CN101374635A

CN101374635A - Method and device for estimating projection condition information using projection device

Info

Publication number: CN101374635A
Application number: CNA2006800529447A
Authority: CN
Inventors: 岩田恭一; 牧野泰育
Original assignee: Sintokogio Ltd
Current assignee: Sintokogio Ltd
Priority date: 2005-12-20
Filing date: 2006-12-20
Publication date: 2009-02-25
Anticipated expiration: 2026-12-20
Also published as: CN101374635B; JP4164835B2; JP2007167979A

Abstract

A method of estimating information on the projection states of projection elements (P) by using an analysis model in which discharged projection elements (P) repeatedly collided with rotation blades (13) in a projection machine having rotating blades (13). The method comprises the step of determining initial conditions including information on the size and rotation of blades (13), discharging information on the projection elements (P), and information on projection elements with respect to the blades (13), the step of storing the initial conditions, a computing step of computing the position of each projection element (P), and its velocity and direction after collision with a blade (13) based on the initial conditions, and the step of estimating information on projection state based on the computation results.

Description

Method and device for estimating projection condition information by using projection device

Technical Field

Generally, the present invention relates to a method of estimating projection condition information of a projected abrasive grain using a projection apparatus and an apparatus therefor. And more particularly, to a method and apparatus for estimating projection condition information without trial-use of projection apparatus components.

Background

In a surface treatment apparatus such as a shot blasting apparatus, an optimum projection condition for projecting abrasive grains is preferably set by a projection apparatus according to the shape of a workpiece, the region of a surface to be treated, and the like. In this case, the abrasive grain projection condition includes a projection area or a projection distribution, and also includes a projection number and a projection speed of the projected abrasive grains. To achieve this object, Japanese laid-open patent No.1996-323629 (Prior Art 1), assigned to the assignee of the present application, discloses a method and apparatus for adjusting the projection distribution according to the article to be processed while changing the number of projected abrasive grains and the projection speed according to the article to be processed.

Another prior art is disclosed in Japanese laid-open patent No.1989-264773 (prior art 2), which discloses a shot peening apparatus. Which defines the range of projection of the abrasive particles by projecting the abrasive particles over an area larger than the surface to be treated and providing a lining layer called an aiming plate between the projecting device and the article to be treated.

Further, japanese patent No.2003-340721 (prior art 3), which was laid out earlier, discloses a device which realizes to maintain a constant projection direction without using a collimator plate by shortening the length of a blade so that abrasive grains are intensively distributed in a predetermined range.

However, in the technique disclosed in prior art 1, a centrifugal projection device is required for determining the projection distribution and the projection speed. Which actually projects abrasive grains onto the processed article and determines a projection distribution and an abrasive grain velocity based on the result of the actual projection. Therefore, it takes a certain time to obtain an accurate relationship between the optimal processing and the projection distribution. In the centrifugal projection apparatus, it is desirable to set an optimum projection distribution according to the object to be processed and the processing method in order to save energy and efficiently project. From this viewpoint, it is inconvenient because time is required to grasp the relationship between the optimum processing and the projection distribution.

Further, in the device of prior art 2, the aiming plate for defining the projection range is worn out by the collision of the abrasive grains, resulting in a change in the projection range of the device. Therefore, there is a possibility that the quality of the processed article is deteriorated, resulting in the necessity of frequent replacement of the collimation plate. Also, since the abrasive particles are reflected from the aiming plate and bounce off the inner wall of the projection chamber, the inner wall of the projection chamber also needs protection against abrasion.

In contrast, the apparatus of the prior art 3 is different in that although the length of the blade is greatly shortened in order to intensively distribute the abrasive grain projection within a predetermined range, the respective abrasive grains collide with each other at the position of the blade due to non-constant supply of the abrasive grains, so that the projection distribution is diffused. Therefore, when the supply of abrasive grains is unstable, it is easily affected. Further, since the abrasive grains may scatter to the outside of the impeller without colliding with the blades, the lower the impeller rotation speed is, the lower the processing efficiency may be. In addition, the change in the shape of the blade due to wear greatly affects the accuracy of the projection distribution, and thus the blade worn due to the collision of abrasive particles needs to be frequently replaced.

Accordingly, an object of the present invention is to provide a method for estimating projection condition information of a projected abrasive grain using a projection apparatus and an apparatus thereof for reducing operation costs and time required for grasping condition information on a state of projection of an abrasive grain, such as at least one of a projection distribution or a projection speed.

Disclosure of Invention

One aspect of the present invention provides a method of estimating projection state information of abrasive grains projected by a projection apparatus including a plurality of blades rotating at a high speed. The method comprises the following steps: the behavior of the abrasive grains projected on the blade by the projection device is analyzed to generate an analytical model, and then projection state information of the abrasive grains projected by the projection device is estimated using the analytical model.

The behavior of each abrasive particle includes contact with at least one other abrasive particle or one rotating blade.

Another aspect of the present invention provides a method of estimating projection state information of abrasive grains projected by a projection apparatus including a plurality of blades rotating at a high speed, and an opening through which the abrasive grains are projected toward a work. The method comprises the following steps: determining initial conditions including information on the size of the blade, the speed of rotation, the projection of the abrasive particles, the information on the abrasive particles associated with the blade; storing the initial conditions; calculating the position of each abrasive particle and the speed and direction after the abrasive particles collide with the blade based on the initial conditions; and estimating projection state information based on the calculation result.

The calculation results may be displayed.

In yet another aspect of the invention, an apparatus for estimating the state of a projection device including a plurality of blades rotating at high speed for projecting abrasive particles using a programmed computer is provided. The computer comprises a) input means for providing initial conditions to the computer, the initial conditions comprising information on the size of the blade, the speed of rotation, the projection of the abrasive particles, the information on the abrasive particles associated with the blade; b) calculating means for calculating the position of each abrasive grain, and the speed and direction after collision with the blade, based on the initial conditions; c) means for estimating projection state information based on the result of the calculation; d) and a means for displaying the estimated information.

