Method for controlling dust collector in blast processing device and blast processing device

Abstract

To maintain an air volume of a dust collector provided in a blast processing apparatus at a constant level in a relatively simple and reliable method.SOLUTION: A control method of a dust collector provided in a blast processing apparatus detects a differential pressure ΔP (a differential pressure ΔP1 between a pressure in a space 38 and an atmospheric pressure in an example shown in the figure) at a prescribed position in a secondary side flow channel 36 of a dust collection filter 33 of a dust collector 30, and executes air volume control that controls rotation speeds of a fan motor 312 provided in an exhauster 31 of the dust collector 30 and a fan 311 driven by the fan motor 312 by PID control by an inverter 61, etc. so that a passage air volume Q of the dust collector 30 which is grasped on the basis of the detected differential pressure ΔP is made to be close to a preset target air volume Q0.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] 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, shot peening, etc. (collectively referred to as "blast processing" in this specification) in which blasting material consisting of granular material such as metals, minerals, ceramics, glass, resin, plant seed shells, etc. is dry-blasted onto a workpiece, and to a blast processing device which executes the method for controlling the dust collector.

[0002] In this specification, "projecting" the projection material may include various known methods of accelerating and projecting the projection material toward the workpiece in a dry manner, such as projection using a jet of compressed gas such as compressed air, projection using centrifugal force, and projection by impact. [Background technology]

[0003] Figure 9 shows an example of the configuration of an air blasting machine that blasts a workpiece with a jet of compressed air along with blast material.

[0004] 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.

[0005] 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.

[0006] The bottom 10a of this cabinet 10 is connected via a recovery duct 13 to a classifier 20 consisting of a wind-powered separator such as a cyclone, and the classifier 20 is connected via an exhaust duct 21 to a dust collector 30 equipped with an exhaust fan 31.

[0007] Therefore, by operating the exhaust fan 31 provided on the dust collector 30 to ventilate the inside of the classifier 20, the blast material collected together with 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.

[0008] On the other hand, the dust separated from the reusable projection material is sucked into the dust collector 30 via the exhaust duct 21 together with the air inside the classifier 20, and after the dust is removed by the dust collection filter 33 provided in the dust collector 30, clean air is discharged outside the machine via the exhaust port 313c.

[0009] The shot material recovered in this manner in the shot material tank 22 is supplied again via the shot 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), thereby enabling the shot material to be recycled and reused.

[0010] The dust collector 30 provided in the blast processing apparatus 1 configured as described above has a dust collection filter 33 provided in the air flow path formed inside, so when dust adheres to the dust collection 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.

[0011] Furthermore, 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 shot material tank 22 together with the shot material increases.

[0012] If the amount of foreign matter such as dust mixed in with the blasting material recovered in this way as reusable blasting material increases, the accuracy of the blasting process carried out using the recovered blasting material will decrease, making it impossible to continue blasting at a consistent quality.

[0013] In addition, the dust collector 30 is provided with a manual shaking lever 35 to deal with clogging of the dust collecting filter 33. If the suction power of the dust collector 30 decreases due to clogging of the dust collecting filter 33, this shaking lever 35 can be operated to shake off the dust captured in the dust collecting filter 33, thereby restoring the airflow (suction power) passing through the dust collector 30.

[0014] However, even if the suction power of the dust collector 30 is restored by removing the dust trapped in the dust collecting filter 33 with the shaking lever 35, the change in the amount of air passing through the dust collector 30 (suction power), and therefore the amount of air passing through the classifier 20, decreases over time as the dust collecting filter 33 becomes increasingly clogged, and is then suddenly restored by operating the shaking lever 35 to brush off the dust adhering to the dust collecting filter 33, resulting in a sawtooth change as shown in Figure 10.

[0015] As a result, restoring the passing air volume (suction force) by operating the shaking lever 35 does not have the effect of stabilizing the passing air volume (suction force) of the dust collector 30, and therefore does not have the effect of stabilizing the classification performance of the classifier 20.

[0016] As such, the classification performance of the classifier 20 provided in the blast processing apparatus 1 decreases as the suction force of the dust collector 30 decreases due to clogging of the dust collecting filter 33 provided in the dust collector 30, etc., so there is a demand for a blast processing apparatus equipped with a dust collector 30 that can always suck in a constant amount of air inside the classifier 20 without being affected by clogging of the dust collecting filter 33, etc.

