EP3170584B1

EP3170584B1 - Gate position detection system, casting device, gate position detection method, and method for manufacturing cast product

Info

Publication number: EP3170584B1
Application number: EP15821561.6A
Authority: EP
Inventors: Seiya Suzuki; Norio HORINOUCHI; Kenichi Kawano
Original assignee: Hamakita Kougyou Kk; Yamaha Motor Co Ltd
Current assignee: Hamakita Kougyou Kk; Yamaha Motor Co Ltd
Priority date: 2014-07-14
Filing date: 2015-07-10
Publication date: 2019-05-08
Anticipated expiration: 2035-07-10
Also published as: EP3170584A1; WO2016009961A1; EP3170584A4; CN105531054B; CN105531054A; JPWO2016009961A1; JP6053243B2

Description

TECHNICAL FIELD

The present invention relates to a pouring cup position detection system for detecting the position of a pouring cup of a mold. Moreover, the present invention relates to a casting apparatus, a pouring cup position detection method, and a method of producing castings.

BACKGROUND ART

Casting techniques are widely used in the manufacture of mass production articles such as automotive vehicle parts. To this day, development efforts have been spent in realizing casting techniques for satisfying various needs.
US 5 757 506 A discloses A video positioning system for positioning a pouring vessel over a mold sprue cup comprising one or more light fixtures for illuminating a notch on a pouring mold, an image sensor for sensing the position of the notch on the mold by producing a video notch image, a vision interface unit connected to the image sensor for converting the video notch image to digital information, and a processor connected to said vision interface unit for determining the relative position of the notch image compared to a reference position for the notch. Position correction information is sent to a position controller connected to the processor. The position controller causes the position of the pouring vessel to be adjusted by a positioning subsystem comprising a positioning driver for converting the positioning control signals to actuating signals for a positioning actuator, a positioning actuator, and at least one position sensor for sensing the position of the pouring vessel. US 4 134 444 A discloses an automatic molten metal pouring apparatus comprising molten metal level detector, mold position detector, ladle tilting angle detector, a ladle tilting servomechanism and a control device. The apparatus permits a suitable pouring flow rate of molten metal to be automatically poured into each of the molds of different types which may be conveyed one after another to the pouring position along the casting line. JP 2010 269345 Arelates to a casting method, in that after a cavity portion is filled by the casting idle with molten metal, a refractory particulate material supply device that is disposed on the upper portion of the sprue cap blows a compressed air and a sand thereinto. JP H09 155502 A relates to a production of casting by self-curing casting mold and its molding flask. JP H09 155502 A discloses a mold that is filled with casting sand that does not contain a binding agent, into a mold form. It is also disclosed in JP H09 155502 A that after the mold is filled with the casting sand a weight is placed on the upper portion of the mold form. Patent Document 1 discloses a technique directed to a cast article releasing apparatus for consecutively releasing cast articles from sand molds which come sequentially conveyed on a casting line. In the technique of Patent Document 1, image processing is performed for sure release of the cast articles. Specifically, an image of a sand mold, including a pouring cup, is captured by a camera (image capture means) which is located near the end of a conveyor; based on this image, the position and dimensions of the pouring cup are calculated by a pouring cup detection/determination means (image processing device); and the releasing apparatus is controlled based on the calculated pouring cup position and the like.

CITATION LIST

PATENT LITERATURE

[Patent Document 1] Japanese Laid-Open Patent Publication No. 9-225625

SUMMARY OF INVENTION

TECHNICAL PROBLEM

However, in the technique disclosed in Patent Document 1, spills of melt around the pouring cup may be visible in the image, thus lowering the accuracy of position detection for the pouring cup.
The present invention has been made in view of the above problem, and an objective thereof is to provide a pouring cup position detection system and a pouring cup position detection method which are capable of accurately detecting the position of a pouring cup of a mold.

SOLUTION TO PROBLEM

A pouring cup position detection system according to an embodiment of the present invention is a pouring cup position detection system for detecting a position of a pouring cup of a mold, comprising: an image processing device including an imager which moves relative to the mold; and at least one marker provided on the mold and positioned relative to the pouring cup, wherein, the imager is configured to capture an image containing the at least one marker; and the image processing device is configured to calculate information concerning the position of the pouring cup based on the image captured by the imager, wherein the at least one marker comprises a plurality of markers.
In one embodiment, the plurality of markers comprise three or more markers.
In one embodiment, the at least one marker is a marker piece which is made of a heat-resistant material.
In one embodiment, the pouring cup position detection system according to the present invention further comprises a protection member surrounding each of the at least one marker.
In one embodiment, the pouring cup position detection system according to the present invention further comprises a light-shielding cover attached to the imager to restrict light entering the imager.
In one embodiment, the mold includes a main mold body having the pouring cup formed therein, and a weight to be placed on the main mold body so as to be clear of the pouring cup in planar perspective; and the at least one marker is provided on the weight.
In one embodiment, the mold includes a flask and a main mold body, the main mold body having the pouring cup formed therein and being situated in the flask; and the at least one marker is provided on the flask.
A casting apparatus according to an embodiment of the present invention comprises: the above pouring cup position detection system; a pouring machine to pour melt into the mold through the pouring cup; and a pressurizing device to feed at least particulate matter, through the pouring cup, to the mold into which the melt has been poured.
In one embodiment, the pressurizing device is configured to feed the particulate matter based on the information concerning the position of the pouring cup calculated by the image processing device.
A pouring cup position detection method according to an embodiment of the present invention is a pouring cup position detection method for detecting a position of a pouring cup of a mold, comprising: step (a) of capturing an image containing at least one marker comprising a plurality of markers provided on the mold and positioned relative to the pouring cup; and step (b) of generating information concerning the position of the pouring cup based on the image captured at step (a).
In one embodiment, the pouring cup position detection method according to the present invention further comprises step (c) of positioning the at least one marker relative to the pouring cup by using a positioning jig, the positioning jig having at least one opening formed in a predetermined position or positions.
A method of producing a casting according to an embodiment of the present invention comprises: step (A) of pouring melt into a mold through a pouring cup; and step (B) of calculating information concerning the position of the pouring cup by the above pouring cup position detection method.
In one embodiment, the method of producing a casting according to the present invention further comprises step (C) of feeding at least particulate matter, through the pouring cup, to the mold into which the melt has been poured, step (C) being executed based on the information concerning the position of the pouring cup calculated at step (B) .

