JP4897734B2 - Differential pressure casting equipment - Google Patents

Description

  The present invention relates to a differential pressure casting apparatus that performs casting by generating a differential pressure between a holding container and a storage container.

  Recently, a storage container in which a mold is stored is installed above the holding container to bring the holding container and the storage container into an airtight state, and the pressure in the holding container and the storage container is increased from the atmospheric pressure. Research has been made on a differential pressure casting apparatus that raises the pressure above the pressure in the storage container and fills the mold with the molten metal by the pressure difference.

  Conventionally, a holding container containing molten metal is disposed below a storage container in which a mold is stored, compressed gas is blown into the holding container, and the molten metal in the holding container is supplied to an upper mold through stalk. There is known a low pressure casting method in which casting is performed.

  In the low pressure casting method, a mold is often used as a mold, which is suitable as a method for mass-producing products having the same shape. The storage container for storing the mold is open to the atmosphere, and the amount of molten metal in the holding container Regardless of this, the pressure in the holding container may be kept substantially constant.

  On the other hand, in the above differential pressure casting apparatus, it is necessary to manage the differential pressure between the holding container and the storage container with high accuracy. For example, when mass-producing castings of the same shape, a mold is used. The amount of molten metal in the holding container can be estimated in advance by the volume of the mold cavity, so that an appropriate differential pressure can be predicted, and the amount of molten metal in the holding container does not have to be measured for each casting. Appropriate differential pressure control is possible.

  However, when producing a large number of castings, it is necessary to change the mold frequently, and the volume of the mold cavity varies depending on each mold, and the amount of molten metal used changes every time the mold is changed. It is difficult to do. Therefore, when producing a small amount of castings, it is necessary to measure the exact molten metal surface height in the holding container before the next casting.

  When the above-mentioned differential pressure casting equipment is used when producing a small amount of castings for the precision of the cylinder head of a racing engine, etc., it is common to use a sand mold as a mold. The amount of molten metal used changes, and in order to make the differential pressure between the pressure in the holding container and the pressure in the storage container appropriate, it is important to control the pressure in the holding container and the storage container.

  More specifically, if the differential pressure between the pressure in the holding container and the pressure in the storage container is too low, a hot water defect in the sand mold occurs, and if the differential pressure is too high, the pressure at the time of filling the molten metal Since collapse and insertion of the molten metal into the sand mold surface occur, and the finish of the casting deteriorates, it is necessary to make the differential pressure between the pressure in the holding container and the pressure in the storage container appropriate.

  Note that the amount of molten metal in the holding container decreases each time it is cast, and if the molten metal is added to the holding container, the amount of molten metal increases. It depends on the height.

  On the other hand, a differential pressure casting apparatus that detects a molten metal surface by providing, for example, a contact-type molten metal surface sensor having an electrode in a holding container is known (see Patent Document 1).

  In addition, a heat-resistant glass or the like is provided in the opening formed in the holding container, a non-contact type distance sensor by a laser is arranged outside the holding container, and a differential pressure casting apparatus that measures the distance from the molten metal surface through the heat-resistant glass, A differential pressure casting apparatus in which a distance sensor is disposed in a holding container is known (see Patent Documents 2 and 3).

Japanese Patent Laid-Open No. 11-156529 JP-A-7-136755 JP-A-8-318361

  However, in a differential pressure casting apparatus using a contact-type molten surface sensor such as an electrode, the molten surface sensor comes into contact with the molten metal, so in order to maintain high-precision measurement by the contact-type molten surface sensor, Maintenance had to be performed frequently, and maintenance was poor. In addition, since the molten surface sensor is brought into contact with the high temperature molten metal, the life of the molten surface sensor is short.

  Also, in a differential pressure casting device that measures the distance from the molten metal surface through heat-resistant glass with a non-contact distance sensor, the heat-resistant glass becomes cloudy and the measurement sensitivity decreases, or the laser light etc. from the distance sensor is heat-resistant glass. It is difficult to accurately measure the molten metal surface due to reflection and scattering.

  Further, in the differential pressure casting apparatus in which the non-contact distance sensor is disposed in the holding container, the distance sensor is always directly subjected to the heat radiation of the molten metal, so that the life of the distance sensor is remarkably reduced.

  From this point of view, it was more reliable for the operator to measure the height of the molten metal surface in the holding container using a gauge than to use a sensor, so the operator had to perform the measurement work. .

  Therefore, the present invention is less susceptible to the heat radiated by the molten metal in the holding container, can accurately measure the distance between the molten metal surface and the distance sensor, and controls the differential pressure based on the measurement result to obtain a finished product. It is an object of the present invention to provide a differential pressure casting apparatus capable of obtaining a good casting.

