JPH0235398Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is used to cast dental dentures, prosthetics, other decorative items, small precision parts, etc., by melting the cast metal in the atmosphere with a gas burner, and then melting it in air or inert. This invention relates to a small precision pressure casting device that pours metal into a mold using gas pressure.

Various types of casting equipment have been used for the above-mentioned small precision castings, but as a melting heat source, a mixed gas of flammable gas such as city gas or acetylene and auxiliary combustion gas such as air or oxygen is ejected and combusted. Devices that use gas burners not only do not require electrical work compared to devices that use electricity as a heat source, but because the heat source is not integrated as a main part of the device, they have a simple structure and are compact, easy to handle, and inexpensive. It is. For this reason, it is widely used, and is especially useful in commercial dental laboratories. This type of conventional device includes, for example, a vertical air cylinder containing a piston rod with a long vertical stroke, a mold pedestal located below the cylinder, and a compression lid that hermetically presses a mold ring onto the lower end of the piston rod. A small diameter through hole is provided at the axis of the piston rod and at the center of the compression lid. With this configuration, after the metal material in the upper crucible part of the mold, which is placed on the mold pedestal and molded with an investment material in a refractory stainless steel ring, is melted by the gas burner, the piston of the air cylinder is heated by pneumatic pressure. The upper part of the stainless steel ring is airtightly closed by a pressure lid, and the molten metal in the crucible is poured into the product cavity inside the mold under pressure by the air pressure introduced from the through hole. It is configured as follows. However, in the configuration of the above device, the casting pressure and the piston descending pressure are maintained at the same air pressure over time, so the initial casting pressure during pouring is low, gradually increases during the process of closing the compression lid, and after a while after complete closure. The predetermined casting pressure is reached. For this reason, the pouring is not done all at once, and especially in the case of high melting point alloys, the temperature difference between the mold and the molten metal is large, so the molten metal is poured into the mold runner and solidifies before the pressure lid is completely closed, resulting in the casting being interrupted. It may fail. Further, there are disadvantages in that the flow into the mold becomes uneven, and the product contains air bubbles and impurities, making it impossible to produce complete products with a high yield. In addition, since the cylinder and compression lid of the above device are located vertically above the mold, when the metal in the crucible at the top of the mold is melted with a gas burner, the operation of the gas burner is restricted by the cylinder, compression lid, or cylinder support. There are also problems in that workability is poor, such as exposure to heat and difficulty in checking the progress of melting.

This idea was made in view of the above-mentioned current situation, and it eliminates the drawbacks and problems of the conventional gas burner-type pressure casting equipment, and creates a mold while leaving the oxide film in the crucible, which is the advantage of the separate dish melting method. To obtain a high-quality cast product free of oxide films, other impurities, and bubbles by incorporating an oxide film removal method by pouring molten metal into the mold, and by instantaneously applying a high initial casting pressure that is appropriately adjusted and pouring the molten metal. , and has excellent workability.
Furthermore, the present invention aims to provide a convenient device that automates the sequence control of melting and pressure casting.
In other words, in a gas burner-type pressure casting device, a bearing is used to swingably support the other end of a boat-shaped crucible with a pouring spout at one end on the inner wall of a cylindrical member having a lower opening facing the sprue of the mold. The metal in the crucible is melted by supporting the part and one end on the pouring spout side, and when the pressure lid is lowered after melting is completed, the support is released and the crucible is momentarily suspended upside down, and the metal in the crucible is poured into the mold sprue. A cylindrical melting chamber equipped with a crucible hooking/unloading mechanism for allowing dripping to occur, a pressurized fixed position above the melting chamber, and a retracted position spaced a predetermined distance horizontally from this melting chamber by, for example, a slide tray or rolling type. A movable structure configured to be movable with a linear motion member is provided with a vertical air cylinder and a compression lid that airtightly presses the cylindrical melting chamber onto the lower end of the piston rod of this cylinder. A mobile pressurizing mechanism, which is provided with an operating rod for a hanging/unloading mechanism, and an air or inert gas pressure inlet in a system separate from the cylinder operation for pouring molten metal under pressure from a mold sprue into a mold cavity. and a position detection means for detecting when the mechanism starts moving from the above-mentioned retreat position and reaches the pressurized fixed position, and a control circuit for sequentially controlling the pressure casting based on the output signal of this means. The present invention relates to a small precision pressure casting device characterized by the following.

