JP2001079647A - Method for vibration-filling molding sand and molding sand vibration-filling apparatus using this method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always execute the excellent closed filling of molding sand to a lost foam pattern, etc., having projecting and recessing parts and hollows part by securing vibration (almost circular movement in a Lissajous' figure) in two-dimensional directions (three-dimensional directions) regardless of the variation of size of a molding flask (the variation of cast product) or the variation of the number of the casting members by stacking up the casting steps (the variation of the number of the steps of casting layers). SOLUTION: In the vibration-filling so as to fill the molding sand supplied into the molding flask where the sand is vibrated with one pair of vibration motors, the variation of vertical movement of the positions of the centers G1, G2, G3 of gravity in the vibration is detected and the phase angle of unbalanced weight of the one side of vibration motor to the other side of vibration motor is adjusted so as to always substantally cancel the varied twist movement of one pair of the vibration motors based on the detected result of the variation of vertical movement of positions of the centers of gravity in the vibration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for filling molding sand into a casting flask, and more particularly to a method for filling molding sand while vibrating the molding flask and a method for filling molding sand with vibration.

[0002]

2. Description of the Related Art Conventionally, molding sand has been loaded into a flask by a spring means by a vibration motor for rotating an unbalanced weight, from a simple filling method in which the flask is vertically vibrated by a cylinder type vibrator. Moved to the vibration method of swinging the flask of the vibration table, and further research on the fluidity of the molding sand to the vanishing model etc., for example, to rotate or reverse two vibration motors in a certain direction In the same manner, the swing of the flask is made unique, and a vertical and horizontal force is applied to the molding sand, that is, a two-dimensional force is applied. It has been studied to provide a three-dimensional force by displacing and providing a dense filling of a vanishing model or the like in a casting flask.

[0003] From the study of the rotation of the vibration motor, the swing of the molding flask and the fluidity of the molding sand, two vibration motors arranged in parallel beneath the vibration table have been used to determine the position of the unbalanced weight. By a predetermined angle, for example,
The swing of the flask obtained by changing the phase by making it different by 90 degrees and rotating it in the same direction at the same number of rotations disappears from applying a substantially uniform two-dimensional force to the molding sand. It is known that the effect of filling the casting sand into a model or the like is high (the three-dimensional direction is obtained by juxtaposition of a pair of vibration motors). Regarding such a technique, the present inventor has already disclosed in Japanese Patent Application Laid-Open Nos. 8-90160 and 8-90160.
90161, and in addition,
It is also proposed in JP-A-9-225586.

[0004]

SUMMARY OF THE INVENTION With the advance of the technology described above, compared to the conventional vibration filling method, it is possible to obtain a vibration of the flask in which the molding sand can be densely filled into the lost model of the flask. However, the initial phases of two (or two more) vibration motors arranged in parallel below the vibration table are made different, for example, by 90 degrees, and rotated in the same direction at the same rotation speed. That is, the swing of the flask obtained thereby always applies substantially uniform two-dimensional force (substantially circular in Lissajous figure) to the casting sand, that is, the one in which an excellent filling effect is always obtained. There is no limit.

That is, such a phenomenon is remarkable when the size of the casting flask is changed (when the casting product is changed) or when the number of casting products with respect to the casting frame is changed (the number of layers of the layered casting is changed). Was seen. Normally, in the above-described vibration filling method, under a certain condition setting, when the phase difference is 90 degrees, a part of the flask that is rocked by the two vibration motors (a part above the vibration table by a predetermined distance from the vibration table). When the vibration of the position) is measured (Lissajous figure), a substantially circular shape (side view) is drawn. However, when the size of the casting frame and the number of cast products are changed, the shape changes to an ellipse. The vibration force on the molding sand is one-dimensionally biased, and as a result, it is difficult to smoothly fill the concave or hollow portion of the disappearing model or the like with the molding sand.