[0017] Incidentally, although not an invention relating to a dust collector for a blast processing device, Patent Document 1 listed below proposes that in a ceiling cassette type air conditioning system incorporating a HEPA filter (High-Efficiency Particulate Air Filter), in order to prevent changes in air volume due to clogging of the HEPA filter, the pressure on the primary and secondary sides of the HEPA filter is measured and 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). [Prior art documents] [Patent documents]

[0018] [Patent Document 1] Japanese Patent Application Publication No. 11-169634 Summary of the Invention [Problem to be solved by the invention]

[0019] The air conditioning device described in Patent Document 1 introduced earlier detects the pressure loss caused by the HEPA filter, and compensates for the reduction in air volume associated with the increase ΔPt in the detected pressure loss relative to the initial pressure loss value by increasing the torque of the fan motor, thereby making it possible to maintain the volume of air passing through the air conditioning device constant even as the HEPA filter becomes clogged.

[0020] 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 in a manner similar to Patent Document 1 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 collecting filter 33, the volume of air passing through the dust collecting filter 33 can be maintained constant, and thereby the volume of air passing through the classifier 20 can also be maintained constant, stabilizing the classification performance of the classifier 20.

[0021] However, when controlling the dust collector 30 provided in the blast processing apparatus 1 by the method described in Patent Document 1, the following problems may arise.

[0022] Fluid flow rate Q(m 3 / s) is the area A (m 2 ) and the fluid flow velocity V (m / s) (Q = AV). 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 of the fluid Q(m 3 / s) is, Q = A V = A (2q / ρ) 1 / 2 ...(Formula 2) It becomes.

[0023] From the above formula 2, the area A (m 2 ) is constant and the fluid density is constant, the flow rate of the fluid Q(m 3 / s) can be calculated based on the change in dynamic pressure q (Pa).

[0024] 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 side and secondary side of the dust collecting filter 33 and the density of the fluid (air) are known, the flow path area A (m 2), that is, the air volume cannot be calculated unless the total area of ​​the filter openings is known.

[0025] The total area of ​​the openings of this dust collecting filter 33 (flow path area A) not only has its own unique initial value depending on various conditions such as the grade of the filter used, manufacturer, and size, but also changes over time as the dust collecting filter 33 becomes clogged, making it difficult to measure.

[0026] 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 cited document 1, and to obtain an increase in the torque 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 a relational equation between the pressure loss increase ΔPt and the corresponding air volume increase ΔFu (paragraph

[0019] of patent document 1).

[0027] Moreover, such a relationship can only be measured by actually causing the dust collecting filter to become clogged, for example by operating a blasting device to collect dust in the dust collecting filter 33, and this measurement takes a long time.

[0028] In addition, in the method of Patent Document 1, the air volume 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). Not only does this require a great deal of effort in the preparations for control, but it also complicates the control because of the large number of calculations that must be performed during control.

[0029] 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 a change in the relationship between the initial values ​​of pressure loss and passing air volume, the increment in pressure loss ΔPt, and the required increment 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.

[0030] 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 address reductions in air volume due to other causes (for example, a reduction 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 recovery duct or exhaust duct).

[0031] Therefore, the present invention has been made in consideration of the above-mentioned shortcomings in the conventional technology, and aims to provide a dust collector control method in a blast processing apparatus and a blast processing apparatus which executes the dust collector control method, which not only makes it possible to maintain constant the classification performance of the classifier by maintaining the passing air volume of the dust collector, and therefore the passing air volume of the classifier, constant in a relatively simple manner, but also makes it possible to maintain constant the passing air volume without resetting the relational equation or rearranging the control program, even if there are fluctuations in the pressure loss of the dust collecting filter, the initial value of the passing air volume, or the relationship between pressure loss and passing air volume, etc., caused by replacing the dust collecting filter with one of a different grade, and which is capable of preventing not only a decrease in air volume due to clogging of the dust collecting filter, but also a general decrease in the passing air volume caused by the adhesion of projectiles and dust to the inner walls of the recovery duct or exhaust duct, narrowing of the flow path caused by the dust collecting filter or its primary side, etc. [Means for solving the problem]

[0032] The means for solving the problems are described below together with the reference numerals used in the description of the embodiment of the invention. The reference numerals are used 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 to restrict the interpretation of the technical scope of the present invention.

