JP6607978B2 - Hollow sand core molding equipment - Google Patents

Description

The present invention relates to a hollow sand core molding apparatus, and more particularly to an apparatus suitable for molding in a horizontal split mold.

As a method for forming a hollow sand core, for example, a vertical split mold is used, the inside of the cavity is filled with thermosetting core sand and heated, and the outer portion is cured by firing the core sand. Mold the core. The intermediate core at this stage is in a state in which unburned sand is filled therein. Subsequently, the mold is inverted to make the blowing port a sand discharge hole, and the unfired sand is discharged therefrom, thereby forming an intermediate core having a hollow portion formed therein. At this stage, the sand core is not closed. Then, just before the discharge of the unfired sand is completed, the heater plate is contacted and closed to the sand discharge hole, and a small amount of unfired sand remaining in the mold without being discharged is put into the sand discharge hole, and the heater is heated. Some of them require a two-step firing process that consists of completing a hollow sand core having a sealed hollow portion by closing a sand removal hole by curing on a plate (see Patent Document 1).

Japanese Unexamined Patent Publication No. 7-39996

In the above conventional method, since the mold is a vertical split mold, that is, a mold that opens and closes in the left-right direction, it is possible to invert the mold to discharge sand, without providing a dedicated sand discharge hole, It was also used as a sand removal hole.
However, in the horizontal split mold, that is, the mold that opens and closes the mold in the vertical direction, a large mold opening / closing mechanism is provided in the vertical direction, and therefore cannot be reversed. Further, it is meaningless to combine the shutter structure described in Patent Document 1 that is assumed to be reversed, and even if it is combined, a hollow sand core cannot be formed without reversing the mold.
Therefore, the present application aims to realize an advantageous hollow core molding apparatus using a horizontal die.

In order to solve the above problems, a hollow sand core molding apparatus according to the present invention is:
Provided in a mold provided with a cavity filled with thermosetting core sand, and an intermediate core (36) formed by hardening the outer shape of the cavity by firing the core sand; A shutter that opens and closes a sand discharge hole for forming a hollow portion by discharging the unfired sand inside;
Hollow sand core molding in which the hollow sand core (38) in which the sand removal hole is closed is formed by firing the unfired sand in which the sand removal hole is closed with the shutter and filling the sand removal hole. In the device
The mold (10a) is a horizontal split mold having an upper mold (11) and a lower mold (12) divided in the vertical direction,
A mold opening (17) communicating with the cavity is provided at a lower portion of the lower mold (12),
The shutter (15) opens and closes the mold opening (17), and has a first molding surface (21) provided with a recess (20) communicating with the cavity through the mold opening (17) when closed. )When,
And a second molding surface (22) having a closing surface for closing the sand removal hole (33) and closing.

In this way, the mold opening provided at the lower part of the lower mold is covered with the first molding surface of the shutter, and the mold and the recess of the first molding surface are communicated with each other through the mold opening. When the shutter is heated, the core sand blown into the mold is cured to form an intermediate core that forms the outer shape of the core. At this time, a part of the intermediate core enters the concave portion of the first molding surface from the mold opening, and when this shutter is opened, the part moves together with the movement of the shutter and is separated from the intermediate core. A sand discharge hole is formed in the intermediate core, and unfired sand is discharged from the sand discharge hole to form a hollow portion in the intermediate core. However, the hollow portion is opened by a sand removal hole.
Therefore, if the sand removal hole is covered with the second molding surface of the shutter before the sand removal is completed, the sand removal hole is closed by the closed surface. As a result, the unfired sand remaining in the intermediate core fills the sand removal hole, and further hardens by the heated shutter to form a closed portion that closes the sand removal hole, thereby forming a bottom portion that seals the hollow portion. As a result, the intermediate core is sealed and becomes a hollow sand core without an opening.

According to the present invention, since the shutter having the first molding surface and the second molding surface is provided, first, the first stage molding is performed in which the mold opening is closed on the first molding surface to mold the intermediate core. At this time, a part of the intermediate core enters and protrudes into the recess communicating with the mold opening, and then the part that protrudes into the recess by the movement of the shutter that opens the mold opening is separated from the intermediate core. As a result, a sand removal hole is formed in the intermediate core. Therefore, the intermediate core having a hollow portion can be formed by discharging unfired sand from the sand removal hole.
Further, by closing and closing the sand removal hole on the second molding surface, a bottom portion without an opening can be formed to form a sealed hollow sand core, whereby a second stage molding can be performed.
Thus, the first stage molding and the second stage molding can be performed continuously without reversing the mold.
Therefore, the opening and closing of the mold opening, the formation of the sand removal hole, and the closing of the sand removal hole can be performed continuously by the shutter, and even if a vertically divided mold that cannot be reversed or rotated is used, it is advantageously hollow. You can mold sand cores.

Front view of hollow sand core molding apparatus according to the first embodiment Plan view of the hollow sand core molding device Cross section of mold in the above device The enlarged plan view which shows the cavity part of the lower mold in the above-mentioned metallic mold A perspective view of a shutter opening / closing mechanism in the above apparatus Cross-sectional views of the intermediate core formed by the above device and the completed hollow sand core The figure explaining operation | movement of the shutter in the said apparatus. The figure explaining the molding process of the hollow sand core in 1st Example Enlarged partial sectional view according to another embodiment A perspective view of a shutter opening and closing mechanism according to another embodiment. The figure explaining the molding process of the hollow sand core which concerns on another Example

An embodiment configured as a molding apparatus for forming a hollow sand core of an oil jacket cast into a hollow shape will be described based on the drawings.
1 to 8 show a first embodiment. 1 is a front view of a hollow sand core molding apparatus, FIG. 2 is a plan view of the molding apparatus, FIG. 3 is a sectional view of a mold for molding a hollow sand core, and FIG. 4 is a cavity part of a lower mold. FIG. 5 is a perspective view of the shutter opening / closing mechanism. In the following description, the respective upper and lower directions coincide with the upper and lower directions of the drawing in FIG.
In these drawings, the hollow sand core molding apparatus 10 includes a mold 10 a, a shutter 15, and a shutter opening / closing mechanism 16.

