 ).

Furthermore,
The control device 60,
The fan 311 may be configured to be stopped in an emergency when the rotation speed of the fan 311 reaches a predetermined upper limit rotation speed (claim 8 ).

With the configuration of the present invention described above, the following effects can be obtained by controlling the dust collector 30 of the blast processing device 1 using the control method of the present invention.

By detecting the pressure ΔP ( _ΔP1 or _ΔP2 ) in the secondary flow path 36 of the dust collecting filter 33 of the dust collector 30 and controlling the rotational speed of the fan 311 so as to bring the passing air volume Q of the secondary flow path 36, determined based on the pressure ΔP ( _ΔP1 or _ΔP2 ), closer to the target air volume _Q0 , the air volume passing through the classifier 20 can be stabilized at a constant volume, and even if the dust collecting filter 33 of the dust collector 30 becomes clogged, the classification performance of the classifier 20 is not changed and the quality of the recovered projection material can be maintained constant.

As a result, in the blast processing device 1 in which the dust collector 30 was controlled using the control method of the present invention, the processing accuracy was able to be maintained constant even when the collected blast material was circulated and used multiple times.

Moreover, although this is an extremely simple and straightforward control in which the passing air volume Q, which is grasped based on the pressure ΔP ( _ΔP1 or _ΔP2 ) in the secondary flow path 36, is brought close to the target air volume _Q0 , even if the characteristics of the dust collecting filter 33 change, for example by changing the dust collecting filter 33 to a different grade with a coarse or fine mesh, the volume of air passing through the classifier 20 can be maintained constant without making any changes to the control program, calculation formulas, etc.

In a configuration in which the secondary flow path 36 is open to the atmosphere on the secondary side of the fan 311, the passing air volume Q of the secondary flow path 36 can be calculated based on a preset simple relational equation [for example, Q = f (ΔP 1, Inv)] from the pressure difference ΔP ₁ between the pressure in the space 38 in the secondary flow path 36 between the dust collecting filter ₃₃ and the fan 311 and atmospheric pressure, and the rotational speed of the fan 311 at the time when the pressure difference ΔP ₁ is detected (in this embodiment, the inverter output Inv corresponding to the rotational speed), and the passing air volume Q of the classifier 20 can be easily maintained constant based on the pressure detected by a single pressure sensor 51 (pressure difference ΔP ₁ from atmospheric pressure).

In addition, in the configuration in which the pressure difference _ΔP2 before and after the orifice 41 provided at a predetermined position in the secondary-side flow path 36 is detected to control the passing air volume Q, the configuration is not limited to a configuration in which the secondary-side flow path 36 is open to the atmosphere, and even if other equipment is further connected to the secondary-side flow path 36, it is possible to control the passing air volume Q of the secondary-side flow path 36 to approach the target air volume _Q0 without being affected by the increase in exhaust resistance due to the connection of the other equipment.

As a result, even if a HEPA filter or the like is further provided in the secondary flow passage 36 on the secondary side of the orifice 41 to purify the exhaust, the passing air volume Q can be maintained constant without being affected by changes in exhaust resistance that accompany the progression of clogging of the HEPA filter.

Moreover, in the configuration in which the above-mentioned air volume control is performed by measuring the differential pressure _ΔP2 across the orifice 41 provided in the secondary-side flow path 36 and controlling the passing air volume Q, it is also possible to control the passing air volume _Q to approach the target air volume _Q0 without calculating the passing air volume Q based on an arithmetic expression or the like, simply by using the detected differential pressure ΔP2 across the orifice 41 directly to control the rotation speed of the fan 311 so as to bring the passing air volume Q close to the set target differential pressure _ΔP0 .

Furthermore, the control method introduced in Patent Document 1 could only deal with a decrease in air volume due to clogging of the filter, but both dust collectors controlled by any of the methods of the present invention can deal with not only a decrease in passing air volume due to clogging of the dust collection filter 33, but also a general decrease in passing air volume Q caused by an increase in flow path resistance occurring on the primary side relative to the measurement position of pressure ΔP ( _ΔP1 or _ΔP2 ), such as narrowing of the flow path due to the accumulation of projection material or dust on the inner walls of the recovery duct 13 or the exhaust duct 21.

The dust collection filter 33 attached to the dust collector 30 is a bag-shaped filter generally known as a "bag filter," and is designed to collect dust by introducing the air to be purified into and passing through this bag-shaped dust collection filter 33.

When the dust collection filter 33 becomes clogged to a certain extent, it expands when air is introduced, allowing air to pass through the entire dust collection filter 33 evenly.

However, even if air is introduced when the filter is first started and there is no clogging, the dust collection filter 33 is in a deflated state and does not expand evenly, so the air passes only through the part of the dust collection filter 33 that is in front of the air introduction direction.

As a result, if the airflow rate Q is excessively increased when the dust collection filter 33 is in an initial state, the mesh in the area where the air passes through intensively may be pushed wider and enlarged compared to the mesh in other areas, which may impair the function of the dust collection filter 33.

