JPS6325864B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention belongs to the technical field of dental centrifugal casting machines.

<Prior Art> As a basic structure of the present invention, for example, as shown in FIGS. 1 to 3 or 5, a rotating frame 2 is rotatably supported on a base frame 1, and the rotating shaft of the rotating frame 2 is The crucible 4 is placed on the side closer to the core 3, and the mold 5 is placed on the side farther from the core 3. The crucible 4 and the mold 5 are fixed to the rotating frame 2, and the outlet 6 is opened on the circumference of the crucible 4, and the mold 5 is placed on the side near the core 3. A sprue 7 is opened in a portion of the surface closer to the rotation axis 3, the sprue 7 is communicated with the sprue 6, and the molten metal melted in the crucible 4 is heated by the centrifugal force generated by the rotation of the rotary frame 2. The present invention relates to a dental centrifugal casting machine configured to cast into a mold 5 through a tap 6 and a sprue 7.

Conventional dental centrifugal casting machines with this structure include:
The device shown in FIG. 5 is known from Japanese Patent Publication No. 56-7413.

That is, the crucible 4 is located far away from the rotation axis 3 of the rotary frame 2, and the melting chamber 11 of the crucible 4 has a structure in which the melting chamber 11 opens straight out and connects to the sprue 7.

<Problem that the invention seeks to solve> However, this structure has the following drawbacks.

(a) The molten metal jumps straight into the sprue 7 of the mold 5 from the melting chamber 11 of the crucible 4. Therefore, if the flow velocity of the molten metal is high, it will collide with the mold 5 with great force, drawing in casting sand or causing rough skin. On the other hand, if the flow rate is slow, problems such as poor water circulation, decreased density of the casting, and blowholes will occur.

Particularly, in the case of a full plate for the upper jaw, which is thin and wide and therefore difficult to cast, it is impossible to cast with high precision and high density due to poor hot water circulation, low density of the casting, etc.

(b) In order to eliminate the above drawback (a),
Publication No. 7413 uses a combination of centrifugal force and gas compression to force the molten metal into the mold.

However, it is difficult to match the timing of centrifugal force and gas compression with high precision, and failure is likely to occur. Moreover, an extra gas compression device and a control device for matching the timing thereof are required, making the structure complicated and expensive.

Since the crucible 4 is far away from the rotation axis 3, the casting machine is large in size and has a large rotation radius.

The purpose of the present invention is to solve the above-mentioned disadvantages A to C by devising the arrangement and shape of the melting chamber of the crucible so that the molten metal gradually accelerates from the melting chamber and flows smoothly and forcefully into the mold. shall be.

<Means for Solving the Problems> In order to achieve this object, the present invention is constructed as shown in FIGS. 1 to 3, for example.

That is, when the melting chamber 21 of the crucible 4 is located on the rotation axis 3 of the rotating frame 2, the distance l from the rotation axis 3 of the rotating frame 2 to the circumferential surface 22 of the melting chamber 21 is
The circumferential surface 22 of the melting chamber 21 is formed in a spiral shape that increases in value toward the rear in the rotation direction 23 of the melting chamber 21.
The outlet 6 is opened at the spirally extending tip of the circumferential surface 22 of the melting chamber 21, and the circumferential surface 22 of the melting chamber 21
A hot water passage from the tip 57 extending in a spiral shape to the middle part of the sprue 7 via the tap 6 is formed so that the cross-sectional area of the hot water passage decreases with continuous smoothness, and inside the mold 5. A cavity 52 for full plate casting for the upper jaw is formed almost parallel to the rotating frame 2,
The cavity 52 is formed on the U plate in a plan view and has a dish-like cross-sectional shape, and the rear edge 53 of the upper jaw of the cavity 52 is directed toward the crucible 4 side, and the rotation frame 2 is formed toward the rear side in the rotation direction 23. The direction of rotation 23 of the rear edge 53 of the upper jaw of the cavity 52 is tilted away from the rotation axis 3.
The sprue 7 is connected to a rear end 54 located at the rear of the upper jaw, and an air vent hole 56 is led out from the front end 55 of the rear edge 53 of the upper jaw.

<Effect> Next, its effect will be explained.

The casting material is placed in the melting chamber 21, melted by the melting device 47, heated to a temperature suitable for casting, and then the rotary frame 2 is rotated by the motor 33.