ADVANTAGEOUS EFFECTS OF INVENTION

Embodiments of the present invention provide a pouring cup position detection system and a pouring cup position detection method that can accurately detect the position of a pouring cup of a mold.
A pouring cup position detection system according to an embodiment of the present invention includes an image processing device including an imager, and at least one marker positioned relative to the pouring cup. In the pouring cup position detection system according to an embodiment of the present invention, based on an image containing the marker(s) that is captured by the imager, the image processing device generates information (pouring cup position information) concerning the position of the pouring cup. Since the pouring cup position can be detected as a relative position on the basis of the marker position, the pouring cup position can be accurately detected without being affected by spills of melt around the pouring cup, or the brightness of the melt immediately after being poured.
From the standpoint of more accurately detecting the pouring cup position, it is more preferable to use a plurality of markers than to use one marker. The reason is that, use of a plurality of markers allows the pouring cup position to be calculated based on a pair consisting of two markers.
Especially when using three or more markers, a pouring cup position may be calculated from a pair of any two markers, and a mean value may be derived of this value being calculated as many times as there are such pairs, thus attaining a further enhanced detection accuracy. In the case of using three or more markers, so long as a good image is obtained with respect to at least two markers, the pouring cup position can be calculated even if the other marker(s) cannot be imaged well for soiling or other causes.
When the marker (s) is a marker piece (s) made of a heat-resistant material, soiling of the marker(s) by spills of melt is less likely to occur.
When a protection member is provided surrounding the marker(s), the protection member can prevent spills of melt from sticking to the marker (s), thus being able to better prevent soiling of the marker(s) by spills of melt.
When a light-shielding cover is attached to the imager, light entering imager can be restricted by the light-shielding cover, thereby restraining light sources around the imager from exerting unfavorable influences (disturbance) on image capturing.
The mold may include a main mold body having the pouring cup formed therein, and a weight to be placed on the main mold body, for example. In this case, the marker(s) may be provided on the weight.
Alternatively, the mold may include a flask and a main mold body situated in the flask. In this case, the marker(s) may be provided on the flask.
The pouring cup position detection system according to an embodiment of the present invention is suitably used in a casting apparatus. The casting apparatus may include, for example, the pouring cup position detection system according to an embodiment of the present invention and a pouring machine to pour melt into the mold through the pouring cup. When the casting apparatus further includes a pressurizing device to feed particulate matter, through the pouring cup, to the mold into which the melt has been poured, it is possible to reduce the amount of melt to be poured into the mold. This improves the pouring yield, and simplifies the processing work after the casting is released.
In a construction where the casting apparatus includes a pressurizing device, it is preferable that the pressurizing device feeds particulate matter based on pouring cup position information which is generated by the image processing device. Since the pouring cup position detection system according to an embodiment of the present invention is able to accurately detect the pouring cup position, feeding of the particulate matter can be suitably performed by using the pouring cup position information which is generated by the image processing device in the pouring cup position detection system.
A pouring cup position detection method according to an embodiment of the present invention includes: step (a) of capturing an image containing at least one marker which is positioned relative to the pouring cup; and step (b) of generating information concerning the position of the pouring cup based on the image captured at step (a). In the pouring cup position detection method according to an embodiment of the present invention, based on the image containing the marker(s) captured at step (a), information (pouring cup position information) concerning the position of the pouring cup is generated at step (b). Since the pouring cup position can be detected as a relative position on the basis of the marker position, the pouring cup position can be accurately detected without being affected by spills of melt around the pouring cup, or by the brightness of the melt immediately after being poured.
The pouring cup position detection method may further include step (c) of positioning the marker(s) relative to the pouring cup by using a positioning jig, the positioning jig having at least one opening formed in a predetermined position(s). By using the positioning jig, the marker(s) can be easily positioned throughout a plurality of molds.
The pouring cup position detection method according to an embodiment of the present invention is suitably used in a method of producing a casting. The method of producing a casting may include, for example, step (A) of pouring melt into a mold through a pouring cup, and step (B) of generating information concerning the pouring cup position by the pouring cup position detection method according to an embodiment of the present invention. Since the pouring cup position detection method according to an embodiment of the present invention is able to accurately detect the pouring cup position, the method of producing a casting involving step (B) above is able to suitably perform casting production.
The method of producing a casting may further include step (C) of feeding particulate matter, through the pouring cup, to the mold into which the melt has been poured. Inclusion of step (C) makes it possible to reduce the amount of melt to be poured into the mold. This improves the pouring yield, and simplifies the processing work after the casting is released. This step (C) is preferably performed based on the pouring cup position information generated at step (B). Since the pouring cup position detection method according to an embodiment of the present invention is able to accurately detect the pouring cup position, executing step (C) based on the pouring cup position information generated at step (B) allows feeding of the particulate matter to be suitably performed.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] An upper plan view schematically showing a pouring cup position detection system 100 according to an embodiment of the present invention.
[FIG. 2 ] A cross-sectional view taken along line 2A-2A' in FIG. 1 .
[FIG. 3 ] A diagram schematically showing how image capturing may be conducted by an imager 12.
[FIG. 4 ] An upper plan view, in the case where two markers 20 (a first marker 20A and a second marker 20B) are used, showing relative positioning of an opening 2a of a weight 2 and the two markers 20.