The mold 10a is divided into an upper mold 11 and a lower mold 12, and has a horizontal split structure with a horizontal split surface. A mold opening 17 that is opened and closed by a shutter 15 is provided at the bottom of the lower mold 12. Yes.
The shutter 15 is moved back and forth by a shutter opening / closing mechanism 16 disposed on the side of the lower mold 12 to open / close the mold opening 17. The movement of the shutter 15 toward the lower mold 12 is called forward, and the movement of the shutter 15 in the reverse direction is called backward. The position of the shutter 15 indicated by the solid line in FIG. 1 is the retracted position, and the position indicated by the phantom line is the advanced position.

As shown in FIG. 6, the core formed in the mold 10a includes an intermediate core 36 formed by the first stage molding, and a completed hollow sand formed by the second stage molding. It consists of a child 38. Each includes a solid thin portion 32 and a hollow thick portion 34 integrally. The thin-walled portion 32 forms a hollow portion in a main body portion of an oil jacket (not shown), and the thick-walled portion 34 forms a hollow portion of a chain case provided integrally with the oil jacket. In addition, thin wall and thick wall are relatively expressing the size of each part in the outer shape of the core.

FIG. 6A shows a cross section of the intermediate core 36. The intermediate core 36 has an outer shape portion obtained by baking and hardening the core sand, but a hollow portion is formed by the waste sand from the pre-sand discharge sand filled with unfired sand. It includes up to the state after sand removal in which the sand removal hole is not blocked and the hollow portion is opened. Even if the sand removal is completed, since the hollow portion 34a is opened by the sand removal hole 33, the intermediate core 36 must be closed by the second stage molding, The core of

Around the sand removal hole 33, a peripheral portion 33 a forming a part of the bottom portion of the thick portion 34 is formed. By forming the sand discharge hole 33, the unfired sand 30 a in the thick part 34 is discharged from here, and a hollow part 34 a is formed in the thick part 34. The illustrated state is a state in which the unfired sand 30a is discharged from the sand discharge hole 33, and the hollow portion 34a is expanding due to this discharge.

FIG. 6B shows a cross section of the hollow sand core 38. The hollow sand core 38 has a hollow portion 34 a sealed by a bottom portion 35. The bottom part 35 is formed as a thing without an opening by integrating the closing part 33b which closed the sand removal hole 33 with the peripheral part 33a.
In the illustrated state, the closed portion 33b and the thick portion 34 such as the peripheral portion 33a are hatched differently, but this is for convenience in order to clearly show the closed portion 33b. 34 is a portion to be shown by the same hatching. Similarly, although the sand removal hole 33 is also shown by a solid line, this is also convenient, and is actually a line that disappears and cannot be seen due to the formation of the closing portion 33b. Moreover, FIGS. 7-9 and 11 are displayed similarly.

The bottom portion 35 is formed by forming an incomplete hollow state in which the hollow portion 34a is not sealed by the sand removal hole 33 provided due to the need for sand removal in an intermediate process, and then the sand removal hole 33 is formed by the closing portion 33b. By closing, it returns to a completely sealed hollow structure. In this sense, closing the sand removal hole 33 is called restoration of the hollow shape.

Hereinafter, the structure of the mold 10a and the shutter 15 will be described with reference to FIG. The upper mold 11 moves up and down by an opening / closing mechanism (not shown), and when it is lowered and closed, it overlaps the lower mold 12 to form a cavity 19 that forms a closed space inside.
The cavity 19 is integrally provided with a thin mold part 19 a that forms the thin part 32 of the hollow sand core 38 (intermediate core 36) and a thick mold part 19 b that forms the thick part 34.
The thin mold part 19a is a space having a relatively small vertical width in FIG. The thick molding part 19b is a space whose vertical width is relatively large due to the space expanded downward in the drawing.

The upper mold 11 includes an upper recess 11a that is opened downward. The lower mold 12 includes a lower recess opened upward, and the lower recess includes a shallow recess 12a and a deep recess 12b. A thin mold part 19a is formed by a part of the upper concave part 11a and the shallow concave part 12a, and a thick mold part 19b is formed by another part of the upper concave part 11a and the deep concave part 12b.
In the cross section shown in FIG. 3, the deep concave portion 12 b that forms the thick-walled mold portion 19 b has a tapered hole shape that extends downward, and a lower end of the deep concave portion 12 b that opens downward at the bottom of the lower mold 12. A mold opening 17 (see FIG. 4) is provided. The mold opening 17 communicates with the cavity 19.

The mold opening 17 is opened and closed by a shutter 15 that moves forward and backward under the lower mold 12. The shutter 15 closes the mold opening 17 when the shutter 15 moves forward (arrow C direction) by the shutter opening / closing mechanism 16 (FIG. 1) and reaches the forward position (shown state). On the contrary, when the shutter 15 moves backward (arrow A direction) from this position, the mold opening 17 is opened.

The shutter 15 has a first molding surface 21 in which a recess 20 corresponding to the mold opening 17 is formed, and a second molding surface 22 which is the opposite surface.
The recess 20 communicates with the cavity 19 through the mold opening 17 to form a sand removal chip 37 (see FIG. 6A). The sand removal chip 37 is also a part in which a part of the intermediate core 36 (a part of the bottom of the thick part 34) is integrally projected into the recess 20, and has an appearance corresponding to that in which the recess 20 is filled. None, and then removing the sand removal tip 37, a sand removal hole 33 (same as above) is formed at the bottom of the thick portion 34. The sand discharge hole 33 is formed inside the mold opening 17.