In response to this, the airflow rate of the dust collector 30 that may cause the mesh of the dust filter 33 to expand in the early stages of use is set as the limit airflow rate Qmax, and the rotation speed of the fan 311 (including stopping) is controlled so that the detected value of the airflow rate Q is less than the value set as the limit airflow rate Qmax, thereby effectively preventing functional loss of the dust filter 33 in the early stages of use.

In addition, in a configuration for detecting a pressure difference _ΔP1 between the pressure in the space 38 in the secondary flow passage 36 between the dust collecting filter 33 and the fan 311 and the atmospheric pressure (the configuration shown in FIGS. 1 and 2), the pressure difference _ΔP1 between the pressure in the space 38 and the atmospheric pressure is always equal to or greater than the pressure difference before and after the dust collecting filter 33.

Therefore, by measuring in advance the pressure difference before and after the dust collecting filter 33 that may cause damage to the dust collecting filter 33 as the withstand pressure limit pressure difference ΔPfmax and controlling the rotation speed (including stopping) of the fan ₃₁₁ so that the measured value of the differential pressure ΔP1 between the pressure in the space 38 and the atmospheric pressure becomes less than the numerical value set as the withstand pressure limit pressure difference ΔPfmax, it is possible to prevent the rotation speed of the fan 311 from increasing to a level that would damage the dust collecting filter 33 in order to bring the passing air volume Q closer to the target air volume _Q0 due to clogging of the dust collecting filter 33.

In addition, in any of the above-mentioned methods for controlling the dust collector 30, the rotation speed of the fan 311 is increased as the clogging of the dust collection filter 33 provided in the dust collector 30 progresses. However, by bringing the fan 311 to an emergency stop when the fan 311 reaches a predetermined upper limit speed, the upper limit speed is appropriately set within a range below the rated rotation speed of the fan motor 312, and it is possible to prevent the fan motor 312 from being damaged by being driven beyond the rated value. In addition, for example, by experimentally determining in advance the correspondence between the change in the rotation speed of the fan motor 312 and the change in the pressure difference between the primary side and the secondary side of the dust collection filter 33, and setting the above-mentioned upper limit speed so that the pressure difference is within a range that does not exceed the pressure resistance of the dust collection filter 33, preferably a value that is lower by a predetermined margin than the pressure resistance, it is possible to prevent the pressure difference between the primary side and the secondary side of the dust collection filter 33 from increasing beyond the pressure resistance of the dust collection filter 33, and thus prevent the dust collection filter 33 from being damaged.

FIG. 13 is an explanatory diagram showing an example of the configuration of a dust collector and a control device when air volume control is performed based on a differential pressure ΔP ₁ between the pressure in the secondary flow path and atmospheric pressure. FIG. 2 is a cross-sectional view of a fan portion of a dust collector used in the configuration of FIG. 1 . 11 is a graph showing an example of the relationship between the pressure difference ΔP ₁ between the pressure in the space 38 and the atmospheric pressure, the passing air volume Q, and the power W (W ₀ , W _0+σ , W _0+2σ ) of the fan motor. FIG. 13 is an explanatory diagram showing an example of the configuration of a dust collector and a control device when air volume control is performed based on a differential pressure ΔP ₂ before and after an orifice provided in a secondary flow path. FIG. 5 is a cross-sectional view of a fan portion of a dust collector used in the configuration of FIG. 4 . FIG. 13 is an explanatory diagram showing another example of the configuration of a dust collector and a control device when controlling the air volume based on the differential pressure ΔP ₂ before and after the orifice provided in the secondary flow path. FIG. 2 is an explanatory diagram of the test apparatus used in [Test 1]. FIG. 2 is an explanatory diagram of the test apparatus used in [Test 2]. An explanatory diagram of a blast processing device (circulation type). A schematic diagram showing the change in airflow through a conventional dust collector (when dust is removed periodically using the shaking lever).

Next, an embodiment of the present invention will be described with reference to the attached drawings.

[Overall configuration of blast processing device]
The blast processing apparatus 1 to which the control method of the present invention is applied is similar to the known blast processing apparatus 1 described with reference to Figure 9 in that it is equipped with a cabinet 10 with a working space 11, a classifier 20 consisting of a wind sorter that introduces and classifies blast material that has been blasted inside the cabinet 10 and recovered together with dust, a blast material tank 22 that stores reusable blast material that has been classified by the classifier 20, and a dust collector 30 equipped with a fan 311 that sucks in and exhausts air inside the classifier 20.