In one embodiment of the invention, the computing means calculates a value of a contact force with which the abrasive particle collides with at least one other abrasive particle or one blade; then, based on the contact force and gravity acting on the abrasive grains, calculating the acceleration of the abrasive grains; then, based on the calculated acceleration, the velocity and position of the abrasive grain after a minute time can be obtained.

The computer may further include a storage medium in which a computing program executed by the computing device is stored.

In the calculating step of the present invention, the calculating method of the second aspect, and the apparatus of the third aspect, the velocities of the respective abrasive grains after the collision are expressed as relative velocities. The relative velocity is obtained from a velocity vector of the abrasive grain and a velocity vector of an impact point of the corresponding blade surface with which the abrasive grain collides, including a vertical component along the Y-axis and a horizontal component along the X-axis, wherein by setting a coefficient, a bounce is represented by using a coefficient of restitution for the vertical component of the relative velocity and a loss of velocity due to frictional resistance is represented by the horizontal component of the relative velocity; then, by adding them and calculating the velocity vector of the blade collision point, the velocity and direction after the abrasive particle collides with the corresponding blade can be calculated. In this case, the calculation step or the calculation means may calculate the distance that the abrasive grain and the corresponding blade move within the sampling time, and sequentially perform the calculation related to the collision of the abrasive grains satisfying the collision condition.

In the method and apparatus of still another aspect of the present invention, in order to adjust the shape of the abrasive grain projection distribution to a predetermined shape and in order to make the amount of change in the frequency of rebounding of each discharged abrasive grain from the blade equal to or smaller than a predetermined value, the size value of each blade, the range of the projection position of the abrasive grain projection opening, and the rotation speed of the blade are selected. The predetermined value is preferably 0.3.

The ratio of the outer diameter to the inner diameter of the vane is preferably in the range of 1.75 to 2.0, 2.5 to 2.9, 3.6 to 4.1.

In the above-described aspects of the present invention, the abrasive particle projection state information is at least one of an abrasive particle projection distribution or an abrasive particle projection speed. The projection device may be, for example, a centrifugal projection device.

The invention also provides a method for projecting the abrasive particles to the processed product by a programmed computer-controlled projection device and estimating the information of the projection state of the abrasive particles, wherein the projection device is provided with a plurality of blades rotating at high speed. The method comprises the following steps: a) inputting blade information, abrasive particle projection conditions, the coefficient of resilience of abrasive particles to the blade and the coefficient of frictional resistance of the abrasive particles into a computer;

b) the computer judges whether the input step is finished, if the input is finished, the computer calculates the position of each abrasive particle after each set sampling time based on the sampling time and the velocity vector of the abrasive particle;

c) the computer rotates the blades to update the angle of the blades;

d) the computer judges whether the abrasive particles impact the corresponding blade, if the computer judges that the abrasive particles impact the corresponding blade, the speed and the direction of the impacted abrasive particles are calculated to update the speed vector of the abrasive particles, and if the computer judges that no abrasive particles impact the corresponding blade, the speed vector is kept unchanged;

e) the computer judges whether the position of the blade is in the abrasive particle discharge range or not, if the position of the blade is in the abrasive particle discharge range, abrasive particles are discharged, and if the position of the blade is out of the abrasive particle discharge range, the abrasive particles are prevented from being discharged;

f) the computer judges whether the blade rotates to a preset position, if so, the speed vectors of the abrasive particles are summed up, and if not, the steps b) to f) are repeated;

g) the computer displays the calculation results of the summed projection distribution and projection speed.

The above and other objects and advantageous effects of the present invention will be further explained in the following embodiments with reference to the accompanying drawings.

Drawings

FIG. 1 is a schematic view of a projection device suitable for use in the present invention, i.e., a cross-sectional view of the main body portion of a centrifugal projection device;

FIG. 2 is a schematic representation of the behavior of abrasive particles on a blade;

FIG. 3 is a schematic velocity vector diagram before and after the impact of the abrasive particles with the blade;

FIG. 4 is a schematic representation of factors that make up initial conditions of an analytical model;

FIG. 5 is a velocity vector diagram after the impact of abrasive particles;

FIG. 6 is a flow chart of one embodiment of a method of the present invention;

FIG. 7 is a schematic diagram showing the calculation results of the embodiment of FIG. 6;

FIG. 8 is a schematic diagram of a calculated projected distribution E1 and an actual projected distribution E;

FIG. 9 is a schematic view showing the relationship between the blade outer diameter and the average projection speed of abrasive grains when the peripheral speed is constant;

FIG. 10 is a block diagram of an exemplary computer of an apparatus for performing the method of the present invention;

FIG. 11 is a flow chart of another embodiment of the method of the present invention;

FIG. 12 is a diagram illustrating a method of solving a contact force between abrasive grains in a mobile analytic model;

FIG. 13 is a schematic illustration of a display of the results of the calculations of the embodiment of FIG. 12;

FIG. 14 is a graph showing the relationship between the variation of the rebound frequency of the abrasive grains and the variation of the projection direction of the abrasive grains;

FIG. 15 is a graph showing the relationship between the average rebound frequency of the abrasive grains and the amount of change in the projection direction of the abrasive grains;

FIG. 16 is a schematic view of a projected distribution corresponding to different ranges of abrasive particle discharge positions;

FIG. 17 is a schematic view showing a relationship between a variation in the projection direction of abrasive grains and a variation in the range of the abrasive grain discharge position;

fig. 18 is a diagram showing a relationship between a ratio of an outer diameter to an inner diameter of a blade, a variation in a rebound frequency of abrasive grains, and a variation in a projection direction of abrasive grains.

Detailed Description

An embodiment of the present invention suitable for a centrifugal projection apparatus will be described below. The centrifugal projection device comprises an impeller with a plurality of blades and a cylindrical control frame arranged in the impeller. The abrasive grains are pushed by the impeller rotating at high speed to pass through the opening of the control frame and are projected onto the workpiece. However, the present invention is not limited to such a centrifugal projection device.