The second molding surface 22 is for forming a closed surface that covers the mold opening 17 and the sand discharge hole 33 and forms a bottom portion 35 (see FIG. 6B) that closes the sand discharge hole 33. In this example, it is a flat surface.
The shutter 15 can be turned upside down by rotating 180 °, and both the first molding surface 21 and the second molding surface 22 can close the mold opening 17.

An upper portion of the upper mold 11 is provided with a long blow hole 11b in the vertical direction. The blowing port 11 b is provided separately from the mold opening 17, its lower end communicates with the cavity 19, and its upper end communicates with the blow head 13 placed above the upper mold 11. Core sand 30 is blown from the blow head 13 into the cavity 19 through the blow port 11b. At this time, the mold opening 17 is closed in advance by the first molding surface 21 of the shutter 15. If necessary, the core sand 30 that is in the blow head 13 is referred to as green sand, and the sand that has been filled into the cavity 19 but has not yet been fired is referred to as unfired sand 30a. .

The unfired sand 30a filled in the cavity 19 is fired by heating the unfired sand 30a for a predetermined time with the upper mold 11, the lower mold 12 and the shutter 15 being set at a predetermined temperature. This is performed by curing the inner surface to a predetermined thickness, and a thin portion 32 and a thick portion 34 are formed in the cavity 19. It is preferable that the mold and the shutter 15 are heated to a predetermined temperature before filling with the core sand.
At this time, since the surfaces of the upper concave portion 11a and the shallow concave portion 12a are relatively close to each other, the core sand filled in the thin molded portion 19a is mostly baked. The molding part 19a becomes a solid part.

On the other hand, the thick wall portion 34 is formed inside the thick wall molding portion 19b, but the thick wall molding portion 19b has a core sand filled in the thick sand portion 19b on the surface side along the inner surface of a mold or the like. Although fired by heating for a certain time, the inner side (core side) is not fired and remains uncured as unfired sand 30a. Therefore, after that, when the shutter 15 is opened and the mold opening 17 is opened, the sand is discharged so that the unburned sand 30a is discharged from the sand discharge hole 33 formed at the bottom of the thick portion 34 to the outside. The inside of the meat part 34 becomes hollow (see (a) of FIG. 6).
At the time of sand discharge, the vibrator 14 (see FIG. 1) provided in the vicinity of the mold opening 17 is operated to prompt the discharge of the unfired sand 30a.

As shown in FIG. 4, the lower mold 12 has a shallow concave portion 12a in a substantially rectangular shape in plan view, and a deep concave portion 12b is continuously provided on the shutter opening / closing mechanism 16 (FIG. 1) side at one end portion in the long side direction. ing. Further, a plurality of push pins 18 are provided at the bottoms of the shallow recess 12a and the deep recess 12b (only a part of the sign instructions). Of these, the two extruding pins 18 indicated by reference numerals are located in the vicinity of the mold opening 17 and if the shutter 15 advances to the position of the extruding pin 18, this and the extruding pin 18 interfere with each other. Therefore, it becomes difficult to install the push pin 18. However, the push pin 18 at this position is extremely important for maintaining the quality at the time of releasing, and it is difficult to change the installation position of the push pin 18.

The shutter 15 in this example has a structure that allows the forward position to be in front of the push pin 18, and the shutter opening / closing mechanism 16 other than the shutter 15 is disposed on the outer side of the lower mold 12, so The mechanism 16 is prevented from interfering with the push pin 18 so that the push pin 18 can be installed at an optimum position.
In addition, in the plan view shown in FIG. 4, the concave portion 20 that opens to the first molding surface 21 of the shutter 15 can be seen inside the mold opening 17. The opening edge of the recess 20 has a slightly similar shape slightly inside the mold opening 17, and there is a predetermined interval between the lower end of the mold opening 17 and the opening upper edge of the recess 20.

Hereinafter, the shutter opening / closing mechanism 16 will be described in detail.
As shown in FIG. 5, the shutter 15 is attached to the tip of the spline shaft 24 by the shutter head 23 and can move forward and backward integrally with the spline shaft 24.
Further, the shutter 15 is rotatable around the axis line integrally with the spline shaft 24 that is rotated by the operation of the reversing actuator 26.

The spline shaft 24 in this example is a hexagonal spline shaft having a hexagonal cross section. However, a plurality of spline grooves may be formed in parallel in the length direction.
The spline shaft 24 is supported by an outer cylinder 25 so as to be movable back and forth in the axial direction, and is driven forward and backward by a cylinder device (not shown).
The outer cylinder 25 and the reverse actuator 26 are supported by a pair of parallel frames 29. The frame 29 has a tip attached to the lower mold 12 and extends laterally from the lower mold 12 (see FIG. 2).

As shown in FIG. 1, the shutter 15 moves forward and backward between a forward position just below the mold opening 17 and a backward position that protrudes outward from the lower mold 12 as the spline shaft 24 advances and retreats. The cylinder that drives this forward / backward movement is controlled by control means (not shown).
The spline shaft mechanism for moving the shutter 15 forward and backward may be replaced with a ball screw / nut mechanism or the like.
A recess 12c into which the shutter head 23 enters is formed in the vicinity of the mold opening 17 of the lower mold 12, and when the shutter 15 closes the mold opening 17, the shutter head 23 contacts the side wall of the recess 12c. The shutter 15 is positioned at the forward movement position.