Embodiments of this invention will be described below with reference to the drawings. FIG. 1 is a front view of a device according to an embodiment of this invention, with its main part cut away, and FIG. 2 is a side (partially cut away) view of the device. The device 1 is movably placed on a workbench 2 and has a small size, for example, a width (W) of about 300 cm, a height (H) of about 430 cm, and a depth (D) of about 240 cm. A mold 7 having a sprue 5 and a cavity 6 communicating therewith is placed on a pedestal 8, and the cast metal M in the crucible 9 is heated in the atmosphere to a gas burner 10 of, for example, acetylene/oxygen. Cylindrical melting chamber 1 that twists and melts
1, a horizontal track 14 provided inside the upper end of the left and right side plates 13, 13' of the underframe part 12, and a straight line in which a large number of balls are arranged in an endless track shape. The movable structure 16 is movably supported by a motion bearing 15 and a movable structure 16. 1 on the bottom plate 17 of the underframe part 12.
A pair of support columns 18 are provided, and the melting chamber substrate 19 that engages with the support columns 18 is made of, for example, a fire-resistant stainless steel material, and the melting chamber outer wall (cylindrical body) 20, which is also made of a fire-resistant stainless steel pipe material, is placed on top. weld,
An opening hole 21 facing the mold sprue 5 is provided at the bottom, and a refractory material such as an asbestos packing 22 is provided on the lower surface to be hermetically pressed against the mold 7 or the mold ring 3. A slide member 24 is provided at (arrow a) which is slidable and has a spherical handle 23 for lifting the melting chamber when inserting the mold. Next, the cylindrical melting chamber 11 is schematically illustrated in a vertical cross-sectional view with the center of the mold sprue 5 as a reference, and the boat-shaped crucible 9, the related crucible fitting member 25, and the swing bearing part 4 are shown.
6, 46' and the hooking/unhooking mechanisms 26, 34 will be explained in detail in FIG. 3, so their explanations will be omitted here. A hood-shaped flameproof wall 27 provided on the upper periphery of the outer wall 20 of the melting chamber is designed to reverse the return flame of the burner as long as 20 cm, which is scattered in all directions from the metal M in the crucible 9, in the direction of arrow b, for example, during the melting operation. This is effective in ensuring the safety of workers and increasing the thermal efficiency of melting. Next, by the horizontal track 14 laid on the left and right side plates 13 mentioned above,
Alternatively, the nozzle of the gas burner 10 described above is provided on the front panel 28 of the body structure 16, which is movable in the d direction, through a flexible tube 29 so that its injection direction can be freely adjusted. An ignition push button 30 for igniting the gas burner 10 when the gas burner 10 is locked by a magnetic catch (not shown) is also provided on the front surface of the panel. A double-acting vertical cylinder 31 that moves a piston up and down using air pressure is fixed inside the structure 16, and the piston rod 3
A compression lid 32 is provided at the lower end of 1R to close the melting chamber 11 in an airtight manner. The compression lid 32 is formed into a bowl shape, and has an aspe ring 33, for example, which is pressed against the upper end of the outer wall 20 of the melting chamber, attached to its lower peripheral edge, and the compression lid 32 is attached to its inner wall when the melting chamber 11 is closed. Alternatively, a hooking/unhooking mechanism operating rod 34 that operates the crucible hooking/unhooking mechanism 36 that supports the crucible 9 immediately before closing is fixed so as to be able to freely adjust the operating time. Further, an air or inert gas introduction hole 35 is provided in the inner wall of the compression lid 32. When the central axis 32C of the compression lid 32 is in the retracted positions S and P shown in FIG. When the worker starts to move the structure 16 in the direction of arrow c after confirming that the structure has been moved by stirring it with a quartz rod, for example, the pneumatic position sensor 37 outputs a signal to start moving the structure 16 at one end of the structure board 38. Further, when the body structure 16 has finished moving a predetermined distance L, the position sensor 4, which is also attached to a predetermined position within the body structure, is activated by an actuating member 39 provided on the right side plate 13.
Pressure fixed position P, P where 0 operates and outputs a signal
is a position where the center axis 32C of the compression lid and the center axis 5C of the mold sprue 5 coincide in the vertical direction. At this time, the hook member 41 provided at the front end of the structure board 38 is fitted into a hook locking member 42 fixed to one end of the right side plate 13 to firmly lock the structure 16 in the pressurized fixed position. A casting pressure pressure gauge 43 is provided on the front panel 28 to monitor the initial casting pressure, for example, 2.5 to 3.0 kg/cm ² , and the one protruding from the right side of the structure is used to adjust the casting pressure. Pressure regulator R ₄ . Above structure 1
The movable compression pressurization mechanism 44 has the configuration shown in 6. Although not shown, inside the structure 16 are the cylinder piston lifting air system and the casting pressurizing system, which will be explained in detail in Figures 5 and below, as well as the gas supply source for the flammable gas and combustion assisting gas system to the gas burner. are provided, and they constitute a sequence control circuit. In FIGS. 1 and 2, gas cylinders for the flammable gas and auxiliary gas and other piping-related components are omitted from illustration.