The present invention (see, for example, FIG. 1 to FIG. 3) includes a holding container (20) for holding a molten metal, a storage container (30) disposed above the holding container and storing a mold (S), And a stalk (40) communicating the holding container (20) and the mold (S) in the storage container (30), wherein the pressure in the holding container (20) is higher than the pressure in the storage container (30). In the differential pressure casting apparatus that creates a differential pressure so as to be higher and fills the mold (S) with the molten metal held in the holding container (20) through the stalk (40),
The storage container (30) has a main body (31) through which an upper end of the stalk penetrates and an upper part is open so that a mold can be attached, and a lid (32) capable of closing the opening of the main body.
Moving means (50) for moving the lid (32) to a retracted position for retracting from above the main body (31) and a closed position for closing the opening of the main body;
A distance sensor (60) provided on a member (51c) that moves integrally with the moving means, and measures a distance (L) from the molten metal surface (M) in a non-contact manner through the stalk (40);
Control means (70) for controlling the differential pressure between the holding container (20) and the storage container (30),
When the lid (32) is moved to the retracted position by the moving means (50) and the next mold (S) is stored in the storage container (30), it moves integrally with the moving means (50). The distance sensor (60) measures the distance (L) of the molten metal surface (M) in the holding container (20), and the control means (70) determines the difference in the next casting based on the measurement result. The pressure casting apparatus is characterized in that the pressure is set.

In the differential pressure casting apparatus, the moving means (50) is disposed above the lid body (32), and an elevating mechanism (51) that supports the lid body so as to be movable up and down with respect to the main body (31). ) And a link mechanism (53) that supports the elevating mechanism (51) so as to be movable in the horizontal direction, and the elevating mechanism (51) lifts the lid (32) in the state where the elevating mechanism (51) is lifted. By moving the mechanism (51) in the horizontal direction, the lid (32) is moved to the retracted position,
The distance sensor (60) is attached to the elevating mechanism (51) so as to protrude in the horizontal direction, and is horizontally integrated with the elevating mechanism (51) when the lid (32) is moved to the retracted position. It moves to the position on the straight line extended from the said stalk (40) by moving to a direction, It is characterized by the above-mentioned.

  In the differential pressure casting apparatus (see, for example, FIGS. 5 to 8), the control means (70) is positioned at the upper end position of the stalk (40) based on the measurement result by the distance sensor (60). The first differential pressure (ΔPx) necessary for the molten metal to rise and the second differential pressure (ΔPy) necessary for filling the mold (S) with the molten metal are calculated, and the molten metal is added to the mold (S). Prior to filling, when the differential pressure is set to the first differential pressure (ΔPx) and it is determined that the molten metal has reached the upper end position of the stalk (40), the differential pressure is set to the second differential pressure. Is set to a differential pressure (ΔPy).

  In the differential pressure casting apparatus, when the control means (70) determines that the mold (S) has been filled with the molten metal, the solid pressure in the mold (S) is solidified when the molten metal is solidified. A third differential pressure (ΔPz) larger than the second differential pressure (ΔPy) is set.

  In the differential pressure casting apparatus, the mold stored in the storage container (30) is a sand mold (S).

  The reference numerals in the parentheses are for comparison with the drawings, but this is for the sake of convenience in understanding the invention and has no influence on the structure of the claims. It is not a thing.

  According to the first aspect of the present invention, when the lid is moved to the retracted position in order to open the mold and take out the casting, the distance sensor is positioned so as to measure the distance of the molten metal surface integrally with the moving means. Since it moves, the distance of the molten metal surface can be accurately measured in a non-contact manner before the next casting, and it becomes unnecessary for the operator to measure using a gauge, and the distance measurement can be automated.

  In addition, since the lid of the storage container is moved to the retracted position by the moving means, the lid of the storage container does not interfere with the measurement when the distance sensor is opposed to the molten metal surface through the stalk. Then, by moving the lid of the storage container to the retreat position where it is retracted from above the main body, the heat of the molten metal rising through the stalk is easily diffused, and when the distance sensor is opposed to the molten metal surface through the stalk. The distance sensor is less susceptible to heat. Since the distance sensor faces the molten metal surface through stalk when distance measurement is required, it is not always exposed to the heat of the molten metal and is not easily affected by the heat, thus extending the life of the distance sensor. be able to. Compared to measuring the distance between the molten metal surface and the distance sensor through heat-resistant glass, etc., the distance from the molten metal surface can be measured directly. Can be measured.

  In addition, since the distance measured by the distance sensor is accurate in the control means, the pressure difference between the pressure in the holding container and the pressure in the storage container can be accurately controlled, thereby suppressing poor hot water. It is possible to manufacture a casting with a good finish.

