JPH049065Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a furnace for continuously firing molds, and more specifically, to a continuous furnace for firing molds that can automate the work of inserting vacuum casting molds into the furnace. This relates to firing furnaces.

[Conventional technology] The lost wax casting method creates a prototype with wax,
After coating the surface with molding sand mixed with a binder and drying it, it was heated to about 160℃ to melt the wax and create a hollow shell-shaped breathable mold, which was then fired at an even higher temperature. Something that pours molten metal,
It is known as one of the precision casting methods. However, the lost wax casting method has traditionally been labor-intensive and difficult to automate, resulting in extremely low production efficiency and product yield compared to other manufacturing methods, and high manufacturing costs.

On the other hand, the lost wax casting method disclosed in Japanese Patent Publication No. 52-38924 was developed by Hitchiner Co., Ltd., a major lost wax product manufacturer in the United States, and was named the "CLA method" by the initials of the inventor's name.
This is a new technology that is attracting attention in this field. Next, this CLA method will be briefly explained with reference to FIGS. 10a to 10d. In FIG. 10a, 100 is a molten metal tank, 101
is a chamber supported above it so that it can be raised and lowered freely, 1
03 is a mold made by firing foundry sand. In this case, the mold 103 connects the sprue 104 to the chamber 101.
It is set in the chamber 101 so as to protrude downward from the bottom opening 105 of the chamber 101 . and the chamber 10
1 is lowered as shown in Fig. 10b, and the sprue 1 is opened.
04 is immersed in the molten metal and the air inlet 106 is connected to a vacuum pump to reduce the pressure inside the chamber 101. Then, since the mold 103 is made in the shape of a breathable hollow shell, the pressure inside the mold 103 is reduced and the sprue 104
The mold is filled with molten metal.
Then, the chamber 101 is raised and once the molten metal in the product section has solidified, the reduced pressure is released, allowing only the unsolidified molten metal in the runner of the mold to flow out, making the runner section hollow. If this mold 103 is taken out and sanded, a product 107 can be taken out as shown in FIG. 10d. However, this lever
In the CLA method, after vacuuming the molten metal directly in the mold,
Since the molten metal that has entered the runner is returned to the molten metal bath and sucked into the next mold, the casting yield is over 70%, which is a significant improvement compared to the 35-40% achieved by the regular top-pouring method that uses a ladle. In addition, the molten metal is sucked under reduced pressure directly in the mold, so the flow of the metal is good.
It has various advantages, such as being able to integrally cast products with complex shapes and extremely thin walls, and improving quality because there is no contamination of the molten metal.

[Problems with conventional technology] However, the conventional lost wax casting method has the above problems.
The CLA method was still labor-intensive and required a great deal of effort. In other words, a mold made by coating with foundry sand has irregular outer diameter dimensions depending on the amount of sand adhered to it, and is extremely brittle, making it difficult to hold with a mechanical hand, which makes it difficult to hold during the firing process. In this case, loading the mold into the furnace required manual labor, which was especially labor-intensive.

[Means for Solving the Problems] Therefore, the present invention aims to save labor in casting work by making it possible to mechanize the charging of molds used in the above-mentioned CLA method, that is, the vacuum suction casting method, into the firing furnace. It is something to do. In order to achieve this purpose, the continuous firing furnace for molds of the present invention has an expanded diameter section formed at the upper end of the upper extension of the cylindrical part that forms the runner connected to the cavity, and a molten metal suction port at the lower end of the downward extension. The vacuum suction casting mold formed is fired, and a cylindrical ceramic support with a funnel-shaped upper end is fixed on the movable hearth, and a support plate that opens and closes on the ceiling wall and side wall of the furnace body, respectively. Open a charging port with a door and a side hole,
a charging device that grips the upper extension of the mold with a mechanical hand and transports the mold from the charging port onto the support stand in the furnace in a suspended state; and The present invention is characterized in that it is equipped with a guide device having a guide finger provided at the tip of an arm that enters laterally to align the downwardly extending portion of the mold with the upper end opening of the support base.