[0033] 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 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 collects the 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 dust collector 30 has a dust collection filter 33 The fan 311 is provided in the secondary flow passage 36, and the secondary flow passage 36 is opened to the atmosphere on the secondary side of the fan 311, A pressure difference ΔP 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 1 is detected, and the detected Differential Pressure ΔP1 To The air volume control is performed by controlling the rotation speed of the fan 311 so that the passing air volume Q of the dust collector 30 grasped based on the above-mentioned measurement is brought close to a preset target air volume Q0. Execute, The pressure difference across the dust collecting filter 33 that may cause damage to the dust collecting filter 33 is defined as a withstand limit pressure difference ΔP fmax Measured in advance as A pressure difference ΔP 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 1 The measured value of the pressure difference ΔP fmax The rotation speed of the fan 311 is controlled (including stopping) so that the rotation speed is less than the set value. This is characterized by the above (Claim 1).

[0034] In the above-mentioned method for controlling the dust collector 30, , InspectionThe flow rate Q of the air passing through the dust collector 30 is calculated based on a predetermined relational equation (e.g., Q=f(ΔP1, Inv)) from the differential pressure ΔP1 between the pressure in the space 38 and atmospheric pressure and the rotational speed of the fan 311 at the time of detecting the differential pressure ΔP1 (in this embodiment, the output Inv of the inverter corresponding to the rotational 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 (claim 2).

[0037] In any of the above configurations The airflow rate of the dust collector 30 that can cause the mesh of the dust collection filter 33 to expand at the beginning of use is the critical airflow rate Q max And set it as The passing air volume Q is the limit air volume Q max It is preferable to control the rotation speed (including stopping) of the fan 311 so that the rotation speed is less than 100 rpm (see claim 3 ).

[0039] 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 (see claim 1). 4 ).

[0040] 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 collects the 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 dust collector 30 has a dust collection filter 33 The fan 311 is provided in the secondary flow passage 36, and the secondary flow passage 36 is opened to the atmosphere on the secondary side of the fan 311, The pressure difference 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 ΔP1 of A pressure detection means 50 for detecting the pressure, The pressure detected by the pressure detection means 50 Differential Pressure ΔP1 To The control device 60 controls the rotation speed of the fan 311 so that the passing air volume Q of the dust collector 30, which is grasped based on the above, approaches a preset target air volume Q0. , The control device 60 includes: The pressure difference across the dust collecting filter 33 that may cause damage to the dust collecting filter 33 is defined as a withstand limit pressure difference ΔP fmax Remember as, A pressure difference ΔP 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 1 The measured value of the pressure difference ΔP fmax The rotation speed (including stopping) of the fan 311 is controlled so that the rotation speed is less than the set value. The present invention is characterized by the following features (claim 5 ).

[0041] In the blast processing device 1 having the above configuration , before The control device 60 detects the atmospheric pressure detected by the pressure sensor 51. The above The airflow control may be configured to calculate the passing airflow Q of the dust collector 30 based on a preset relational expression (e.g., Q=f(ΔP1, Inv)) from the pressure difference ΔP1 and the rotation speed of the fan 311 at the time of detecting the pressure difference ΔP1 (in the embodiment, the inverter output Inv corresponding to the rotation speed), and to control the rotation speed of the fan 311 so that the calculated passing airflow Q approaches the target airflow Q0 (see claim 1). 5 ).

[0044] Both of the above blast processing devices 1, The control device 60 includes: The airflow rate of the dust collector 30 that can cause the mesh of the dust collection filter 33 to expand at the beginning of use is the critical airflow rate Q max As well as remembering The passing air volume Q is the limit air volume Q max Alternatively, the rotation speed of the fan 311 may be controlled (including stopping) so that the rotation speed is less than 7 ).

[0046] 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 (see claim 1). 8 ). Effect of the Invention

[0047] 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 with the control method of the present invention.

[0048] Dust collection filter 33 of dust collector 30 Second In the secondary flow path 36 pressure ΔP (ΔP1 or ΔP2) is detected. pressure By performing air volume control to control the rotational speed of the fan 311 so as to bring the passing air volume Q of the secondary side flow passage 36, determined based on 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 collection filter 33 of the dust collector 30 becomes clogged, the quality of the recovered projection material can be maintained constant without changing the classification performance of the classifier 20.

[0049] As a result, in the blast processing apparatus 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 recovered blast material was circulated and used multiple times.

[0050] Moreover, in the secondary flow passage 36 pressure Although this is an extremely simple and straightforward control that brings the passing air volume Q, which is determined based on ΔP (ΔP1 or ΔP2), closer to the target air volume Q0, it is possible to maintain a constant volume of air passing through the classifier 20 without making any changes to the control program, calculation formulas, etc., 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.

[0051] 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 relationship formula [for example, Q = f (ΔP1, Inv)] from the pressure difference ΔP1 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 ΔP1 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 ΔP1 from atmospheric pressure).