  According to the second aspect of the present invention, the distance sensor is disposed at a position sufficiently separated from the upper end of the stalk by attaching the distance sensor to the elevating mechanism disposed above the lid body. It is even less susceptible to the effects of heat. And only by attaching a distance sensor to a raising / lowering mechanism, a distance sensor can be moved to the position which opposes a molten metal surface, and it becomes possible to measure the distance of a molten metal surface accurately with a simple structure.

  According to the third aspect of the present invention, since the distance measured by the distance sensor is accurate, the accuracy of the calculation result of the first differential pressure and the second differential pressure is improved. Further, during casting, since the differential pressure between the pressure in the holding container and the pressure in the storage container is first set to be the first differential pressure, the molten metal is decelerated or stopped immediately before the mold, The molten metal is not poured into the mold vigorously. After the molten metal reaches the upper end of the stalk, the differential pressure between the pressure in the holding container and the pressure in the storage container is controlled so that the second differential pressure is obtained. Therefore, it is possible to suppress poor hot water in the mold, and it is possible to manufacture a casting with a good finish.

  According to the fourth aspect of the present invention, when the casting is solidified, the hot metal effect is enhanced, casting defects can be reduced, and a casting with a good finish can be manufactured.

  According to the fifth aspect of the present invention, since the mold is a sand mold, the molten metal can be prevented from being inserted into the sand mold by stabilizing the differential pressure control.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  1 to 3 are explanatory views showing a schematic configuration of a partial pressure section of the differential pressure casting apparatus according to the present embodiment.

  In FIG. 1, a differential pressure casting apparatus 100 includes a base 10, an upper end supported by the base 10, a holding container 20 that holds molten metal, a storage that is disposed above the holding container 20, and stores a sand mold S. The container 30 is provided with a stalk 40 extending in the up-down direction for communicating the holding container 20 and the sand mold S stored in the storage container 30. The molten metal is a molten metal such as aluminum.

  The storage container 30 includes a bottom portion 31A and a side wall portion 31B standing upward from the bottom portion 31A, a bottomed main body 31 having an open top, and a side wall portion 32B standing downward from the top portion 32A and the top portion 32A. And a lid 32 capable of closing the opening in the upper part of the main body 31. When the upper portion of the main body 31 is closed by the lid body 32, the lower end of the side wall portion 32 </ b> B of the lid body 32 is pressed and mounted on the upper end of the side wall portion 31 </ b> B of the main body 31.

  A through hole 31a is formed in the bottom 31A of the main body 31, and the upper end 40a of the stalk 40 is fixed through the through hole 31a. And the main body 31 can mount | wear with the sand mold S in the position corresponding to the upper end 40a of the stalk 40 in the bottom part 31A. The stalk 40 extends into the holding container 20 so that the lower end 40b is immersed in the molten metal in the holding container 20.

  Further, the differential pressure casting apparatus 100 includes a moving device 50 as a moving means for moving the lid 32 to a retracted position for retracting from above the main body 31 and a closed position for closing the opening of the main body 31. When the lid 32 moves to the closed position and closes the opening of the main body 31, the inside of the holding container 20 and the storage container 30 are in a sealed state, and when the lid 32 moves to the retracted position, Since the upper part of 31 opens, the sand mold S can be removed and installed.

  The moving device 50 is disposed above the lid body 32 of the storage container 30, and is supported by the elevating mechanism 51 that supports the lid body 32 so as to be movable up and down with respect to the main body 31, and the base 10. And a link mechanism 53 that supports 51 in a movable manner in the horizontal direction.

  The elevating mechanism 51 has a box body 51a for storing various drive sources, and four (plural) hydraulic cylinders 51b arranged below the box body 51a and extending in the vertical direction, and one end of the hydraulic cylinder 51b is a box. The other end is fixed to the top portion 32 </ b> A of the lid body 32. And the cover body 32 can be raised / lowered up and down by the expansion-contraction operation | movement of the hydraulic cylinder 51b (refer FIG. 2).

  In FIG. 1, the link mechanism 53 has a pair of link portions 54, 54 disposed on both sides of the storage container 30 and the lifting mechanism 51. The link portion 54 includes a first arm 55, a second arm 56, and a hydraulic cylinder 57 that connects the arms 55, 56 to each other. Each of the arms 55 and 56 has base portions 55a and 56a that are fixed to the base 10 at one end so as to be swingable and fixed at the other end to the box 51a of the lifting mechanism 51 so as to be swingable. The base portions 55a and 56a of the arms 55 and 56 are arranged in parallel. And the 1st arm 55 has the overhang | projection part 55b projected on the 2nd arm 56 side perpendicularly with respect to the base 55a in the edge part by the raising / lowering mechanism 51 side, and 2nd The arm 56 has an overhanging portion 56b that protrudes toward the first arm 55 in the direction perpendicular to the base portion 56a at the end on the base 10 side. One end of the hydraulic cylinder 57 is fixed to the overhang portion 55 b of the first arm 55, and the other end of the hydraulic cylinder 57 is fixed to the overhang portion 56 b of the second arm 56. Then, by extending and contracting the hydraulic cylinder 57, the first arm 55 and the second arm 56 can swing together while maintaining the parallel state, and the lifting mechanism 51 can be moved in the parallel direction. (See FIG. 3).