First, an initial experiment was conducted to investigate the behavior of abrasive particles freely released from the control frame of the centrifugal projection device on the rotating blade. In this initial experiment, pressure sensitive paper was used to confirm the behavior of the abrasive particles on the blade.

As shown in fig. 1, the centrifugal projection device used in the initial experiment included: a housing (impeller case) 2 provided on an upper wall 1 of a ceiling of a protection chamber of a main body of the projector apparatus; a driving device 3 located outside the first side wall 2a of the housing 2 and disposed on the upper wall 1; an impeller 4 disposed on the drive shaft 3a of the drive device 3. The centrifugal projection device further includes: a distributor 5 disposed in the inner peripheral space S of the impeller 4 coaxially with the drive shaft 3a for stirring abrasive grains; a cylindrical control frame 6 provided on the second side wall 2b, the side wall 2b being disposed opposite to the first side wall 2a of the housing 2 for limiting the projection direction of the abrasive grains; an inlet pipe 7 is provided on the second side wall 2b of the housing 2.

The impeller 4 is mounted on the drive shaft 3a by means of a bolt 11 by means of a hub 10. The impeller 4 includes: a first side plate 12a on the drive shaft 3a side of the drive device 3; a second side plate 12b, spaced from the first side plate 12a, close to the inlet duct 7; and further includes a plurality of vanes 13 radially mounted between the first side plate 12a and the second side plate 12 b.

The dispenser 5 is mounted on the first side plate 12a by bolts 14. The dispenser 5 is provided with openings (notches) 15 at equal intervals on its periphery. The number of openings 15 may be equal to, smaller than or larger than the number of vanes 13.

On the control frame 6, a cylindrical portion of the distal end 6a thereof has a quadrangular opening 17 for restricting the projection direction of the abrasive grains. The control frame 6 is mounted on the second side plate 2b side of the casing 2 to extend between the dispenser 5 and the blade 13.

Fig. 2 is a schematic view of the results of an initial test, i.e. the behaviour of the abrasive particles P on the blade. Since the pressure of the abrasive grains P on the blade is concentrated at two or three points, the behavior of the abrasive grains P on the blade can be assumed as a rebound phenomenon on the blade, rather than a sliding on the blade. That is, the abrasive grains P are supplied from the inlet pipe of the centrifugal projection device, stirred by the rotating distributor 5, and then discharged from the opening 17 of the control frame 6 to reach around the root of the rotating blade 13. Then, the abrasive grains P are accelerated so as to rebound on the blade 13 and be projected toward the distal end (outer periphery) of the blade 13.

That is, the analysis model of the projection distribution can be represented by an analysis model of the rebound phenomenon of the abrasive grain P.

Thus, as shown in FIG. 3, V₀Is the velocity vector, V, of the abrasive grain P₁Is the velocity vector of the abrasive particle P after leaving the point of impact on the blade surface. The velocity of the abrasive grains is decomposed into relative velocities (V) in the X-axis and Y-axis directions_0x，V_0y，V_1x，V_1y). Vertical component V_1yA rebound is represented by a rebound coefficient, a horizontal component V_1xRepresenting a loss of speed due to frictional resistance. Thus by setting their respective coefficients, one can obtainThe following two equations (1-1) and (1-2).

V_1y＝-e·V_0y ...(1-1)

V_1x＝(1-μ)·V_0x ...(1-2)

Wherein e is a coefficient of restitution and μ is a coefficient of frictional resistance.

The initial conditions of the analytical model of the projection profile may include, for example, information on the size and rotation of the blade (hereinafter referred to as "blade information") corresponding to various conditions of the actual apparatus, and information on the projection of the abrasive grains from the control frame. For example, factors such as the outer diameter, inner diameter, length, width, number, and rotational speed (rotational speed of the impeller) of the blades may be specified to be considered within the initial conditions. As shown in fig. 4, the range (angle α) of discharging the abrasive grains P from the opening 17 of the control frame 6, the direction of projecting the abrasive grains, the initial velocity, and the variation of the ranges thereof may be considered as the initial conditions. The discharge range of the abrasive grains P corresponds to the discharge range thereof from the control frame 6. The range may be represented by an angle and is determined based on the shape of the opening 17 and the shape of the dispenser 5 (not shown in fig. 4). The range changes correspond to the distribution range of the projection direction and the initial velocity of the abrasive grains P from the control box 6. Since the variation of the distribution range is based on the shape of the opening 17 of the control frame 6 and the shape of the dispenser 5, it may be distributed in a rectangular shape, the probability magnitude is kept constant within the variation range, or it may be distributed normally by providing the standard deviation as the variation range. In order to determine the coefficient of restitution and the coefficient of frictional resistance of the analytical model, the actual coefficient of restitution can be obtained by using the real abrasive grain P and the blade 13 and calculating the measurement result of the amount of restitution of the abrasive grain P on the blade 13. Further, by an actual projection experiment, the measurement results of the actual projection distribution and the projection velocity are compared with the calculation results of the projection distribution, and an appropriate combination is selected and set.

In the analytical model, under the above initial conditions and assuming that each blade 13 is point-symmetric, each blade 13 accelerating abrasive grains is calculated. Information including the projection direction, position, and velocity is given to each abrasive particle P for calculating the distance that the abrasive particle P and the blade 13 move within the sampling time, which is preferably 100 μ S or less in view of the accuracy of the calculation. Calculations relating to collision of the abrasive grains P satisfying the collision condition are sequentially performed. The position of the abrasive particle P may be represented by polar coordinates (ra, θ a). When the angle θ b on the blade surface corresponding to the blade radius ra is larger than the angle θ a of each abrasive grain P, collision occurs. Then, equations (1-1) and (1-2) respectively based on the vertical and horizontal components of the blade surface can be derived. As shown in fig. 5, the final velocity vector of the abrasive grain at the collision point on the blade 13 (actual velocity vector of the abrasive grain) is the sum of the velocity vector of the collision point on the blade 13 and the relative velocity vector of the abrasive grain. The velocity and direction of the abrasive grains P after colliding with the blade 13 are calculated again using the above-described final vector (calculation of collision is repeated). The analysis result of this calculation may be displayed on a touch screen of a device equipped with a general computer having a calculation function and a display function, or on a display screen such as a control panel, but the present invention is not limited thereto.