As shown in FIGS. 5 and 1, the outer cylinder 25 is provided with a cross-sectional outline shape (hexagon) of the spline shaft 24 and a hexagonal hole 25 a that substantially matches the size and through which the spline shaft 24 passes. Yes.
For this reason, the spline shaft 24 can rotate integrally with the outer cylinder 25 and can slide in the axial direction. Further, when the outer cylinder 25 is rotated by the reversing actuator 26, the outer cylinder 25 rotates integrally with the outer cylinder 25.

The reversing actuator 26 includes a motor 27 and a drive gear 28, and the drive gear 28 meshes with an external gear 25 b (FIG. 1) provided at one end of the outer cylinder 25.
When the drive gear 28 is rotated by the motor 27, the outer cylinder 25 integrated with the external gear 25b rotates, and the spline shaft 24 is rotated integrally around the axis.

As the spline shaft 24 rotates, the shutter 15 also rotates together. Therefore, when the shutter 15 rotates 180 °, the motor 15 is stopped and the rotation of the outer cylinder 25 is stopped, so that the shutter 15 is turned upside down.
The rotation of the drive gear 28 is controlled by control means (not shown) provided in the reversing actuator 26.

Next, the structure of the intermediate core 36 and the hollow sand core 38 and the method of using the shutter 15 will be described.
The shutter 15 performs the first-stage molding using the first molding surface 21 to form the intermediate core 36, and then forms the hollow sand core 38 using the second molding surface 22 obtained by inverting the shutter 15. The second stage molding is performed.

FIG. 7 is a view for explaining a method of using the first molding surface 21 and the second molding surface 22 of the shutter 15, and the first stage molding using the first molding surface 21 in (a), (b) and (c). , (D), (e), and (f) show the second stage molding using the second molding surface 22. (A) And (d) is the figure which expanded the deep recessed part 12b and the mold opening 17 vicinity part, (b) and (e) are the expanded sectional views of the shutter 15, (c) and (f) are the sand removal holes 33. It is an expanded sectional view of the neighborhood.
First, when using the first molding surface 21, as shown in (b), the first molding surface 21 is in a state (first state) facing upward in the figure, and in this state, as shown in (a), The first molding surface 21 is brought into contact with the lower surface of the lower mold 12 near the mold opening 17 to close the mold opening 17.

Since the unfired sand 30a filled in the cavity 19 is also filled into the thick mold part 19b and the concave part 20, when the lower mold 12 and the shutter 15 are heated, the surface of the thick mold part 19b and the inside of the concave part 20 are filled. A hardened layer 31 is formed along the surface, and the hardened layer 31 becomes a thick portion 34 along the deep concave portion 12 b and a sand removal tip 37 having a substantially cup-shaped cross section formed in the concave portion 20. However, the core sand on the inner side of the hardened layer 31 in the thick mold part 19b and the concave part 20, that is, the core side part, remains the unfired sand 30a.

Further, the recess 20 is located inside the mold opening 17, and the opening area at the upper end of the recess 20 is smaller than the opening area at the lower end of the mold opening 17 (see FIG. 4). The peripheral portion 33a is formed as a part of the bottom portion around the upper edge of the opening of the recess 20 and inside the mold opening 17. The peripheral portion 33a surrounds the upper edge of the opening of the recess 20 and continues to the upper end of the sand removal chip 37 formed in the recess 20 along the inner wall surface thereof. The sand removal tip 37 protrudes downward from the peripheral portion 33a in a step shape on the lower end central side of the thick portion 34. The opening area at the upper edge of the opening of the recess 20 is set to a size that is necessary and sufficient for discharging the unfired sand 30a in a predetermined time. The size is easy to cut.

Therefore, when the shutter 15 is moved backward, the upper end portion of the sand removal tip 37 is cut from the connection portion with the peripheral portion 33a and separated from the lower end of the thick portion 34, and as shown in FIG. A sand discharge hole 33 is opened at the lower end of the. This sand removal hole 33 is formed inside the mold opening 17 and forms an opening that communicates the inside and outside of the thick portion 34, so that the unfired sand 30 a in the thick portion 34 is discharged from here. Further, since the upper end portion of the sand removal tip 37 is continuous with the peripheral portion 33a and is relatively small, the sand discharge tip 37 is easily cut from the peripheral portion 33a by the movement of the shutter 15.

The product obtained in this way is an intermediate core 36 shown in FIG. The intermediate core 36 has a hollow portion 34a formed in the thick portion 34 and is similar to the completed hollow sand core 38 (see FIG. 6B). Since the sand removal chip 37 is separated from the bottom, a sand discharge hole 33 is formed at the lower end of the thick portion 34 and is not sealed only here. The sand removal hole 33 is finally closed during casting using the hollow core, and the hollow portion is required to be completely sealed, and is sealed by the second molding surface 22.

When the second molding surface 22 is used, the sand removal hole 33 is blocked by the second molding surface 22 of the shutter 15 as shown in FIG. 7 (d) following the sand removal in FIG. 7 (c). . At this time, as shown in FIG. 7E, the shutter 15 is turned upside down so that the second molding surface 22 faces upward and the concave portion 20 faces downward. In this state, the second molding surface 22 was brought into contact with the lower surface of the lower mold 12 in the vicinity of the mold opening 17 to cover the mold opening 17 and the sand discharge hole 33, and the sand was left in the thick portion 34 without being discharged. Unbaked sand 30a enters the sand removal hole 33 and fills it.

Since the shutter 15 and the lower mold 12 are heated, the unfired sand 30a that has entered the sand discharge hole 33 is cured by this heating and becomes a closed portion 33b that closes the sand discharge hole 33. Since the closing portion 33b is continuously integrated with the inner peripheral portion of the peripheral portion 33a, the bottom portion 35 is formed by the peripheral portion 33a and the closing portion 33b. As a result, as shown in (f), the bottom part of the thick part 34 becomes the bottom part 35 with the sand removal hole 33 closed and no opening part.
Thereby, the demolded product becomes the hollow sand core 38 of the finished product shown in FIG.