  The differential pressure casting apparatus 100 according to the present embodiment includes a non-contact type distance sensor 60 that measures a distance from an object with a laser beam. The distance sensor 60 protrudes and is attached to an elevating mechanism 51 as a member that moves integrally with the moving device 50. Specifically, the distance sensor 60 is fixed to a protruding piece 51 c that protrudes from the box 51 a of the lifting mechanism 51.

  Further, the differential pressure casting apparatus 100 controls the pressure in the holding container 20 and the pressure in the storage container 30, and a control device as control means for controlling the differential pressure between the holding container 20 and the storage container 30. 70. A distance sensor 60 is connected to the control device 70, and the control device 70 is configured to be able to acquire a measurement result measured by the distance sensor 60. The differential pressure casting apparatus 100 according to the present embodiment includes an operation unit 71 that is operated by an operator when the moving device 50 is operated or when casting is performed. It is connected. That is, the control device 70 controls the entire differential pressure casting apparatus 100 including the moving device 50 according to the setting of the operation unit 71.

  Next, the case where the sand mold S used for the previous casting is taken out and the sand mold S used for the next casting is installed in the differential pressure casting apparatus 100 will be described.

  FIG. 4 is a flowchart showing a series of operations by the differential pressure casting apparatus 100.

  In FIG. 4, first, when the operator sets the lid 32 of the storage container 30 to move to the retracted position in the operation unit 71, the control device 70 moves the lid 32 of the storage container 30 to the retracted position. The moving device 50 is controlled to do so (step S1). Specifically, when the lid 32 is moved from the closed position to the retracted position, first, as shown in FIG. 2, the lid 32 is lifted by the lifting mechanism 51, and in this state, as shown in FIG. The elevating mechanism 51 is moved in the horizontal direction by the link mechanism 53. As a result, the lid 32 of the storage container 30 moves from the closed position (FIG. 1) for closing the opening of the main body 31 to the retreat position (FIG. 3) for retreating from above the main body 31 of the storage container 30. At this time, the distance sensor 60 moves to a position (measurement position) on a straight line extending from the stalk 40 by moving in the horizontal direction integrally with the lifting mechanism 51 of the moving device 50, as shown in FIG. That is, the distance sensor 60 is positioned at a position on a straight line extending from the stalk 40 by the moving device 50. Furthermore, since the distance sensor 60 is attached to the elevating mechanism 51, the distance sensor 60 is positioned so that the distance from the upper end 40a of the stalk 40 becomes a predetermined distance when the lid 32 is moved to the retracted position.

  Then, when the sand mold S used for the previous casting protrudes from the upper part of the main body 31 by moving in the horizontal direction with the cover 32 moved upward, the cover 32 is horizontally moved by the link mechanism 53. Since the lid 32 is lifted upward by the lifting mechanism 51 when moved in the direction, the lid 32 can be prevented from contacting the sand mold S. Further, by moving the lid 32 in the horizontal direction, it is easy to take out the sand mold S when the sand mold S is opened and to newly install the sand mold S. In the present embodiment, since the sand mold S is used as the mold, it is necessary to replace the sand mold S every time one casting is manufactured.

  Here, when the sand mold S used for the previous casting is stored in the main body 31 of the storage container 30, the sand mold S is opened by the operator, the casting is taken out, and the sand mold S is taken out ( In FIG. 4, step S2). Alternatively, after the sand mold S is taken out, the mold is opened and the casting is taken out.

  Thus, when the sand mold S is taken out, the upper end 40a of the stalk 40 is exposed to the outside in the main body 31 of the storage container 30, as shown in FIG. Since the distance sensor 60 attached to the lifting mechanism 51 has been moved to a position (measurement position) on a straight line extending from the stalk 40 by the operation of step S1, the sand mold S is removed and the stalk 40 is removed. It will face the molten metal surface M. Thereby, the distance sensor 60 can measure the distance L between the distance sensor 60 and the molten metal surface M.

  When the distance sensor 60 is set to measure the distance in the operation unit 71 in a state where the distance sensor 60 faces the molten metal surface M in the holding container 20, the distance sensor 60 irradiates the molten metal surface M with laser light. The distance L from the molten metal surface M is measured by detecting the reflected light (step S3 in FIG. 4).