Fig. 6 is a flowchart showing an example of the projection state information estimation method of the present invention. FIG. 10 is a block diagram of a system that performs the method. The system 20 of FIG. 10 is a general-purpose computer, comprising: including an input device (input means) 22 such as a keyboard, mouse, etc., an internal or external data storage medium 24 for storing data, an internal or external program storage medium 26 for storing programs, a CPU (evaluation means) 28, a computing unit (computing means) 30 including an arithmetic processor for assisting the CPU28, and a display (display means) 32, all connected via an information bus 34. The display 32 may be a touch screen to double as an input device. A program for performing the method of the present invention, such as a computing program executed by the computing unit 30, is stored in the program storage medium 26.

Referring to the flowchart of fig. 6, a general-purpose computer 20 is used to perform an embodiment of the projection state information estimation method of the present invention.

(1) First, data of the outer diameter, the inner diameter, the number, and the rotational speed of the blades 13 are input to the data storage medium 24 of the computer 20 as blade information used in the projection distribution analysis model (step S1). The input value of step S1 may be, for example, 360mm in outer diameter, 135mm in inner diameter, 8 in the number of blades 13, and 3000rpm in rotation speed.

(2) The discharge range (angle), discharge direction, initial velocity, and their changes of the abrasive grains P are input to the data storage medium 24 as information of the discharge from the control box 6 (step S2). The input value of step S2 may be, for example, a discharge range of 35 °, a direction such that 90 ° is formed from the projection position to the rotation direction, which varies to ± 15 °, an initial velocity of 10m/S, which varies to ± 5 m/S.

(3) The coefficient of restitution and the coefficient of frictional resistance are input to the data storage medium 24 (step S3). The input values of step S3 may be, for example, a coefficient of restitution of 0.2 and a coefficient of frictional resistance of 0.6. The data in the steps S1, S2, S3 are inputted to the data storage medium 24 of the computer 20 through the input device 22.

(4) The CPU28 determines whether the input is completed (step S4).

(5) If the input in S4 is completed, the calculation unit 30 calculates the position of each abrasive particle after 80 μ S per sampling time based on the sampling time and the velocity vector (step S5). Specifically, assuming that the position of any abrasive grain at time t is (X, Y), the velocity vector (V) based on the abrasive grain is_x，V_y) The movement distance (Δ x, Δ y) of the abrasive grain after the sampling time Δ t is obtained as Δ x ═ V_x×Δt，Δy＝V_yX Δ t. Then, the position of the abrasive grain at time t + Δ t is (X + Δ X, Y + Δ Y).

(6) The CPU28 turns the blade 13 to update its angle (step S6).

(7) The CPU28 determines whether each abrasive particle P collides with the blade 13 (step S7).

(8) If it is determined in step S7 that a collision is generated, the calculation unit 30 calculates the velocity and direction of the colliding abrasive particles to update the velocity vector (step S8).

Specifically, the position (X, Y) of the abrasive grain P may be converted into polar coordinates (ra, θ a). If the angle θ b on the surface of the blade 13 corresponding to the radius ra is larger than the angle θ a of the abrasive grains, the collision is considered to occur. Equations (i) and (ii) above for the vertical and horizontal components, both with the blade surface as the reference plane, are then calculated. Adding them to the velocity vector of the point of impact on the blade 13 results in the actual velocity vector of the abrasive particles. The velocity and direction of the abrasive particles P after impact with the blade 13 can then be calculated.

If it is determined in step S7 that no collision has occurred, the velocity vector of the abrasive grains P is not updated.

(9) The CPU28 determines whether the position of the blade 13 is within the discharge range of the abrasive grains P (step S9).

(10) If it is determined in step S9 that the position of the blade 13 is within the discharge range of the abrasive particles P, the CPU28 causes the abrasive particles P to be discharged (step S10). The discharge of the abrasive grains P means that the abrasive grains P are agitated by the dispenser 5 and discharged from the opening 17 of the control frame 6 during the processing of the processed article, and then are continuously discharged to the blade 13.

The reason why it is necessary to determine whether or not the position of the blade 13 is within the discharge range of the abrasive grains P in step S9 is as follows: because, as described above, in order to calculate any one of the blades 13 that make up the impeller, the abrasive grains P should be prevented from being discharged when the position of the blade 13 (e.g., the position where the blade 13 is rotationally advanced to miss the opening 17 of the control frame 6) makes the discharged abrasive grains P unsuitable for analysis.

(11) If it is determined in step S9 that the position of the blade 13 is not within the discharge range of the abrasive grains P, the CPU28 displays the calculation result of the projected current state on the display 32 (step S11). Although the display depends on the computing power of the computer used, typically 100- "200 abrasive particles P are displayed in this step. Fig. 7 is a display example of the calculation result. The display of the initial conditions is omitted in this example.

(12) The CPU28 determines whether the position of the blade 13 has been rotated back to a predetermined position. If not, steps S5-S12 are repeated, and the position of each abrasive particle, the angle of the blade, and the velocity vector of the abrasive particle are sequentially calculated after the next sampling time (step S12).

(13) If it is determined at step S12 that the blade 13 has rotated to the predetermined position, the velocity vectors of the respective abrasive grains P are summed up (step S13).

(14) The calculation results of the summed projection distribution and projection speed are displayed (S14).