Next, the structure and operation of the cylindrical melting chamber 11, which is one of the essential parts of this invention, will be explained with reference to FIGS. 3 and 4. Components with the same symbols as those in FIGS. 1 and 2 will not be described in detail. FIG. 3 is a plan view of the cylindrical melting chamber 11 seen from above (however, the flameproof wall 27 is not shown). 3 is a sectional view on the -' side of FIG. 3 for explaining the operation of the crucible hooking and unhooking mechanism 26, and FIG. 4 is a sectional view on the -' side of FIG. 3, partially showing the flameproof wall 27. ing. In the figure, a boat-shaped crucible 9 is a commercially available crucible commonly used in centrifugal casting machines, and has a narrow pouring port 9H at one end for melting the cast metal M at the position shown in the figure. The fitting member 25 into which the crucible 9 is removably fitted and supported also has an opening hole 25H at one end and a pivot 25S at the other end.
has been established. A pair of bearings 46 and 46' that swingably support this pivot 25S are welded to the inner wall 20I of the cylindrical body 20. The above crucible pouring port 9
The crucible hooking and unhooking mechanism 26 that supports the H-side fitting member 25 is mounted on a pedestal 47 that is also formed on the inner wall 20I.
It is composed of a support shaft 48 installed in the support shaft 48, and a beak-shaped hook 49 that is rotatably supported in the horizontal direction at the tip of the support shaft 48. As shown in FIG.
The operating rod 3 provided on the compression lid 32 shown in FIG.
4 is lowered in the direction of arrow e as the compression lid 32 is lowered, and its tapered portion 34T is connected to the other end 4 of the hook 49.
By pushing 9S in the direction of arrow f, hook 4
9 rotates to the position indicated by the two-dot chain line in FIG. 3, and its tip releases the crucible support as shown at 49T'.
Therefore, the fitting member 25 and the crucible 9 instantaneously rotate in the direction of the arrow g due to their own weight, and are hung upside down as indicated by two-dot chain lines 25' and 9' in FIG. are opposed to the lower opening hole 21 of the melting chamber. Therefore, the molten metal M in the crucible flows through the narrow pouring spout 9 due to its own weight plus the centrifugal force of the rotation.
When passing through H, the mold sprue 5 which is in contact with the opening hole 21 leaves an oxide film in the crucible (see Fig. 1).
Air or inert gas having a predetermined casting pressure is instantly introduced from the pressure gas introduction hole 35 of the compression lid 32, pressurizing the molten metal M poured into the mold sprue 5 and molding it into the mold cavity. 6.
With the above configuration and operation, it is possible to not only remove the oxide film as in separate dish melting methods such as centrifugal casting, but also to pressurize pouring with an initial casting pressure several times higher than the centrifugal force of centrifugal casting. This is possible. Next, one embodiment of the pneumatic sequence control circuit of this device will be explained with reference to FIGS. 5 and 6. FIG. 5 is a block diagram of the circuit, and FIG. 6 is a time chart thereof. The sequence control circuit 55 performs all of its operations using air pressure and does not use any electricity, so it can be used in, for example, a laboratory where only a pressurized air source is available. The control circuit 55 consists of a melting system and a casting system, and the melting system has a supply source of flammable gas and auxiliary gas, and in this example, the former is an acetylene gas cylinder 5.
6, and the latter is assumed to be an oxygen cylinder 57. 1st in the diagram
Items with the same symbols as in Figures ~4 will not be described in detail. V ₁ , V ₂ ,
V ₃ is an on-off throttle valve, R ₁ , R ₂ , R ₃ , and R ₄ are pressure or flow rate regulators, and T ₁ and T ₂ are pneumatic timers that are normally closed and turn on at a set time, for example, 2 seconds. For example, the air pressure from the pressure supply source 58, which is a compressor, is turned ON when the position sensor 37 shown in FIGS. When the preparation is completed, the valve configured on the push button 30 is opened, and the flip-flop elements F and F-2, which are self-holding elements, are activated.
Turn it on, first send acetylene gas to the gas burner 10 using the sequence valve 61, inject it, and then open the sequence valve 62 after 2 seconds, set in advance in the timer _T1 , to send oxygen to the gas burner 10 for mixed combustion. let When the operator starts moving the structure 16 in the direction of arrow c in FIG. 2 when the melting is completed, the position sensor 30
By turning off, the gas burner 10 is extinguished. When the body structure 16 reaches the pressurized fixed position P/P, the position sensor 40 turns ON, and air pressure is input to the pilot port P of the NOT element 59, so that the output port O is opened to the atmosphere, and the flip-flop elements F/F Pressure is output from the output port O ₁ of -1, and the output port O ₂ is opened to the atmosphere.
The piston 63 is lowered by the descending air system DA input from O ₁ to the port 31A of the cylinder 31, and the above-mentioned melting chamber 11 is brought into airtight contact with the pressure cover 32. By the operation of timer T ₂ whose falling time is set in advance, the pressurized air accumulated in the pressure accumulator 60 immediately after the pressurized closure instantly pressurizes the inside of the melting chamber 11 via the casting pressurization system CA, and pours the metal. will be carried out. When the body structure 16 is returned to the retracted position S/P after casting, the position sensor 40 is turned OFF, and the input to the pilot port P of the NOT element 59 disappears.Therefore, pressure is output from the output port O, and the pressure is output from the F/F-2.
O ₁ and O ₂ are repeated. This causes the piston 63 to rise and return to its original position. Furthermore, F・F-
The piping from No. 2 to F.F-1 is a safety air system that prevents the gas burner 10 from igniting even if the push button 30 is pressed by mistake during the pressure casting. In this way, by only opening and closing the valves V ₁ , V ₂ , and V ₃ , operating the push button 30, and moving the moving structure 16, the other sequences are automatically controlled. The progress of melting can be carefully monitored and overheating, which can cause cavities and rough casting surfaces, can be prevented.