Then, when the air in the classifier 20 is sucked in and exhausted by the rotation of the fan 311 provided in the dust collector 30, the blast material accumulated at the bottom 10a of the cabinet 10 is introduced into the classifier 20 together with the dust via the recovery duct 13, and the reusable blast material is recovered into the blast material tank 22 by classification in the classifier 20, and the dust is recovered into the dust collector 30 together with the air in the classifier 20 via the exhaust duct 21, and the clean air after the dust is removed by the dust collection filter 33 in the dust collector 30 can be exhausted from the exhaust port of the dust collector 30 (Figure 1; 313c), which is the same as the configuration of the known blast processing device 1 described with reference to Figure 9.

In the blast processing device 1 described with reference to FIG. 9, a "circulating" blast processing device 1 configuration example is shown in which the blast material collected in the blast material tank 22 can be introduced into the blast nozzle 12 arranged in the cabinet 10 via the blast material hose 23. However, the blast processing device 1 to which the control method of the present invention is applied does not necessarily need to be configured to recirculate the collected blast material to the blast nozzle 12 as long as it is capable of carrying out the process of collecting the blast material in the blast material tank 22.

[Outline of Control in the Present Invention]
In contrast to the known blast processing device 1 described above, the blast processing device 1 of the present invention is provided with a pressure detection means 50 ( ₅₁ , ₅₂ ) for detecting pressure ΔP (ΔP1 or ΔP2) in the secondary side flow passage 36, which is an air flow passage provided on the secondary side of the dust collection filter 33 of the dust collector 30, so that changes in the passing air volume Q of the dust collector 30 can be grasped based on the detected pressure ΔP ( _ΔP1 or _ΔP2 ).

In the blast processing apparatus 1 of the present invention, a control device 60 is provided that performs air volume control to control the rotational speed of the fan 311 provided in the dust collector 30 so that the passing air volume Q, which is determined based on the pressure ΔP (ΔP1 or ΔP2) detected by the pressure detection means 50 ( ₅₁ , ₅₂ ), approaches a preset target air volume _Q0 , thereby making it possible to maintain the flow rate of air passing through the classifier 20 at a constant amount, thereby maintaining the classification performance of the classifier 20 without changing it.

To enable control of the rotation speed of the fan 311 of the dust collector 30, the dust collector 30 of the blast processing device of the present invention uses a three-phase AC motor as the fan motor 312, preferably a three-phase AC motor for inverter control, and as shown in Figures 1, 4 and 6, the configuration of the control device 60 described above includes an inverter 61 that converts AC from a power source (e.g., a commercial power source) not shown in the figure into DC, and then converts it into AC of any frequency and outputs it, making it possible to change the frequency of the AC output to the fan motor 312.

This inverter 61 is configured by known methods such as V/f control so that the output Inv (kW) increases as the output frequency (Hz) increases, and the output Inv (kW) decreases as the output frequency (Hz) decreases. Therefore, by increasing the output Inv (kW) of the inverter 61, the rotation speed increases along with the power (W) of the fan motor 312, and by decreasing the output Inv (kW) of the inverter 61, the rotation speed decreases along with the power (W) of the fan motor 312.

Then, by using the PID control function of the inverter 61, the output Inv (kW) of the inverter 61 is changed so that the passing air volume Q, which is grasped based on the pressure ΔP ( _ΔP1 or _ΔP2 ) in the secondary flow path 36 detected by the pressure detection means 50, approaches a preset target air volume _Q0 , so that the passing air volume Q passing through the dust collector 30 can be made to match the target air volume _Q0 as closely as possible.

[Control device configuration example 1]
FIG. 1 shows an example of the configuration of the control device 60 in the case where the dust collector 30 whose exhaust port 313c is open to the atmosphere is the object to be controlled.

The dust collector 30 to be controlled in FIG. 1 is configured, as an example, as shown in FIG. 2, with a filter casing 32 housing a dust collection filter 33, an intake port 32a to which an exhaust duct 21 communicating with the classifier 20 is connected, and an outlet 32b for discharging air that has passed through the dust collection filter 33, and an exhaust fan 31 equipped with a fan 311 and a fan motor 312 is attached to this outlet 32b, so that the inside of the filter casing 32 can be sucked by this exhaust fan 31.

This exhaust fan 31 is equipped with a cylindrical duct 314 attached to the outlet 32b of the filter casing 32, an inlet 313a communicating with the duct 314, an accommodation space 313b that accommodates the fan 311, and a fan casing 313 equipped with an exhaust port 313c that is open to the atmosphere.

Therefore, in the configuration of the dust collector 30 in FIG. 2, the portion extending from the duct 314 of the exhaust fan 31 to the exhaust port 313c of the fan casing 313 constitutes the secondary flow passage 36 provided on the secondary side of the dust collection filter 33, the fan 311 is disposed in this secondary flow passage 36, and the end of the secondary flow passage 36 (exhaust port 313c) on the secondary side of the fan 311 is open to the atmosphere.

