Particle size distribution measuring device and particle size distribution measuring method

Abstract

To measure a particle size distribution of a shot used for shot processing, by a simple device structure.SOLUTION: A particle size distribution measurement device (1) for measuring a particle size distribution of a shot used for shot processing includes: a box body (10) of which inside is divided in a plurality of sections by a separation plate including a classification shifter; a swing supporting unit (20) in the box body (10), the swing supporting unit supporting the box body (10) swingably; and a measuring unit in the box body (10), the measuring unit measuring the shot in each section.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a particle size distribution measuring device and a particle size distribution measuring method. [Background technology]

[0002] Various prior art techniques are known for measuring the particle size distribution or classifying powders and granular materials. For example, Patent Document 1 discloses a semiconductor sieve that can accurately select and extract fine particles such as microlenses according to their particle size. The technique disclosed in Patent Document 1 involves stacking three tiers of sieves and vibrating them, and extracting particles selected at each tier to obtain particles of a desired size. This technique is said to enable highly aligned, fine through-holes to be formed in a semiconductor plate using techniques such as photolithography, enabling the selection and extraction of microlenses and other particles of a desired particle size. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-222739 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the device disclosed in Patent Document 1 is a device for extracting powder or granular material of a desired particle size, and is not a device for measuring the particle size distribution of powder or granular material. Of course, it is possible to determine the particle size distribution by individually collecting and measuring the particles sorted at each stage, but this requires additional work, which is a problem.

[0005] For example, the projection material or abrasive material (hereinafter, at least one of the projection material and the abrasive material will be referred to as "shot") used in a blasting process or a shot peening process (hereinafter, at least one of the blasting process and the shot peening process will be referred to as "shot process") is used repeatedly, and the number of particles gradually becomes smaller. As the number of small particles increases, the finishing ability of the shot process gradually decreases, and new shot must be added. Therefore, workers periodically measure the particle size distribution of the shot to determine whether or not new shot needs to be added. However, there is a problem in that measuring the particle size distribution of the shot requires a lot of effort from the worker.

[0006] An object of one aspect of the present invention is to measure the particle size distribution of shot used in shot processing using a simple device configuration. [Means for solving the problem]

[0007] In order to solve the above problems, a particle size distribution measuring device according to one embodiment of the present invention is a particle size distribution measuring device that measures the particle size distribution of shots used in shot processing, and includes: a box whose interior is divided into multiple compartments by partition plates including classification sieves; a swing support unit provided on the box that supports the box so that it can swing; and a weighing unit provided on the box that weighs the shots in each compartment.

[0008] In order to solve the above-mentioned problems, a method for measuring the particle size distribution of shot according to one embodiment of the present invention includes a feeding step of feeding shot to be used in shot processing into the uppermost compartment of a box whose interior is divided into multiple compartments by partition plates including classification sieves; a classification step of classifying the shot by shaking the box; a collection step of collecting the classified shot at the end of the compartment; and a weighing step of weighing the shot in a state where it is collected at the end of the compartment. [Effects of the Invention]

[0009] According to one aspect of the present invention, the particle size distribution of shots used in shot processing can be measured with a simple device configuration. [Brief explanation of the drawings]

[0010] [Figure 1] 1A to 1C are a top view, a front view, and a side view of a particle size distribution measuring device according to an embodiment of the present invention. [Figure 2] 1A to 1C are a perspective view, a top view, a front view, and a cross-sectional view of a box body of a particle size distribution measuring device according to an embodiment. [Figure 3] 2A to 2C are a perspective view, a front view, a side view of a holding frame according to the embodiment, and an enlarged view of a mounting portion. [Figure 4] FIG. 2 is a plan view showing an example of the configuration of a partition plate according to the embodiment. [Figure 5] 1A and 1B are a front view and an enlarged view of a scale plate, illustrating a method for measuring powder or granular material classified into each compartment according to an embodiment. [Figure 6] 10 is a front view showing a state in which the box body placed on the holding frame body according to the embodiment is swung around a swing axis. FIG. [Figure 7] 1 is a flowchart showing a method for measuring the particle size distribution of powder or granular material according to an embodiment of the present invention. [Figure 8] 10A and 10B are diagrams showing how the swing angle of the box body changes depending on the position of the mounting groove on which the swing shaft is mounted. [Figure 9] FIG. 10 is a diagram showing the change over time in particle size distribution of shots used in shot processing. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Embodiment 1] An embodiment of the present invention will be described in detail below with reference to the drawings. The particle size distribution measuring device 1 according to this embodiment is a measuring device for measuring the particle size distribution of a shot material or abrasive used in shot processing. First, shot processing and shot material or abrasive will be described. Shot processing is a surface treatment in which minute particles of metal, glass, ceramic, or the like are struck against the surface of a workpiece to improve the properties or characteristics of the surface. In this embodiment, shot processing includes blasting and shot peening. Blasting is a process for adjusting surface roughness, deburring, descaling, and removing deposits, while shot peening is a process for modifying the surface, such as by increasing surface hardness. The minute particles struck against the surface of the workpiece are referred to as shot material or abrasive depending on their size. For example, particles with a diameter of approximately 0.2 mm to 2.5 mm are referred to as shot material, and particles with a diameter less than 0.2 mm are referred to as abrasive, but these are not rigid distinctions. In this embodiment, at least one of the projection material and the aerosol material is referred to as a "shot."