FIG. 6 is a time chart of the above sequence control, and the horizontal axis t indicates the passage of time.
indicates the opening of the V ₁ valve, and indicates that the position sensor 37 is in the retracted position of the structure 16, and the signal turns ON.
is output, indicating that the melting preparation is complete. indicates that the gas burner ignition push button 30 is pressed at time t ₂ , which is the time Ta required to put the metal into the crucible from t ₁ , and , and , both indicate that the push button 30 is turned ON.
This is the operation of F-1 and the sequence valve 61, which starts the operation of timer _T1 , and by the operation of _T1 , _t2
The sequence valve 62 is turned ON at time t ₃ after the set time Tb from , and the gas burner 10 injects the mixed gas, melts the metal, and completes the structure at time t ₄ . Extinguish the fire by starting the movement of 16. Next, at time _t5 when the movement is completed, the position sensor 40 turns ON, the pressure chart of the cylinder port 31A starts from the output _O1 of F-F-2 that lowers the piston 63, and the timer _T2 starts operating at the same time. Chart, accumulator 60 at time t ₆ after time Tc set by timer T ₂ .
This is a chart that applies pressure to the melting chamber 11.

Next, with reference to FIG. 7, a description will be given of another embodiment of the circuit of this invention in which part of the above sequence control is carried out electrically. That is, the position sensor 37 in FIG.
40 is an electric micro switch, push button 30 is also a normally open push button switch, and timers T ₁ and T ₂ are connected.
An electric timer with contacts T ₁ -a and T ₂ -a,
61, 62 sequence valves and F/F-2
By replacing the four solenoid valves SL ₁ , SL ₂ , SL ₃ , and SL ₄ with the provision of a relay R, a circuit can be obtained in which the sequence control shown in FIG. 6 can be performed in the same manner. In the figure, 66 and 67 are for example AC100V or
The 200V low-voltage, low-power power supply terminal 68 serves as a circuit breaker and equipment power switch.
Ra ₁ and Ra ₂ are normally open contacts of the relay R, and are the a contacts of the operating time. In this configuration, pressurization is not limited to air, but inert gas can also be used. Moreover, the power supply does not require any special construction and can be used with a light line, making it a device that can be used even in small-scale technical laboratories.

The above is a description of one or two embodiments of this invention, but this invention is not limited to the illustrations and description. For example, the gas burner may be separated from the movable structure, and the flameproof wall is not limited to the shape shown, and may be one without a flameproof wall. The cylinder may also be a single acting cylinder with a spring. Furthermore, the position detecting means is not limited to pneumatic or electrical types, but optical types can also be considered, and various types of sequence control circuits can be considered, all of which belong to the scope of this invention.