[FIG. 5 ] An upper plan view, in the case where three markers 20 (a first marker 20A, a second marker 20B, and a third marker 20C) are used, showing relative positioning of an opening 2a of a weight 2 and the three markers 20.
[FIG. 6 ] A perspective view schematically showing a specific example of markers 20.
[FIG. 7 ] A perspective view schematically showing a specific example of markers 20.
[FIG. 8 ] (a) and (b) are an upper plan view and a perspective view showing an example of more detailed construction of a marker 20 in the form of a marker piece.
[FIG. 9 ] A perspective view schematically showing an example where a protection member 22 is provided so as to surround each marker 20.
[FIG. 10 ] (a) and (b) are an upper plan view and a side view showing an example of more detailed construction of the protection member 22.
[FIG. 11 ] A perspective view schematically showing a specific example of markers 20.
[FIG. 12 ] An upper plan view showing a specific example of positions of markers 20 on the weight 2.
[FIG. 13 ] An upper plan view schematically showing a positioning jig 24.
[FIG. 14 ] (a) and (b) are diagrams illustrating a positioning method using a positioning jig 24.
[FIG. 15 ] (a) and (b) are diagrams illustrating a positioning method using a positioning jig 24.
[FIG. 16 ] An upper plan view showing a specific example of positions of markers 20 on a metal flask (flask) 1F.
[FIG. 17 ] (a) and (b) are a side view and a lower plan view schematically showing an example of the imager 12.
[FIG. 18 ] A block diagram schematically showing a casting apparatus 200 according to an embodiment of the present invention.
[FIG. 19 ] A diagram showing a pressurizing device 120 included in the casting apparatus 200.
[FIG. 20 ] A diagram showing a state immediately after melt m has been poured into a mold M (main mold body 1) through a pouring cup 1g.
[FIG. 21 ] A diagram showing a state in which a gas G is being blown into the cavity of the main mold body 1 from a nozzle portion 121 of the pressurizing device 120.
[FIG. 22 ] A diagram showing a state in which particulate matter 129 is being sent (blown) from the nozzle portion 121 of the pressurizing device 120 into the cavity of the main mold body 1.
[FIG. 23 ] A diagram showing a state in which blowing of particulate matter 129 into the cavity of the main mold body 1 has been completed.
[FIG. 24 ] A flowchart showing an exemplary pouring cup position detection method according to an embodiment of the present invention.
[FIG. 25 ] A flowchart showing another exemplary pouring cup position detection method according to an embodiment of the present invention.
[FIG. 26 ] A flowchart showing an exemplary method of producing a casting according to an embodiment of the present invention.
[FIG. 27 ] A flowchart showing a more detailed example of position detection for the pouring cup 1g.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not to be limited to the following embodiments.
First, with reference to FIG. 1 and FIG. 2 , a pouring cup position detection system 100 according to an embodiment of the present invention will be described. FIG. 1 is an upper plan view schematically showing the pouring cup position detection system 100 being installed in a casting line CL, and FIG. 2 is a cross-sectional view taken along line 2A-2A' in FIG. 1 .
As shown in FIG. 1 , on the casting line CL, a plurality of molds M are conveyed in a predetermined direction D1. Each mold M includes a main mold body 1 having a pouring cup 1g formed therein, a flask (which herein is a metal flask) 1F, and a weight 2. The main mold body 1 is a sand mold, with a cavity formed therein. The main mold body 1 is located within the metal flask 1F. Note that the main mold body 1 is not limited to a sand mold, but may be any of various molds for casting methods which perform gravity pouring. For example, it may be a mold made of ceramic particles, or a mold made of metal particles.
As shown in FIG. 2 , the cavity of the main mold body 1 is composed of a sprue 1a, runners 1b, risers 1c, and a product portion 1d. In the example shown in FIG. 1 and FIG. 2 , a weight 2 is placed on the main mold body 1. The weight 2 has an opening 2a, and is disposed so that the pouring cup 1g of the main mold body 1 is exposed through the opening 2a (i.e., so that the pouring cup 1g overlaps the opening 2a). In other words, the weight 2 is placed on the main mold body 1 so as to be clear of the pouring cup 1g in planar perspective.
The pouring cup position detection system 100 detects the position of the pouring cup 1g (which typically is the center position of the pouring cup 1g) of a mold M. As shown in FIG. 1 and FIG. 2 , the pouring cup position detection system 100 includes: an image processing device 10, which in turn includes an imager (digital camera) 12; and at least one marker 20 that is provided on the mold M and positioned relative to the pouring cup 1g. The pouring cup position detection system 100 (i.e., the part thereof excluding the marker (s) 20) is able to move in a direction D2, which is opposite to the direction D1 of conveyance of the mold M. Therefore, the imager 12 is able to move relatively to the mold M.
In the present embodiment, a plurality of (or more specifically, two) markers 20 are provided for one mold M. The markers 20 are situated on the weight 2.
In addition to the aforementioned imager 12, the image processing device 10 includes a calculation section 14. The calculation section 14 is typically a computer (e.g., a panel computer). The image processing device 10 may further include an illuminator which is not shown.
As shown in FIG. 2 and further in FIG. 3 , the imager 12 captures an image containing the markers 20. Based on the image which has been captured by the imager 12 (i.e., an image containing the markers 20), the image processing device 10 generates information concerning the position of the pouring cup 1g (hereinafter referred to also as "pouring cup position information"). Generation of the pouring cup position information occurs as predetermined image processing is applied to the image containing the markers 20.
As described earlier, in the pouring cup position detection system 100 of the present embodiment, pouring cup position information is generated based on the image containing the markers 20, whereby the position of the pouring cup 1g of the mold M can be accurately detected. In detecting the position of the pouring cup through image processing, one possible technique might be to capture an image containing the pouring cup 1g, and directly detect the position of the pouring cup 1g from that image. However, such a technique may not be able to accurately detect the position of the pouring cup 1g. For example, spills of melt around the pouring cup 1g may be visible in the image, thus lowering the accuracy of detecting the position of the pouring cup 1g. On the other hand, in the pouring cup position detection system 100 of the present embodiment, pouring cup position information is generated based on an image containing the markers 20, which are positioned relative to the pouring cup 1g; therefore, the position of the pouring cup 1g is detectable as a relative position based on the positions of the markers 20. As a result, the position of the pouring cup 1g can be detected more accurately than by a technique of imaging the pouring cup 1g.