[0006] The present invention provides a substantially uniform two-dimensional direction of the flask (regardless of the above-mentioned change in the size of the flask (change of the cast product) or change in the number of castings (change in the number of steps of the casting layer) by stacking). (3D direction) (Large circular motion in Lissajous figure) is ensured, and it is intended to always be able to perform excellent dense filling of foundry sand for uneven models with voids, etc. I do.

[0007]

In order to achieve the above-mentioned object, a method for filling a molding sand with vibration according to the present invention is provided in which a vibration table is swingably supported on a base via a spring means.
Under the vibration table, a pair of vibration motors having a parallel and horizontal rotation axis are provided, the phase angle of the unbalance weight of each vibration motor is adjustable, and the vibration motors are rotated in the same direction. A molding sand vibration filling method in which molding sand supplied to a molding flask mounted on a vibration table is filled while vibrating, and a change in a vertical position of a vibration center of gravity located in the molding flask is detected, and the vibration is detected. The phase angle of the unbalanced weight of one of the vibration motors with respect to the other vibration motor is adjusted based on the detection result of the position of the center of gravity such that the fluctuating torsional moment of the pair of vibration motors is always substantially cancelled. ,
We took the measure. Foundry sand vibration filling method.

In the method of the present invention, the offset of the moments M1 and M2 of the pair of vibration motors is M1 / M2 =
Assuming the case of 1 and the case of M1-M2 = 0, the phase angle β of the unbalanced weight of one vibration motor to be adjusted with respect to the other vibration motor is obtained by the following equation. tanα = L / h (1) M1 = SIN (α−θ) (2) M1 / M2 = 1 or M1-M2 = 0 (.) 3) M2 = SIN (α + θ + β) (4) Therefore, β = 180-2α (5) In the above equation, the vertical line from a certain vibration center of gravity G1 , The height intersecting with the horizontal line formed by the rotation axis of each vibration motor is h, the distance between the rotation axis of both vibration motors is 2L, θ
Is the rotation angle of the vibration motor.

In the method of the present invention, the spring means for supporting the vibration table is constituted by an air cushion spring capable of freely filling and discharging compressed air, and the position of the vibration center of gravity is detected by a predetermined position of the air cushion spring. It is preferable to calculate by detecting the air pressure which balances with.

In the method of the present invention, at least the center of gravity (G1) at the time when the molding sand is supplied to the vanishing model of the lowermost layer of the flask is detected, and the one of the one vibration motors with respect to the other vibration motor is detected. The filling operation is performed by adjusting the phase angle of the vibration motor, and the vibration center of gravity (G2, G3) displaced upward when new molding sand is supplied to the disappearing model of the next layer is detected. It is preferable that the filling operation is performed by adjusting the phase angle of the corresponding vibration motor, and the filling operation of the molding sand is successively performed in the same process for the casting of a plurality of lost models.

In order to achieve the above object, a molding sand vibration filling apparatus according to the present invention supports a vibration table in a swingable manner with respect to a base via a spring means. A pair of vibration motors having a parallel and horizontal rotation axis are provided, and unbalance weight position adjusting means for adjusting the phase angle of the unbalance weight of each vibration motor is provided. This is a molding sand vibration filling apparatus that fills the molding sand supplied to the molding flask mounted on the table while vibrating, and detects a change in the vertical position of the vibration center of gravity located in the molding flask. Means for operating the unbalanced weight position adjusting means based on the detection result of the position of the center of gravity of the vibration, and the torsion moment of the pair of vibration motors which fluctuates is controlled. There always be substantially canceled,
In this case, the phase angle of the unbalance weight of the one vibration motor with respect to the other vibration motor is adjusted.