As shown in fig. 8, the calculated projected distribution E1 is very close to the actual projected distribution E.

The projection distribution and the projection speed of the abrasive grains P projected from the blade 13 are as follows. The direction of the velocity vector of each abrasive grain P is represented by an angle, and the projection distribution (probability of the number of abrasive grains projected per 1 °) is represented by a histogram. The projection velocity can be found by calculating the average of the magnitudes of the velocity vectors. The variation in projection speed can be obtained by calculating the standard deviation.

Next, a test was conducted to investigate the effect of the outer diameter of the blade 13 on the variation of the projection speed. As shown in fig. 9, the actual measured value is close to the calculated value (indicated by the dotted line).

In this embodiment, the abrasive particle projection state information may be estimated by the above-described movement analysis model. The information includes projection distribution, projection velocity, and variation in projection velocity. Therefore, various conditions necessary to obtain predetermined projection state information (such as the length, shape, number, and rotation speed of the rotary vanes, and the shape of the opening 17 of the control frame 6) can be determined by making necessary modifications to the initial conditions without actually trying them. In the related art, in order to obtain predetermined projection state information, experiments are repeated a plurality of times while changing design conditions of the blade and the control frame that may affect the projection state to reduce required design conditions. In contrast, the method and apparatus of the present invention reduces both the operating cost and time required to reduce the required design conditions since no trial runs are required for both the blade and control frame to determine the predetermined projection state information.

Referring to the flowchart of fig. 11, another embodiment of the projection state information estimation method of the present invention performed by using the general-purpose computer 20 will be described.

(1) First, data of the outer diameter, inner diameter, number, and rotation speed of the rotating blades 13 are input to the data storage medium 24 of the computer 20 as blade information of the projection distribution analysis model. The particle size and density of the discharged abrasive grains, the number of discharged abrasive grains, the discharge range (angle) of the abrasive grains P, the discharge direction of the abrasive grains, the initial velocity, and their changes are input to the data storage medium 24 as information of discharge from the control box 6. Further, the coefficient of restitution, coefficient of frictional resistance, is input to the data storage medium 24 (step S31). Step 31 is inputting data into the data storage medium 24 via the input device 22. The input values of the blades 13 may be, for example, 360mm in outer diameter, 135mm in inner diameter, 8 in number of blades 13, and 3000rpm in revolution speed. The input value of the abrasive grains P may be, for example, a grain size of 1mm in diameter and a density of 7850Kg/m³The number of discharged abrasive grains was 200kg/min, the discharge range was 35 °, the discharge direction was such that 90 ° was formed from the projection position to the rotation direction, the variation thereof may be ± 15 °, the initial velocity was 10m/s, and the variation thereof may be ± 5 m/s. The coefficient of restitution of the input may be, for example, 0.2 and the coefficient of frictional resistance may be, for example, 0.6. These input values are merely illustrative and the present invention is not limited thereto.

(2) Next, the CPU28 turns the vane 13 to the next position after a minute time (for example, one sampling time 80 μ S after the time t becomes 0) (steps S32, S33, and S34).

(3) Cpu28 then determines whether each abrasive particle collides with another movable object based on the calculation by calculation unit 30. If the CPU28 determines that a collision has occurred, the contact force acting on each abrasive grain is analyzed for all abrasive grains (step S35). The term "other movable objects" refers to the blade 13 and other abrasive particles. If the abrasive grain collides with another abrasive grain as another movable object, the force acting between any two abrasive grains i and j is calculated based on the distance between these abrasive grains, and whether or not the abrasive grain collides is determined. If the abrasive grain i collides with the abrasive grain j, based on the result of this determination, a vector directed from the center of the abrasive grain i to the center of the abrasive grain j is defined as a "normal vector", and a vector obtained by rotating the normal vector 90 ° clockwise is defined as a "tangential vector".

As shown in fig. 12, it is assumed that a virtual device is provided between two abrasive grains (discrete elements) i, j colliding with each other, along the normal direction and the tangential direction of the abrasive grains i, j, respectively, and the virtual device includes a spring and a buffer parallel to each other for calculating the contact force of the abrasive grain j to the abrasive grain i. The contact force, which is calculated by the calculation unit 30, can be synthesized by adding the contact force component in the normal direction to the contact force component in the tangential direction.

In step S35, first, the normal direction components of all the abrasive grain contact forces are calculated. The relative movement of the abrasive grains i and j in a minute time is represented by the following equation using the amount of increase in the elastic resistance and the spring constant of the elastic spring proportional to the amount of contact:

Δe_n＝k_nΔx_n ...(1)

wherein Δ e_n: the amount of increase in the elastic resistance is,

k_n: the spring constant of the elastic spring proportional to the amount of contact,

Δx_n: in a minute time, the abrasive grain i and the abrasive grain j are relatively displaced.

The subscript n denotes the component of the normal direction.

The viscous resistance is expressed by the following equation using the viscosity coefficient of the damper, which is proportional to the speed of the relative displacement,

Δd_n＝η_nΔx_n/Δt ...(2)

wherein, Δ d_n: the viscous resistance of the adhesive is reduced,

η_n: coefficient of viscosity of damper proportional to speed of relative displacement

At time t, the elastic resistance and the viscous resistance in the normal direction component of the force that the abrasive grain j acts on the abrasive grain i can be expressed by equations (3) and (4).

[e_n]_t＝[e_n]_t-Δt+Δe_n ...(3)

[d_n]_t＝Δd_n ...(4)

Wherein, [ e ]_n]_tAt time e of finger t_nThe value is obtained.

Therefore, the normal direction component of the contact force can be expressed by the following equation (5).

[f_n]_t＝[e_n]_t+[d_n]_t ...(5)

Wherein, [ f ]_n]t denotes the normal direction component of the contact force at time t.

Thus, at time t, by taking into account the contact forces from all the abrasive particles, the contact force acting on abrasive particle i can be calculated.