  Thus, when the lid 32 is moved to the retracted position in order to open the sand mold S and take out the casting, the distance sensor 60 moves to the measurement position together with the moving device 50, so that the next casting is performed. Prior to this, the distance L of the molten metal surface M can be accurately measured in a non-contact manner, and it becomes unnecessary for the operator to measure using the gauge, and the distance measurement can be automated.

  Further, since the lid 32 of the storage container 30 is moved to the retracted position by the moving device 50, the lid 32 of the storage container 30 obstructs the measurement when the distance sensor 60 is opposed to the molten metal surface M through the stalk 40. There is nothing. Then, by moving the lid 32 of the storage container 30 to the retracted position where the cover 31 is retracted from above the main body 31, the heat of the molten metal rising through the stalk 40 is easily diffused. When opposed to the distance sensor 60, the distance sensor 60 is not easily affected by heat. In particular, since the distance sensor 60 is attached to the protruding piece 51c that protrudes from the box 51a of the lifting mechanism 51, the distance sensor 60 is located sufficiently away from the upper end 40a of the stalk 40, and the molten metal in the holding container 20 is Less susceptible to heat.

  Since the distance sensor 60 faces the molten metal surface M through the stalk 40 when distance measurement is required, the distance sensor 60 is not always exposed to the heat of the molten metal and is not easily affected by the heat. Can extend the lifespan. Further, since the distance L from the molten metal surface M can be directly measured without using a heat-resistant glass or the like, the distance L can be accurately compared with the case of measuring the distance between the molten metal surface and the distance sensor through a heat-resistant glass or the like. Can be measured.

  The distance sensor 60 can be moved to a position facing the molten metal surface M simply by attaching the distance sensor 60 to the lifting mechanism 51, and the distance L of the molten metal surface M can be accurately measured with a simple structure. It becomes.

  Furthermore, since the distance sensor 60 moves integrally with the moving device 50 and is positioned at a fixed position, variations in measurement results are reduced, and the distance L from the molten metal surface M can be accurately measured.

  After the distance L with the molten metal surface M is measured by the distance sensor 60, the sand mold S used for the next casting is installed on the main body 31 of the storage container 30 (step S4). When the lid 32 is set to move to the closed position, the control device 70 controls the moving device 50 so as to move the lid 32 of the storage container 30 to the closed position (step S5). More specifically, when moving the lid 32 from the retracted position to the closed position, first, the link mechanism 53 moves the lifting mechanism 51 from the state of FIG. 3 to the state of FIG. The lid 32 is moved downward from the state of FIG. 2 to the state of FIG. At this time, the distance sensor 60 is retracted from directly above the holding container 20 and the storage container 30.

  Next, when the operation unit 71 is set to execute casting, the control device 70 controls the differential pressure based on the measured distance L from the molten metal surface M (that is, the height of the molten metal surface M). A casting process is executed (step S6).

  Then, when the casting process is completed, the procedure returns to the step S1 again, the sand mold S (casting) is taken out, and prior to installing the sand mold S used for the next casting, the distance sensor 60 and the molten metal surface M The distance L is measured. In this way, by measuring the molten metal surface M every time one lot of casting is produced (each time the sand mold S is replaced), the amount of the molten metal in the holding container 20 can be grasped, and in the next casting, the holding container The pressure difference between the pressure in the container 20 and the pressure in the storage container 30 can be accurately controlled, thereby suppressing poor hot water and insertion into the sand mold S, and producing a casting with a good finish. can do.

  Next, the casting process in step 6 will be described in detail.

  FIG. 5 is a block diagram showing a piping configuration of the differential pressure casting apparatus 100 according to the present embodiment, and FIG. 6 is a flowchart showing a casting process. FIG. 7 is a diagram illustrating changes in pressure in the holding container 20 and the storage container 30.

  In FIG. 5, the differential pressure casting apparatus 100 includes a gas supply device 80 that supplies a high-pressure gas suitable for casting such as air, rare gas, or nitrogen gas. The gas supply device 80 includes a pressurization valve (electromagnetic valve). A first air supply pipe 82 connected to the storage container 30 and a second air supply pipe 83 connected to the holding container 20 are connected via 81. The first air supply pipe 82 is provided with a first pressure adjustment valve 84 as a first pressure adjusting means and a first air supply valve (electromagnetic valve) 85, and a second air supply pipe 83. Are provided with a second pressure adjusting valve 86 as a second pressure adjusting means, and a second air supply valve (electromagnetic valve) 87.