Next, the whole molding method of the hollow sand core will be described. FIG. 8 is a schematic cross-sectional view of a mold or a part thereof for each molding process.
First step of blowing core sand into the cavity in FIG. 8 (a), second step of firing part of the core sand in (b) and (c), and moving the shutter in the A direction to (d). A third step of (retreating) and discharging sand, a fourth step of inverting the shutter and discarding the discharged sand chip, and (f) showing a fifth step of forming a bottom without a sand discharging hole are shown. The first to third steps correspond to the first stage modeling, and the fourth and fifth processes correspond to the second stage modeling.

First, in the first step shown in (a), the upper die 11 and the lower die 12 are closed in the vertical direction, and the cavity 19 is formed inside. Further, the shutter 15 in the first state is advanced below the lower mold 12 to close the mold opening 17 with the first molding surface 21. At this time, the mold opening 17 communicates with the recess 20.
Further, the blow head 13 is placed above the upper mold 11, the inside is communicated with the blowing port 11 b, and the core sand 30 (raw sand) is filled into the blow head 13.
In this state, the upper die 11, the lower die 12, and the shutter 15 are heated to a predetermined temperature in advance, and a predetermined amount of core sand 30 is blown and filled into the cavity 19 from the blow head 13 through the blow port 11b. Thereafter, the blowing of core sand is terminated.

In the second step (b), the heating of the upper mold 11, the lower mold 12, and the shutter 15 is continued for a predetermined time. Thereby, the hardened layer 31 in which a part of the core sand 30 is hardened to a predetermined thickness is formed along the surfaces of the upper concave portion 11a and the shallow concave portion 12a. A peripheral portion 33 a is also formed on the surface of the shutter 15. Further, in the recess 20, a part of the core sand 30 is hardened along the inner surface thereof, thereby forming a substantially cup-shaped container opened upward, and a substantially truncated cone shape with the upper side expanded. A sand chip 37 is integrally formed. The core sand inside the hardened layer 31 remains unfired sand 30a and has fluidity.
The heating conditions regarding the heating temperature and heating time of the core sand 30 in this step are set in advance so that the hardened layer 31 has a predetermined thickness.

(C) is an enlarged view showing the vicinity of the mold opening 17 formed in the second step.
In the thick molding part 19b, the hardened layer 31 formed along the surface of the deep recessed part 12b forms a peripheral part 33a on the surface of the shutter 15, and further extends into the recessed part 20 in a stepped manner to form a sand removal chip 37. The hardened layer 31 in the deep concave portion 12b forms a thick portion 34, but the lower end is closed with a sand removal tip 37.
If the shutter 15 is moved backward in the direction of arrow A in this state, the third step shown in FIG.

As shown in (d), when the shutter 15 is retracted and the mold opening 17 is opened, the sand removal chip 37 is moved separately from the peripheral portion 33a that forms the lower end of the thick portion 34 together with the shutter 15. The sand discharge hole 33 is formed inside the peripheral portion 33a at the lower end of the thick wall portion 34, and the unfired sand 30a in the thick wall portion 34 is discharged downward (in the direction of arrow D) through this, The thick part 34 becomes hollow. In the cavity 19, an intermediate core 36 having a hollow thick portion 34 shown in FIG.

In this sand removal step, the vibrator 14 (FIG. 1) is operated to vibrate the lower mold 12 and the like, thereby facilitating smooth discharge of unfired sand.
The operation of the vibrator 14 is continued for a predetermined time, and is stopped for a short time immediately before the fifth step (f).
The sand discharge time is set so that the unburned sand in the cavity 19 is not completely discharged and a small amount remains in the thick portion 34. The remaining amount of unfired sand is an amount necessary and sufficient to form the bottom 35 of the hollow sand core 38 shown in FIG.

In the fourth step of (e), when the retracted shutter 15 is rotated 180 ° around the axis of the shutter 15 in the forward / backward direction (coincided with the axis of the spline shaft 24) as indicated by arrow B, the shutter 15 moves up and down. Is inverted, the second molding surface 22 is upward, the first molding surface 21 is downward, and the concave portion 20 faces downward, so that the sand removal chip 37 naturally falls from the concave portion 20 downward (arrow D direction) and is discarded. Is done.
At this time, since the side surface of the sand removal tip 37 is tapered so as to expand downward in the illustrated state, the shape becomes easy to remove and falls smoothly downward.

Subsequently, the shutter 15 in the inverted state is advanced as indicated by an arrow C, and the mold opening 17 and the sand removal hole 33 are closed. The closing timing is set so that the entire amount of unfired sand is not discharged and a sufficient amount remains to fill at least the sand removal hole 33.
In this step, the inverted second molding surface 22 of the shutter 15 closes and closes the mold opening 17 and the sand removal hole 33. At this time, since the second molding surface 22 is a flat closed surface, the second molding surface 22 is in close contact with the lower surface of the peripheral portion 33 a and closes the sand removal hole 33.

When the operation of the vibrator 14 is resumed, a little amount of unfired sand remaining inside the thick portion 34 of the intermediate core 36 forms a sand discharge hole 33 on the second molding surface 22 inside the mold opening 17. It falls so that it may fill, and it hardens | cures on the 2nd molding surface 22 heated, and forms the closing part 33b. The closing portion 33b forms a bottom portion 35 that is continuously integrated with the peripheral portion 33a.
The bottom part 35 is flush with the lower surface of the lower mold 12, the mold opening 17 and the sand removal hole 33 are completely closed, the sand removal hole 33 is closed, and is restored to a state without an opening. .