At the end of step S35, the tangential direction component of the contact force is calculated for all abrasive particles. The tangential direction component is similar to the normal direction component, the elastic resistance is proportional to the relative displacement, and the viscous resistance is proportional to the speed of the relative displacement. Therefore, it can be calculated by the following equation (6).

[f_t]_t＝[e_t]_t+[d_t]_t ...(6)

Wherein,f_tbeing the tangential component of the contact force,

e_tis the tangential component of the elastic resistance,

d_tis the tangential component of viscous drag.

Since there may be slippage when abrasive particle i and abrasive particle j are in contact, the Coulomb's rule for slippage is used.

In general, when the tangential direction component is larger than the normal direction component, the following equation holds:

[e_t]_t＝(μ₀[e_n]_t+f_coh)·sign([e_t]_t) ...(7)

[d_t]_t＝0 ...(8)

when the normal direction component is larger than the tangential direction component, the following equation holds:

[e_t]_t＝[e_t]_t-Δt+Δe_t ...(9)

[d_t]_t＝Δd_t ...(10)

in equations (7) to (10),

μ₀: coefficient of friction

f_coh: adhesion force

sign (Z) is the sign of variable Z.

Since the abrasive particles used in this embodiment are dry, the adhesion between the abrasive particles is negligible.

(4) In step S36, the equation of motion is analyzed based on the forces acting on the abrasive grain i and the abrasive grain j, i.e., the contact force and the gravity, and the expression equation (11) of the acceleration can be obtained, and further, in this step, similar analysis is performed for all the abrasive grains,

\overset{. .}{r} = f_{c} / m_{c} + g . . . (11)

wherein, r: position vector

m_c: the mass of the abrasive grains (obtainable from the size and density in the initial condition)

f_c: contact force

g: acceleration of gravity.

In addition, the angle of impact when in contact causes a turn around. The angular acceleration can be calculated from the following equation.

Wherein, omega is the angular acceleration,

T_cin order to contact the generated torque, the contact surface,

and I is inertia moment.

Based on the acceleration obtained by equation (11), the acceleration can be obtained by equations (13), (14) and (15) belowSpeed and position after a minute time. v. of₀And r₀Representing the velocity vector and the position vector at the current time.

Fig. 13 is a schematic view showing the calculation result.

Where v is the velocity vector and Δ t is the minute time.

(5) Then, it is determined whether or not the position of the blade 13 has rotated to a set position, for example, 270 ° from the starting position in the present embodiment (step S37). If it is determined that the rotation to the set position is not made, the steps S34 to S37 are repeated, and the angle of the blade after a minute time, the contact force acting on the abrasive grain, and the equation of motion are calculated. When it is determined that the blade revolution reaches the predetermined position, the calculation is ended.

(6) And displaying the calculation results of the aggregated projection distribution and the projection speed. The result is similar to fig. 8 of the first embodiment, and the calculated projection distribution E1 is close to the actual projection distribution E.

The projection distribution and the projection speed of the abrasive grains projected from the blade are as follows. The direction of the velocity vector of each abrasive grain is represented by an angle, and the projection distribution is represented by a histogram. The projection velocity can be found by calculating the average of the magnitudes of the velocity vectors. The variation in projection speed can be obtained by calculating the standard deviation.

Next, a test was conducted to investigate the effect of blade outer diameter on the variation of the projection speed. The test results are similar to those of fig. 9, with actual measured values being very close to calculated values (indicated by dashed lines).

The other movable objects in contact with each abrasive particle described in this embodiment are other abrasive particles. However, in the movement analysis model of the present invention, the projection distribution and the projection speed when each abrasive grain is in contact with the blade can also be calculated similarly. In this case, by replacing other movable objects in contact with the respective abrasive grains in the above-described method with blades, similar steps are performed to perform movement analysis of the abrasive grains. In addition, considering that each abrasive particle is contacted with other abrasive particles and contacted with the blade, the projection distribution and the projection speed can be calculated by using the mobile analysis model.

In another embodiment of the present invention, a method for adjusting a projection profile of abrasive particles to a predetermined shape is described. In order to numerically express the degree of spread of the projection distribution, the scattering direction of each abrasive grain is expressed by an angle. The standard deviation of the angle of the abrasive grain is set as the variation of the projection direction of the abrasive grain.

In this embodiment, the shape of the projection distribution of the abrasive grains may be adjusted so that the amount of change in the rebound frequency of the abrasive grains on the blade 13 is smaller than a predetermined value. In order to achieve the above object, the size of the blade 13, the range of the abrasive grain discharge position of the abrasive grain discharge opening, and the rotation speed of the blade 13 are set or combined. The shape of the abrasive grain projection distribution can also be adjusted using the analysis model of the collision between the abrasive grains and the rotating blade 13.

Fig. 14 shows the amount of change in the rebound frequency of the abrasive grains as a function of the amount of change in the projection direction of the abrasive grains. In this relation, the amount of change in the rebound frequency of the abrasive grain refers to the standard deviation of the rebound frequency of the abrasive grain. As can be seen from fig. 14, as the amount of change in the rebound frequency increases, the amount of change in the projection direction of the abrasive grains increases. That is, the angle of the projection direction of the abrasive grains is spread. Therefore, by adjusting the amount of change in the rebound frequency to a predetermined value, such as 0.3 or less, the projection angle can be made concentrated.

Fig. 15 shows the average rebound frequency value of the abrasive grain as a function of the amount of change in the projection direction of the abrasive grain. If the average rebound frequency value is less than 2, the amount of change in the abrasive grain discharge position on the control box 6 makes the projection angle extremely easy to spread, and thus the abrasive grains cannot be stably accelerated. As a result, the projection speed varies. Therefore, it is preferable that the average rebound frequency value is 2 or more. In order to change the amount of change in the rebound frequency and the average rebound frequency value, the outer diameter, inner diameter, and revolution speed of the blade 13 are changed in the calculation.