[0012] Before describing the particle size distribution measuring device 1 according to this embodiment, the reason for measuring the particle size distribution of shot will be explained. The shot used in shot processing is reused. That is, since the used shot contains scale powder, sand, etc. removed from the object to be processed, these are separated using a separation method that utilizes airflow, and the remaining shot is reused in shot processing. However, when the shot is used repeatedly in shot processing, the particle size of the shot gradually becomes finer, the energy generated when the shot impacts the object to be processed decreases, and the finishing ability for the object to be processed gradually decreases.

[0013] FIG. 9 shows an example of the change over time in the particle size distribution of shot used in shot processing. The horizontal axis of FIG. 9 represents the sieve opening size, with the opening size (i.e., shot particle size) increasing toward the right and the opening size increasing toward the left. The vertical axis of FIG. 9 represents the weight percentage of shot classified by the sieve. In FIG. 9, the graph indicated by black circles shows the particle size distribution of new shot. The graph indicated by white circles shows the particle size distribution of shot after shot processing for T1 hour. The graph indicated by white triangles shows the particle size distribution of shot after shot processing for T2 hour, which is longer than T1 hour. As shown in the figure, the particle size distribution shifts toward finer sieve openings as time passes. In other words, the proportion of shot with smaller particle sizes increases as time passes.

[0014] Therefore, it is necessary to replenish the shot with new shot before the particle size distribution becomes too fine. Therefore, workers periodically measure the shot particle size distribution to determine whether replenishment is necessary. For example, in the case of blast finishing, it is known that if the specifications of the shot used, such as the shape, dimensions, and material of the shot, are the same, the blasting conditions during blasting machine operation, such as the projection speed and projection amount per unit time, are the same, and the particle size distribution of the shot is roughly the same, there will be no difference in the quality of the blast finishing, such as the gloss and surface roughness of the finished surface. Therefore, workers check whether the particle size distribution of the shot is within a specified range.

[0015] The particle size distribution of shot is measured using a standard JIS Z 8801 sieve, typically using a low-tap sieve tester or a sieve shaker with equivalent sieving effectiveness. However, such measurement equipment is expensive, and the measurement requires time and effort, placing a heavy burden on the operator. Alternatively, the measurement can be outsourced, but frequent outsourcing can be costly.

[0016] The particle size distribution measuring device 1 according to this embodiment is an inexpensive device that enables an operator to easily measure the particle size distribution of shot. However, the particle size distribution measuring device 1 does not need to be used only to measure the particle size distribution of shot, but can also be used to measure the particle size distribution of powder or granular materials in general. Therefore, in the following description, shot (projection material or abrasive material) will be referred to as "powder or granular material."

[0017] FIG. 1 shows a top view 101, a front view 102, and a side view 103 of a particle size distribution measuring device 1 according to this embodiment. The front view 102 is a view seen from direction A in the top view 101, and the side view 103 is a view seen from direction B in the top view 101. As shown in FIG. 1, the particle size distribution measuring device 1 includes a box body 10 and a holding frame 50. The box body 10 is a box-shaped container the interior of which is divided into multiple compartments by partition plates including a classification sieve. The holding frame 50 is a frame that holds the box body 10 in a swingable manner.

[0018] As shown in top view 101, box 10 has a swing support that swingably supports box 10. In the embodiment shown in FIG. 1, the swing support is a pair of swing shafts 20A and 20B provided on two opposing side surfaces 14A and 14B of box 10, respectively. The swing shafts 20A and 20B are one form of the "swing support" described in the claims. The swing is a movement that alternately rotates box 10 clockwise around the swing support to tilt it to the right, and rotates box 10 counterclockwise around the swing support to tilt it to the left. By providing a pair of swing shafts 20A and 20B on two opposing side surfaces 14A and 14B of box 10, box 10 can be swung with a simple structure.

[0019] As shown in a top view 101 and a front view 102, by placing the swing shafts 20A and 20B of the box body 10 on the mounting portions 55A and 55B of the holding frame 50, respectively, the holding frame 50 can swingably hold the box body 10. The holding frame 50 is used when classifying powder or granular material put into the box body 10, as will be described later.

[0020] The front view 102 shows the particle size distribution measuring device 1 placed on a floor surface F as viewed from direction A in the top view 101. The side view 103 shows the particle size distribution measuring device 1 placed on the floor surface F as viewed from direction B in the top view 101. In the following description, the up-down direction in the front view 102 is the direction of gravity when in use, and the left-right direction in the front view 102 is the horizontal direction when in use. However, as will be described later, although the box 10 shown in the front view 102 is drawn horizontally, when not in use, the box 10 is tilted so that the left end of the bottom of the box 10 abuts against the floor surface F.