When the motor 33 starts to rotate, the distance l from the rotation axis 3 of the rotation frame 2 to the circumferential surface 22 of the melting chamber 21 increases as it moves toward the rear in the rotation direction 23 of the rotation frame 2 (and decreases as it moves toward the front). By forming the circumferential surface 22 of the melting chamber 21 in a spiral shape, a reaction force that directs the molten metal toward the rear side in the rotation direction 23 acts on the molten metal, causing the melting chamber 21 to move toward the rotation axis 3 of the rotating frame 2.
Coupled with the fact that the centrifugal force acting on the molten metal is weak due to the upper position, the molten metal flows out smoothly and slowly within the melting chamber 21 toward the outlet 6.

As the rotational speed of the motor 33 increases, the molten metal is gradually accelerated, and when the rotational speed of the motor 33 is sufficiently increased, the molten metal in the melting chamber 21 reaches the outlet 6,
It is forcefully pushed through the sprue 7 into the cavity 52 for full plate casting of the upper jaw in the mold 5.

At this time, the molten metal in the melting chamber 21 is smoothly guided through a smooth channel from the inside of the tap 6 to the middle of the sprue 7, and because the channel is formed in a tapered shape. , a large flow velocity is obtained in this channel and reaches the cavity 52 in the mold 5.

Then, the molten metal flows from the rear end 54 of the cavity 52 to the cavity 5.
It flows smoothly and powerfully into 2.

Next, when the cavity 52 is filled with molten metal, the excess hot water upstream from the rear end 54 acts as a riser to replenish the amount of hot water that has shrunk due to cooling and solidification. Also, due to the pressure of the riser, most of the gas remaining in the mold 5 is released from the air vent hole 56 led out from the front end 55 of the rear edge 53 of the upper jaw of the cavity 52, and is not released from the mold. A small amount of gas remaining within 5 reduces its volume.

At this time, the further the rear edge 53 of the upper jaw of the cavity 52 goes to the rear side in the rotation direction 23, the more the rotation axis 3 of the rotation frame 2
Since the sprue 7 is connected to the rear end 54 of the rear edge 53 of the upper jaw of the cavity 52, compared to the case where the cavity 52 is directly opposed to the rotation axis 3. Therefore, a larger centrifugal force acts on the riser.

<Effects of the Invention> Since the present invention is configured and operates as described above, it has the following effects.

(a) The molten metal begins to flow slowly, and gradually accelerates and gains momentum as it smoothly flows toward the spout along the spiral-shaped circumference of the melting chamber, and is smoothly guided from the sprue to the sprue, and from the sprue into the mold. It flows smoothly and powerfully. Therefore, the molten metal flows smoothly into the mold without colliding with the mold head-on, thereby eliminating the entrainment of casting sand and roughening of the casting surface.

Moreover, the circumferential surface of the melting chamber is formed in a spiral shape in which the distance from the rotation axis of the rotating frame to the circumferential surface of the melting chamber increases as it goes toward the rear in the rotating direction of the rotating frame, so centrifugal force acts on the molten metal. By effectively utilizing the reaction force at the start of rotation, the molten metal in the melting chamber can be directed smoothly and forcefully to the sprue. Since the flow rate of the molten metal is increased in the tapered channel, the flow rate of the molten metal into the cavity for casting a full plate for the upper jaw is sufficiently increased, and the molten metal flows forcefully into the cavity of the mold. As a result, water circulation is sufficient, high-density dental castings are obtained, and blowholes are suppressed. Therefore, high-quality, high-precision dental castings can be manufactured easily and accurately.

Furthermore, by connecting the sprue to the rear end of the rear edge of the upper jaw of the cavity, a large centrifugal force is applied to the feeder upstream from the rear end of the rear edge of the upper jaw of the cavity. The effect of rising water can be obtained, blowholes are further suppressed, and the flow of the hot water is very good.Even if the inside of the cavity is thin and wide, the molten metal is distributed to every corner of the cavity in a dense and high density manner. . Therefore, thin and wide items such as full plates for the upper jaw can be cast with high precision and high density.

B. The above effect A is that the molten metal can be sufficiently pushed into the mold by centrifugal force alone, and gas compression can be omitted compared to the conventional example that combines centrifugal force and gas compression. It is possible to eliminate casting failures due to timing errors with gas compression, and furthermore, the configuration of the entire casting machine can be simplified by omitting the gas compression device and its timing control device.

Since the crucible is located on the rotation axis, the mold is also close to the rotation axis, allowing the casting machine to be made compact with a small rotation radius.

Additionally, along with this, the rotation of the casting machine can be stabilized, and the rotational moment of the casting machine can be reduced to improve safety.

(d) The molten metal can be divided into multiple directions within the melting chamber located on the rotation axis, and in this case, it can be poured into multiple molds placed around the crucible at once, making the casting process easier. Efficiency can be greatly increased.