[0052] In addition, the configuration in which the pressure difference ΔP2 before and after the orifice 41 provided at a predetermined position in the secondary side flow passage 36 is detected to control the passing air volume Q is not limited to a configuration in which the secondary side flow passage 36 is open to the atmosphere, and even if other equipment is connected to the secondary side flow passage 36, the passing air volume Q of the secondary side flow passage 36 can be controlled to approach the target air volume Q0 without being affected by the increased exhaust resistance associated with the connection of the other equipment.

[0053] As a result, even when a HEPA filter or the like is further installed in the secondary flow path 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 due to the progression of clogging of the HEPA filter.

[0054] Furthermore, in the configuration in which the aforementioned air volume control is performed by measuring the differential pressure ΔP2 across the orifice 41 provided in the secondary 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 formula, etc., by simply using the detected differential pressure ΔP2 across the orifice 41 directly to control the rotational speed of the fan 311 to approach the set target differential pressure ΔP0.

[0055] Furthermore, the control method introduced in Patent Document 1 could only cope with a decrease in air volume caused by clogging of the filter, but both dust collectors controlled by the methods of the present invention can cope with a decrease in the air volume caused by clogging of the dust collection filter 33, as well as narrowing of the flow path caused by the accumulation of projectiles and dust on the inner walls of the recovery duct 13 and the exhaust duct 21, etc. pressure It was possible to address the general decrease in the passing air volume Q caused by an increase in flow resistance on the primary side from the measurement position of ΔP (ΔP1 or ΔP2).

[0056] The dust collecting filter 33 attached to the dust collector 30 is a bag-shaped filter generally known as a "bag filter," and is structured to collect dust by introducing the air to be purified into this bag-shaped dust collecting filter 33 and allowing it to pass through.

[0057] 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.

[0058] However, even if air is introduced when the filter is first started and there is no clogging, the dust collecting filter 33 is in a deflated state rather than expanding uniformly, so the air passes through only the part of the dust collecting filter 33 that is in front of the direction in which the air is introduced.

[0059] As a result, if the passing air volume Q is increased excessively when the dust collecting filter 33 is in an initial state of use, the meshes in the area where the air passes through in a concentrated manner may be pushed open and enlarged compared to the meshes in other areas, which may impair the functionality of the dust collecting filter 33.

[0060] In response to this, the air volume passing through the dust collector 30, which may cause the mesh of the dust collecting filter 33 to enlarge when use is first started, is set as the limit air volume Qmax, and the rotation speed (including stopping) of the fan 311 is controlled so that the detected value of the air volume passing through Q is less than the value set as the limit air volume Qmax, thereby making it possible to effectively prevent functional loss of the dust collecting filter 33 when use is first started.

[0061] In addition, in a configuration for detecting the pressure difference ΔP1 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 (the configuration shown in Figures 1 and 2), the pressure difference ΔP1 between the pressure in the space 38 and atmospheric pressure is always greater than or equal to the pressure difference before and after the dust collecting filter 33.

[0062] Therefore, by measuring in advance the pressure difference before and after the dust collecting filter 33 that could cause damage to the dust collecting filter 33 as the pressure resistance limit pressure difference ΔPfmax, and controlling the rotation speed (including stopping) of the fan 311 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 resistance 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.

[0063] Furthermore, in any of the above-mentioned control methods for the dust collector 30, the rotation speed of the fan 311 is increased as the clogging of the dust collecting filter 33 provided in the dust collector 30 progresses, but by bringing the fan 311 to an emergency stop when the fan 311 reaches a predetermined upper limit speed, and by appropriately setting the upper limit speed within a range below the rated rotation speed of the fan motor 312, it is possible to prevent the fan motor 312 from being driven beyond the rated value and being damaged.In addition, for example, by experimentally determining in advance the correspondence between the change in rotation speed of the fan motor 312 and the change in the pressure difference between the primary and secondary sides of the dust collecting 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 collecting filter 33, preferably to a value that is lower by a predetermined margin compared to the pressure resistance, it is possible to prevent the pressure difference between the primary and secondary sides of the dust collecting filter 33 from rising beyond the pressure resistance of the dust collecting filter 33, and to prevent the dust collecting filter 33 from being damaged. [Brief description of the drawings]