The bounce frequency has a great influence on the determination factors of the projection distribution and the velocity. Since each abrasive grain bounces on the blade 13 several times, the larger the number of bounces, the closer the abrasive grain projection direction is to the rotation direction of the blade 13, and can be sufficiently accelerated by collision. Conversely, the smaller the number of times of bounce, the more the direction of projection of the abrasive grains tends to be opposite to the direction of rotation of the blade 13, and sufficient acceleration cannot be obtained due to less collision. Therefore, mixing the abrasive particles with different bounce frequencies makes the projection direction of the abrasive particles different, resulting in divergent projection distribution. Therefore, by controlling the amount of change in the bounce frequency of each abrasive grain on the blade 13 to be less than or equal to a predetermined value, the abrasive grain projection distribution can be made concentrated. Conversely, if the bounce frequency variation is controlled to exceed a predetermined value, the abrasive particle projection profile may be caused to diverge.

Fig. 16 shows the analysis results of the projection distribution of the projection experiment when the range of the abrasive grain discharge position (discharge range) on the control frame 6 was 35 ° and 10 °. The conditions used in this experiment were such that the outer diameter of the blade 13 was 360mm, the inner diameter was 135mm, and the revolution speed was set at 3000 rpm. As a result, the smaller the range of the abrasive particle discharge position, the more concentrated the projection distribution.

In order to confirm the influence of the range, fig. 17 shows the amount of change in the abrasive particle projecting direction when the range of the abrasive particle discharge position is changed under the similar experimental conditions to fig. 16. Fig. 17 shows that the smaller the range of the abrasive grain discharge position, the smaller the amount of change in the abrasive grain projection direction, but if the range of the abrasive grain discharge position is too small, the greater the resistance of the opening 17 of the control frame 6. This reduces the maximum number of shots of the centrifugal projection device and makes the abrasive particles jammed in the control box 6 during operation. To avoid this problem, the abrasive grain discharge position is preferably in the range of 5 ° to 20 °. From experiments, it can be seen that this range is preferable regardless of the conditions used (e.g., the outer diameter, inner diameter, and rotational speed of the blades 13).

Fig. 18 shows the relationship between the ratio of the outer diameter to the inner diameter of the blade 13 and the amount of change in the projection direction of the abrasive grains and the amount of change in the rebound frequency of the abrasive grains. By changing the ratio of the outer diameter to the inner diameter of the blade 13, the amount of change in the rebound frequency and, therefore, the amount of change in the projection direction of the abrasive grains are significantly changed. Therefore, by setting the ratio of the outer diameter to the inner diameter of the blade 13 to a predetermined value, the projection distribution can be made concentrated. That is, by setting the ratio of the inner diameter to the outer diameter of the vane 13 to 1: 1.75 to 1: 2.0,1: 2.5 to 1: 2.9, or 1: 3.6 to 1: 4.1 in any of these ranges, the abrasive grain rebound frequency variation amount can be made 0.3 or less. Because these ranges bring the average bounce frequency value n close to an integer, the amount of change in the bounce frequency of the abrasive particle is reduced. These ranges correspond to average rebound frequency values n of 2, 3, and 4. When the size of the vane to be actually used is considered, although the case where n is an integer equal to or larger than 5 is not described in detail here, the same applies when the ratio of the inner diameter to the outer diameter of the vane 13 is close to n being an integer equal to or larger than 5. If the ratio of the inner diameter to the outer diameter of the blade 13 is set out of these ranges, the abrasive particle projection distribution diverges.

The experimental conditions of this example were such that the revolution speed was 3000rpm, the range of the abrasive grain discharge position was 10 °, and the ratio of the outer diameter to the inner diameter of the blade 13 was varied. The rotation speed is preferably 2500rpm or more. If the rotation speed is lower than 2500rpm, the acceleration of the abrasive grains is insufficient, and the initial velocity of the abrasive grains is affected, so that the moving distance of the abrasive grains before the abrasive grains collide with the blade 13 is increased, and the variation amount of the positions of the abrasive grains is increased. Therefore, the abrasive grains are easily dispersed on the blade 13. The amount of change in the projection direction of the abrasive grains is also increased. Similarly, the abrasive grain discharge position is preferably in the range of 5 ° to 20 °.

The above-described embodiments are merely illustrative of the present invention and are not intended to limit the present invention. For example, the projector device to which the present invention can be applied is not limited to the centrifugal projector device in the embodiment. The projection device to which the present invention can be applied may also be a device including: the abrasive grain supplying apparatus includes a rotating plate rotated by a driving motor, a plurality of blades mounted on the rotating plate, and a supply line having an outlet from which abrasive grains are supplied to the blades.

Although in the above-described embodiment, the projection distribution and the projection speed are obtained as the information on the projection state of the abrasive grains, only either one of them may be obtained if necessary.

Claims

1. A method for estimating projection state information of an abrasive grain projected by a projection apparatus including a plurality of blades rotating at a high speed, the method comprising the steps of:

analyzing the behavior of the abrasive particles projected on the blade by the projection device to generate an analytical model;

and estimating projection state information of the abrasive particles projected by the projection device by using the analytical model.

2. The method of claim 1, wherein the act of each abrasive particle comprises contacting at least one of another abrasive particle or a rotating blade.

3. The method according to claim 1, wherein the abrasive particle projection state information is at least one of a projection distribution of the abrasive particles and an abrasive particle projection speed.

4. The method of claim 1, wherein the projection device is a centrifugal projection device.

5. A method for estimating projection state information of abrasive grains projected by a projection device, the projection device comprising a plurality of blades rotating at a high speed and an opening for projecting the abrasive grains to a processed article through the blades, the method comprising the steps of:

determining initial conditions including information on the size and the swing speed of the blade, information on the projection of abrasive particles and information on abrasive particles associated with the blade;

storing the initial conditions;

calculating the position of each abrasive particle and the speed and direction of the abrasive particle after the abrasive particle collides with the blade based on initial conditions; then, the user can use the device to perform the operation,

and estimating the projection state information based on the calculation result.