[0021] Next, details of the box 10 will be described. Fig. 2 shows a perspective view 201, a top view 202, a front view 203, and a cross-sectional view 204 of the box 10. The front view 203 is a view seen from direction A in the top view 202, and the cross-sectional view 204 is a cross-sectional view taken along line BB in the top view 202. The shape of the box 10 is not limited, but in this embodiment, as shown in the perspective view 201, it has a substantially rectangular parallelepiped shape.

[0022] Hereinafter, when there is no need to distinguish between the oscillating shafts 20A and 20B, they will be simply referred to as oscillating shaft 20. Similarly, when there is no need to distinguish between the components distinguished by the symbols A and B described below, they will be described without the A and B.

[0023] The top surface of the box 10 has an inlet 15 through which powder or granular material whose particle size distribution is to be measured is introduced. The top view 202 shows the lid 11 that covers the inlet 15. The lid 11 is box-shaped and has a handle 12 on its top surface. As will be described later, the lid 11 is configured to function as both a collection container for collecting a predetermined amount of powder or granular material and a measuring measure. Therefore, a constant amount of shot is always supplied into the box 10. When the lid 11 is used as a measuring measure, after the shot is collected, the surface is leveled along the edge of the measure to ensure the predetermined amount. A powder or granular material outlet lid 13 is provided on the right side of the box 10. The outlet lid 13 is a cover that covers the outlet for discharging the powder or granular material collectively after classification.

[0024] As shown in the cross-sectional view 204, the interior of the box 10 is divided into three compartments 31, 32, and 33 by a first partition plate 21 and a second partition plate 22. The first partition plate 21 and the second partition plate 22 are each provided with a sieve section (details of which will be described later). Hereinafter, when there is no need to distinguish between the first partition plate 21 and the second partition plate 22, they will be collectively referred to as "partition plates 21, 22."

[0025] The partition plates 21 and 22 have a substantially rectangular shape. There are no limitations on the shape of the partition plates 21 and 22, but considering the weighing of the classified powder or granular material, it is preferable that the vertical cross-sectional area of ​​the compartments 31 to 33 is constant throughout the compartment. For example, it is preferable that the compartments 31 to 33 are rectangular, and accordingly, it is preferable that the partition plates 21 and 22 are rectangular. It is not necessary for the height H1 of compartment 31, the height H2 of compartment 32, and the height H3 of compartment 33 to be the same, but considering the weighing of the classified powder or granular material, it is preferable that H1 = H2 = H3.

[0026] In this embodiment, the box 10 is divided into three compartments 31-33 by two partition plates 21 and 22, but the number of compartments is not limited to three. The number of compartments necessary for checking the particle size distribution can be appropriately set. For example, as shown in cross-sectional view 204, intermediate partition members 16A and 16B, 17A and 17B, and 18A and 18B defining heights H1, H2, and H3 can be provided at both horizontal ends of the interior of the box 10. That is, the compartments 31-33 can be defined by setting the width of the first intermediate partition member to H1, the width of the second intermediate partition member to H2, and the width of the third intermediate partition member to H3. By using such intermediate partition members, it is possible to set any number of compartments in a single box 10. The intermediate partition members 16-18 are preferably made of an elastic material such as rubber or resin, or may be made of different elastic materials. The intermediate partitions 16-18 are arranged at opposite ends of the compartments 31-33 (opposing ends in the left-right direction in the cross-sectional view 204 of FIG. 2), and serve to support the partition plates 21 and 22 so that they do not move within the box 10 and to maintain predetermined height distances H1, H2, and H3. Furthermore, the intermediate partitions 16-18 also function as seals to prevent shots from moving from the left and right end faces of the compartments 31, 32, and 33 to adjacent compartments. Therefore, the intermediate partitions 16-18 may be arranged around the entire side surfaces of the compartments 31-33. In this case, the intermediate partitions 16-18 may be transparent members to enable measurement of the shot volume using a scale plate (described below).

[0027] The partition plates 21 and 22 are equipped with sieve sections that classify powder and granular material. That is, a sieve section is disposed in at least a portion of each of the partition plates 21 and 22. The sieve openings of the partition plate 21 are coarser than the sieve openings of the partition plate 22. That is, the box 10 has a structure in which two sieve sections with different opening sizes are disposed one above the other. When a user puts powder and granular material into the compartments 31 through the inlet 15 of the box 10 and performs a classification operation, the powder and granular material is classified, with the coarsest particles remaining in the top compartment 31, the next coarsest particles remaining in the next compartment 32, and the finest particles falling and piling up in the bottom compartment 33.