[0064] [Figure 1] FIG. 13 is an explanatory diagram showing a configuration example of a dust collector and a control device when air volume control is performed based on a pressure difference ΔP1 between the pressure in the secondary flow path and atmospheric pressure. [Diagram 2] FIG. 2 is a cross-sectional view of a fan portion of a dust collector used in the configuration of FIG. 1 . [Diagram 3] 13 is a graph showing an example of the relationship between the pressure difference ΔP1 between the pressure in the space 38 and the atmospheric pressure, the passing air volume Q, and the power W (W0, W0+σ, W0+2σ) of the fan motor. [Figure 4] 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 ΔP2 before and after an orifice provided in a secondary flow path. [Diagram 5] FIG. 5 is a cross-sectional view of a fan portion of a dust collector used in the configuration of FIG. 4 . [Figure 6] 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 a differential pressure ΔP2 before and after the orifice provided in the secondary flow path. [Figure 7] FIG. 1 is an explanatory diagram of the test equipment used in [Test 1]. [Figure 8]FIG. 1 is an explanatory diagram of the test equipment used in [Test 2]. [Figure 9] An explanatory diagram of blast processing equipment (circulation type). [Figure 10] A schematic diagram showing the change in airflow through a conventional dust collector (when dust is removed periodically using the shaking lever). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0065] Next, an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0066] [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 which introduces and classifies the blast material blasted within the cabinet 10 and recovered 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 draws in and exhausts the air within the classifier 20.

[0067] When the air inside the classifier 20 is sucked in and exhausted by rotating 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 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 inside the classifier 20 via the exhaust duct 21, so that the clean air after the dust has been 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 similar to the configuration of the known blast processing device 1 described with reference to Figure 9.

[0068] In addition, in the blast processing apparatus 1 described with reference to Figure 9, an example of a configuration of a ``circulating'' blast processing apparatus 1 is shown in which the shot material recovered in the shot material tank 22 can be introduced into the blast nozzle 12 arranged in the cabinet 10 via the shot material hose 23. However, the blast processing apparatus 1 to which the control method of the present invention is applied does not necessarily need to be configured to recirculate the recovered shot material to the blast nozzle 12, so long as it is capable of performing the process of recovering the shot material in the shot material tank 22.

[0069] [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 has a 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, and a pressure A pressure detection means 50 (51, 52) is provided to detect ΔP (ΔP1 or ΔP2). pressure It is possible to grasp the change in the volume of air Q passing through the dust collector 30 based on ΔP (ΔP1 or ΔP2).

[0070] In the blast processing device 1 of the present invention, the pressure detected by the pressure detection means 50 (51, 52) pressure By providing a control device 60 that controls 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 ΔP (ΔP1 or ΔP2), approaches a preset target air volume Q0, the flow rate of air passing through the classifier 20 can be maintained at a constant amount, thereby maintaining the classification performance of the classifier 20 without changing it.

[0071] In order to enable control of the rotation speed of the fan 311 of such a dust collector 30, in the dust collector 30 of the blast processing apparatus of the present invention, the fan motor 312 is a three-phase AC motor, preferably a three-phase AC motor for inverter control, and as shown in Figures 1, 4 and 6, the configuration of the above-mentioned control device 60 includes an inverter 61 that first 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.

[0072] 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 decreases as the output frequency (Hz) decreases. Therefore, by increasing the output Inv (kW) of the inverter 61, the rotation speed and power (W) of the fan motor 312 increase, and by decreasing the output Inv (kW) of the inverter 61, the rotation speed and power (W) of the fan motor 312 decrease.

[0073] Then, the inverter 61 has a PID control function to detect the pressure in the secondary flow path 36 detected by the pressure detection means 50. pressure By changing the output Inv (kW) of the inverter 61 so as to bring the passing air volume Q, which is grasped based on ΔP (ΔP1 or ΔP2), closer to a preset target air volume Q0, 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.

[0074] [Control device configuration example 1] FIG. 1 shows an example of the configuration of the control device 60 when the dust collector 30 whose exhaust port 313c is open to the atmosphere is to be controlled.

[0075] The dust collector 30 to be controlled in Figure 1 is, as an example, configured as shown in Figure 2, to have an air intake 32a in a filter casing 32 that houses a dust collecting filter 33, 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 collecting 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 in by this exhaust fan 31.

[0076] This exhaust fan 31 has 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 for accommodating the fan 311, and a fan casing 313 having an exhaust port 313c open to the atmosphere.

[0077] Therefore, in the configuration of the dust collector 30 in Figure 2, the portion extending from the duct 314 of the exhaust fan 31 to the exhaust port 313c of the fan casing 313 forms a secondary side flow path 36 provided on the secondary side of the dust collecting filter 33, the fan 311 is arranged in this secondary side flow path 36, and the end (exhaust port 313c) of the secondary side flow path 36 on the secondary side of the fan 311 is open to the atmosphere.