6. The method according to claim 4, wherein the abrasive particle projection state information is at least one of a projection distribution of the abrasive particles and an abrasive particle projection speed.

7. The method of claim 5, wherein the calculating step comprises:

expressing the speed of each abrasive particle after collision in terms of relative speed, which is obtained from a speed vector of the abrasive particle and a speed vector of a collision point of the corresponding blade surface with which the abrasive particle collides, including a vertical component along the Y-axis and a horizontal component along the X-axis, wherein a bounce is expressed by setting a coefficient using a coefficient of restitution with respect to the vertical component of the speed, and the horizontal component of the relative speed expresses a speed loss due to frictional resistance; then, the user can use the device to perform the operation,

by adding them and calculating the velocity vector of the blade impact point, the velocity and direction of the abrasive particles after impacting the corresponding blade can be calculated.

8. The method of claim 5, wherein the calculating step comprises:

calculating a value of a contact force with which each abrasive particle collides with at least one of one blade or one other abrasive particle; then, the user can use the device to perform the operation,

and calculating the acceleration of the abrasive particles based on the acting force on the abrasive particles, wherein the acting force comprises the contact force and the gravity, and then obtaining the speed and the position of the abrasive particles after a minute time based on the calculated acceleration.

9. The method of claim 4, wherein the step of calculating the acceleration comprises calculating the distance traveled by the abrasive particles and the corresponding blade over the sample time, and performing calculations relating to the impact of abrasive particles meeting the impact condition in turn.

10. The method of claim 4, further comprising the step of displaying the results of the calculations.

11. The method of claim 4, wherein the projection device is a centrifugal projection device.

12. The method of claim 4, wherein the method further comprises the steps of: in order to make the variation amount of the frequency of rebounding of each discharged abrasive particle from the blade smaller than or equal to a predetermined value, the size value of the blade, the range of the projection position of the abrasive particle projection opening, and the rotation speed of the blade are selected, so that the abrasive particle projection distribution is adjusted to a predetermined shape.

13. The method of claim 10, wherein the predetermined value is 0.3.

14. The method of claim 11, wherein the projection position of the abrasive particle projection opening ranges from 5 ° to 20 °.

15. The method of claim 10, wherein the blades have a dimensional value with a ratio of outer diameter to inner diameter in any one of the ranges 1.75 to 2.0, 2.5 to 2.9, and 3.6 to 4.1.

16. An apparatus for estimating the state information of a projection device projecting abrasive particles using a programmed computer, the projection device comprising a plurality of blades rotating at high speed, the computer comprising:

a) an input device for providing initial conditions to a computer, the initial conditions including information on the size of the blade, the speed of rotation, the projection of the abrasive particles, the information on the abrasive particles associated with the blade;

b) calculating means for calculating the position of each abrasive grain, and the speed and direction of the abrasive grain after collision with the blade, based on the initial condition;

c) means for estimating said projection condition information based on said calculation; and

d) means for displaying the estimated information.

17. The apparatus of claim 16, wherein the computing device calculates a value of a contact force with which each abrasive particle collides with at least one of one blade or one other abrasive particle; then, the acceleration of the abrasive particles is calculated based on the force on the abrasive particles, wherein the force comprises the contact force and gravity, and then the velocity and position of the abrasive particles after a minute time are obtained based on the calculated acceleration.

18. The apparatus of claim 16, wherein the computer further comprises a storage medium in which the computing program executed by the computing device is stored.

19. The apparatus according to claim 16, wherein the calculating means represents the speed of each abrasive grain after collision with a relative speed obtained from a speed vector of the abrasive grain and a speed vector of a collision point of the corresponding blade surface with which the abrasive grain collides, including a vertical component along the Y-axis and a horizontal component along the X-axis, wherein a bounce is represented by setting a coefficient using a coefficient of restitution with respect to the vertical component of the speed, and the horizontal component of the relative speed represents a speed loss due to frictional resistance;

then, by adding them and calculating the velocity vector of the blade collision point, the velocity and direction of the abrasive particles after colliding with the corresponding blade can be calculated.

20. The apparatus according to claim 16, wherein the calculating means calculates the distance of movement of the abrasive particles and the corresponding blade in the sampling time, and sequentially performs the calculation related to the collision of the abrasive particles satisfying the collision condition.

21. The device of claim 14, wherein the projection device is a centrifugal projection device.

22. The apparatus according to claim 14, wherein the abrasive grain projection distribution is adjusted to a predetermined shape by selecting a size value of the blade, a range of a projection position of the abrasive grain projection opening, and a rotation speed of the blade in order that a variation amount of a frequency at which each discharged abrasive grain rebounds from the blade is less than or equal to a predetermined value.

23. The apparatus of claim 19, wherein the predetermined value is 0.3.

24. The apparatus of claim 20, wherein the projection position of the abrasive particle projection opening ranges from 5 ° to 20 °.

25. The apparatus of claim 10, wherein the vane is sized such that the ratio of the vane outer diameter to the vane inner diameter is in the range of any one of 1.75 to 2.0, 2.5 to 2.9, and 3.6 to 4.1.

26. A method of projecting abrasive grains onto a workpiece by a programmed computer-controlled projection device having a plurality of blades rotating at high speed and estimating information on the projection state of the abrasive grains, the method comprising the steps of: a) inputting blade information, abrasive particle projection conditions, abrasive particle resilience coefficients and abrasive particle frictional resistance coefficients into the computer;

b) the computer judges whether the input step is finished or not, and if the input is finished, the computer calculates the position of each abrasive particle after each set sampling time based on the sampling time and the velocity vector of the abrasive particle;

c) the computer rotating the blades to update the angle of the blades;

f) the computer judges whether the blade rotates to a preset position, if so, the speed vectors of the abrasive particles are summed up, and if not, the steps b) to f) are repeated; and