In the configuration of FIG. 1 in which such a dust collector 30 is the object to be controlled, a pressure sensor 51 that detects a differential pressure (absolute value of gauge pressure) _ΔP1 between the pressure in the space (space inside the duct 314) ₃₈ between the dust collecting filter 33 and the fan 311 and atmospheric pressure is provided as the above-mentioned pressure detection means 50, and a calculation device 62 is provided that calculates a passing air volume Q by using a predetermined relational expression based on the differential pressure _ΔP1 detected by the pressure sensor 51 and the rotation speed of the fan 311 at the time of detection of the differential pressure ΔP1 [output Inv (kW) of the inverter 61 corresponding to the rotation speed of the fan 311].

The passing air volume Q, which is the result of the calculation by the calculation device 62, is input to the inverter 61, whereby the inverter 61 performs the above-mentioned air volume control by PID control that changes the output Inv to the fan motor 312 so that the passing air volume Q approaches the target air volume _Q0 .

Therefore, in the configuration shown in FIG. 1, the aforementioned arithmetic unit 62 and inverter 61 realize a control device 60 that controls the rotation speed of the fan 311 of the dust collector 30.

There is a relationship between the pressure difference _ΔP1 between the pressure in the space 38 between the dust collecting filter 33 and the fan 311 (the space inside the duct 314) and atmospheric pressure, the air flow rate Q through the dust collector 30, and the power W of the fan motor 312 corresponding to the rotational speed of the fan 311, as shown in FIG. 3 as an example, and the air flow rate Q through the dust collector 30 is a function of the pressure difference _ΔP1 between the pressure in the space 38 and atmospheric pressure and the power W of the fan motor 312, and is related by the relational equation Q=f( _ΔP1 , W).

Here, since the power W of the fan motor 312 is proportional to the inverter output Inv (kW) input to the fan motor 312, the air volume Q passing through the secondary flow path 36 is a function of the pressure difference _ΔP1 between the pressure in the space 38 and atmospheric pressure and the inverter output Inv, and is related by the relational equation Q = f ( _ΔP1 , Inv).

Therefore, by experimentally determining this relational equation Q = f ( _ΔP1 , Inv) and storing it in advance in the arithmetic device 62, the arithmetic device 62 can calculate the passing air volume Q based on the differential pressure ΔP1 between the pressure in space 38 detected by the pressure sensor ₅₁ and the atmospheric pressure, as shown in Figure 1, and the inverter output Inv.

The passing air volume Q calculated by the calculation device 62 is input to the inverter, and the inverter 61 changes the output Inv (kW) by known control such as PID control so as to bring the input passing air volume Q closer to a preset target air volume _Q0. This makes it possible to maintain the air volume passing through the dust collector 30 constant not only when the dust collecting filter 33 becomes clogged, but also when the dust collecting filter 33 is replaced with one of a different grade, and even when there is any increase in flow path resistance on the primary side of the dust collecting filter 33.

[Control device configuration example 2]
In the above description given with reference to FIG. 1, a configuration example in which the dust collector 30 with the exhaust port 313c open to the atmosphere is the object to be controlled has been described.

In this configuration, the exhaust resistance (back pressure) of the air passing through the secondary flow path 36 is constant at atmospheric pressure and does not change, so it is possible to obtain the change in the flow rate Q of the air passing through the secondary flow path 36 from the gauge pressure (differential pressure from atmospheric pressure) ΔP1 in the space 38 in the duct 314 detected by a general pressure sensor ₅₁ and the output Inv of the inverter 61 when the differential pressure _ΔP1 is detected.

However, as shown in FIGS. 4 and 5 , when an exhaust pipe 40 is further connected to the exhaust port 313c of the exhaust fan 31 and a downstream device such as a HEPA filter is further connected to the secondary side of this exhaust pipe 40, it becomes impossible to grasp the passing air volume Q of the secondary flow path ₃₆ based on the gauge pressure (pressure difference from atmospheric pressure) ΔP1 in the space 38.

Therefore, in the case where a downstream device is further connected to the secondary flow path 36, for example, as shown in FIGS. 4 and 5 , an exhaust pipe 40 equipped with an orifice 41 is connected to an exhaust port 313 c provided in a fan casing 313 of the exhaust fan 31 to extend the secondary flow path 36, and the differential pressure _ΔP2 before and after the orifice 41 is detected as the differential pressure ΔP in the secondary flow path, and the above-mentioned air volume control is executed to control the passing air volume Q based on the differential pressure ΔP2 before and after this orifice ₄₁ .

When the blast processing device 1 is used within the normal operating temperature range, there is a relationship between the passing air volume Q of the secondary flow passage ₃₆ and the differential pressure ΔP2 before and after the orifice 41, that is, Q = f( _ΔP2 ), and the passing air volume Q can be calculated as a function of only the differential pressure _ΔP2 before and after the orifice 41.

Therefore, as described above, the change in the differential pressure ΔP ₂ before and after the orifice 41 provided at a predetermined position in the secondary flow passage 36 can be understood as a change in the passing air volume Q of the dust collector 30 as it is.