[0028] The box 10 is provided with a measuring unit that measures the powder or granular material in each compartment 31-33. In this embodiment, the measuring unit is configured to be able to read the bulk or weight of the powder or granular material in each compartment. The bulk is the volume of the powder or granular material, including the space between the powder or granular material. The method of indicating the bulk or weight is not limited. In the embodiment shown in FIG. 2, as shown in a perspective view 201, a scale plate 40 is provided as a measuring unit in an end region of the side surface 14A of the box 10. The scale plate 40 is one form of a measuring unit described in the claims. In this embodiment, the scale plate 40 is a transparent plate disposed in an opening provided in at least a portion of the side surface of the box 10, and is a scale plate with graduations indicating the bulk. The scale plate 40 is made of, for example, a transparent synthetic resin or glass. The method of using the scale plate 40 will be described later. The box 10 can classify powder or granular material introduced inside by swinging it about the swing axes 20A and 20B.

[0029] Next, the holding frame 50 will be described with reference to the drawings. Fig. 3 shows a perspective view 301 of the holding frame 50, a front view 302 seen from direction A of the perspective view 301, a side view 303 seen from direction B of the perspective view 301, and an enlarged view 304 of the mounting portion 55A. As shown in the perspective view 301, the holding frame 50 is configured to include a bottom surface 52 and two side surfaces 51A and 51B.

[0030] Two side surfaces 51A and 51B of the holding frame 50 are provided with a pair of mounting portions 55A and 55B on which the swing shaft (swing support portion) 20 of the box body 10 is mounted. The mounting portions 55A and 55B are formed by cutting out the side surfaces 51A and 51B from the top to near the center. As shown in the enlarged view 304, the mounting portion 55A is provided with mounting grooves 551A, 552A, and 553A on which the swing shaft 20A of the box body 10 is mounted. Similarly, the mounting portion 55B is provided with mounting grooves 551B, 552B, and 553B (not shown) on which the swing shaft 20B of the box body 10 is mounted. The mounting grooves 551A, 552A, and 553A are each at a different height from the bottom surface 52 of the holding frame 50. The heights of the mounting grooves 551B, 552B, and 553B from the bottom surface 52 are approximately the same as the heights of the mounting grooves 551A, 552A, and 553A from the bottom surface 52. The tilt of the swing of the box body 10 can be adjusted depending on whether the swing shaft 20 of the box body 10 is placed in the mounting groove 551, 552, or 553.

[0031] The swing shaft 20 of the box body 10 and the mounting portion 55 of the holding frame 50 form a pair to support or hold the box body 10 in a swingable manner. This combination is not limited to the configuration described above. For example, the swing shaft 20 may be replaced with a shaft hole provided on the side of the box body 10, and the mounting portion 55 may be replaced with a swing shaft that can be inserted into the shaft hole, which would also enable the box body 10 to be supported or held in a swingable manner. Alternatively, the swing shaft 20 may be a swingable suspension hook, and the mounting portion 55 may be a protrusion on which the suspension hook is hung. This configuration also allows the box body 10 to be swung with a simple structure.

[0032] A handle (not shown) or the like may be attached to either the cover 13 of the outlet of the box 10 or the opposing side surfaces 14A, 14B to facilitate manual movement of the box up and down. The position of the handle is not limited.

[0033] Next, the partition plates 21 and 22 will be described in detail. Fig. 4 shows a plan view 401 of a first configuration example of the partition plate 21, a plan view 402 of a second configuration example, and a plan view 403 of a third configuration example. The partition plates 21 and 22 separate the interior of the box body 10 so that the powder and granular material does not move to adjacent compartments, except for the sieve section where the sieve is arranged.

[0034] As shown in plan view 401, the partition plate 21, which is a first configuration example, has a structure in which a sieve portion 211 is provided on a rectangular plate-shaped member (plate material). The material of the plate material is not limited, but metal, synthetic resin, etc. can be used. The sieve portion 211 has a net (mesh) formed by plain weave of wire. It is preferable that the sieve portion 211 is replaceable. In the first configuration example, the density of the wires extending in the longitudinal direction (long side direction) (wires extending left and right in the figure) is the same as the density of the wires extending in the width direction (wires extending up and down in the figure).

[0035] Note that there is an area on the left end side of the partition plate 21, indicated by 401 in FIG. 4, where the sieve section 211 is not formed. The reason for this is to prevent the powder and granular material from moving into an adjacent compartment through the sieve section 211 when the powder and granular material is piled toward the left side during weighing, as will be described later. In other words, the area on the left end side of the partition plate 21 where the sieve section 211 is not formed is provided so that the powder and granular material does not move into an adjacent compartment through the opening of the sieve section 211 when piled toward the left end side of the box body 10. The distance from the left end of the partition plate 21 to the area where the sieve section 211 is not formed is preferably greater than the maximum pile height of the powder and granular material expected when piled toward the left end side of the box body 10. Note that the partition plates 21 according to the second and third configuration examples described below also have an area on the left end side where the sieve section is not formed.