While the present embodiment illustrates an example where there are two markers 20, the number of markers 20 is not limited thereto. There may be one marker 20, or three or more markers 20. However, a plurality of markers 20 will enable more accurate detection of the position of the pouring cup 1g than does one marker 20. Moreover, three or more markers 20 will enable more accurate detection of the position of the pouring cup 1g than do two markers 20.
Now, an exemplary method of calculating the position of the pouring cup 1g in the case of using a plurality of markers 20 will be described. In the following example, calculation is conducted by assuming that the center of the circular opening 2a which is made in the weight 2 coincides with the center of the pouring cup 1g.
FIG. 4 is an upper plan view, in the case where two markers 20 are used, showing relative positioning between the opening 2a of the weight 2 and the two markers 20. Herein, between the two markers 20 shown in FIG. 4 , the marker 20A that is located relatively to the right is referred to as the first marker, and the marker 20B that is located relatively to the left is referred to as the second marker.
In FIG. 4 (i.e. in the captured image), a coordinate system is envisaged where, given a certain point as an origin, an x axis is defined by an axis extending along the right-left direction from the origin (the right side of the origin being positive, the left side negative), and a y axis is defined by an axis extending along the top-bottom direction from the origin (the upper side of the origin being positive, the lower side negative).
The center of the opening 2a is designated as P0(x₀ , y₀); the center of the first marker 20A as P1 (x₁, y₁) ; and the center of the second marker 20B as P2 (x₂, y₂). Moreover, there is a distance R between the center P0 of the opening 2a and the center P1 of the first marker 20A; and an angle α (counterclockwise being positive) is constituted by a line connecting the center P1 of the first marker 20A and the center P2 of the second marker 20B and a line connecting the center P1 of the first marker 20A and the center P0 of the opening 2a. Furthermore, an angle θ (counterclockwise being positive) is constituted by a line connecting the center P1 of the first marker 20A and the center P2 of the second marker 20B and the negative direction of the x axis.
The angle θ is expressed by eq. (1) below, and the coordinates (x₀, y₀) of the center P0 of the opening 2a are expressed by eqs. (2) and (3) below. The distance R and the angle α can be determined in advance by using a positioning jig 24 described later, for example. Therefore, by applying image processing to an image containing the first marker 20A and the second marker 20B to determine the coordinates (x₁, y₁) of P1 and the coordinates (x₂, y₂) of P2, it is possible to calculate the coordinates (x₀, y₀) of the center P0 of the opening 2a, i.e., the position of the center of the pouring cup 1g.
[eq. 1] $θ = \sin^{- 1} ((y_{1} - y_{2}) / \sqrt{{(x_{2} - x_{1})}^{2} + {(y_{2} - y_{1})}^{2}})$
[eq. 2] $x_{0} = x_{1} - Rcos (α - θ)$
[eq. 3] $y_{0} = y_{1} + Rsin (α - θ)$
FIG. 5 is an upper plan view, in the case where three markers 20 (a first marker 20A, a second marker 20B, and a third marker 20C) are used, showing relative positioning of the opening 2a of the weight 2 and the three markers 20.
In the case where three or more markers 20 are used, any two markers 20 may be selected from among the three or more markers 20, and similarly to the method which has been described with reference to FIG. 4 , coordinates (x₀, y₀) of the center P0 of the opening 2a may be calculated with respect to that pair (i.e., two markers 20). By calculating the coordinates (x₀, y₀) of the center P0 of the opening 2a as many times as there are pairs (combinations) of two such markers 20 (e.g., three in the case of using three markers 20), and taking a mean value of the calculated values, the detection accuracy can be enhanced.
Moreover, in the case of using three or more markers 20, so long as a good image is obtained with respect to at least two markers 20, the coordinates (x₀, y₀) of the center P0 of the opening 2a can still be calculated even if the other marker(s) 20 cannot be imaged well for soiling or other causes.
As has already been described, there may only be one marker 20. In the case of using one marker 20, the position of the pouring cup 1g can be calculated in the following manner, for example.
Herein, it is assumed that all molds M are arranged parallel to the direction of conveyance D, and that any clockwise (or counterclockwise) shift in planar perspective would be negligible.
Assuming that there is a difference (Δx, Δy) between the coordinates (x0, y0) of the center P0 of the opening 2a and the coordinates (x₁, y₁) of the center P1 of the marker 20, then, the coordinates (x0, y0) of the center P0 of the opening 2a are expressed by eqs. (4) and (5) below. $x_{0} = x_{1} - Δx$
$y_{0} = y_{1} - Δy$
Δx and Δy can be determined in advance by using a positioning jig 24 described below, for example. Therefore, by applying image processing to an image containing one marker 20 to determine the coordinates (x₁, y₁) of the center P1 thereof, it is possible to calculate the coordinates (x₀, y₀) of the center P0 of the opening 2a, i.e., the position of the center of the pouring cup 1g.
Next, with reference to FIG. 6 to FIG. 11 , a specific construction of the marker(s) 20 will be described.
In an example shown in FIG. 6 , planar markers 20 are formed through application of a heat-resistant paint, or attaching sheets of heat-resistant material. In order to suitably recognize the markers 20, the markers 20 are preferably white. The example shown in FIG. 6 has an advantage of being able to form the markers 20 easily. However, since the markers 20 are planar (i.e., having substantially zero thickness), the markers 20 are likely to be soiled by spills of melt in the example shown in FIG. 6 .
In an example shown in FIG. 7 , the markers 20 are cylindrical marker pieces which are made of a heat-resistant material (e.g. iron). The example shown in FIG. 7 has an advantage in the markers 20 are less likely to be soiled by spills of melt. Although the height (thickness) of the markers 20 in the form of marker pieces is not particularly limited, it is preferably 25 mm or more from the standpoint of unlikeliness of soiling.
FIGS. 8(a) and (b) are an upper plan view and a perspective view showing an example of more detailed construction of a marker 20 in the form of a marker piece. In order to enable suitable recognition of the marker 20, it is preferable that the marker 20 has a white upper face 20u, and that the marker 20 has a matte-black side face 20s. The marker 20 has a diameter d1 of e.g. 30 mm. The marker 20 has a height h1 of e.g. 30 mm. As shown in FIGS. 8(a) and (b) , the marker 20 is attached to the weight 2 with a bolt 21, for example.