For this reason, as shown in FIG. 4, a pressure difference _ΔP2 detected by a pressure difference sensor 52 (pressure detection means 50) that detects a pressure difference _ΔP2 across the orifice 41 is input to an inverter 61, and the inverter 61 is caused to perform PID control for changing the output Inv so as to bring the input pressure difference _ΔP2 across the orifice 41 close to a target pressure difference _ΔP0 that has been stored in advance as a pressure difference corresponding to the target air volume _Q0. This makes it possible to execute air volume control for bringing the passing air volume Q of the secondary flow path 36 as close as possible to the target air volume _Q0 .

In this configuration, as shown in FIG. 4 , the differential pressure ΔP ₂ across the orifice 41 detected by the differential pressure sensor 52 (pressure detection means 50) is directly input to the inverter 61 to control the operation of the fan motor 312 of the dust collector 30, and therefore a control device 60 is configured to control the operation of the dust collector 30 only by the inverter 61.

However, instead of the configuration shown in FIG. 4, as shown in FIG. 6, a calculation device 62 may be provided that receives a pressure difference _ΔP2 across the orifice 41 detected by a differential pressure sensor ₅₂ and calculates the passing air volume Q of the secondary flow path 36 based on the pressure difference ΔP2 across the orifice 41 and a relational equation Q=f(ΔP) that has been stored in advance, and the passing air volume Q obtained as a result of the calculation by the calculation device 62 is input to an inverter 61, which performs the above-mentioned air volume control by PID control that changes the output Inv so that the input passing air volume Q approaches a preset target air volume _Q0 .

In the configuration shown in Figure 6, the combination of the aforementioned arithmetic unit 62 and inverter 61 constitutes a control device 60 that controls the operation of the dust collector 30.

As described with reference to FIGS. 4 and 6, in the configuration in which the passing air volume _Q is grasped based on the differential pressure ΔP2 before and after the orifice 41 provided in the secondary side flow path 36, the change in the passing air volume Q can be grasped without being affected by the change in exhaust resistance. Therefore, even if a downstream device such as a HEPA filter is further connected to the secondary side of the exhaust pipe 40, the passing air volume Q can be controlled to be constant.

In addition, since the passing air volume Q can be controlled without being affected by exhaust resistance on the secondary side of the exhaust pipe 40, the passing air volume Q can be maintained constant even when a configuration is adopted in which the end of the secondary side of the exhaust pipe 40 is open to the atmosphere, without being limited to a configuration in which a downstream device is connected to the secondary side of the exhaust pipe 40.

〔others〕
In the configuration described with reference to Figures 1 to 6, as the clogging of the dust collecting filter 33 progresses, the output Inv of the inverter 61 increases and the rotation speed of the fan motor 312 increases. Therefore, if the output Inv of the inverter 61 is increased without limit as the clogging progresses, the power of the fan motor 312 will exceed the rated value.

In addition, as the rotation speed of the fan 311 increases, the pressure difference between the primary and secondary sides of the dust collection filter 33 increases. If the rotation speed of the fan motor 312 is increased without limit, the pressure difference between the primary and secondary sides of the dust collection filter 33 will increase beyond the pressure resistance capacity of the dust collection filter 33, and there is a risk that the dust collection filter 33 will be damaged and become unusable.

For this reason, for example, the aforementioned inverter 61 constituting the control device 60 of the dust collector 30 may be provided with an upper limit setting means (not shown) for setting an upper limit value of the output Inv, so that when the output Inv of the inverter 61 reaches an upper limit value that is set in advance taking into account the rated power of the fan motor 312 and the pressure resistance performance of the dust collection filter 33, the inverter 61 stops outputting and brings the fan motor 312 to an emergency stop.

In addition, when the output Inv of the inverter 61 reaches the upper limit value described above, or when it reaches a predetermined lower value than the upper limit value described above, a warning light may be turned on or a warning sound may be generated to warn the operator, so that the operator is prompted to operate the shaking lever 35 to shake off the dust accumulated in the dust collection filter 33 or to replace the dust collection filter 33.

Furthermore, as mentioned above, if the airflow rate Q of the dust collection filter 33 is excessively increased when the filter is not clogged at the beginning of use, the mesh in the area where the air passes through intensively may be pushed wider and enlarged compared to the mesh in other areas, which may impair the function of the dust collection filter 33. However, by setting the airflow rate of the dust collector 30 that may cause such enlargement of the mesh as a limit airflow rate Qmax and controlling the rotation speed (including stopping) of the fan 311 so that the detected value of the airflow rate Q is less than the value set as the limit airflow rate Qmax, it is possible to prevent the dust collection filter 33 from losing its function at the beginning of use.

In addition, in a configuration for detecting a pressure difference _ΔP1 between the pressure in the space 38 in the secondary flow passage 36 between the dust collecting filter 33 and the fan 311 and atmospheric pressure (the configuration shown in FIGS. 1 and 2), the pressure difference _ΔP1 between the pressure in the space 38 and atmospheric pressure is always equal to or greater than the pressure difference before and after the dust collecting filter 33.