In the apparatus of the present invention, the spring means for supporting the vibration table is constituted by an air cushion spring, and the vibration center-of-gravity position detecting means comprises a pressure detector for detecting an air pressure in a predetermined balance of the air cushion spring. It is preferable that the weight of the molding frame including the supplied molding sand and the vibration table is calculated based on the detection result of the pressure detector, and the position of the fluctuating center of gravity of the vibration is detected.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The inventor of the present invention has conceived the following as a means for solving the above-mentioned problems of the present invention. That is, the above-described vibration (oscillation) of the flask is substantially circular (two-dimensional direction to three-dimensional direction bias) which is preferable for filling the molding sand.
In order to describe the above, when the phase angle β of the two initial vibration motors is set to, for example, 90 degrees under certain conditions, the torsional moment M
The relationship between 1 and the other torsional moment M2 is M1 / M2
= 1 or M1-M2 = 0.

The torsional moments M1 and M2 of the two vibration motors are determined by the distance 2L between the two vibration motors juxtaposed and the height h to the vibration center of gravity G1 located in the flask above the vibration motors. The angle formed between the axis of one vibration motor and the perpendicular of the vibration center of gravity G1 is tan α = L /
h, and the torsional moment M1 is M1 = S
IN (α−θ), and as a result, the torsional moment M2 of the other vibration motor from which the torsional moment M1 is canceled out is M2 = SIN (α + θ + β), and the phase angle β is β = 180-2α.

From the above, since the distance 2L between the two vibration motors whose positions are fixed is constant and the initially set phase angle β is fixed at 90 degrees, the two torsional moments M1 , M2 satisfy the condition, that is, M1 /
The reason why M2 = 1 or M1−M2 = 0 is not satisfied is that the position of the vibration center of gravity G1 is changed, that is, the size of the flask is different or the number of castings is increased (the number of steps of the casting layer is increased).
And so on, the height h from the vibration motor to the vibration center of gravity (G2, G3) located in the upper casting flask fluctuates, and the value of the tan α changes. According to β = 180−2α in the above equation, the torsional moment cannot be canceled when the value of β is 90 degrees, which is the initial setting, and as a result, the swing of the predetermined position of the flask maintains the initial substantially circular motion. It turned out that I could not do it.

Therefore, the torsional moment between the two vibration motors is not canceled out, and as a result, the vibration at the predetermined position of the flask does not substantially shift from circular motion (Lissajous figure) to elliptical or elliptical motion. Thus, the center of gravity G1, G2, G3 which is displaced is detected, that is, the height h of the above-mentioned factor is detected, and based on the flowchart of FIG.
The phase angle β of the unbalanced weight with respect to one of the other is adjusted so that the torsional moments of the two vibration motors are substantially canceled each other as initially, by nα and the phase angle β. The term “substantially canceling the torsional moment” as used herein includes not only a case where the torsional moment is completely canceled but also a case where the torsional moment can be regarded as substantially canceled by the predetermined phase angle β.

Therefore, in the present invention, the vibration center of gravity G
If the change in the position (height h) of 1 (G2, G3) is caused by, for example, a change in the number of steps of the casting layer of the lost model with respect to the flask, at least the molding sand for the lost model of the lowest layer of the flask. Detecting the center of gravity G1 of the vibrating motor at the time of supplying, and performing the filling operation by adjusting the phase angle of the vibrating motor with respect to the other one, and performing the filling operation when the casting sand is supplied to the disappearing model of the next layer. Displaced center of gravity of vibration G
2, G3 is detected, and similarly, the filling operation is performed by adjusting the phase angle of the vibration motor with respect to the other one, and the filling operation of the molding sand is sequentially performed in the same process.