[0036] A plan view 402 showing a second configuration example shows a sieve unit 212 in which the mesh size of the wires differs in the longitudinal and width directions. As shown in plan view 402, the number density of the wires extending in the longitudinal direction is greater than the number density of the wires extending in the width direction. This is because the powder and granular material slide or roll in the longitudinal direction during classification. The wires extending in the width direction impede the movement of the powder and granular material sliding or rolling in the longitudinal direction. Therefore, a smaller number density of the wires extending in the width direction impedes the movement of the powder and granular material to a lesser extent. This results in higher classification efficiency.

[0037] Plan view 403 showing a third configuration example shows a partition plate 21 including multiple elongated openings in the long-side direction of the rectangular plate-shaped member. As shown in plan view 403, partition plate 21 of the third configuration example includes elongated openings 213 in the long-side direction and elongated openings 214 in the width direction, which function as a sieve section. A plate-shaped member having such openings is also called a plate-shaped sieve. The openings 213, 214 (mesh) of the sieve section are holes punched into the plate material approximately perpendicular to its surface. There are no burrs around the openings 213, 214, and they are shaped to allow the powder or granular material to easily pass through. The openings 213, 214 are positioned in the flow direction of the powder or granular material and in a direction intersecting the flow so that the powder or granular material can easily pass through and fall.

[0038] In the third configuration example, for example, eight openings 213 of the same length in the longitudinal direction are arranged at equal intervals in the width direction. These eight openings 213 are arranged in four rows in the longitudinal direction. For example, openings 214 are arranged at both ends and the center in the longitudinal direction of the four-row arrangement of openings 213. Two openings 214 provided at both ends of the arrangement of openings 213 are arranged in series in the width direction. Five openings 214 provided in the center of the arrangement of openings 213 are arranged in two rows with their positions shifted alternately. The openings 214 mainly function to reduce the flow speed of the powder or granular material.

[0039] Another advantage of plate-shaped sieves is that they do not impede the movement of powder and granular material as much as wire mesh. With wire mesh, the wires form convex sections that impede the movement of powder and granular material, but plate-shaped sieves have no such convex sections. Plate-shaped sieves also have the advantage of being less likely to clog than mesh sieves because the openings have right-angled edges. Furthermore, by having elongated openings 213 in the longitudinal direction, they impede the movement of powder and granular material to a lesser extent. Conversely to openings 213, elongated openings 214 in the width direction serve to impede the movement of powder and granular material. If the sliding or rolling speed of powder and granular material becomes too fast, the classification efficiency decreases, but openings 214 serve to slow down the speed of the powder and granular material.

[0040] The configuration and mesh of the mesh sieve shown in FIG. 4, or the size and arrangement of the openings of the plate sieve, can be selected appropriately depending on the type of shot to be classified (shape, material, particle size range, etc.) to prevent clogging and improve classification efficiency.

[0041] Suitable sieves for this embodiment include mesh sieves using welded wire mesh, plain woven wire mesh, etc., and plate sieves, regardless of type and material. However, plate sieves are particularly durable and suitable for a wide variety of powders and granular materials, regardless of the type, shape, or particle size range of the powder or granular material. Plate sieves are particularly suitable for particles with large diameters of 0.5 mm or more, or particles with roughly spherical or polygonal shapes. On the other hand, mesh sieves such as welded wire mesh or plain woven wire mesh are weaker than plate sieves, but have the advantages of being readily available and inexpensive. Materials for mesh sieves include stainless steel, hard steel, and mild steel. These are suitable for use with round samples with fine particle sizes of less than 0.5 mm. When using wire mesh, it is preferable to secure the sieve section to the frame of the partition plate 21 (excluding the sieve section) with a void ratio equal to or greater than that of the plate sieve.

[0042] The partition plates 21 and 22 configured as described above can be appropriately selected and used optimally depending on the shape, size, material, etc. of the powder or granular material. The configuration of the partition plates 21 and 22 is not limited as long as the mesh of the first partition plate 21 is coarser than that of the second partition plate 22.

[0043] Next, the scale plate 40 will be described. FIG. 5 shows a front view 501 and an enlarged view 502 of the scale plate 40, illustrating a method for weighing the powder or granular material classified into each of the compartments 31 to 33. The front view 501 shows the box 10 placed with the scale plate 40 facing downwards. The enlarged view 502 shows an example of the scale provided on the scale plate 40. When the box 10 is placed as shown in the front view 501, the powder or granular material accumulates at the bottom of each of the compartments 31 to 33, as indicated by the hatched areas. The operator reads the height of the powder or granular material accumulated at the end of each of the compartments 31 to 33 using the scale plate 40. The piled height indicates the bulk volume of the powder or granular material. However, when weighing the shot to be used in the shot processing, the information required is not the bulk volume itself, but the ratio of the bulk volumes of the powder or granular material classified into each of the compartments 31 to 33. That is, when measuring the shot, it is sufficient to determine whether the particle size distribution of the shot falls within a predetermined ratio range that serves as a reference.