In the example shown in FIG. 9 , a protection member 22 is provided so as to surround each marker 20. Herein, a cylindrical protection member 22 is disposed on the outside of each cylindrical marker 20. The protection member 22 is made of a heat-resistant material (e.g. iron). In the example shown in FIG. 8 , the protection member 22 prevents spills of melt from sticking to the markers 20, thus better preventing soiling of the marker 20 by spills of melt.
FIGS. 10(a) and (b) are an upper plan view and a side view showing an example of more detailed construction of the protection member 22. In order to enable suitable recognition of the marker 20, it is preferable that the entire protection member 22 is matte black. In the example shown in FIGS. 10(a) and (b) , the protection member 22 includes a cylindrical base portion 22a and a semicylindrical collar portion 22b provided on the base portion 22a. The protection member 22 is to be disposed so that the collar portion 22b is located on the side of the marker 20 facing the pouring cup 1g (i.e., facing the opening 2a). The base portion 22a has an outer diameter d2 of e.g. 70 mm, and the collar portion 22b has an inner diameter d3 of e.g. 48 mm. The base portion 22a has a height h2 of e.g. 25 mm, and the collar portion 22b has a height h3 of e.g. 10 mm.
Although the coloration of the marker 20 and the protection member 22a is not limited to the above example, the coloration is preferably one that maximizes the contrast between the marker 20 (or the upper face 20u of the marker 20) and its surroundings.
FIG. 6 to FIG. 10 show cases where the shape of each marker 20 (i.e., a planar shape of the marker 20) appears circular when viewed in the direction of image capturing (i.e., parallel to the center axis of the opening 2); however, the planar shape of the marker 20 is not limited to circular, but may be any arbitrary shape. For example, as shown in FIG. 11 , the planar shape of the marker 20 may be rectangular. FIG. 11 shows an example where marker pieces which are shaped in quadrangular prisms are provided as markers 20. Even if the markers 20 have a planar shape other than a circular shape, the center position of the opening 2a can be calculated by extracting the centroid point, or an edge, of the marker 20.
Moreover, the positions of the markers 20 on the weight 2 are not limited to those shown in the figures above. The markers 20 may be disposed at arbitrary positions 20P on the weight 2 as shown in FIG. 12 , for example. However, preferably all disposed markers 20 are capable of being imaged through a single capturing.
Now, an exemplary method of positioning the markers 20 relative to the pouring cup 1g will be described. The markers 20 can be positioned relative to the pouring cup 1g by using a positioning jig 24 shown in FIG. 13 , for example. The positioning jig 24 has at least one (e.g., plural as shown herein) opening formed in a predetermined position(s). In the example shown in FIG. 13 , the positioning jig 24 has a first opening 24a corresponding to the opening 2a of the weight 2 and a second opening 24b corresponding to a marker 20.
FIGS. 14(a) and (b) and FIGS. 15(a) and (b) are diagrams showing a positioning method using the positioning jig 24. First, as shown in FIG. 14(a) , a plug (lid) 26 made of resin is fitted in the opening 2a of the weight 2. Herein, since the opening 2a is circular, the plug 26 has a disk shape. Next, as shown in FIG. 14(b) , the positioning jig 24 is placed on the weight 2 so that the first opening 24a fits around the plug 26.
Then, as shown in FIG. 15(a) , the marker 20 is fitted in the second opening 24b of the positioning jig 24, and fixed with the bolt 21. This produces a weight 2, as shown in FIG. 15(b) , having a marker 20 attached thereon which is positioned relative to the opening 2a (i.e., relative to the pouring cup 1g).
Use of the positioning jig 24 facilitates positioning of the marker 20 with respect to a plurality of molds 1 (i.e., a plurality of weights 2). Note that the plug 26 can also be used for calibrating the position of the opening 2a of the weight 2. From an image which is captured with the imager 12 while the positioning jig 24 is placed on the weight 2 (i.e., on the mold M), coordinates (x₀, y₀) of the center P0 of the opening 2a can be determined, and by using these resultant (x₀, y₀), the aforementioned R, α, Δx, Δy can be obtained.
In the illustrated construction, the positioning jig 24 itself is positioned relative to the weight 2 by the plug 26; however, the positioning jig 24 may be positioned relative to the weight 2 (or the mold M) by means of any structure, including constructions other than the illustrated construction. Therefore, the positioning jig 24 does not need to have an opening formed corresponding to the opening 2a of the weight 2, and may at least have an opening(s) which is formed corresponding to the marker(s) 20. Therefore, in the case where there is one marker 20, only one opening may be formed.
The markers 20 does not need to be provided on the weight 2 so long as they are positioned relative to the pouring cup 1g. For example, as shown in FIG. 16 , the markers 20 may be provided at arbitrary positions 20P on the metal flask (flask) 1F of the mold M.
FIGS. 17(a) and (b) show an example of specific construction of the imager 12. FIGS. 17(a) and (b) are a side view and a lower plan view schematically showing the imager 12.
As shown in FIG. 17(a) , the imager 12 is connected to a communication cable 13, so that an image which is captured by the imager 12 is output to the calculation section 14 via the communication cable 13. Moreover, a dust cover 15 and a light-shielding cover 16 are attached on the imager 12. The dust cover 15 prevents dust from attaching to a lens 12a of the imager 12.
The light-shielding cover 16 restricts light that enters the imager 12. Herein, as shown in FIG. 17(b) , the light-shielding cover 16 is disposed so as to partially cover the lens 12a when the imager 12 is viewed from below. The light-shielding cover 16 restrains light sources around the imager 12 from exerting unfavorable influences (disturbance) on image capturing.
As described above, with the pouring cup position detection system 100 of the present embodiment, the position of the pouring cup 1g of the mold M can be detected accurately. The pouring cup position detection system 100 can be suitably used for a casting apparatus.
FIG. 18 shows a casting apparatus 200 including the pouring cup position detection system 100. FIG. 18 is a block diagram schematically showing the casting apparatus 200.
As shown in FIG. 18 , the casting apparatus 200 includes the pouring cup position detection system 100, a pouring machine 110, and a pressurizing device 120. The casting apparatus 200 further includes a control device 130.
The pouring machine 110 pours melt into the mold M through the pouring cup 1g. There is no particular limitation as to the construction of the pouring machine 110. Various types of pouring machines can be used as the pouring machine 110, e.g., an automatic pouring machine of the type that tilts a ladle. A ladle-tilting type automatic pouring machine includes a ladle, a ladle tilting mechanism for tilting the ladle, and the like.