In the present invention, as the means for detecting the position of the vibration center of gravity G1, the spring means for supporting the vibration table is constituted by an air cushion spring, and the spring means for supporting the vibration table is constituted by an air cushion spring. Means for detecting the air pressure at a predetermined balance of the air cushion spring, calculating the weight of the molding flask and the vibration table including the supplied molding sand, and changing the vibration center of gravity G1, G
2. The position (height h) of G3 is detected. However, as means for detecting the position (height h) of the vibration centers of gravity G1, G2, and G3, in addition to the weight of the flask and the weight of the lost model, which are fixed factors, every time these lost models are embedded in layers. The means for calculating by a method of directly measuring the molding sand supplied to the container may be adopted, and other appropriate means may be adopted.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method for filling a molding sand with vibration according to the present invention and a vibration-filling apparatus for molding sand used in the method will be described in detail below with reference to the drawings. FIG. 1 shows a principle diagram of a molding sand vibration filling method according to the present invention, FIG. 2 is a schematic front view of a molding sand vibration filling device used in the method, and FIG. 3 shows a flowchart of the molding sand vibration filling method. . In FIG.
Reference numeral 1 denotes a casting frame in which a plurality of vanishing models are set. Here, a mold (size) capable of three steps of casting is used, and the casting steps are 1a, 1b, and 1c from below.
Indicated by 2 shows a plurality of vanishing models set in each of the casting steps 1a, 1b and 1c.

Reference numeral 3 denotes a vibration table for detachably fixing the casting flask 1, and the vibration table 3 is swingably supported by spring means 4 including air cushion springs disposed on the lower surfaces of four corners. ing. 5a and 5b
Are a pair of vibration motors juxtaposed at a predetermined interval on the lower surface of the vibration table 3 so that their rotation axes are parallel to each other. The structure of each vibration motor is a rotation rotated by an electric motor. An unbalance weight is fixed to a shaft, and both electric motors are disclosed in, for example, JP-A-8-90161 so that the initial position of the unbalance weight, that is, the mutual phase can be made different. It is of a configuration known per se, which is provided with the phase angle adjusting means for electrically controlling as described above. In this embodiment, for the sake of simplicity, the vibration motors 5a and 5b are described as a pair. However, according to this, a substantially circular swing (Lissajous) in a vertical plane and a horizontal direction is used. Graphic), that is, a vibration in two-dimensional directions can be obtained. Further, by installing a pair of vibration motors shifted by 90 degrees in plan view, vibrations in one horizontal direction different by 90 degrees are added, Thus, vibration in a three-dimensional direction can be obtained.

Reference numeral 6a denotes a pressure detector for detecting the pressure of the compressed air supplied to the spring means 4 of the air cushion spring. The pressure detector 6a constitutes a part of the vibration center-of-gravity position detecting means 6. . That is, the spring means 4 of the air cushion spring that supports a predetermined weight includes the weight of the vibration table 3 and the weight of the casting flask 1 serving as fixed factors and the molding sand (and / or the additional casting step 1) serving as a variation factor.
The weights of b) and 1c) are balanced and supported under a predetermined air pressure, and the center of gravity G1 of the vibration center G1 is calculated from the already known shapes (dimensions) of the vibration table 3 and the flask 1 by using an arithmetic circuit. , G2, G3 are calculated.

In this case, the air cushion spring is
Instead of being used at the maximum expansion, the vibration table 3 is used so as to perform a cushioning action with a margin to facilitate swinging of the vibration table 3 within a predetermined range. When the compression pressure on the air cushion spring increases due to the weight change (increase in weight) of the molding sand (and / or additional pouring steps 1b, 1c), the air cushion spring is deformed when the deformation of the air cushion spring is small. However, if the deformation of the air cushion spring becomes relatively large, which may hinder the easy swing of the vibration table 3 in a predetermined range, the supply pressure of the compressed air may be appropriately adjusted. And adjust the control so as to maintain an initial shape that has enough room for the swing of the air cushion spring.

As shown in the principle diagram of FIG. 1, in the method of the present invention, the position of the vibration center of gravity G1 located in the casting flask 1, for example, the lowermost casting step 1a, is detected by the pressure of the above-mentioned air cushion spring. One of the vibration motors 5b, 5a is detected by the vibration center-of-gravity position detecting means 6 by the pressure detector 6a and based on the detection result of the position of the vibration center of gravity G1, so that the torsional moments M1, M2 of the pair of vibration motors 5b, 5a are offset. This is performed by adjusting the phase angle of the unbalanced weight of one vibration motor 5b with respect to the other vibration motor 5a.