  The secondary side of the first air supply valve 85 in the first air supply pipe 82 and the secondary side of the second air supply valve 87 in the second air supply pipe 83 are connected by a connection pipe 88. The connecting pipe 88 is provided with a connecting valve (solenoid valve) 89. A first atmosphere release pipe 91 having a first atmosphere release valve (solenoid valve) 90 connected to the end is connected to the secondary side of the first supply valve 85 in the first supply pipe 82. A second atmosphere release pipe 93 having a second atmosphere release valve (solenoid valve) 92 connected to the end is connected to the secondary side of the second supply valve 87 in the second supply pipe 83. Has been.

  The differential pressure casting apparatus 100 includes a first pressure sensor 94 that detects the pressure in the storage container 30 and a second pressure sensor 95 that detects the pressure in the holding container 20.

  With this configuration, the control device 70 controls the pressure P1 in the storage container 30 and the pressure P2 in the holding container 20 by controlling the valves 81, 84, 85, 86, 87, 89, 90, and 92. ing. In FIG. 4, in steps S <b> 1 to S <b> 5, the pressurization valve 81 and the first and second air supply valves 85 and 87 are closed, and the connection valve 89 and the first and second air release valves 90 and 92 are closed. Is open.

  In FIG. 6, first, the control device 70 is a differential pressure between the pressure P1 in the storage container 30 and the pressure P2 in the holding container 20 based on the measured distance L, and the upper end position of the stalk 40 (with respect to the molten metal surface M). The first differential pressure ΔPx required for the molten metal to rise to the height h1 of the upper end 40a of the stalk 40 is filled with the molten metal in the sand mold S (the height h2 of the upper end in the cavity Sc of the sand mold S with respect to the molten metal surface M). The second differential pressure ΔPy necessary for the molten metal to rise) and the third differential pressure ΔPz larger than the second differential pressure ΔPy are calculated (step S11).

  Specifically, first, the control device 70 calculates the height h1 and the height h2 based on the measured distance L.

Next, the required differential pressure ΔP (= P2−P1) is such that the density of the molten metal is ρ, the height with respect to the molten metal surface M is h, the sectional area of the cavity in the sand mold S is S, the sectional area of the holding container 20 is A, If the acceleration of gravity is g,
ΔP = ρ × h × (1 + S / A) × g Equation 1
The control device 70 calculates the differential pressure ΔPx and the differential pressure ΔPy based on the calculated height h1 and height h2 using Equation 1, and calculates the differential pressure ΔPz based on the differential pressure ΔPy. Is calculated.

  Next, the control device 70 performs control to set the pressure P1 in the storage container 30 and the pressure P2 in the holding container 20 to a predetermined pressure (for example, 800 kPa) P higher than atmospheric pressure (step S12: in FIG. 7). Boosting period T1).

  Specifically, since the first and second atmospheric release valves 90 and 92 are in the open state, the control device 70 first closes the first and second atmospheric release valves 90 and 92. Then, the pressurizing valve 81 and the first and second air supply valves 85 and 87 are opened, and the first and second pressure regulating valves 84 and 86 are set so that the pressure in each of the containers 30 and 20 is a predetermined pressure P. Adjust so that At this time, since the connecting valve 89 is in the open state, both the containers 30 and 20 are boosted to the predetermined pressure P at the same speed. In this way, by increasing the pressure of each container 30 and 20 to a predetermined pressure P, when the molten metal in the sand mold S is solidified, generation of hydrogen gas bubbles is prevented and casting defects such as pinholes due to the hydrogen gas bubbles are prevented. can do.

  The control device 70 detects the pressures P1 and P2 of the containers 30 and 20 by the first and second pressure sensors 94 and 95, and when the pressures P1 and P2 reach a predetermined pressure P, the control device 70 Each pressure P1, P2 is set so that the differential pressure with respect to the inside of the holding container 20 becomes the first differential pressure ΔPx (step S13: molten metal push-up period T2 in FIG. 7). More specifically, the control device 70 closes the connecting valve 89 when the pressures P1 and P2 reach the predetermined pressure P, so that the pressure in the holding container 20 becomes the first differential pressure ΔPx. The second pressure regulating valve 86 is set so as to increase P2 above the predetermined pressure P. By setting the second pressure regulating valve 86 in this way, the pressure P2 in the holding container 20 is gradually increased, and the differential pressure between the storage container 30 and the holding container 20 is the first pressure. It becomes the differential pressure ΔPx. By setting the differential pressure to the first differential pressure ΔPx in this way, the molten metal is decelerated or temporarily stopped immediately before the sand mold S, and the molten metal is not injected into the sand mold S vigorously.