To the mold M into which the melt has been poured, the pressurizing device 120 feeds at least particulate matter through the pouring cup 1g. The pressurizing device 120 includes a nozzle portion which sends out particulate matter, a moving mechanism which moves the nozzle portion, and a particulate matter supplier which supplies the particulate matter to the nozzle portion. The particulate matter is made of a heat-resistant material, and may be sand or steel balls, for example. Typically, the pressurizing device 120 blows the particulate matter into the mold M through the pouring cup 1g together with a gas (e.g., compressed air).
The control device 130 controls the operating timing, amount of motion, and the like of the pouring machine 110 and the pressurizing device 120. The control device 130 is able to perform the aforementioned control based on information which is output from the image processing device 10. The control device 130 is, for example, a programmable logic controller (PLC).
Because of having the pressurizing device 120, the casting apparatus 200 is able to reduce the amount of melt to be poured into the mold M. This improves the pouring yield, and simplifies the processing work after the casting is released.
Note that the feeding of particulate matter by the pressurizing device 120 is to take place promptly after the melt is poured into the mold M. However, if the pouring cup 1g is imaged immediately after the melt has been poured, the very bright melt may make it difficult to precisely recognize the shape of the pouring cup 1g. However, in the casting apparatus 200, the pressurizing device 120 carries out feeding of the particulate matter (i.e., blowing of the gas and particulate matter) based on the information concerning the position of the pouring cup 1g which is generated by the image processing device 10 (i.e., the position of the pouring cup 1g which is detected as relative position based on the position(s) of the marker(s) 20). Therefore, the nozzle portion can be accurately located above the pouring cup 1g, thus to suitably perform feeding of the particulate matter. It also prevents the nozzle portion from breaking by interfering with the metal flask (flask) 1F or the weight 2 of the mold M.
Now, with reference to FIG. 19 , an example of specific construction of the pressurizing device 120 will be described. In the example shown in FIG. 19 , the pressurizing device 120 includes a nozzle portion 121, a moving mechanism 122, and a particulate matter supplier 123.
The nozzle portion 121 is a portion which blows out (sends out) the gas and particulate matter 129 into the pouring cup 1g of the mold M.
The moving mechanism 122 is able to move the nozzle portion 121. Specifically, the moving mechanism 122 is able to move the nozzle portion 121 along the right-left direction (i.e., a parallel direction to the direction of conveyance D1 of the mold M), the front-rear direction (i.e., an orthogonal direction to the direction of conveyance D1) and the top-bottom direction. There is no particular limitation as to the specific construction of the moving mechanism 122 so long as it is capable of moving the nozzle portion 121 in the aforementioned manners; for example, servo motors for enabling movement along each of the right-left direction, the front-rear direction, and the top-bottom direction are encompassed.
The particulate matter supplier 123 supplies the particulate matter 129 to the nozzle portion 121. The particulate matter supplier 123 includes a particulate matter tank 124 which holds the particulate matter 129, a particulate matter feed pipe 125 through which the particulate matter tank 124 and the nozzle portion 121 are allowed to communicate, and an open-close slide member 126 which is provided between the particulate matter tank 124 and the particulate matter feed pipe 125. The particulate matter supplier 123 further includes a gas feed pipe 127 which is connected to the particulate matter feed pipe 125, and an open-close valve 128 which is attached to the gas feed pipe 127.
As already described, because of having the pressurizing device 120, the casting apparatus 200 is able to reduce the amount of melt to be poured into the mold M.
Generally speaking, the cavity of a mold is composed of a sprue, runners, risers, and a product portion (see FIG. 2 ). When producing a casting, the melt is poured not only into the product portion, but also into the sprue, runners, and risers. Once the melt completes its solidification as the mold is cooled after melt pouring, the mold is broken apart in order to release the casting. At this time, the portion corresponding to the product portion is isolated and subjected to finishing, thus becoming a final product. The portions corresponding to the sprue, runners, and risers are redissolved as return material. Thus, pouring of the melt elsewhere other than the product portion (i.e., the region of the cavity that corresponds to the actual product) has been a cause for a low pouring yield. Moreover, such excess pouring has also been a cause for increased processing work after the casting is released from the mold.
In contrast to this, since the pressurizing device 120 feeds at least the particulate matter 129 into the mold M through the pouring cup 1g after the melt has been poured, the amount of melt to be poured into the sprue 1a and the runners 1b can be reduced. This improves the pouring yield, and simplifies the processing work after the casting is released.
Hereinafter, with reference to FIG. 20 to FIG. 23 , an operation of the pressurizing device 120 will be described.
FIG. 20 shows a state immediately after melt m has been poured into the mold M (main mold body 1) through the pouring cup 1g. The volume of the poured melt m is smaller than the total volume of the cavity of the main mold body 1, and substantially equal to the volume of the product portion 1d and the risers 1c (or, slightly greater than the volume of the product portion 1d and the risers 1c).
As shown in FIG. 21 , the nozzle portion 121 of the pressurizing device 120 is moved by the moving mechanism 122 (not shown in FIG. 21 ) to over the pouring cup 1g of the mold M which has finished pouring, and a gas G is blown from the nozzle portion 121 into the cavity of the main mold body 1. Blowing of the gas G is performed by placing the open-close valve 128, which is attached to the gas feed pipe 127, in an open state. This pushes in the melt m so as to fill the product portion 1d and the risers 1c.
Next, as shown in FIG. 22 , the particulate matter 129 is fed into the cavity from the nozzle portion 121. Feeding of the particulate matter 129 is performed by placing the open-close slide member 126, which is provided between the particulate matter tank 124 and the particulate matter feed pipe 125, in an open state. At this point, the open-close valve 128 also remains in an open state, so that the particulate matter 129 is blown in together with the gas G.
FIG. 23 shows a state where blowing of the particulate matter 129 has been completed. As shown in FIG. 23 , at this point, the uppermost portion of the melt m is at a higher position than is its rearmost portion; therefore, a flowing force acts on the melt m to restore the state shown in FIG. 20 , but its flow is restrained by the frictional force due to the particulate matter 129 that has been blown in (i.e., a frictional force within particulate matter 129 and a frictional force between the particulate matter 129 and the inner surface of the cavity).