[Example] Next, an example of the continuous firing furnace of the present invention will be described with reference to FIGS. 1 to 9.

A furnace body 1 formed into a planar annular shape has a rotary hearth 2 supported on an annular pedestal 3 on its bottom surface. A roller 4 rotatably supports the rotary hearth via an annular pedestal 3. 5,
A water seal tank 5 is provided to close the gap on both sides of the rotary hearth 2 at the bottom of the furnace body 1 to prevent gas leakage. As shown in FIG. 3, a plurality of engagement pins 6, 6, . 7 is the engagement pin 6, 6
. . . to rotate the rotary hearth 2 intermittently in the direction of the arrow, and 8 is a stopper mechanism that similarly engages with the engagement pins 6, 6 . That is, the rotary drive mechanism 7 includes a drive body 12 equipped with rollers 11 so as to be slidable along guide rails 10, 10 disposed on the machine base 9 in the tangential direction of the rotation thereof, and the drive body 12 is a cylinder. 13, and a cylinder 14 is provided on the drive body 12 in a direction perpendicular to the guide rails 10, 10, and an engaging member 15 is provided on the cylinder 14. The cylinder 13 is moved forward and engaged with one of the engagement pins 6, 6, . . . in this state, and the cylinder 13 is contracted.
2, the rotary hearth 2 rotates in the direction of the arrow. The stopper mechanism 8 is provided with an engaging member 18 so as to be moved forward and backward by a cylinder 17 fixed on a support base 16, and the engaging member 18 is made to face the engaging pins 6, 6, . . . . Therefore, by disengaging the engagement member 18 from the engagement pins 6, 6, . . ., and contracting the cylinder 13 by engaging the engagement member 15 with the engagement pins 6, 6, . As a result, the rotating hearth 2 rotates by one pitch of the engaging pins 6, 6, . . . Subsequently, the engagement member 18 is engaged with the engagement pin 6, and the engagement between the engagement member 15 and the engagement pin 6 is released, and the cylinder 13 is released.
is extended, the engaging member 15 is returned to its original position, and then the engaging member 15 is engaged with the engaging pin 6 again.
In this way, the rotary hearth 2 is connected to the engaging pins 6, 6...
It is designed so that it can be rotated intermittently in the direction of the arrow for one pitch.

Two rows of support stands 20 are fixedly installed on the rotary hearth 2. The support stand 20 is made of ceramics, and is formed into a cylindrical shape with an upper end surface 21 opened in the shape of a funnel, and a ventilation hole 22 is provided in the peripheral wall. A charging port 23 is opened in a part of the ceiling wall of the furnace body 1, and an opening/closing door 24 is disposed in the charging port 23 so as to be movable by a cylinder 25. Reference numeral 26 denotes an extraction port opened in the ceiling wall of the furnace body 1, and an opening/closing door 27 is disposed thereon so as to be movable by the operation of a cylinder 28. Further, in the side wall of the furnace body portion where the charging port 23 is opened, a horizontal hole 30 is provided as shown in FIG.
has been established. 31 is an opening/closing door that opens and closes the horizontal hole 30, and 32 is a cylinder that moves the opening/closing door. 33, 33... are burners provided on the furnace side wall.

The vacuum suction casting mold 40 used in the CLA method has a cylindrical portion 40a forming a runner connected to a cavity of the product shape, an expanded diameter portion 40c formed at the upper end of an upper extension portion 40b, and a lower extension portion 40d. A molten metal suction port 40e is formed at the lower end of the molten metal.