Therefore, the pressure difference before and after the dust collecting filter 33 that may cause damage to the dust collecting filter 33 may be measured in advance as a pressure-resistant limit pressure difference ΔPfmax, and the rotation speed (including stopping) of the fan 311 may be controlled so that the measured pressure difference _ΔP1 between the pressure in the space 38 and atmospheric pressure is less than the numerical value set as the pressure-resistant limit pressure difference ΔPfmax, thereby making it possible to prevent damage to the dust collecting filter 33.

The following are the results of a test to confirm the effectiveness of controlling a dust collector for a blast processing device using the method of the present invention.

The tests were conducted in two patterns: [Test 1], which corresponds to the device configuration described with reference to Figures 1 and 2, and [Test 2], which corresponds to the device configuration described with reference to Figures 4 and 5, as described below.

[Test 1]
(1) Test Equipment As shown in FIG. 7 , a dust collector for a blast processing device (manufactured by Fuji Manufacturing Co., Ltd., model number "D4715") 30 having an exhaust port 313c open to the atmosphere was used as the control object, and the fan motor 312 (rated output 0.75 kW) of this dust collector 30 was controlled by a control device 60 consisting of an arithmetic unit (sequencer) 62 and an inverter 61.

A pressure sensor 51 for detecting the gauge pressure of the space 38 (see FIG. 2 ) in the duct 314 provided in the exhaust fan 31 of the dust collector 30 was provided as the pressure detection means 50, and the absolute value of the gauge pressure detected by this pressure detection means 50 (51) was input to the calculation device 62 as the differential pressure ΔP ₁ between the pressure in the space 38 and the atmospheric pressure.

The calculation device 62 and the inverter 61 are connected so as to be able to communicate with each other, so that the calculation device 62 can monitor the output Inv of the inverter 61 in real time, and so that the calculation device 62 can output to the inverter 61 the passing air volume Q calculated by a pre-stored relational equation [Q = f (ΔP ₁ , Inv)] based on the pressure difference ΔP ₁ with respect to atmospheric pressure detected by the pressure detection means 50 (51) and the inverter output Inv, and so that the inverter 61 can perform air volume control by PID control that changes the output Inv so as to bring the received passing air volume Q closer to a pre-set target air volume Q ₀ .

In order to actually measure the air volume passing through the dust collector 30, Anemometers (not shown) were installed at five locations on the same vertical cross section near the exhaust port 313c, and the air volume passing through the dust collector 30 ( ^m3 /min) was calculated by multiplying the average wind speed measured by the five anemometers by the cross-sectional area of the exhaust port 313c.

(2) Advance preparations
(2-1) Acquisition and setting of the relational equation [Q = f (H, Inv)] By gradually narrowing the opening of the intake port 32a of the dust collector 30 shown in FIG. 7 to simulate a state in which the dust collection filter is clogged, the pressure difference _ΔP1 between the pressure in the space 38 in the duct 314 and the atmospheric pressure is changed in the range of 1.4 kPa to 1.9 kPa, and the inverter output Inv is changed in the range of 0.4 kW to 0.7 kW, and the relational equation Q = f ( _ΔP1 , Inv) is obtained as follows:
Q=0.55・Inv/ΔP ₁
This relational expression was then stored in the arithmetic unit 62.

(2-2) Obtaining and setting the target air volume _Q0 The intake port 32a of the dust collector 30 was fully opened, and the passing air volume of 11.44 ^m3 /min obtained when a commercial power source (50 Hz, 200 V) was connected directly to the fan motor 312 without going through the inverter 61 was stored in the inverter 61 as the target air volume _Q0 .

(3) Test method and test results The air intake 32a of the dust collector 30, whose fan motor 312 is controlled by the control method of the present invention, was changed from a fully open state to a half-open state to simulate a state in which the dust collection filter 33 was increasingly clogged, and the changes in the passing air volume (actual measured value), the rate of change in air volume (rate of change compared to when fully open), the pressure difference with atmospheric pressure ΔP ₁ , the inverter output Inv (kW), and the inverter output frequency (Hz) were measured.

As a comparative example, the fan motor 312 of the dust collector 30 was directly connected to a commercial power source (50 Hz, 200 V) without going through the inverter 61, and the intake port 32a of the dust collector 30 was changed from a fully open state to a half open state, and the passing air volume (actual measured value) and the rate of change in the air volume (rate of change relative to when fully open) were measured.

The measurement results are shown in Table 1 below.

From the above results, in a dust collector not using the control of the present invention (comparison example), the air flow rate was 11.44 ^m3 /min when the air intake 32a was fully open, whereas when it was half open, the air flow rate was 10.12 ^m3 /min, a decrease of 11.5%.