Thus, by feeding the particulate matter 129 into the cavity with the pressurizing device 120, the amount of melt to be poured into the sprue 1a and runners 1b can be reduced (substantially eliminated).
The above example illustrates that the feeding of the particulate matter 129 is performed after blowing the gas G; however, the gas G may be blown at the same time as feeding the particulate matter 129, or after feeding the particulate matter 129.
Instead of the construction involving blowing the particulate matter 129 into the cavity together with the gas G, a construction may be adopted such that the particulate matter 129 is pushed into the cavity by a pushing member (e.g., a rod of a pneumatic cylinder).
Next, a pouring cup position detection method and a method of producing a casting, as performed by the aforementioned pouring cup position detection system 100 and the casting apparatus 200, will be described with reference to flowcharts.
FIG. 24 is a flowchart showing an exemplary pouring cup position detection method according to the present embodiment.
In the pouring cup position detection method according to the present embodiment, first, an image containing at least one marker 20 that is positioned relative to the pouring cup 1g is captured (step S1). As will be seen from what has been described above, a more accurate detection of the position of the pouring cup 1g at this step S1 will be enabled by capturing an image containing a plurality of markers 20 (preferably three or more markers 20).
Next, image processing is applied to the image which was acquired at step S1 to generate information concerning the position of the pouring cup 1g (step S2). In this manner, the position of the pouring cup 1g of the mold M can be detected.
In the pouring cup position detection method according to the present embodiment, pouring cup position information is generated based on an image containing a marker(s) 20 that is positioned relative to the pouring cup 1g; therefore, the position of the pouring cup 1g can be detected as relative position with respect to the position(s) of the marker(s) 20. This allows the position of the pouring cup 1g to be accurately detected.
FIG. 25 is a flowchart showing another exemplary pouring cup position detection method according to the present embodiment.
In the example shown in FIG. 25 , before step S1, the positioning jig 24 is used to position at least one marker 20 relative to the pouring cup 1g (step S0). As has been described with reference to FIG. 13 , at least one (e.g., plural, in the example shown in FIG. 13 ) opening is formed at a predetermined position(s) of the positioning jig 24. By using the positioning jig 24, the marker(s) 20 can be easily positioned throughout a plurality of molds M.
FIG. 26 is a flowchart showing an exemplary method of producing a casting according to the present embodiment.
In the method of producing a casting according to the present embodiment, first, melt is poured into the mold M through the pouring cup 1g (step S11). Next, information concerning the position of the pouring cup 1g is generated (step S12). This step S12 is executed by the aforementioned pouring cup position detection method.
Then, to the mold M into which the melt has been poured, at least particulate matter 129 is fed through the pouring cup 1g (step S13). This step S13 is executed based on the pouring cup position information generated at step S12. Thereafter, when the melt completes its solidification, mold breaking and finishing are carried out (step S14). Thus, a casting is produced.
The method of producing a casting according to the present embodiment includes step S13 of feeding particulate matter 129 to the mold M, into which the melt has been poured, through the pouring cup 1g. As a result, the amount of melt to be poured into the mold M can be reduced. Thus, the pouring yield is improved, and the processing work after the casting is released can be simplified. Moreover, since this step S13 is performed based on information concerning the position of the pouring cup 1g which is generated by the image processing device, feeding of the particulate matter 129 can be suitably performed.
Although the above description illustrates an example where feeding of the particulate matter 129 is performed based on pouring cup position information which is generated by the image processing device 10, this is not the only example of control that is based on pouring cup position information. For example, melt pouring may be performed based on the pouring cup position information. Performing the melt pouring based on the pouring cup position information makes for more efficient or automated pouring work.
FIG. 27 is a flowchart showing a more detailed example of position detection for the pouring cup 1g.
When the casting apparatus 200 moves to the position of a mold, the imager 12 captures an image containing the markers 20, with an instruction from the control device 130 (step S21).
Next, markers 20 are extracted from within the captured image (step S22). Extraction of the marker 20 is performed by, for example, determining the color (brightness), shape, and size. At this time, any spills of melt (i.e., regions of largest brightness) within the image are excluded.
Then, from a pair of markers 20 (i.e., two markers 20), the position of the pouring cup 1g (or the center position of the opening 2a of the weight 2) is calculated (step S23). In doing this, an amount of translational motion of the position of the pouring cup 1g is calculated from one marker 20 in the pair, whereas an amount of rotational motion of the position of the pouring cup 1g is calculated from the other marker 20 (which is the technique described with reference to FIG. 4 ). In the case where three or more markers 20 are provided, any two arbitrary markers 20 are selected, calculation is provided for each such pair, and a mean value and variance are determined.
Next, plausibility of the calculated position of the pouring cup 1g (or the center position of the opening 2a of the weight 2) is determined (step S24). If the calculated position is not within the expected range, then it is deemed as a result of failure in the extraction of the markers 20 or movement of the casting apparatus 200, and an error signal is output. In the case of three or more markers 20, if the variance exceeds the expected range, an error signal may be output, or a mistake in the extraction of the markers 20 due to soiling of the markers 20 or the like may be recognized and only the calculation results for the pair(s) that can be deemed as having been correctly extracted may be used.
Then, a difference between the calculated position of the pouring cup 1g (or the center position of the opening 2a of the weight 2) and the expected position is calculated (step S25). The result of calculation is output as a correction value to the control device 130.
Next, the casting apparatus 200 moves based on the correction value, and a casting operation is performed (step S26) .
Then, the value of the calculation result and the image are stored in computer file form (step S27). Thereafter, the casting apparatus 200 is moved to the position of a next mold. In this manner, detection of the position of the pouring cup 1g and the subsequent casting operation can be executed.