Next, the operation and effect of the present embodiment will be described.
As shown in FIG. 3 and the like, the hollow sand core molding apparatus 10 is provided with a core sand mold opening 17 at a lower portion of a mold 10a and a shutter 15 for opening and closing the sand discharge hole. ,
The mold 10a is a horizontal split mold including an upper mold 11 and a lower mold 12 that are divided in the vertical direction, and a mold opening 17 is provided at a lower portion of the lower mold 12,
The shutter 15 has a recess 20 on the surface, a first molding surface 21 that closes the mold opening 17 in a state where the recess 20 communicates with the mold opening 17, and a flat surface that covers the mold opening 17 in a flat shape. And a second molding surface 22 having (corresponding to an example of a blocking surface in the present invention).

As a result, the mold opening 17 is closed at the first molding surface 21 of the shutter 15 to fire the core sand 30, and then the shutter 15 is opened to separate the sand removal chip 37 formed in the recess 20. An intermediate core 36 having a sand discharge hole 33 opened in the vicinity of the mold opening 17 is formed, and sand can be discharged by discharging the unfired sand from the sand discharge hole 33.
Further, the closed portion 33b is formed by firing the unfired sand 30a that closes the mold opening 17 and the sand discharge hole 33 and fills the sand discharge hole 33 with the flat surface of the second molding surface 22 of the shutter 15. By forming the bottom portion 35 that closes the hole 33, the hollow portion 34a is sealed, and a hollow sand core 38 having no opening can be formed.

Therefore, the shutter 15 can continuously open and close the mold opening 17, form the intermediate core 36, form the sand discharge hole 33, and discharge the sand and the sand discharge hole 33 by the closing portion 33 b. And a special process for forming the sand removal hole 33 is not required, so that the mold 10a can be reversed or rotated even in a vertically divided mold that is difficult to flip or rotate the mold 10a. The hollow sand core 38 in which the unfired sand 30a is removed and the sand removal hole 33 is closed can be formed without damaging.

In particular, by reversing the relatively small shutter 15, the hollow sand core 38 can be easily formed without reversing the entire large mold.
In addition, since the sand removal tip 37 can be discarded at the same time by reversing the shutter 15, a special mechanism and labor for disposal of the sand removal tip 37 can be dispensed with.

At this time, by providing the first molding surface 21 on one of the upper and lower surfaces of the shutter 15 and the second molding surface 22 on the other surface, one shutter 15 is turned upside down, and the upper and lower surfaces of the shutter 15 are Since the first molding surface 21 and the second molding surface 22 can be reversed, the structure of the shutter 15 can be simplified and made compact.

The shutter opening / closing mechanism 16 for opening / closing the shutter 15 includes an advance / retreat mechanism for moving the shutter 15 forward / backward with respect to the mold opening 17 and a reversing mechanism for reversing the shutter 15 up / down. Can be done easily. In addition, the amount of advancement of the shutter 15 is reduced by moving the shutter 15 forward and backward from the outer side of the lower mold 12 and reversing the outer side thereof, and the shutter opening / closing mechanism 16 is disposed on the side of the lower mold 12. In addition, a compact design that does not interfere with the arrangement of the extrusion pin 18 in the mold 10a can be achieved, and the extrusion pin 18 can be arranged at an optimum position.

Furthermore, when the shutter 15 is reversed and the first molding surface 21 faces downward, the concave portion 20 formed in the first molding surface 21 has a tapered shape that opens downward and expands downward. By doing so, simply by reversing the shutter 15 so that the second molding surface 22 faces upward, the first molding surface 21 faces downward and the recess 20 also faces downward. It is discarded by natural fall from 20 by its own weight. In addition, since the wall surface of the recess 20 and the side surface of the sand removal tip 37 along this form a tapered shape with an upper concavity when reversed, the sand removal tip 37 falls smoothly under its own weight.
Therefore, it is possible to eliminate the need for a special process or device for the disposal of the sand removal chip 37, and the disposal of the sand removal chip 37 is facilitated.

Since the vibrator 14 (vibration device) is provided in the vicinity of the mold opening 17 of the mold 10a, vibration can be intermittently applied to the mold 10a into which the core sand 30 has been blown.
Accordingly, the first molding surface 21 is moved in the horizontal direction after firing for a certain period of time to be in an open state, and the vibrator 14 is operated when sand is discharged from the sand removal hole 33 formed in the vicinity of the mold opening 17. Sand removal can be promoted by applying vibration.

Further, after vibrating for a certain period of time, the vibration is temporarily stopped before the mold opening 17 and the sand removal hole 33 are closed by the second molding surface 22 reversed and replaced, and the second molding surface 22 is closed. By vibrating again, the unburned sand 30a remaining inside the thick portion 34 of the intermediate core 36 is dropped into the sand discharge hole 33 covered with the second molding surface 22 to fill the sand discharge hole 33. Since it can be made into the closed part 33b by baking in a state, the bottom part 35 which closed the sand removal hole 33 by the closed part 33b can be formed reliably.

Next, another embodiment will be described with reference to FIGS.
9 and 11 are schematic enlarged cross-sectional views of the mold opening 17 and the shutter mechanism portion as in the previous embodiment. In addition, a common code | symbol is used for a common part with a previous Example.
FIG. 9 is a view corresponding to FIG. 8B showing a second step of firing the core sand to form the intermediate core 36. Since the structure of the mold excluding the shutter opening / closing mechanism 40 is the same as that of the previous embodiment, the description thereof is omitted.