[0078] In the configuration of Figure 1 in which such a dust collector 30 is the object to be controlled, a pressure sensor 51 that detects the differential pressure (absolute value of gauge pressure) ΔP1 between the pressure in the space (space within 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 the passing air volume Q using a predetermined relational equation based on the differential pressure ΔP1 detected by the pressure sensor 51 and the rotational speed of the fan 311 at the time of detection of the differential pressure ΔP1 [the output Inv (kW) of the inverter 61 corresponding to the rotational speed of the fan 311].

[0079] The passing air volume Q, which is the result of the calculation by the calculation device 62, is input to the inverter 61, which 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.

[0080] Therefore, in the configuration shown in FIG. 1, the above-mentioned arithmetic device 62 and inverter 61 realize a control device 60 that controls the rotation speed of the fan 311 of the dust collector 30.

[0081] 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 equation Q=f(ΔP1, W).

[0082] 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 the atmospheric pressure and the inverter output Inv, and is related by the relationship Q=f(ΔP1, Inv).

[0083] Therefore, by experimentally determining this relationship 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.

[0084] The passing air volume Q calculated by this 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 the preset target air volume Q0. This makes it possible to maintain a constant air volume passing through the dust collector 30 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 the flow path resistance on the primary side of the dust collecting filter 33.

[0085] [Control device configuration example 2] In the above description given with reference to FIG. 1, a configuration example has been described in which the dust collector 30 with the exhaust port 313c open to the atmosphere is the object to be controlled.

[0086] In this configuration, since the exhaust resistance (back pressure) of the air passing through the secondary flow path 36 is constant at atmospheric pressure and does not change, it is possible to determine 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.

[0087] However, as shown in Figures 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 air volume Q passing through the secondary flow path 36 based on the gauge pressure (pressure difference from atmospheric pressure) ΔP1 in the space 38.

[0088] Therefore, in cases where further downstream equipment is connected to the secondary flow path 36, for example, as shown in Figures 4 and 5, an exhaust pipe 40 equipped with an orifice 41 is connected to the exhaust port 313c provided in the 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 aforementioned air volume control is performed to control the passing air volume Q based on the differential pressure ΔP2 before and after this orifice 41.

[0089] When the blast processing equipment 1 is used within the normal operating temperature range, there is a relationship between the air flow rate Q of the secondary flow passage 36 and the pressure difference ΔP2 before and after the orifice 41, that is, Q=f(ΔP2), and the air flow rate Q can be calculated as a function of only the pressure difference ΔP2 before and after the orifice 41.

[0090] 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 .

[0091] Therefore, as shown in FIG. 4, the differential pressure ΔP2 detected by a differential pressure sensor 52 (pressure detection means 50) which detects the differential pressure ΔP2 across the orifice 41 is input to an inverter 61, and the inverter 61 is made to perform PID control which changes the output Inv so as to bring the input differential pressure ΔP2 across the orifice 41 close to the target differential pressure ΔP0 which has been pre-stored as a differential pressure corresponding to the target air volume Q0, thereby making it possible to perform air volume control which brings the passing air volume Q of the secondary flow path 36 as close as possible to the target air volume Q0.

[0092] In this configuration, as shown in Figure 4, the differential pressure ΔP2 before and after 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.

[0093] However, instead of the configuration shown in FIG. 4, a calculation device 62 may be provided as shown in FIG. 6, which receives the differential pressure ΔP2 across the orifice 41 detected by the differential pressure sensor 52 and calculates the passing air volume Q of the secondary flow path 36 based on the differential pressure ΔP2 across the orifice 41 and a previously stored relational equation Q=f(ΔP), 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.

[0094] In the configuration shown in FIG. 6, the above-mentioned arithmetic device 62 and inverter 61 are combined to form a control device 60 that controls the operation of the dust collector 30.

[0095] As explained with reference to Figures 4 and 6, in a configuration in which the passing air volume Q is grasped based on the pressure difference 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, so that the passing air volume Q can be controlled to be constant even if further downstream equipment such as a HEPA filter is connected to the secondary side of the exhaust pipe 40.

[0096] Furthermore, since it is possible to control the passing air volume Q without being affected by exhaust resistance on the secondary side of the exhaust pipe 40 in this manner, the passing air volume Q can be maintained constant even if 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 downstream equipment is connected to the secondary side of the exhaust pipe 40.

[0097] 〔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 indefinitely as the clogging progresses, the power of the fan motor 312 will exceed the rated value.