In contrast, in the dust collector controlled by the method of the present invention, the air volume passing through the intake port 32a when it was fully open was 11.62 ^m3 /min, while when it was half open the air volume passing through was 11.27 ^m3 /min, so the decrease in air volume was limited to 3%, confirming that the air volume passing through the dust collector 30 could be maintained constant with high precision.

Moreover, in the dust collector controlled by the method of the present invention, even when the opening area of the intake port 32a of the dust collector is narrowed to half open, it is clear that the amount of air passing through can be controlled to be substantially constant. This makes it possible to prevent not only a decrease in the amount of air passing through due to clogging of the dust collection filter, but also all decreases in the amount of air caused by a decrease in the flow path area on the primary side of the measurement position of the differential pressure _ΔP1 (for example, narrowing of the flow path area caused by adhesion of projection material or dust to the inner walls of the recovery duct or exhaust duct).

[Test 2]
(1) Testing Equipment Tests were conducted using the testing equipment shown in Fig. 8. The dust collector 30 to be controlled in this testing equipment was a dust collector for blast processing equipment (manufactured by Fuji Manufacturing Co., Ltd., "D4715") having a fan motor with a rated output of 0.75 kW. An inverter 61 was connected as a control device 60 to the fan motor 312 of this dust collector.

An exhaust pipe 40 having an orifice 41 is connected to the exhaust port 313c of the dust collector 30 to extend the secondary flow path 36, and a differential pressure sensor 52 for detecting a differential pressure _ΔP2 before and after the orifice 41 is provided as a pressure detection means 50 in the exhaust pipe 40 constituting the secondary flow path 36.

The differential pressure _ΔP2 across the orifice 41 detected by the differential pressure sensor 52 is input to an inverter 61, and air volume control is performed by PID control that changes the output Inv so that the differential pressure _ΔP2 across the orifice 41 received by the inverter 61 approaches a preset target differential pressure _ΔP0 .

In order to actually measure the air volume passing through the dust collector 30, Anemometers (not shown) were installed at five locations on the same vertical cross section near the outlet of the exhaust duct 40 (a location that is sufficiently far from the orifice 41 and does not affect the measurement of the differential pressure _ΔP2 before and after the orifice 41), and the air volume passing through the dust collector ( ^m3 /min) was calculated by multiplying the average wind speed measured by the five anemometers by the cross-sectional area of the exhaust duct 40.

(2) Advance preparations
(2-2) Acquisition and setting of target differential pressure _ΔP0 With the intake port 32a of the dust collector 30 fully open and a commercial power supply (50 Hz, 200 V) directly connected to the fan motor 312 without going through an inverter, the differential pressure ΔP2 across the orifice 41 detected by the differential pressure sensor ₅₂ , that is, 260 Pa, was stored in the inverter 61 as the target differential pressure _ΔP0 .

(3) Test method and test results The intake port 32a of the dust collector 30 controlled by the method of the present invention was changed from a fully open state to a half-open state to simulate a state in which the dust collection filter was increasingly clogged, and the changes in the passing air volume (actual measured value), the air volume change rate (change rate compared to when fully open), the differential pressure _ΔP2 (Pa) before and after the orifice, the inverter output Inv (kW), and the inverter output frequency (Hz) were measured.

As a comparative example, the air intake 32a of a dust collector in which the fan motor 312 is driven by being directly connected to a commercial power source (50 Hz, 200 V) without going through the inverter 61 was changed from a fully open state to a half open state, and the passing air volume (actual measured value) and the rate of change in the air volume (rate of change relative to when fully open) were measured.
The measurement results are shown in Table 2 below.

From the above results, in a dust collector not using the control of the present invention (comparison example), the air flow rate was 10.81 ^m3 /min when the air intake 32a was fully open, whereas when it was half open, the air flow rate was 9.49 ^m3 /min, a decrease of 12.2%.

In contrast, in the dust collector controlled by the method of the present invention, the air passing volume was 10.85 ^m3 /min when fully open and 10.89 ^m3 /min when half open, limiting the decrease in air volume to 0.4%, confirming that the air passing volume of the dust collector can be maintained constant with high precision.

Furthermore, as is clear from the fact that the passing air volume can be controlled to be approximately constant even when the opening area of the intake port of the dust collector is half open, the configuration of _this test example in which the rotation speed of the fan motor is controlled based on the differential pressure ΔP2 before and after the dust collector orifice can also deal with not only the decrease in the passing air volume caused by clogging of the dust collection filter, but also the general decrease in air volume caused by a decrease in the flow path area caused on the primary side of the measurement position of the differential pressure _ΔP2 (for example, narrowing of the flow path area caused by adhesion of projection material or dust to the inner wall of the recovery duct or exhaust duct).

