JP2002046068A - Blasting machine with flow measuring apparatus for grinding/polishing/cleaning material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blasting machine having a flow measuring apparatus for accurately measuring the flow of even an electrically non-conductive grinding/polishing/cleaning material as variation in electrostatic capacity. SOLUTION: The capacitance type flow measuring apparatus 70, in which the source electrode 73, the sensing electrode 74 and the guard electrode 75 of a measuring electrode 76 are arranged with angles of 45 deg. to one another over a range of 90 deg. in the circumferential direction of the outer periphery of a cylindrical pipe 72, is positioned on the incident side of a grinding/polishing/ cleaning material projection device, whereby flow of an electrically non-conducting grinding/polishing/cleaning material can be measured with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blast machine provided with a polishing material flow rate measuring device, and more particularly to an electrostatic blasting machine capable of accurately measuring the flow rate of a non-conductive polishing material. The present invention relates to a blasting machine provided with a capacity-type polishing material flow rate measuring device.

[0002]

2. Description of the Related Art Conventionally, large structures, such as ships, bridges, and large tanks, which are manufactured using thick steel plates, often store materials, semi-finished products, and assemble outdoors, and the construction period is long. For this reason, it is common practice to first remove scale from a steel plate as a material and perform a primary rust prevention treatment to prevent rust during construction, to remove rust after the product is completed, and to facilitate painting. For that purpose, a blasting machine is generally used as a means of the primary rust prevention treatment.

[0003] Such blasting machines are roughly classified into the following three types according to the type of abrasive material. That is, a sand blasting machine that projects mineral particles such as silica sand and abrasives onto the abrasive material, a shot blasting machine that projects iron particles and cut wires, and a grid blasting machine that projects iron particles having sharp corners. Kind. Here, a description will be given using a shot blast machine, which is the most generalized representative example. There are two types of this shot blast machine, a vertical type and a horizontal type. Since the horizontal type is the mainstream due to the auxiliary equipment, the horizontal type equipment will be described as an example.

As shown in FIG. 5, a horizontal shot blasting machine includes an abrasive material projecting device 1 and a projecting chamber 2, an abrasive material collecting and circulating device 3, an abrasive material blowing-down device 4, a steel sheet conveying device 5, and a collecting device. It is composed of a dust device 6. As shown in FIG. 6, the abrasive material projection device 1 includes a distributor 12,
The control cage 13 and the impeller blade 14 are housed and configured.

[0005] Then, the abrasive material S supplied from the introduction cylinder 15
Is supplied to the impeller blade 14 via the distributor 12, but the projection width and the projection angle of the abrasive material S are adjusted by the control cage 13, and the abrasive material S is supplied to the impeller blade 14. Due to the centrifugal action of the rotation, the steel sheet transport device 5 in the projection chamber 2 at a speed of 70 to 80 m / s.
Is projected onto the steel plate P held in the first position.

As a result, the mill scale on the front and back surfaces of the steel sheet P is peeled around the dent due to the impact of the blasted material S, and the mill scale at the dent portion is removed by the blasted material S hitting the vicinity. Peeled off. These used abrasive materials S
Is recovered by the abrasive cleaning material circulating device 3 and supplied to the abrasive cleaning material projection device 1 again. The abrasive material S projected on the surface of the steel sheet P is blown off from the steel sheet by the air pressure by the abrasive material blow-off device 4. In addition, the steel sheet P
Mill-scale fines peeled off from the crusher and fine-grained shots that cannot be used due to crushing or abrasion are removed by the dust collector 6.

FIG. 7 shows such a circulation system of the abrasive material. The abrasive material recovered by the lower screw 32 is lifted upward by a bucket elevator 33 and separated by an abrasive material separator 34. Then, it is supplied to the upper screw 31. In order to grasp the flow rate of the abrasive material at this time, conventionally, a flow rate measuring device 7 is attached between the upper screw 31 and the impeller blade 14, and the flow rate of the abrasive material is measured based on the measured value. It is generally done.

[0008] The measurement of the flow rate of the abrasive material is important from the viewpoint of controlling the degree of rust removal and surface roughness. That is, in order to stabilize the degree of rust removal, since the stability of the shot projection amount is the point, accurate flow measurement of the abrasive material must be performed. Also, obtaining a stable surface roughness of the steel sheet is important for enhancing the adhesion of the paint. For this purpose, it is important to control the particle size of the polishing material S, and the polishing used for the polishing is important. The point is to know the amount of consumables consumed and supply new abrasives.

For the flow rate measurement of the abrasive material such as the grit, the cut wire, and the shot, any method using, for example, a reactance L can be applied.