  Next, the control device 70 determines whether or not the molten metal has reached the upper end 40a of the stalk 40 (step S14). More specifically, since the pressure P2 in the holding container 20 is gradually increased, the molten metal in the holding container 20 increases the stalk 40 as the pressure P2 in the holding container 20 increases. Then, when the differential pressure between the storage container 30 and the holding container 20 reaches the first differential pressure ΔPx, the molten metal reaches the upper end 40a of the stalk 40. And the control apparatus 70 hold | maintains 1st differential pressure | voltage (DELTA) Px only for the time required for a molten metal to be stabilized. Therefore, in the present embodiment, in step S14, the control device 70 requires the time required for the molten metal to stabilize because the differential pressure between the storage container 30 and the holding container 20 reaches the first differential pressure ΔPx. It is determined whether or not elapses.

  When the molten metal reaches the upper end 40a of the stalk 40 (step S14: Yes), the control device 70 sets the differential pressure between the storage container 30 and the holding container 20 to be the second differential pressure ΔPy. The molten metal is filled into the cavity Sc of the sand mold S (step S15: molten metal filling period T3 in FIG. 7).

  Specifically, the control device 70 sets the first pressure regulating valve 84 so as to reduce the pressure P1 in the storage container 30 from the predetermined pressure P so that the differential pressure becomes the second differential pressure ΔPy. To do. And by setting the 1st pressure regulation valve 84 in this way, the pressure P1 in the storage container 30 will reduce pressure gradually, and the differential pressure | voltage between the storage container 30 and the holding container 20 will become 2nd. It becomes the differential pressure ΔPy.

  Thus, instead of setting directly to the second differential pressure ΔPy, the first differential pressure ΔPx is set in advance and then set to the second differential pressure ΔPy. It is possible to suppress the molten metal from being ejected vigorously, to suppress the sand mold S from being damaged, and to produce a casting having a good finish.

  Further, since the pressure P1 in the storage container 30 is reduced, when the molten metal is filled in the sand mold S, the pressure P2 in the holding container 20 on the side of pushing out the molten metal does not fluctuate, so that the flow of the molten metal is smooth. Yes, it is possible to produce castings with good finish.

  Next, the control device 70 determines whether or not the filling of the molten metal into the cavity Sc of the sand mold S has been completed (step S16). In the present embodiment, it is determined whether or not the time required for filling has elapsed since the differential pressure between the storage container 30 and the holding container 20 becomes the second differential pressure ΔPy.

  When the controller 70 completes filling the cavity Sc of the sand mold S with the molten metal (step S16: Yes), the differential pressure between the storage container 30 and the holding container 20 becomes the third differential pressure ΔPz. (Step S17: coagulation period T4 in FIG. 7). Specifically, the control device 70 sets the pressure P1 in the storage container 30 to a predetermined pressure P and increases the pressure P2 in the holding container 20 so that the differential pressure becomes the third differential pressure ΔPz. The pressure regulating valves 84 and 86 are set so that In this way, by increasing the pressure P2 in the holding container 20 and applying a follow-up pressure to the molten metal that leads to the sand mold S, it is possible to increase the hot metal effect, reduce casting defects, and produce a casting with good finish. it can.

  Next, the control device 70 determines whether or not the molten metal in the sand mold S has solidified (step S18). More specifically, the control device 70 determines whether or not the time required for the molten metal to solidify has elapsed.

  When the controller 70 determines that the molten metal in the sand mold S has solidified (step S18: Yes), first, the connecting valve 89 is opened, and the pressures in the containers 30 and 20 are balanced. The pressure in 30, 20 is reduced to atmospheric pressure (step S19: decompression period T5 in FIG. 7). More specifically, the pressurization valve 81 and the first and second air supply valves 85 and 87 are closed, and then the first and second atmosphere release valves 90 and 92 are opened.

  As described above, according to the present embodiment, the distance L between the molten metal surface M can be accurately measured by the distance sensor 60, and when the casting process is executed, the inside of the storage container 30 and the holding container are based on the measurement result. Since the differential pressure with respect to the inside 20 is controlled, the control operation is stable and a casting with a good finish can be manufactured.

  Although the present invention has been described based on the above embodiment, the present invention is not limited to this.

  In the present embodiment, in step S15 in FIG. 6, the pressure in the storage container 30 is reduced when the differential pressure between the storage container 30 and the holding container 20 is set to the second differential pressure ΔPy. However, the present invention is not limited to this, and as shown in FIG. 8, the pressure P2 in the holding container 20 may be increased to set the differential pressure to the second differential pressure ΔPy.

  In the present embodiment, the case where the member to which the distance sensor is attached (the member that moves integrally with the moving device) is the protruding piece 51c of the elevating mechanism 51 is not limited to this. It may be a lid of the container or a member fixed to the lid, or a link mechanism or a member fixed to the link mechanism. In addition, a moving member that moves in conjunction with the moving device may be provided, and a distance sensor may be provided on the moving member.