Here, the pair of vibration motors 5b, 5
The moments M1 and M2 of a are offset when M1 / M2 = 1 and M1-M2 = 0, and the phase of the unbalanced weight of one vibration motor 5b to be adjusted with respect to the other vibration motor 5a is to be adjusted. The angle β is obtained by the following equation. tanα = L / h (1) M1 = SIN (α−θ) (2) M1 / M2 = 1 or M1-M2 = 0 (.) 3) M2 = SIN (α + θ + β) (4) Therefore, β = 180-2α (5) In the above equation, the vertical line from a certain vibration center of gravity G1 The height at which the rotation axes of the vibration motors 5a and 5b intersect with the horizontal line is h, the distance between the rotation axes of the vibration motors 5a and 5b is 2L, and θ is the rotation angle of the vibration motors.

As described above, when the casting frame 1 is a three-stage stack (vibration center of gravity G1), the phase angle β corresponding to the lowest casting stage 1a is, for example, 90 degrees and a required substantially circular shape. When a vibration (Lissajous figure) can be obtained, when the molding sand is filled in the casting layer 1b of the next layer, the vibration center of gravity is displaced to G2, and the above-described height h changes. Tanα = L
/ H changes, and the factor β of the torsional moment M2 of the vibration motor 5b to be adjusted is β = 180-2α
Therefore, at the initial 90 degrees, the torsional moment M2 does not balance with the torsional moment M1 of one vibration motor 5a, and the phase angle of the unbalanced weight of the vibration motor 5b is changed to a new phase. It will be adjusted by the angle β.

The adjustment of the phase angle β is further performed in the same procedure as described above, since the vibration center of gravity G3 moves further upward when the casting steps 1c are stacked. A substantially circular vibration (in a Lissajous figure) of the casting flask 1 that is preferable for filling the casting sand in the two (three) dimensional directions can be obtained. Of course, such adjustment of the phase angle β is accompanied by a change in the vertical position of the vibration centers of gravity G1, G2, G3, and the cause is the above-described casting steps 1a, 1
Not only the stacking of b and 1c, but also a desired substantially circular vibration at a phase angle of 90 degrees (in Lissajous figure)
A casting flask 1 (and a certain cast product) where
When the size, size, size of the casting product (disappearance model) of the casting flask, etc. change based on the molding sand filling of Needless to say, the present invention is also required when the vibration and the filling action are performed stepwise by the supply, and it is needless to say that the present invention can be applied to such a case.

[0027]

According to the present invention, the vibration center of gravity is displaced by stacking a plurality of casting steps for setting a vanishing model or the like, or by changing the size of a casting frame or the size of a cast product. The offset state of the torsional moment of both vibration motors, which was obtained at the phase angle of the unbalanced weight set at the initial stage, cannot be obtained. (Circular motion), but the strength of the vibration force in one direction is biased (elliptical motion displaced in a certain direction), and the flask becomes unstable and shakes, and the effect of filling the molding sand (recess to concaves and cavities) To compensate for the deterioration of filling, the phase angle of the unbalanced weight is corrected by detecting the change in the center of gravity of the vibration, so that a suitable vibration state is always maintained in the filling of molding sand when stacking multiple frames. And fill with foundry sand Effect which has led to a marked effect that it is possible to prevent decrease.

Regarding other effects according to the present invention,
The details are as described in the section of the embodiment of the invention and the section of the embodiment.

[Brief description of the drawings]

FIG. 1 shows a principle diagram of a molding sand vibration filling method according to the present invention.

FIG. 2 is a schematic front view of a molding sand vibration filling apparatus according to the present invention.