This mold 40 is used by a transport robot 5 which is a charging device.
0 into the furnace from the charging port 23. The transport robot 50 is equipped with a mechanical hand configured as follows at the tip of an arm 51. That is, as shown in FIG.
3a, 54a, 53b, 53b are fixedly installed, and links 55a, 56a, 55b, 5 parallel to these, respectively.
6b, and a fitting 59a is pivotally supported at the tips of the links 55a and 56a via pins 57a and 58a, and a pin 57 is attached to the tips of the links 55b and 56b.
a connecting member 60a that pivotally supports the fitting 59b via the fittings 59b and 58b and is horizontal to the fittings 59a and 59b;
60b is fixed, and vertical connecting members 61a, 61b are suspended from the other ends of the connecting members 60a, 60b. On the other hand, the links 55a and 56b are linear, and a cylinder 62 is pivotally connected between the other ends with pins 63a and 63b. Also links 56a, 56b
is bent into a hook shape, and its other ends intersect, and a pin 64 fixed at one end of the intersection is loosely fitted into an elongated hole 65 formed at the other end. Therefore, when the cylinder 62 expands and contracts, the links 55a and 55b simultaneously swing symmetrically around the pins 53a and 53b, and the links 56a and 56b swing accordingly, causing the pins 53a, 54a, 57a, and 58a to
Parallelogram and pins 53b, 54b, 5 connecting
The parallelogram connecting 7b and 58b is similarly inclined symmetrically so that the connecting members 61a and 61b can contact in parallel. At the tips of the connecting members 61a and 61b, there are claw pieces 67a formed in a substantially V-shape in plan view.
67b are fixed substantially horizontally so that their expanded sides face each other. One tip portion 68 of this claw piece 67a
A cuts the lower half of the thickness. Also, the claw piece 67
One tip 69a of b cuts the upper half of its thickness, the other tip 68b cuts the lower half of its thickness, and the other tip 69b cuts the upper half of its thickness. It's being cut. When the claw pieces 67a and 67b are brought close together, the tip portion 6 as shown in FIG.
The tip portion 69a is superposed on top of the tip portion 6a.
The tip portions 69b are superimposed below 8b so that they intersect with each other and intersect with each other.

On the other hand, the arm 71 enters the furnace horizontally through the horizontal hole 30, and guide fingers 82a and 82b provided at the tip of the arm 71 guide the downwardly extending portion 40d of the mold 40 into the vertical hole of the support base 20. A cylinder 74 and a movable frame 75 that moves forward and backward by the cylinder 74 are provided on a frame 73 fixed outside the horizontal hole 30, and a cylinder 76 is further mounted on the movable frame 75.
A hollow pipe-shaped arm 71 is supported by trochanters 78, 78 and a roller 79 so as to be moved forward and backward by the cylinder 76, and is attached to the tip of the arm 71 as shown in FIG. A metal fitting 80 is fixed, and a pair of doglegged guide fingers 82a and 82b are pivotally supported on the mounting metal fitting 80 by pins 81a and 81b so as to be openable and closable.
Links 83a, 83b are provided at the base ends of 2a, 82b.
through pins 85a and 85b, respectively, and the links 83a and 83b are further connected to pins 86a and 86.
It is pivotally connected to the joint fitting 87 via b. The fitting 87 is fixed to the tip of a connecting rod 88 inserted into the arm 71, and the other end of the connecting rod 88 is attached to the arm 71.
It is connected to the piston rod of the cylinder 89 provided at the rear end of the cylinder. Therefore, when the connecting rod 88 moves forward or backward due to the operation of the cylinder 89, the guide finger 82
a and 82b move to open and close as shown by broken lines in the figure, and when closed, a closed ring is formed by both guide fingers. Note that the tip end 90a of one guide finger 82a has a lower half of its thickness cut off, and the tip end 90b of the other guide finger 82b has an upper half of its thickness cut off, so that it can be closed as shown in the figure. When completed, the tip portion 90a is configured to overlap the tip portion 90b.