[0044] The graduations on the scale plate 40 are preferably uniform, as shown in the enlarged view 502. This is because it is easy for an operator to read the graduations and the particle size distribution is easy to understand visually. For this reason, it is preferable that the compartments 31 to 33 have the same cross-sectional area throughout. This is why, in this embodiment, the box 10 has a rectangular parallelepiped shape, and each of the compartments 31 to 33 also has a rectangular parallelepiped shape.

[0045] The scale plate 40 is preferably replaceable. The amount of powder or granular material accumulated in each of the compartments 31-33 varies depending on the shape or size of the powder or granular material to be classified or the type of sieve used. Therefore, it is preferable to configure the scale plate 40 so that it can be selected and replaced according to the expected particle size distribution. The arrangement of the scale lines on the scale plate 40 is preferably determined by calculation based on the apparent specific gravity of the powder or granular material to be measured within a predetermined particle size range. By preparing a scale plate 40 with such determined scale lines in advance for each powder or granular material to be measured and replacing the scale plate 40 according to the powder or granular material to be measured, accurate measurements can be achieved. This configuration also has the advantage that only the scale plate 40 needs to be replaced according to the powder or granular material to be measured, eliminating the need to replace the particle size distribution measuring device 1.

[0046] Note that, although the scale plate 40 is one form of the measuring unit, the measuring unit is not limited to the scale plate 40. For example, a weight sensor (not shown) serving as a measuring unit may be disposed on the bottom surface of each of the compartments 31 to 33 where the powder or granular material accumulates when the box 10 is turned on its side, and a display unit that digitally displays the weight of the powder or granular material classified for each compartment may be disposed (the position of the display unit is not limited). Alternatively, a distance sensor (not shown) serving as a measuring unit may be disposed above each of the compartments 31 to 33 where the powder or granular material accumulates when the box 10 is placed upright, and a display unit that digitally displays the height of the powder or granular material classified for each compartment may be disposed (the position of the display unit is not limited).

[0047] Next, a classification method using the particle size distribution measuring device 1 will be described with reference to the drawings. Fig. 6 is a diagram showing how the box 10 placed on the holding frame 50 is swung around the swing axis 20. A front view 601 shows the arrangement when no operation is performed on the box 10. Because the swing axis 20 is located to the right of the center of gravity of the box 10, when no operation is performed, the left side of the box 10 tilts downward and the left end abuts on the floor surface F. The angle of inclination formed between the floor surface F and the bottom surface of the box 10 at this time is defined as α.

[0048] A front view 602 shows a state in which, for example, a worker has lifted the left end of the box 10 with his / her hand and made it approximately horizontal. A front view 603 shows a state in which, for example, a worker has further lifted the left end of the box 10 and swung (rotated) it, causing the right end of the box 10 to abut against the floor surface F. The inclination angle between the floor surface F and the bottom surface of the box 10 at this time is defined as β. α and β are absolute values ​​of the inclination angle of the box 10 when the horizontal direction is defined as 0 degrees.

[0049] The preferred inclination angles α and β of the box 10 vary depending on the shape of the powder and the rolling friction coefficient, but are generally 15 to 50 degrees from the horizontal, and the angle at which the powder moves on the sieve is preferably 20 to 35 degrees.

[0050] Next, an example of a classification method (classification operation) using the particle size distribution measuring device 1 will be described with reference to Fig. 7. Fig. 7 is a flowchart showing a particle size distribution measuring method S1 of powder or granular material performed by an operator. First, as shown in step S11, the operator removes the lid 11 and loads a predetermined amount of powder or granular material into the box 10 through the loading port 15. The powder or granular material is loaded into the uppermost compartment 31. Next, the operator places the box 10 with the powder or granular material loaded on the holding frame 50 and arranges it in the state shown in front view 601.

[0051] Next, as shown in step S12, the worker rocks the box 10 to perform a classification operation to classify the powder and granular material. Specifically, the worker rocks the box 10 from the state shown in front view 601 to the state shown in front view 603. As a result, the powder and granular material in compartment 31 slides or rolls from the left side to the right side of the box 10. At this time, powder and granular material smaller than the mesh size of the sieve section of the first partition plate 21 falls into compartment 32. Furthermore, of the powder and granular material that fell into compartment 32, powder and granular material smaller than the mesh size of the sieve section of the second partition plate 22 falls into compartment 33. Next, the worker rocks the box 10 again to the state shown in front view 601 to return the box 10. At this time, the powder and granular material in compartments 31 and 32 are classified by the first partition plate 21 and the second partition plate 22, respectively. Furthermore, the worker rocks the box 10 again to the position shown in front view 603. The operator repeats this operation a predetermined number of times. In this way, by tilting the box 10 and sliding or rolling the powder or granular material on the sieve to classify it, the powder or granular material is classified into three sections.

[0052] Next, as shown in step S13, the worker collects the classified powder or granular material at the ends of the compartments 31 to 33. For example, the worker removes the box 10 from the holding frame 50 and places the box 10 upright so that the scale plate 40 is on the bottom side. This causes the powder or granular material to accumulate at the ends of the compartments 31 to 33 of the box 10.