The shutter opening / closing mechanism 40 includes a first shutter 41, a second shutter 42, and a third shutter 43. Each shutter is interlocked as will be described later.
In contrast to the previous embodiment, the upper surface 41a of the first shutter 41 corresponds to the first molding surface 21, and the recess 20 is a sand removal tip hole 45 that is a through hole in the vertical direction. When closing the mold opening 17, the upper surface 41 a of the first shutter 41 is in contact with the lower surface of the lower mold 12 around the mold opening 17 in a state where the sand removal chip hole 45 communicates with the mold opening 17. .
The upper surface 42a of the second shutter 42 forms a flat closed surface corresponding to the second molding surface 22, and the closed surface comes into contact with the lower surface of the lower mold 12 around the mold opening 17, so that the flat closed surface becomes the mold. The opening 17 is covered and closed.

The first shutter 41 and the third shutter 43 are used in a process of forming the intermediate core 36 (see FIG. 6A), and the third shutter 43 is a process of discarding the sand discharge chip 37. The second shutter 42 is used in the process of forming the bottom 35 and forming the hollow sand core 38 (see FIG. 6B).

In the step of forming the intermediate core 36 shown in FIG. 9 (second step), the mold opening 17 is closed by the first shutter 41 and the third shutter 43. At this time, the sand removal tip hole 45 of the first shutter 41 communicating with the mold opening 17 is closed by the third shutter 43 overlapping the first shutter 41.
The second shutter 42 is moved integrally with the first shutter 41 by the connecting member 44, and in this step, is moved below the lower mold 12 away from the mold opening 17 in the forward direction. It is assumed that the movement of the first shutter 41 in the direction closing the mold opening 17 is forward, the reverse direction is backward, and the moving directions are forward and backward directions.

A thick portion 34 is formed by the hardened layer 31 inside the deep recess 12b, and a sand removal chip 37 is continuously formed at the lower end portion via a peripheral portion 33a. The peripheral portion 33a surrounds the upper opening opening edge of the sand removal tip 37, forms part of the bottom of the thick portion 34, and is formed in the sand removal tip hole 45 of the first shutter 41 closed by the third shutter 43. The sand removal chip 37 is continuous. The sand removal tip 37 is formed by firing the core sand that has entered the sand removal tip hole 45 from the mold opening 17, and is formed integrally with a part of the bottom of the thick portion 34. 45 is a protrusion protruding into 45.

Accordingly, the mold opening 17 is closed by the first shutter 41 and the third shutter 43, and the sand discharge tip hole 45 of the first shutter 41 is closed by the third shutter 43, whereby the sand discharge tip hole 45. A sand removal tip 37 is formed inside.
The sand removal tip hole 45 is a hole penetrating the first shutter 41 in the vertical direction. The hole diameter on the lower surface side is larger than the hole diameter on the upper surface side. It has a substantially truncated cone shape. The sand removal chip 37 formed on the inner side has the same shape, and has a bottom shape but an open top surface, and is hollow and has a substantially truncated cone shape with an upward concavity.

FIG. 10 is a perspective view showing the shutter opening / closing mechanism 40.
As shown in this figure, the first shutter 41 and the second shutter 42 are connected by a connecting member 44 so as to always maintain a predetermined interval, and the first shutter 41 is moved forward and backward by a main rod 46. The main rod 46 is advanced and retracted by appropriate means such as an air cylinder (not shown).

A third shutter 43 is slidably attached to the main rod 46 by a sub rod 47. The sub rod 47 is also advanced and retracted by appropriate means such as an air cylinder. The third shutter 43 overlaps the first shutter 41 at the forward position, and the upper surface 43a has a flat plate shape that closes the sand removal tip hole 45.
When the main rod 46 moves forward / backward, the third shutter 43 moves integrally at its forward position (that is, the position overlapping the first shutter 41). At the retracted position of the main rod 46, the third shutter 43 is further retracted by the sub rod 47 and moved from the first shutter 41 in the retracting direction to open the shutter 15.

In addition, the first shutter 41 is moved back and forth in the most advanced first position (see FIG. 11A), the intermediate second position retracted about half (see FIG. 11B), and the most retracted position. There is a third position (see FIG. 11C).
In the first position, the first shutter 41 and the third shutter 43, which overlap vertically, close the mold opening 17, and in the second position, both the first shutter 41, the third shutter 43, and the second shutter 42 overlap vertically. In both cases, the mold opening 17 is opened. In the third position, only the second shutter 42 closes the mold opening 17, and the first shutter 41 and the third shutter 43 that overlap vertically are positioned away from the lower mold 12 laterally.

Next, a method for forming a hollow sand core according to the present embodiment will be described.
FIG. 11 shows a second step of forming the intermediate core including the thick portion 34 in (a), a third step of discharging sand in (b), and a second step of forming the bottom 35 of the thick portion 34 in (c). 4th process and the 5th process which discards the sand removal chip | tip 37 to (d) are shown. The first step is a core sand blowing step, which is the same as in the previous embodiment, and a description thereof will be omitted.

First, in the second step (a), the first shutter 41 closes the mold opening 17, and the third shutter 43 closes the lower opening of the sand discharge tip hole 45 of the first shutter 41.
For this reason, the hardened layer 31 is formed inside the thick molding part 19b to form the thick part 34, and the sand removal chip 37 is formed in the sand removal chip hole 45. Sand removal tips 37 are continuously formed through the peripheral portion 33a (see FIG. 9).

In the third step shown in (b), the first shutter 41, the second shutter 42, and the third shutter 43 are all moved together in the direction indicated by the arrow A, and the first shutter 41 is displaced from the mold opening 17. In the second position, the second shutter 42 is positioned forward from the mold opening 17 to open the mold opening 17. Due to the backward movement of the first shutter 41 and the third shutter 43, the sand removal chip 37 is cut from the peripheral portion 33 a at the bottom of the thick portion 34 to form a sand discharge hole 33. The calcined sand naturally falls in the direction of arrow D and is discharged, and the intermediate core 36 (see FIG. 6A) is formed.
At this time, the third shutter 43 remains under the first shutter 41, and the sand removal tip 37 is located in the sand removal tip hole 45.