This idea is structured as above, so
This eliminates the drawbacks and problems of conventional gas burner type additional pressure casting equipment. In other words, by rotating and hanging the crucible, an oxide film is left on the crucible and removed, similar to the separate dish melting method such as centrifugal casting, and pressure casting is performed using a high initial casting pressure that cannot be obtained with centrifugal force. This method not only has the great effect of completely manufacturing small, dense castings without containing oxide films, other impurities, or air bubbles, but also eliminates the solidification in the runners of conventional equipment, and eliminates pressure. Since the structure can be retracted during the melting work, the melting workability is much better and there is no fear of overheating, and furthermore, it has been possible to provide a small, convenient, easy-to-handle, and inexpensive device that can automatically perform sequence control.

[Brief explanation of the drawing]

Fig. 1 is a front view (partially sectional view) of a small precision pressure casting machine according to an embodiment of this invention, Fig. 2 is a side view (partially cut away) of the above device, and Fig. 3 is a cylinder of the above device. Fig. 3 is a sectional view on the -' side of Fig. 3, Fig. 4 is a sectional view on the -' side of Fig. 3, and Fig. 5 is a pneumatic sequence of the above device. FIG. 6 is a block diagram of the control circuit, FIG. 6 is a time chart of the above-mentioned sequence control, and FIG. 7 is a block diagram of an electrical sequence control circuit according to another embodiment of this invention. 5...Mold sprue, 6...Mold cavity, 7...
Mold, 9... Boat-shaped crucible, 9H... Crucible pouring port, 10... Gas burner, 11... Cylindrical melting chamber, 16... Moving structure, 20... Cylindrical member, 21
... Melting chamber lower opening hole, 26... Crucible hanging/unhooking mechanism, 34... Crucible hanging/unhooking mechanism operation rod, 27
...Flameproof wall, 29...Flexible tube, 31...Vertical air cylinder, 31R...Piston rod, S/P
... Retreat position, L ... Predetermined distance, P.P ... Pressure fixed position, 31R ... Piston rod, 32 ... Pressure cover, M ... Molten metal, 35 ... Pressurized gas introduction hole, 37, 40...Sensor of position detection means, 44
...Mobile pressure addition pressure mechanism, 46, 46'...A pair of bearings, CA...Casting pressurized air system, DA...Pressure addition cover lowering pressure air system, 55...Control circuit.

Claims (1)

[Claims for Utility Model Registration] 1. A cast metal material in a swingably supported crucible is heated and melted in the atmosphere with a gas burner, and then is melted into a cavity in a mold using air or an inert gas. 1. A small precision pressure casting device for pouring molten metal under pressure, characterized by having each of the following structural requirements. (A) Pressure fixed position P, P above the cylindrical melting chamber 11
A vertical air cylinder 31 is attached to the movable structure 16, which is configured to be movable between this position and retreat positions S and P at a predetermined distance L in the horizontal direction from this position.
A compression lid 32 is provided at the lower end of the piston rod 31R of this cylinder to close the cylindrical melting chamber and press the crucible in an airtight manner. A movable pressurizing mechanism 44 provided with an air or inert gas introduction hole 35 for pressurizing hot water. (a) A boat-shaped crucible whose upper part is open and whose one end is pivotally supported by bearing parts 46, 46' of a cylindrical melting chamber, which has an opening hole 21 communicating with the sprue 5 of the mold 7 at the lower part. Pouring port 9H at the other end of 9
The operating rod of the compression lid that supports the crucible horizontally and closes the cylindrical melting chamber after melting is completed is lowered to release the crucible and open the crucible's pouring port and the mold's sprue. and a crucible hooking/unhooking mechanism 26 which is adapted to hang down and coincide with the vertical line. (C) When the movable compression mechanism starts moving from the retreat position and reaches the fixed pressurization position,
Position detection means 37, 40 detecting this, and a control circuit 55 that sequentially controls pressure casting based on the output signal of this means. 2. A small precision pressure casting apparatus according to claim 1, which is a utility model, in which a gas burner 10 is protruded from a movable compression mechanism 44 through a flexible tube 29. 3 Cast pressurized air system CA introduced into the compression lid 32
2. A small precision pressure casting apparatus according to claim 1 or 2, wherein the pressure air system DA and the compression lid lowering pressure air system DA are separated and independent. 4. A small precision pressure casting apparatus according to any one of claims 1 to 3, which is provided with a flameproof wall 27 on the upper periphery of the cylindrical melting chamber 11. 5. The small precision pressure casting apparatus according to any one of claims 1 to 4, wherein the position detection means 37, 40 and the control circuit 55 are pneumatic.