<Example> Hereinafter, an example of the present invention will be described based on FIGS. 1 to 3.

A rotating frame 2 is rotatably supported on a base frame 1 via an attitude changing device 31 and a rotating shaft 32. The rotating frame 2 is fixed to the upper end of the rotating shaft 32, and the motor 33 is interlocked to the lower end thereof.

The attitude changing device 31 allows the rotation frame 2 to be adjusted to any one of a horizontal attitude, an inclined attitude, and a vertical attitude. That is, a pair of left and right horizontal shafts 36 fixed to a swing arm 35 are rotatably supported by a pair of left and right support arms 34 fixed to the base frame 1 and are frictionally fixed by a friction brake 37 .
A rotating shaft 32 vertically passes through the swing cylinder 35 and is rotatably supported by a bearing 38. Swing tube 3
A motor 33 is fixed to the lower end of 5.

A crucible 4 is placed on a rotating shaft 32 of a rotating frame 2, and molds 5 are placed on both left and right sides of the crucible 4. A seat hole 39 is formed on the rotation axis 3 of the rotating frame 2, and a copper seat 4 is formed in the seat hole 39.
0 is removably inserted. The crucible 4 is fixed on the rotating frame 2 by removably fitting the fitting hole 41 on the lower surface of the crucible 4 into the upper part of the copper seat 40 .

A pair of threaded rods 42 are fixed to the front and rear of the rotating frame 2 and run left and right. Nuts 43 are screwed onto the left and right ends of both threaded rods 42, and the nuts 43 at the front and rear of the left end
Attach the locking collars 4 at the front and rear ends of the left presser band 44.
5 is rotatably fitted, and with the same structure, the right presser band 44 is also connected to the front and rear nuts 43 on the right side. By tightening each nut 43, the mold 5 is pressed and fixed against each of the left and right sides of the crucible 4 by the presser band 44. Furthermore, a balance adjusting screw 51 is screwed into one end of the threaded rod 42.

A lid 46 is attached to the rotating frame 2 so as to be able to swing open and close, and is locked in the closed state by a locking or screw type lid locking device (not shown). A tungsten electrode rod 47 of the arc melting device is fixed to the center of the lid 46 so as to be vertically adjustable by vertical adjustment means (not shown). The electrode rod 47 faces the melting chamber 21 of the crucible 4 from above and faces the copper seat 40 facing the bottom of the melting chamber 21. This copper seat 40 serves as an electrode on the other side of the electrode rod 47.

A sprue 6 is opened on both left and right sides of the circumferential surface of the crucible 4, a sprue 7 is opened on a surface of the circumferential surface of the mold 5 facing the sprue 6, and the sprue 7 communicates with the sprue 6.

The casting material in the melting chamber 21 of the crucible 4 is melted by the arc generated between the electrode rod 47 and the copper seat 40 to become molten metal, and the centrifugal force generated by the rotation of the rotating frame 2 by the motor 33 So, hot water outlet 6
and is configured to be cast into the mold 5 through a sprue 7.

The melting chamber 21 of the crucible 4 is located on the rotation axis 3 of the rotation frame 2. The circumferential surface 22 of the dissolution chamber 21 is wider than the upper inlet 48, has a concave vertical cross section, and a spiral horizontal cross section. This spiral shape is such that the distance 1 from the rotation axis 3 of the rotation frame 2 to the circumferential surface 22 of the melting chamber 21 becomes larger toward the rear in the rotation direction 23 of the rotation frame 2. The outlet 6 opens at the front end of the circumferential surface 22 of the melting chamber 21, which extends in a spiral shape, and extends from the tip 57 of the circumferential surface 22 of the melting chamber 21, passing through the outlet 6, to the sprue 7. The channel leading to the section is formed so that the cross-sectional area of the channel decreases with continuous smoothness.

The crucible 4 is made by casting a mold material 50 into a metal frame 49. In this case, the crucible 4 is easy to construct and is reinforced with the metal frame 49, making it durable. When the bottom surface of the melting chamber 21 is formed of the copper seat 40, the entire copper seat 40 stabilizes the temperature of the molten metal, making it easier to pour the molten metal at an appropriate temperature.

When adjusting the attitude of the rotary frame 2 between a horizontal attitude, an inclined attitude, and a vertical attitude, the initial speed of casting can be adjusted by adjusting the attitude. Further, in the inclined position or the vertical position, it becomes easier to adjust the left and right balance of the rotating frame 2.

When it is particularly desired to increase the initial speed of casting, it is conceivable to melt the casting material while rotating the rotary frame 2 in reverse at a slow speed, and then switch to rapid forward rotation to perform casting.