[0098] Furthermore, as the rotational speed of the fan 311 increases, the pressure difference between the primary and secondary sides of the dust collecting filter 33 increases, so if the rotational speed of the fan motor 312 is increased indefinitely, the pressure difference between the primary and secondary sides of the dust collecting filter 33 will increase beyond the pressure resistance capacity of the dust collecting filter 33, and there is a risk that the dust collecting filter 33 will be damaged and become unusable.

[0099] 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 has been set in advance taking into account the rated power of the fan motor 312 and the pressure resistance performance of the dust collecting filter 33, the inverter 61 may be configured to stop output and bring the fan motor 312 to an emergency stop.

[0100] In addition, when the output Inv of the inverter 61 reaches the upper limit value mentioned above, or when it reaches a predetermined lower value than the upper limit value mentioned above, a warning light may be turned on or a warning sound may be emitted to warn the operator, thereby encouraging the operator to operate the shaking lever 35 to shake off the dust accumulated in the dust collecting filter 33 or to replace the dust collecting filter 33.

[0101] Furthermore, as mentioned above, if the airflow rate Q of the dust collecting 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 apart and enlarged compared to the mesh in other areas, which may impair the function of the dust collecting 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 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 Qmax, it is possible to prevent loss of function of the dust collecting filter 33 at the beginning of use.

[0102] In addition, in a configuration for detecting the pressure difference ΔP1 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 (the configuration shown in Figures 1 and 2), the pressure difference ΔP1 between the pressure in the space 38 and atmospheric pressure is always greater than or equal to the pressure difference before and after the dust collecting filter 33.

[0103] Therefore, it is possible to prevent damage to the dust collecting filter 33 by measuring in advance the pressure difference before and after the dust collecting filter 33 as the pressure resistance limit pressure difference ΔPfmax, and controlling the rotation speed (including stopping) of the fan 311 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 resistance limit pressure difference ΔPfmax. EXAMPLES

[0104] Next, 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 are shown below.

[0105] 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.

[0106] [Test 1] (1) Test equipment As shown in Figure 7, the controlled object is a dust collector for a blast processing device ("D4715" manufactured by Fuji Manufacturing) 30, whose exhaust port 313c is open to the atmosphere, and the fan motor 312 (rated output 0.75 kW) of this dust collector 30 is controlled by a control device 60 consisting of an arithmetic unit (sequencer) 62 and an inverter 61.

[0107] A pressure sensor 51 that detects the gauge pressure of the space 38 (see Figure 2) in the duct 314 provided in the exhaust fan 31 of the dust collector 30 is provided as the pressure detection means 50, and the absolute value of the gauge pressure detected by this pressure detection means 50 (51) is input to the calculation device 62 as the differential pressure ΔP1 between the pressure in the space 38 and the atmospheric pressure.

[0108] 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(ΔP1, Inv)] based on the pressure difference ΔP1 from the 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 close to a preset target air volume Q0.

[0109] In order to measure the air volume passing through the dust collector 30, an anemometer (not shown) was installed at five points on the same vertical cross section near the exhaust port 313c, and the average value of the wind speeds measured by the five anemometers was multiplied by the cross-sectional area of ​​the exhaust port 313c to calculate the air volume passing through the dust collector 30 (m 3 / min) was calculated.

[0110] (2) Advance preparations (2-1) Obtaining and setting the relational expression [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 clogging of the dust collection filter progresses, 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 / ΔP1 This relational expression was then stored in the arithmetic unit 62.

[0111] (2-2) Acquiring and setting the target air volume Q0 The airflow rate obtained when the intake port 32a of the dust collector 30 was fully opened and the fan motor 312 was directly connected to a commercial power source (50Hz, 200V) without going through the inverter 61 was 11.44m 3 / min was stored in the inverter 61 as the target air volume Q0.

[0112] (3) Test methods and test results The intake port 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 measurements were made of how the passing air volume (actual measured value), the rate of change in the air volume (rate of change relative to when fully open), the pressure difference from atmospheric pressure ΔP1, the inverter output Inv (kW), and the inverter output frequency (Hz) changed.

[0113] 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 compared to when fully open) were measured.

[0114] The measurement results are shown in Table 1 below.

[0115] [Table 1]

[0116] From the above results, in the dust collector (comparative example) not controlled by the present invention, the air flow rate when the intake port 32a was fully opened was 11.44 m 3 / min, whereas at half-open it was 10.12m 3 / min, a decrease of 11.5% in the airflow was observed.