In the fourth step shown in (c), in a predetermined state where the unburned sand is not completely discharged, each shutter is further retracted in the direction indicated by the arrow A, the first shutter 41 is set to the third position, and the second shutter 42 The mold opening 17 and the sand removal hole 33 are closed by the upper surface 42a.
Thereby, the unburned sand remaining in the thick wall portion 34 falls into the sand discharge hole 33 inside the mold opening 17, fills the sand discharge hole 33 and is stacked on the upper surface 42 a of the second shutter 42. A closed portion 33b that is baked and hardened to close the sand removal hole 33 is formed, and the closed portion 33b and the peripheral portion 33a are continuously integrated to form a bottom portion 35 having no opening, and a hollow sand core 38 ((b in FIG. )) Is obtained.
At this time, the third shutter 43 still remains under the first shutter 41, and the sand removal tip 37 is located in the sand removal tip hole 45.
Note that the vibration by the vibrator 14 is applied at the same timing as in the previous embodiment.

In the fifth step (d), only the third shutter 43 is further retracted in the direction indicated by the arrow A, and the lower portion of the sand removal chip hole 45 is opened by shifting the third shutter 43 from the first shutter 41.
As a result, the sand removal tip 37 is naturally dropped from the sand removal tip hole 45 in the direction of arrow D by its own weight and discarded.
At this time, since the sand removal tip hole 45 is a tapered hole having a substantially truncated cone shape with an upper constriction, the sand removal tip 37 can be smoothly dropped.
In addition, this 5th process may be made to open the sand removal chip | tip hole 45 by retracting the 3rd shutter 43 simultaneously with closing the metal mold | die opening 17 with the 2nd shutter 42, without becoming independent from a 4th process.

In this way, the shutter opening / closing mechanism 40 can be configured without requiring a reversing mechanism as in the previous embodiment.
Therefore, the drive device for the shutter opening / closing mechanism 40 can be configured only by the cylinder mechanism that moves forward and backward in the opening / closing direction, and thus the configuration can be simplified.

In addition, this invention is not limited to embodiment, Various application and deformation | transformation are possible. For example, the target casting is not limited to an oil jacket, but can be applied to various other vehicles and other vehicle parts that require a hollow sand core.
Moreover, the thick part 34 does not necessarily need to be a cylindrical projecting part, and the mold opening 17 may be formed at the lowest part of the hollow sand core.

10: hollow sand core molding apparatus, 10a: mold, 11: upper mold, 11b: blow inlet, 12: lower mold, 12b: deep recess, 15: shutter, 16: shutter opening / closing mechanism, 17: mold opening, 19: cavity, 19b: thick molding part, 20: concave part, 21: first molding surface, 22: second molding surface, 32: thin part, 33: sand removal hole, 33b: closing part, 34: thick part 34a: hollow portion, 37: sand removal tip, 40: shutter opening / closing mechanism, 41: first shutter, 42: second shutter, 43: third shutter, 44: connecting member, 45: sand removal tip hole

Claims (7)

Provided in a mold provided with a cavity filled with thermosetting core sand, and an intermediate core (36) formed by hardening the outer shape of the cavity by firing the core sand; A shutter that opens and closes a sand discharge hole for forming a hollow portion by discharging the unfired sand inside;
Hollow sand core molding in which the hollow sand core (38) in which the sand removal hole is closed is formed by firing the unfired sand in which the sand removal hole is closed with the shutter and filling the sand removal hole. In the device
The mold (10a) is a horizontal split mold having an upper mold (11) and a lower mold (12) divided in the vertical direction,
A mold opening (17) communicating with the cavity is provided at a lower portion of the lower mold (12),
The shutter (15) opens and closes the mold opening (17), and has a first molding surface (21) provided with a recess (20) communicating with the cavity through the mold opening (17) when closed. )When,
A hollow sand core molding apparatus, comprising: a second molding surface (22) having a closing surface for closing the sand removal hole (33) and closing. The shutter (15) according to claim 1, wherein the first molding surface (21) is provided on one of the upper and lower surfaces, and the second molding surface (22) is provided on the other surface. Hollow sand core molding equipment. A shutter opening / closing mechanism (16) for opening and closing the shutter (15);
The shutter opening / closing mechanism (16) includes an advancing / retracting mechanism for advancing / retreating the shutter (15) with respect to the mold opening (17);
The hollow sand core molding apparatus according to claim 2, further comprising a reversing mechanism for reversing the shutter (15) up and down. When the shutter (15) is reversed and the first molding surface (21) is directed downward, the recess (20) formed in the first molding surface (21) is opened downward and downward. 4. The hollow sand core molding apparatus according to claim 3, wherein the hollow sand core molding apparatus has a taper shape that expands toward the front. The shutter has a first shutter (41) whose surface (41a) is the first molding surface;
A second shutter (42) having the surface (42a) as the second molding surface;
A third shutter (43) overlaid under the first shutter (41),
The first shutter (41) and the second shutter (42) are arranged in a line in the opening and closing direction,
The concave portion provided in the first molding surface can be communicated with the mold opening (17) through the first shutter (41), and is opened and closed at one end by the third shutter (43). The hollow sand core molding apparatus according to claim 1, wherein the hollow sand core is a through hole (45). A vibration device (14) that intermittently vibrates the mold (10a) into which core sand has been blown is provided in the vicinity of the mold opening (17) of the mold (10a). Item 6. A molding apparatus for a hollow sand core according to any one of Items 1 to 5. The recess (20) of the first molding surface (21) is located inside the mold opening (17) in plan view, and the opening area of the recess (20) is the opening of the mold opening (17). 2. The hollow sand core molding apparatus according to claim 1, wherein the molding apparatus is smaller than an area .

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