[0010]

By the way, since the surface roughness of the steel sheet greatly varies due to the dents of the abrasive material,
The higher the quality of a steel sheet, the more important its surface roughness management becomes. Therefore, in order to reduce the surface roughness, it is necessary to use a fine abrasive material, and for example, alumina such as polishing powder is considered to be suitable.

However, since such alumina is non-conductive, it cannot be measured accurately with a conventional reactance type flow meter, so that the above-mentioned cleaning operation can be performed efficiently. There is a problem that can not be. The present invention has been made to solve the problems of the prior art as described above, and has a means capable of accurately measuring the flow rate of the abrasive material even when using a non-conductive abrasive material. The purpose of the present invention is to provide a blasting machine equipped with the blasting machine.

[0012]

SUMMARY OF THE INVENTION The present invention is directed to an abrasive material projecting device, a projection chamber, an abrasive material collecting and circulating device, an abrasive material blow-down device, a steel sheet conveying device, and a dust collecting device. A blasting machine comprising a blasting material flow rate measuring device, wherein a capacitance type flow rate measuring device is arranged on an input side of the blasting material projecting device.

Further, the capacitance type flow rate measuring device used in the present invention comprises a cylindrical tube serving as a flow path of the granular material, and a pair of curved source electrodes arranged to face the outer periphery of the cylindrical tube. Using a measurement electrode consisting of a sense electrode and a guard electrode provided between the source electrode and the sense electrode,
Detecting the flow rate of the granular material sent to the inner surface passage of the cylindrical tube as a change in capacitance, wherein a source electrode, a sense electrode, and a guard electrode of the measuring electrode are arranged on the outer circumference of the cylindrical tube; It is characterized by being arranged at an angle of 45 ° in each direction and over a range of 90 °.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention applied to a shot blast machine will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing a main part of a shot blasting machine according to the present invention, and FIG. 2 is a schematic view showing a main part of one embodiment of a capacitance type flow rate measuring device mounted on the shot blasting machine. FIG.
In the drawings, the same members as those in the conventional example are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 1, the flow rate of the abrasive material S supplied to the shot blast machine is measured by a capacitance type flow rate measuring device 70 mounted between the upper screw 31 and the impeller blade 14. It is measured and the measured value is
Entered into 80. After the necessary arithmetic processing is performed by the personal computer 80, a flow control signal is output to output the flow control device 90.
, The required flow rate of the abrasive material S is controlled.

As shown in FIG. 2, the flow rate measuring device 70 includes a cylindrical pipe 72 serving as a flow path of the cleaning material S, and a pair of curved source electrodes 73 arranged opposite to the outer periphery thereof. A measurement electrode 76 including a sense electrode 74, a pair of guard electrodes 75 provided between the source electrode 73 and the sense electrode 74, and an outer cylinder made of, for example, aluminum or copper, which shields the outer periphery of the cylindrical tube 72. It consists of 77. The source electrode 73, the sense electrode 74, and the guard electrode 75 are formed on the surface of the cylindrical tube 72 by printing or copper foil.

The cylindrical tube 72 has a thermal expansion coefficient of, for example, 5 to 6 ×
A quartz glass tube of about 10 ⁻⁷ / K is used, and the inner surface thereof is subjected to Teflon (registered trademark) processing to prevent powder adhesion. In addition to the quartz glass tube, alumina, ordinary glass, plastic, or the like is used.
Next, each electrode 73, 74, provided on the outer surface of the cylindrical tube 72,
3 will be described. As shown in the side view of FIG. 3, a pair of curved source electrodes 73 and sense electrodes 74 face each other and extend in a circumferential direction from the upper end 72a to the lower end 72b of the cylindrical tube 72. Are arranged at an angle of 45 ° and over a range of 90 °, respectively, and a guard electrode 75 is similarly arranged at an angle of 45 ° between the source electrode 73 and the sense electrode 74.
It is arranged over a range of 90 °.

As described above, the source electrode 73, the sense electrode 74 and the pair of guard electrodes 75 constituting the measuring electrode 76 are respectively
By arranging at an angle of 45 ° and over a range of 90 ° in the circumferential direction, the magnetic lines of force between the source electrode 73 and the sense electrode 74 can be made uniform at any location on the inner wall of the cylindrical tube 72. From the abrasive material S flowing through the cylindrical tube 72
The accuracy in the flow rate measurement can be improved. Also,
Since the length of each electrode can be extremely short, the sensor can be downsized, and can be applied compactly to an existing shot blast machine.