However, now the mold 40 has an upper extension 40b.
If the robot 50 is suspended by being held between the pair of claws 67a and 67b with sufficient play, the expanded diameter portion 40c will be prevented from coming out, and even a fragile mold will be supported in a suspended state without being damaged. can. Then, the mold 40 is suspended onto the support stand 20 in the furnace by opening the charging port 23. Then, the cylinder 74 of the guide device 70 is contracted and the arm 71 is moved into the furnace through the side hole 30. At that time, both guide fingers 8
2a and 82b are left open. The ring created when both guide fingers close is the support base 2.
Proceed until you are located directly above the 0 pit. Then, by operating the cylinder 89 and pushing the connecting rod 88 to close both guide fingers 82a and 82b, the downwardly extending portion 40d of the mold 40 is held between the two guiding fingers 82a and 82b.
0d is placed directly above the vertical hole of the support base 20. That is, since the mold 40 has different amounts of sand adhesion and uneven outer diameter dimensions, when suspended by the claws 67a and 67b, the downwardly extending portion 40d does not necessarily face straight down; In this case, the downwardly extending portion 40d of the mold 40 in the suspended state is clamped by the guide fingers 82a and 82b to ensure that it faces directly above the hole. I can do it. Thereafter, by releasing the clamping of the downwardly extending portion 40d by the guide fingers 82a, 82b and lowering the claw pieces 67a, 67b, the downwardly extending portion 40d can be inserted into the vertical hole of the support base 20 and supported. The mold 20 supported on the support stand 20 goes around the furnace once as the rotary hearth 2 rotates in the direction of the arrow, and during that time it receives direct fire from the burners 33, 33... and remains in the mold. Incinerate the wax and harden the sand. Then, the opening/closing door 27 is opened, and the claws 67a and 67b of the robot 50 enter through the extraction port 26 to grip the upper extension 40b of the baked mold 40, thereby lifting out the mold 40.

A cylindrical support stand 10 with a funnel-shaped upper end fixedly installed on the movable hearth to support the mold vertically supports the mold without deforming the shape during transportation within the furnace. Because it is made of aluminum, it has excellent spalling resistance and position reproducibility.

[Effects of the invention] As described above in the embodiments, the continuous mold firing furnace of the present invention is such that the mold for vacuum casting is carried in in a suspended state from the charging port provided in the ceiling wall of the furnace body.
The guide finger inserted through the side hole of the furnace body guides the downwardly extending part of the mold so that it matches the vertical hole of the support base, so even if the mold varies in shape and size, it can always be placed in the furnace reliably. It can be supported on a support stand inside. This eliminates the need for manpower to charge the mold, which saves labor and enables unmanned firing, which is beneficial in reducing casting costs.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a continuous mold firing furnace showing an embodiment of the present invention, Fig. 2 is its plan view, Fig. 3 is a horizontal cross-sectional plan view, and Fig. 4 is the furnace body near the mold charging port. Figure 5 is an enlarged cross-sectional view of the other parts of the furnace body, Figure 6 is an enlarged front view of the mechanical hand, Figure 7 is a perspective view of its claw pieces, and Figure 8 is its claw piece. FIG. 9 is a horizontal sectional view of the guide finger when it is closed, and FIG. 9 is a plan view of the guide finger. Figures 10a to 10d are process diagrams sequentially showing the working steps of the vacuum wicking casting method. 1...Furnace body, 2...Rotating hearth, 20...Support stand, 23...Charging port, 40...Mold, 40a...
Cylindrical part, 40b... Upper extension part, 40c... Expanded diameter part, 40d... Lower extension part, 40e... Molten metal suction port, 50... Transport robot (charging device), 67
a, 67b...Claw piece, 70...Guide device, 82
a, 82b...Guide finger.

Claims (1)

[Scope of utility model registration request] A continuous firing furnace for vacuum suction casting molds, which has an expanded diameter section formed at the upper end of the upper extension part of the cylindrical part that forms a runner connected to the cavity, and a molten metal suction port formed at the lower end of the downward extension part. A cylindrical ceramic support with a funnel-shaped upper end is fixed above the moving hearth.
A charging port and a side hole each having an opening/closing door are opened in the ceiling wall and side wall of the furnace body, and a mechanical hand grasps the upper extension of the mold to move the mold from the charging port into the supporting table in the furnace. A charging device is carried in the furnace in a suspended state, and a guide finger is provided at the tip of an arm that enters the furnace laterally from the side hole to align the downward extension of the mold with the upper end opening of the support. A continuous firing furnace for vacuum suction casting molds, characterized in that it is equipped with a guide device.