INDUSTRIAL APPLICABILITY

According to embodiments of the present invention, a pouring cup position detection system and a pouring cup position detection method that can accurately detect the position of a pouring cup of a mold are provided. The pouring cup position detection system and pouring cup position detection method according to embodiments of the present invention can be broadly used in casting methods which perform gravity pouring.

REFERENCE SIGNS LIST

M: mold
1: main mold body
1a: sprue
1b: runner
1c: riser
1d: product portion
1g: pouring cup
1F: flask (metal flask)
2: weight
2a: opening
10: image processing device
12: imager
13: communication cable
14: calculation section
15: dust cover
16: light-shielding cover
20: marker
20u: upper face of marker
20s: side face of marker
21: bolt
22: protection member
22a: base portion
22b: collar portion
24: positioning jig
24a: first opening
24b: second opening
26: plug
100: pouring cup position detection system
110: pouring machine
120: pressurizing device
121: nozzle portion
122: moving mechanism
123: particulate matter supplier
124: particulate matter tank
125: particulate matter feed pipe
126: open-close slide member
127: gas feed pipe
128: open-close valve
129: particulate matter
130: control device
200: casting apparatus

Claims

A pouring cup position detection system (100) for detecting a position of a pouring cup (1g) of a mold (M), the pouring cup position detection system (100) comprising:
an image processing device (10) including an imager (12) which moves relative to the mold (M); and

at least one marker (20) provided on the mold (M) and positioned relative to the pouring cup (1g), wherein,

the imager (12) is configured to capture an image containing the at least one marker (20);

the image processing device (10) is configured to calculate information concerning the position of the pouring cup (1g) based on the image captured by the imager (12), characterized in that the at least one marker (20) comprises a plurality of markers.
The pouring cup position detection system (100) of claim 1, wherein the plurality of markers comprise three or more markers (20).
The pouring cup position detection system (100) of any of claims 1 to 2, wherein the at least one marker (20) is a marker piece which is made of a heat-resistant material.
The pouring cup position detection system of any of claims 1 to 3, further comprising a protection member (22) surrounding each of the at least one marker (20).
The pouring cup position detection system (100) of any of claims 1 to 4, further comprising a light-shielding cover (16) attached to the imager (12) to restrict light entering the imager (12).
The pouring cup position detection system (100) of any of claims 1 to 5, wherein,
the mold (M) includes a main mold body (1) having the pouring cup (1g) formed therein, and a weight (2) to be placed on the main mold body (1) so as to be clear of the pouring cup (1g) in planar perspective; and

the at least one marker (20) is provided on the weight (2).
The pouring cup position detection system (100) of any of claims 1 to 5, wherein,
the mold (M) includes a flask (1F) and a main mold body (1), the main mold body (1) having the pouring cup (1g) formed therein and being situated in the flask (1F); and

the at least one marker (20) is provided on the flask (1F).
A casting apparatus (200) comprising:
the pouring cup position detection system (100) of any of claims 1 to 7;

a pouring machine (110) to pour melt into the mold (M) through the pouring cup (1g); and

a pressurizing device (120) to feed at least particulate matter, through the pouring cup (1g), to the mold (M) into which the melt has been poured.
The casting apparatus (200) of claim 8, wherein the pressurizing device (120) is configured to feed the particulate matter based on the information concerning the position of the pouring cup (1g) calculated by the image processing device (10).
A pouring cup position detection method for detecting a position of a pouring cup (1g) of a mold (M), comprising:
step (a) of capturing an image containing at least one marker (20) comprising a plurality of markers provided on the mold (M) and positioned relative to the pouring cup (1g) and; and

step (b) of calculating information concerning the position of the pouring cup (1g) based on the image captured at step (a).
The pouring cup position detection method of claim 10, further comprising step (c) of positioning the at least one marker (20) relative to the pouring cup (1g) by using a positioning jig, the positioning jig (24) having at least one opening formed in a predetermined position or positions.
A method of producing a casting, comprising:
step (A) of pouring melt into a mold (M) through a pouring cup (1g); and

and step (B) of'calculating information concerning the position of the pouring cup (1g) by the pouring cup position detection method of claim 10 or 11.
The method of producing a casting of claim 12, further comprising step (C) of feeding at least particulate matter, through the pouring cup (1g), to the mold (M) into which the melt has been poured, step (C) being executed based on the information concerning the position of the pouring cup (1g) calculated at step (B).