[0117] 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 is fully opened is 11.62 m 3 / min, the airflow when half open is 11.27 m 3 / min, the decrease in air volume could be suppressed to 3%, and it was confirmed that the air volume passing through the dust collector 30 could be kept constant with high precision.

[0118] Moreover, in the dust collector controlled by the method of the present invention, the air flow rate can be controlled to be approximately constant even when the opening area of ​​the intake port 32a of the dust collector is narrowed to half-open, which makes it possible to prevent not only the reduction in air flow rate caused by clogging of the dust collection filter, but also all reductions in air flow rate caused by a reduction 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).

[0119] [Test 2] (1) Test equipment The test was carried out using the test equipment shown in Fig. 8. The dust collector 30 to be controlled in this test equipment was a dust collector for a blast processing device (manufactured by Fuji Manufacturing Co., Ltd., "D4715") having a fan motor with a rated output of 0.75 kW, and an inverter 61 was connected as a control device 60 to the fan motor 312 of this dust collector.

[0120] An exhaust pipe 40 equipped with 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 the 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.

[0121] The differential pressure ΔP2 across the orifice 41 detected by this 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.

[0122] In order to actually measure the airflow rate of the dust collector 30, an anemometer (not shown) was installed at five points on the same vertical cross section near the outlet of the exhaust pipe 40 (a position that is far enough away from the orifice 41 and does not affect the measurement of the differential pressure ΔP2 before and after the orifice 41), and the average value of the wind speeds measured by the five anemometers was multiplied by the cross-sectional area of ​​the exhaust pipe 40 to calculate the airflow rate (m 3 / min) was calculated.

[0123] (2) Advance preparations (2-2) Obtaining and setting the target differential pressure ΔP0 When the intake port 32a of the dust collector 30 was fully opened and a commercial power source (50 Hz, 200 V) was connected directly 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, which was 260 Pa, was stored in the inverter 61 as the target differential pressure ΔP0.

[0124] (3) Test methods 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 rate of change in air volume (rate of change relative 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.

[0125] 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 compared to when fully open) were measured. The measurement results are shown in Table 2 below.

[0126] [Table 2]

[0127] From the above results, in the dust collector (comparative example) not controlled by the present invention, the air flow rate when the intake port 32a was fully opened was 10.81 m 3 / min, whereas at half-open it was 9.49m 3 / min, the airflow rate decreased by 12.2%.

[0128] In contrast, the dust collector controlled by the method of the present invention has a passing air volume of 10.85 m at full opening. 3 / min, the airflow when half open is 10.89 m 3It was confirmed that the decrease in air volume was suppressed to 0.4% at 1000 / min and the air volume passing through the dust collector was kept constant with high precision.

[0129] In addition, even when the opening area of ​​the dust collector's intake port is half open, the amount of air passing through can be controlled to a nearly constant level, which is evident from the fact that the pressure difference before and after the dust collector's orifice ΔP Even in the configuration of this test example in which the rotation speed of the fan motor is controlled based on 2, it is possible to deal with not only the reduction in the passing air volume due to clogging of the dust collection filter, but also any reduction in air volume due to a reduction in the flow path area occurring on the primary side of the measurement position of the differential pressure ΔP2 (for example, narrowing of the flow path area due to adhesion of projection material or dust to the inner walls of the recovery duct or exhaust duct). [Explanation of symbols]

[0130] 1 Blasting equipment 10 Cabinet 10a Bottom (of cabinet) 11. Working Space 12 Blast Nozzle 13 Recovery duct 20 Classifier 21 Exhaust duct 22 Projectile tank 23 Projection 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 Air intake 32b exit 33 Dust collection filter 35 Shaking lever 36 Secondary flow passage 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 ΔP1 pressure difference (between space 38 and atmospheric pressure) ΔP2 differential pressure (before and after the orifice) ΔP0 target differential pressure Q Passing air volume Q0 target air volume

Claims

1. 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 collecting 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:

2. Calculating the passing air volume of the dust collector based on a predetermined relational equation from the differential pressure between the detected pressure in the space and atmospheric pressure and the rotational 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.

3. 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.

4. 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.

5. A blast processing device having a cabinet with a working space, a classifier consisting of an air sorter which introduces and classifies blast material blasted in 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 sucks in and exhausts air from within the classifier, and which collects 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 collecting 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 the 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.

6. The blast processing apparatus of claim 5, characterized in that the control device calculates the passing air volume of the dust collector based on a predetermined 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 the differential pressure is detected, and performs 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.

7. 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.

8. 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.

Images