When casting a full plate for the upper jaw, mold 5
If formed as shown in FIGS. 2 and 3, a good cast product can be obtained. That is, the cavity 52 for full-plate casting for the upper jaw is aligned almost parallel to the rotating frame 2, the cavity 52 is formed into a U plate shape in plan view, and a dish shape in cross section. Back edge of jaw 5
3 toward the crucible 4 side, and rotation direction 2
The rear side of the rotary frame 2 is inclined so that it becomes farther away from the rotation axis 3 of the rotary frame 2. A sprue 7 is provided at the rear end 54 of the upper jaw rear edge 53 of the cavity 52 located at the rear in the rotational direction 23.
The air vent hole 56 is led out from the front end 55 of the air vent hole 56 . In this case, the centrifugal force enhances the effect of the riser, and a full plate with high density can be obtained.

FIG. 4 shows a part of the structure of the above embodiment modified as follows.

That is, the rotating frame 2 is formed into a container shape, and the rotating frame 2
The lid 46 is pivotally supported by a hinge 61 so as to be able to swing open and close, and can be closed and fixed with wing bolts 62. A viewing window 63 and a window hole 64 are provided in the lid 46, and the window hole 64 is closed with a screw plug 65.

A swinging arm 66 is swingably supported on the rotating frame 2 by a support shaft 67, and is fixed at a position after swinging by a friction plate 68. An electrode rod 47 is supported at the tip of the swinging arm 66.

As a result, when the casting material has a high melting point, the electrode rod 47 is placed on the crucible 4 and melted by arc discharge, and when the casting material has a low melting point, the electrode rod 47 is released from above the crucible 4 and the screw plug 65 is closed. It opens, draws in the gas torch's nozzle through the window hole 64, and melts it with the gas flame.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, in which FIG. 1 is a plan view, FIG. 2 is a longitudinal sectional front view, FIG. 3 is a longitudinal sectional side view of main parts, and FIG. 4 is a structure of the above embodiment. FIG. 5 is a longitudinal sectional side view of a part of the improved example, and FIG. 5 is a longitudinal sectional front view of the conventional example. DESCRIPTION OF SYMBOLS 1...Base frame, 2...Rotation frame, 3...Rotation axis center, 4...Crucible, 5...Mold, 6...Tap gate, 7...Gate, 21...
Melting chamber, 22...Surrounding surface of 21, 23...Rotation direction, 5
2...Cavity, 56...Air vent hole, l...Distance.

Claims (1)

[Claims] 1 A rotating frame 2 is rotatably supported on a base frame 1, a crucible 4 is placed on the side closer to the rotation axis 3 of the rotating frame 2, and a mold 5 is placed on the far side, and the crucible 4 and the mold 5 are connected to the rotating frame. A sprue 6 is opened on the circumferential surface of the crucible 4, a sprue 7 is opened on a portion of the circumferential surface of the mold 5 closer to the rotation axis 3, the sprue 7 is communicated with the sprue 6, and the crucible 4 is fixed to the sprue 2. In a dental centrifugal casting machine, the molten metal melted in the crucible 4 is cast into the mold 5 through the sprue 6 and the sprue 7 using the centrifugal force generated by the rotation of the rotary frame 2. The melting chamber 21 is located on the rotation axis 3 of the rotating frame 2, and the rotating frame 2
The circumferential surface 22 of the dissolving chamber 21 is formed in a spiral shape in which the distance l from the rotation axis 3 of the dissolving chamber 21 to the circumferential surface 22 of the dissolving chamber 21 becomes larger toward the rear of the rotating direction 23 of the rotating frame 2. The outlet 6 is opened at the spirally extending tip of the circumferential surface 22 of the melting chamber 21, and the hot water that extends from the spirally extending tip 57 of the circumferential surface 22 of the melting chamber 21 through the outlet 6 to the middle of the sprue 7 is opened. The channel is formed so that the cross-sectional area of the channel decreases with continuous smoothness, and a cavity 52 for casting a full plate for the upper jaw is placed inside the mold 5 almost parallel to the rotating frame 2. The cavity 52 is formed into a U plate shape in plan view and a dish shape in cross section, and the rear edge 53 of the upper jaw of the cavity 52 is directed toward the crucible 4 side, and rotates toward the rear in the rotation direction 23. The rear edge 53 of the upper jaw of the cavity 52 is sloped away from the rotation axis 3 of the frame 2.
A dental centrifugal casting machine characterized in that a sprue 7 is communicated with a rear end 54 located at the rear in a rotational direction 23, and an air vent hole 56 is led out from a front end 55 of an upper jaw rear edge 53.