Then, as shown in the equivalent circuit of FIG.
AC power supply 78 to the ground electrode 73, the sense electrode 74, and the guard electrode 75.
When a voltage E is applied from above, the abrasive material S flowing through the cylindrical tube 72
The capacitance changes depending on the flow rate of the
Impedance Z₀Since the current I flowing through the
V at terminals a and b using the change of ₀
Measuring the flow rate of the abrasive S by detecting
Can be. In addition, Z in the figure₁Is the source electrode 73 and the guard electrode
Impedance between poles 75, Z_TwoIs guard electrode 75 and sense
Impedance between electrodes 74, Z_ThreeIs connected to the source electrode 73
Impedance between the outer cylinders 77, Z_FourIs sense electric
This is the impedance between the pole 74 and the outer cylinder 77.

That is, the dielectric constant of the polishing material S is set in advance as a circuit constant, and the capacitance of the zero adjustment variable capacitor is set so that the current I flowing through the measurement impedance Z ₀ becomes zero when the flow rate is zero. Adjust with. Thereafter, when the cleaning material S flows through the cylindrical tube 72, the capacitance between the electrodes changes in proportion to the flow rate.
_By measuring it as _{0 and} displaying it as a flow rate in an appropriate unit, the instantaneous value or integrated value of the flow rate of the abrasive material S can be known.

Although the above example has been described for a shot blasting machine, the present invention is not limited to this, and is similarly applied to a sand blasting machine or a grid blasting machine to reduce the flow rate of the abrasive material. It goes without saying that it can be measured. Also, the abrasive material flow rate measuring device used in the present invention is not limited to a non-conductive abrasive material, and it is needless to say that a conventional conductive abrasive material can be measured. Nor.

[0022]

EXAMPLE When the surface of a thick steel plate was shot blasted using alumina as the abrasive material S, the capacitance type flow rate measuring device 70 of the present invention was attached to a shot blasting machine to measure the flow rate of alumina. , While controlling the flow control device 90 via the personal computer 80. As a result, the rotation speed of the shot blasting machine was normally 6000 to 8000 rpm,
pm, it was possible to increase the efficiency of shot blast. Furthermore, there is a possibility that it can be brought to 9000 rpm.

[0023]

As described above, according to the blasting machine provided with the abrasive material flow rate measuring device of the present invention, since the capacitance type is used for the flow rate measuring device, even if the abrasive material is non- Even with conductive alumina, the flow rate can be accurately measured, so that the efficiency can be increased. Also, by making the length of the measuring electrode extremely short, the size of the sensor can be reduced, so that it goes without saying that it contributes to cost reduction.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a main part of a shot blast machine according to the present invention.

FIG. 2 is a plan view schematically showing a main part of one embodiment of a capacitance type flow rate measuring device arranged in the shot blasting machine of FIG.

FIG. 3 is a side view showing an outline of the cylindrical tube of FIG. 2;

FIG. 4 is an explanatory diagram of an equivalent circuit of the capacitance type flow rate measuring device according to the embodiment of the present invention.

FIG. 5 is a schematic view of a conventional example of a horizontal shot blast machine.

FIG. 6 is a side sectional view of a conventional example of a cleaning material projection device.

FIG. 7 is an explanatory diagram showing a circulation system of a polishing material of a conventional shot blast machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Abrasive material projection device 2 Projection chamber 3 Abrasive material collection and circulation device 4 Abrasive material blow-off device 5 Steel plate transport device 6 Dust collecting device 11 Casing 12 Distributor 13 Control cage 14 Impeller blade 15 Introductory cylinder 31 Upper screw 32 Lower Screw 70 Capacitive flow meter of the present invention 72 Cylindrical tube 72a Upper end of cylindrical tube 72b Lower end of cylindrical tube 73 Source electrode 74 Sense electrode 75 Guard electrode 76 Measurement electrode 77 Outer cylinder 78 AC power supply 80 Personal computer 90 Flow control device P Steel plate S Cleaning material

Claims (2)

[Claims] 1. A blasting machine comprising an abrasive cleaning material projecting device, a projection chamber, an abrasive cleaning material collecting and circulating device, an abrasive cleaning material blow-down device, a steel sheet conveying device, and a dust collecting device. A blasting machine equipped with a polishing material flow rate measuring device, wherein a capacitance type flow rate measuring device is arranged on the entrance side of the polishing material projecting device. 2. The capacitance-type flow rate measuring device comprises: a cylindrical tube serving as a flow path of a granular material; and a pair of curved source and sense electrodes disposed to face the outer periphery of the cylindrical tube. Using a measurement electrode composed of a guard electrode provided between the source electrode and the sense electrode, the flow rate of the granular material sent to the inner surface passage of the cylindrical tube is detected as a change in capacitance. The source electrode, the sense electrode, and the guard electrode of the measurement electrode are arranged at an angle of 45 ° and a range of 90 ° in the circumferential direction of the outer periphery of the cylindrical tube, respectively. A blast machine equipped with the abrasive material flow rate measuring device as described in the above.