[0053] Next, as shown in step S14, the worker weighs the powder or granular material in a state where it is collected at the end of the compartments 31 to 33. For example, the worker measures the bulk of the powder or granular material sorted into each compartment 31 to 33 using the scale plate 40. Before reading the scale, the worker may slightly shake the box 10 to smooth the top surface of the collected powder or granular material.

[0054] Next, the operator may compare the distribution of the weighed powder or granular material with a reference distribution, as shown in step S15. For example, if the powder or granular material is shot to be used in shot processing, if the difference between the particle size distribution of the shot and a predetermined reference distribution exceeds a predetermined range, it is necessary to perform work such as adding new shot or replacing a portion of the shot with new ones. Therefore, by comparing the reference particle size distribution with the measured particle size distribution, it is possible to determine whether or not some work is necessary.

[0055] In the particle size distribution measuring method S1 using the particle size distribution measuring device 1 described above, an operator shakes the box 10 to classify powder or granular material. If the shaking method differs between operators, the particle size distribution measurement results may differ depending on the operator. However, with the particle size distribution measuring device 1 described above, the powder or granular material is shaken while placed on the holding frame 50, so the shaking range is specified. Therefore, by determining the number of shakes and the number of shakes per time, the classification operation conditions can be standardized. Therefore, the same results can be obtained even if the operator changes.

[0056] As described above, the mounting portion 55 of the holding frame 50 has three mounting grooves 551, 552, and 553 at different heights from the bottom surface 52. This configuration allows the rocking angle of the box body 10 to be changed. The rocking angle is the angle at which the box body is rocked. As an example, the rocking angle can be defined as the angle that the box body 10 forms with respect to the floor surface F when the box body 10 is rocked until the bottom edge of the box body 10 abuts against the floor surface F. FIG. 8 is a diagram showing how the rocking angle β of the box body 10 changes depending on the position of the mounting groove in which the rocking shaft 20 is placed. A front view 801 shows a rocking angle β1 of the box body 10 when the rocking shaft 20A is placed in the mounting groove 551A. A front view 802 shows a rocking angle β3 of the box body 10 when the rocking shaft 20A is placed in the mounting groove 553A. As shown in the figure, when the oscillating shaft 20A is placed in the mounting groove 551A, which is located relatively high from the bottom surface 52, the oscillation angle β1 of the box body 10 is relatively large. Conversely, when the oscillating shaft 20A is placed in the mounting groove 553A, which is located relatively low from the bottom surface 52, the oscillation angle β3 of the box body 10 is relatively small. When the oscillating shaft 20A is placed in the mounting groove 552A, the oscillation angle β2 of the box body 10 is smaller than β1 and larger than β3. In this way, the oscillation angle β can be changed depending on the properties of the powder or granular material, the type of sieve, etc., to set optimal classification conditions.

[0057] The rocking angle of the box 10 is an important parameter for classifying powder and granular materials using a sieve. The rocking angle of the box 10 is preferably set based on the rolling coefficient of the powder and granular materials. Multiple preferable rocking angles are determined based on the rolling coefficient, which is determined based on the shape, size, particle size range, material, etc. of the powder and granular materials, and the mounting groove 55 is designed to achieve these rocking angles. Then, the mounting groove 55 is selected so that the appropriate rocking angle is achieved depending on the powder and granular materials to be measured.

[0058] According to the particle size distribution measuring device 1 and particle size distribution measuring method S1 described above, an operator can easily measure the particle size distribution of powder or granular material, for example, shot used in shot processing, using the particle size distribution measuring device 1 with a simple device configuration. In other words, the particle size distribution measuring device 1 has the advantages of being simple in structure, measuring the particle size distribution after classification by sieving in a very short time, and being able to immediately determine whether the particle size distribution state is suitable or unsuitable, or whether adjustment is necessary.

[0059] [Embodiment 2] Another embodiment of the present invention will be described below. This embodiment relates to a method for managing the particle size distribution of shots used in shot processing to adjust the surface roughness of a processing object to within a specified range, and relates to a method for managing the particle size distribution of shots used in shot processing to adjust the surface roughness of a processing object to within a specified range, and relates to a method for managing the particle size distribution of shots used in shot processing to periodically measure the particle size distribution of shots using the particle size distribution measuring device and the particle size distribution measuring method described above, thereby maintaining the quality of the shot-treated surface of the processing object.

[0060] As mentioned above, the shot used in the shot treatment includes scale powder, sand, or finely divided shot, etc., removed from the object to be treated. Hereinafter, "scale powder, sand, or finely divided shot, etc., removed from the object to be treated" will be referred to as "foreign matter." These foreign matters are separated and removed using a separator that utilizes airflow, and the remaining shot is reused in the shot treatment. While a vibrating screen or other device could be used to remove the foreign matter, the large amount of shot containing foreign matter would require a significantly larger screen, making it uneconomical. Therefore, a separator that utilizes airflow, which is inexpensive and compact, is generally used.