1 Blast processing device 10 Cabinet 10a Bottom (of cabinet)
REFERENCE SIGNS LIST 11 Working space 12 Blast nozzle 13 Recovery duct 20 Classifier 21 Exhaust duct 22 Shot material tank 23 Shot material hose 30 Dust collector 31 Exhaust fan 311 Fan 312 Fan motor 313 Fan casing 313a Inlet (of fan casing)
313b Storage space (of fan casing)
313c Exhaust port 314 Duct 32 Filter casing 32a Intake port 32b Outlet 33 Dust collection filter 35 Shaking lever 36 Secondary flow path 38 Space 40 Exhaust pipe 41 Orifice 50 Pressure detection means 51 Pressure sensor 52 Differential pressure sensor 60 Control device 61 Inverter 62 Calculation device (sequencer)
ΔP pressure
ΔP ₁ pressure difference (between space 38 and atmospheric pressure)
_ΔP2 differential pressure (before and after the orifice)
ΔP ₀ Target differential pressure Q Passing air volume Q ₀ Target air volume

Claims (8)

A blast processing device comprising: a cabinet with a working space; a classifier comprising an air sorter which introduces and classifies blast material blasted within the cabinet and collected together with dust; a blast material tank which stores the reusable blast material classified by the classifier; and a dust collector equipped with a fan which draws in and exhausts air within the classifier, the device recovering the reusable blast material in the blast material tank by air sorting using an air flow generated within the classifier by suction using the dust collector,
The fan is provided in a secondary flow passage of a dust collection filter of the dust collector, and the secondary flow passage is opened to the atmosphere on the secondary side of the fan,
a pressure difference between the pressure in the space in the secondary flow passage between the dust collecting filter and the fan and atmospheric pressure is detected, and an air volume control is performed to control a rotation speed of the fan so that the air volume passing through the dust collector, which is grasped based on the detected pressure difference , approaches a preset target air volume;
A pressure difference across the front and rear of the dust collecting filter that may cause damage to the dust collecting filter is measured in advance as a pressure resistance limit pressure difference,
The rotation speed of the fan is controlled so that a measured value of a differential pressure between the pressure in the space in the secondary flow passage between the dust collecting filter and the fan and atmospheric pressure is less than a value set as the withstand limit pressure difference.
A method for controlling a dust collector in a blast processing apparatus, comprising: calculating the passing air volume of the dust collector based on a preset relational expression from the differential pressure between the detected pressure in the space and atmospheric pressure and the rotation speed of the fan at the time of detecting the differential pressure;
2. The method for controlling a dust collector in a blast processing apparatus according to claim 1, further comprising the step of controlling the rotation speed of the fan so as to bring the calculated passing air volume closer to the target air volume. The air volume passing through the dust collector that can cause the mesh of the dust collection filter to expand at the beginning of use is set as a limit air volume,
3. The method for controlling a dust collector in a blast processing apparatus according to claim 1, further comprising controlling a rotation speed of said fan so that said passing air volume is less than said critical air volume. 3. The method for controlling a dust collector in a blast processing apparatus according to claim 1, further comprising the step of bringing said fan to an emergency stop when the rotation speed of said fan reaches a predetermined upper limit rotation speed. A blast processing device comprising: a cabinet with a working space; a classifier comprising an air sorter which introduces and classifies blast material blasted within the cabinet and collected together with dust; a blast material tank which stores the reusable blast material classified by the classifier; and a dust collector equipped with a fan which draws in and exhausts air within the classifier, the device recovering the reusable blast material in the blast material tank by air sorting using an air flow generated within the classifier by suction using the dust collector,
The fan is provided in a secondary flow passage of a dust collection filter of the dust collector, and the secondary flow passage is opened to the atmosphere on the secondary side of the fan,
a pressure detection means for detecting a pressure difference between a pressure in a space in the secondary flow passage between the dust collecting filter and the fan and atmospheric pressure ;
a control device that controls a rotation speed of the fan so as to bring a passing air volume of the dust collector, which is grasped based on the differential pressure detected by the pressure detection means, closer to a preset target air volume ;
The control device includes:
A pressure difference across the dust collecting filter that may cause damage to the dust collecting filter is stored as a withstand limit pressure difference;
A blast processing device characterized in that the rotational speed of the fan is controlled so that a measured pressure difference between the pressure in the space in the secondary side flow passage between the dust collecting filter and the fan and atmospheric pressure is less than the pressure resistance limit pressure difference . The blast processing apparatus according to claim 5, characterized in that the control device calculates the passing air volume of the dust collector based on a preset relational equation from the differential pressure from the atmospheric pressure detected by the pressure sensor and the rotational speed of the fan at the time when the differential pressure was detected, and executes the air volume control by controlling the rotational speed of the fan so as to bring the calculated passing air volume close to the target air volume . The control device includes:
A passing air volume of the dust collector that can cause the mesh of the dust collection filter to expand at the beginning of use is stored as a limit air volume,
7. The blast processing device according to claim 5 , wherein the rotation speed of the fan is controlled so that the passing air volume is less than the critical air volume. The control device includes:
7. The blast processing device according to claim 5 , wherein the fan is brought to an emergency stop when the rotation speed of the fan reaches a predetermined upper limit rotation speed.

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