  In the present embodiment, the distance sensor 60 is described as being a laser type, but the distance sensor may be a radio wave type.

  Moreover, although the case where the holding container 20 is in a sealed state has been described in the present embodiment, the present invention is not limited thereto, and a case in which a chamber that covers the holding container in a sealed state may be provided.

  In the present embodiment, the case where the holding container 20 and the storage container 30 are increased to a predetermined pressure P higher than the atmospheric pressure has been described. However, the present invention is not limited to this, and the pressure is not increased to the predetermined pressure P. The case where a casting process is performed may be sufficient.

  In this embodiment, the case where a sand mold is used as a mold has been described. However, the present invention is not limited to this, and a small amount of various castings may be produced using a mold as a mold. Also in this case, the distance L is measured every time a casting is produced, and accurate differential pressure control is possible.

  Further, in the present embodiment, the case where the operator removes and installs the mold has been described. However, the present invention is not limited to this, and automation is performed by removing and installing the mold with a lift device (not shown). Also good.

It is a differential pressure casting apparatus which concerns on this Embodiment, Comprising: Explanatory drawing which shows schematic structure made into a partial cross section. It is a differential pressure casting apparatus which concerns on this Embodiment, Comprising: Explanatory drawing which shows schematic structure made into a partial cross section. It is a differential pressure casting apparatus which concerns on this Embodiment, Comprising: Explanatory drawing which shows schematic structure made into a partial cross section. The flowchart which shows a series of operation | movement by a differential pressure casting apparatus. The block diagram which shows the piping structure of the differential pressure casting apparatus which concerns on this Embodiment. The flowchart which shows a casting process. The figure which shows the pressure change of a holding | maintenance container and a storage container. The figure which shows another example of the pressure change of a holding | maintenance container and a storage container.

Explanation of symbols

20 Holding container 30 Storage container 31 Main body 31A Bottom 32 Cover body 40 Stoke 40a Upper end 50 Moving device (moving means)
51 Lifting mechanism 51c Projection piece 53 Link mechanism 60 Distance sensor 70 Control device (control means)
100 Differential pressure casting equipment

Claims (5)

A holding container that holds the molten metal; a storage container that is disposed above the holding container and that stores the mold; and a stalk that communicates the holding container and the mold in the storage container. In the differential pressure casting apparatus that creates a differential pressure so that the pressure is higher than the pressure in the storage container, and fills the mold with the molten metal held in the holding container through the stalk,
The storage container has a main body through which an upper end of the stalk passes and an upper part is open so that a mold can be attached;
Moving means for moving the lid to a retracted position for retracting from above the main body and a closed position for closing the opening of the main body;
A distance sensor that is provided on a member that moves integrally with the moving means and that measures the distance from the molten metal surface in a non-contact manner through the stalk;
Control means for controlling the differential pressure between the holding container and the storage container,
When the lid is moved to the retracted position by the moving means and the next mold is stored in the storage container, the distance of the molten metal surface in the holding container is determined by the distance sensor that moves integrally with the moving means. Measuring, and based on the measurement result, the control means sets the differential pressure in the next casting,
A differential pressure casting apparatus characterized by that. The moving means includes an elevating mechanism that is disposed above the lid and supports the lid so as to be movable up and down with respect to the main body, and a link mechanism that supports the elevating mechanism so as to be movable in the horizontal direction. In the state where the lid is lifted by the lifting mechanism, the lifting mechanism is moved in the horizontal direction to move the lid to the retracted position,
The distance sensor is attached to the elevating mechanism so as to protrude in the horizontal direction, and moves in the horizontal direction integrally with the elevating mechanism when the lid is moved to the retracted position, thereby extending from the stalk. Move to the upper position,
The differential pressure casting apparatus according to claim 1. The control means has a first differential pressure necessary for the molten metal to rise to the upper end position of the stalk based on the measurement result by the distance sensor, and a second differential necessary for filling the mold with the molten metal. Prior to calculating the differential pressure and filling the mold with the molten metal, the differential pressure is set to the first differential pressure, and when it is determined that the molten metal has reached the upper end position of the stalk, the differential pressure is , Set to the second differential pressure,
The differential pressure casting apparatus according to claim 1 or 2, characterized in that The control means sets the differential pressure to a third differential pressure larger than the second differential pressure when solidifying the molten metal in the mold when it is determined that the molten metal has been filled into the mold.
The differential pressure casting apparatus according to claim 3. The mold stored in the storage container is a sand mold,
The differential pressure casting apparatus according to any one of claims 1 to 4, wherein the differential pressure casting apparatus is provided.

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