[0061] When using a separator that utilizes airflow, proper airflow speed and airflow volume control are necessary to properly remove foreign matter from the shot. Furthermore, it is also necessary to maintain a uniform flow of the shot / foreign matter mixture so that it is in stable contact with the airflow. The purpose of separator management is to remove foreign matter that has become mixed into the shot. Therefore, an increase in the proportion of foreign matter may indicate not only deterioration of the shot but also a decline in the separator's separation capabilities. In other words, measuring the particle size distribution of the powder and granular material, including the shot, can be used to determine whether the separator's airflow volume and other parameters are being properly managed.

[0062] For example, if the particle size distribution of the powder or granular material deviates toward the finer side compared to the standard distribution even though a new shot should be added and the particle size distribution is maintained appropriately, the air volume of the separator may be reduced. Therefore, it is necessary to check whether the air volume of the separator is appropriate. If the air volume is reduced, it is possible that the dust collector filter connected to the separator via the exhaust duct piping is clogged, or that the blower is malfunctioning, or that the exhaust duct piping has holes, etc., and appropriate measures can be taken. Alternatively, the air volume setting for removing unwanted fine particles may be inappropriate. In this case, it is possible to increase the air volume and check whether the particle size distribution returns to the standard distribution.

[0063] As described above, measuring the particle size distribution of shot used in shot blasting can determine whether the separation device's air volume settings and powder flow are appropriate, as well as whether the dust collector and exhaust duct piping are properly maintained. By managing the separation device and its peripheral equipment in this way, the quality of the shot-treated surface of the object being treated can be maintained. The above-mentioned particle size distribution measurement is preferably performed once or twice per 8 hours of operation for general shot blasting processes for oxide scale, rust removal, and sand removal. However, for blasting machines that adjust the surface roughness of treated steel materials within specifications during shot blasting, it is preferable to measure the distribution more frequently than the aforementioned interval.

[0064] [Additional Notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0065] 1...particle size distribution measuring device, 10...box body, 11...lid part, 12...grip, 13...removal port, 14...side, 15...feed port, 16, 17, 18...intermediate partition material, 20...oscillating axis (oscillating support part), 21...first partition plate, 22...second partition plate, 31, 32, 33...compartment, 40...scale plate (measuring part), 50...holding frame body, 51...side, 52...bottom, 55...placing part, 551, 552, 553...placing groove,

Claims

1. A particle size distribution measuring device for measuring the particle size distribution of shots used in shot processing, a box body whose interior is divided into a plurality of compartments by partition plates including a sieve for classification; a swing support portion provided on the box body to swingably support the box body; a measuring unit provided in the box body for measuring the shots in each compartment; the swing support portion is a pair of swing shafts provided on two opposing side surfaces of the box body, The apparatus further includes a holding frame having a pair of mounting portions on which the swing shaft is mounted. Particle size distribution measuring device.

2. The particle size distribution measuring device according to claim 1 , wherein the measuring unit is configured to be able to read the volume or weight of the shot in each compartment.

3. 3. The particle size distribution measuring device according to claim 2, wherein the measuring unit is a transparent plate disposed in an opening formed in at least a part of a side surface of the box body and having a scale for measuring the bulk height of the shot.

4. 4. The particle size distribution measuring device according to claim 3, wherein the scale plate is attached so as to be replaceable.

5. 5. The particle size distribution measuring device according to claim 1, wherein the partition plate is a plate-like sieve having a plurality of elongated openings in the long side direction of a rectangular plate-like member.

6. The particle size distribution measuring device according to claim 1 , wherein the mounting portion includes a plurality of mounting grooves having different heights from the bottom surface of the holding frame.

7. a step of introducing shot to be used in the shot processing into the uppermost compartment of a box whose interior is divided into a plurality of compartments by partition plates including a sieve for classification; a classification step of classifying the shots by shaking the box; a collecting step of collecting the classified shot at an end of the compartment; a measuring step of measuring the shots while they are collected at the end of the compartment; Including, The classification step is a step of inclining the box and sliding or rolling the shot on the sieve to classify it. Method for measuring shot particle size distribution.

8. 8. The particle size distribution measuring method according to claim 7, wherein the accumulation step is a step of placing the box body upright, and the measuring step is a step of measuring a height of the shots accumulated at an end of the compartment.

9. The particle size distribution measuring method according to claim 7 or 8, further comprising a step of comparing the distribution result of the shots measured in the measuring step with a reference distribution.

10. A method for controlling the particle size distribution of shot used in shot processing for adjusting the surface roughness of a processing object to a specified value, comprising: Using the particle size distribution measuring device according to claim 1, A particle size distribution management method, comprising: periodically measuring the particle size distribution of the shot using the particle size distribution measurement method according to claim 7, thereby maintaining the quality of the shot-treated surface of the processing object.

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