FIG. 3 is a flowchart of a molding sand vibration filling method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casting frame 1a Lower casting step 1b Middle casting step 1c Upper casting step 2 Elimination model 3 Vibration table 4 Spring means 5a One vibration motor 5b The other vibration motor 6 Vibration center of gravity position detection means 6a Pressure sensor G1 Lower vibration center of gravity G2 Middle vibration center of gravity G3 Upper vibration center of gravity

Claims (6)

[Claims] 1. A vibration table is supported on a base via a spring means so as to be swingable, and a pair of vibration motors having a parallel and horizontal rotation axis are provided below the vibration table.
The phase angle of the unbalanced weight of each vibration motor is adjustable, and the vibration motors are rotated in the same direction,
A molding sand vibration filling method in which molding sand supplied to a molding flask mounted on the vibration table is filled while vibrating, and a change in a vertical position of a vibration center of gravity located in the molding flask is detected.
Based on the detection result of the position of the center of vibration, the phase angle of the unbalanced weight of the one vibration motor with respect to the other vibration motor is changed so that the fluctuating torsional moment of the pair of vibration motors is always substantially canceled out. Adjust the molding sand vibration filling method. 2. A moment M of the pair of vibration motors.
1, M2 is offset when M1 / M2 = 1 and M1-M2
= 0, and the phase angle β of the unbalanced weight of one vibration motor to be adjusted with respect to the other vibration motor is determined by the following equation. tanα = L / h (1) M1 = SIN (α−θ) (2) M1 / M2 = 1 or M1-M2 = 0 (.) 3) M2 = SIN (α + θ + β) (4) Therefore, β = 180-2α (5) In the above equation, a vertical line from a certain vibration center G is , The height intersecting with the horizontal line formed by the rotation axis of each vibration motor is h, the distance between the rotation axis of both vibration motors is 2L, θ
Is the rotation angle of the vibration motor. 3. A spring means for supporting the vibration table,
3. The method according to claim 1, wherein the air cushion spring is configured to freely charge and discharge compressed air, and the position of the vibration center of gravity is calculated by detecting an air pressure balanced at a predetermined position of the air cushion spring. Foundry sand vibration filling method. 4. A method for detecting a vibration center of gravity at the time of supplying the molding sand to at least the vanishing model of the lowermost layer of the flask, and adjusting a phase angle of the vibration motor of the one vibration motor with respect to the other vibration motor. The filling operation is performed, and the center of gravity of the vibration that is displaced upward when new molding sand is supplied to the lost model of the next layer is detected, and the phase angle of the vibration motor corresponding to this is adjusted and filled. Do the work,
4. The molding sand vibration filling method according to claim 1, further comprising the step of performing a molding sand filling operation in a similar step in order to cast a plurality of layers of the disappearing model. 5. A vibration table is swingably supported on a base via a spring means, and a pair of vibration motors having a rotation axis parallel and horizontal to each other are provided below the vibration table.
An unbalance weight position adjusting means for adjusting the phase angle of the unbalance weight of each vibration motor is provided, and the vibration motor is rotated in the same direction to vibrate the molding sand supplied to the molding flask mounted on the vibration table. A molding sand vibration filling device that is configured to perform filling while providing vibration center of gravity position detecting means for detecting a change in the vertical position of the vibration center of gravity located in the casting flask, and based on the detection result of the position of the vibration center of gravity, The phase angle of the unbalanced weight of the one vibration motor with respect to the other vibration motor such that the unbalanced weight position adjusting means is operated so that the fluctuating torsional moment of the pair of vibration motors is always substantially canceled out. A molding sand vibratory filling device configured to adjust the pressure. 6. A spring means for supporting said vibration table is constituted by an air cushion spring, and said vibration center-of-gravity position detecting means is constituted by a pressure detector for detecting an air pressure in a predetermined balance of said air cushion spring. 6. The molding sand vibration filling according to claim 5, wherein the weight of the molding frame and the vibration table including the supplied molding sand is calculated based on the detection result of the detector, and the position of the fluctuating vibration center of gravity is detected. apparatus.