JPS6260100B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in resin capsules and molding devices used for injection molding of resin-based dentures and crowns.

Conventionally, thermosetting resin was used to produce products by direct pressure molding, but the precision was poor and
There were problems with the material, such as impact resistance, abrasion resistance, and conformability.

Recently, excellent polycarbonate thermoplastic resins for dental use have been developed, and resin-based dentures and crowns are being manufactured by injection molding, which overcomes the drawbacks of conventional thermosetting resins.

To manufacture resin dentures and crowns by injection molding, first a mold of the alveolar ridge and teeth is made using a sand mold material containing alumina, silica, etc., and a special wax is injected into this mold to make it look like the real thing. A female mold of a resin-based denture or crown is obtained using the so-called lost wax method, in which a model is made of a 2-part light alloy flask, filled with plaster mold material, buried, and heated to wash away the wax. Polycarbonate thermoplastic resin is injected into the female mold in this flask to mold resin-based dentures and crowns.

As this injection molding method, the present inventors sealed the resin in an aluminum resin capsule,
Previously, we proposed a method in which the resin was loaded into the cylinder of an injection molding machine and heated to dissolve the resin, and then the resin capsule was crushed and the resin was injected into the flask, but this method had the following drawbacks. .

(1) Since the resin capsule is crushed, the aluminum of the capsule sticks to the inner wall of the cylinder, and it takes a lot of effort to remove it.

(2) Since melted resin remains attached to the cylinder, the cylinder must be cleaned every time in dental molding, where molding is often done in a different color each time to match the tooth color.

(3) Since the resin capsule is loaded into a horizontal cylinder, air tends to enter the product, creating bubbles and resulting in a high defect rate.

(4) A large amount of power is required to crush the resin capsule.

(5) Loading resin capsules into a horizontal injection machine is difficult to operate.

The present invention improves the resin capsule and the molding apparatus in order to eliminate the above-mentioned drawbacks.

The present invention will be described below based on embodiments shown in the accompanying drawings.

The molding device shown in FIG. 1 is supported by a frame 4 supported by two pillars 3, 3a such that the lower part of the cylinder 1 can freely rotate around supporting points 2, 2a opposite to each other, and a clamping device is installed to hold the upper end of the cylinder 1. 5 to keep it vertical. As shown in FIG. 3, this cylinder 1 is equipped with a heating device 1a having a heating wire wrapped around its outer periphery, and a cylindrical hole 1b provided in the center of the cylinder 1 is equipped with a heating device 1a that is used to store molding material such as pellets. A thermoplastic resin 9 is filled and the heating device 1a dissolves it into a liquid state. and,
A piston 6 operated by pneumatic or hydraulic pressure is arranged above the cylindrical hole 1b, and a mold of a desired shape of the resin-based denture or cylinder is placed inside the cylinder 1 between the lower end of the cylinder 1 and a table 8. space 7
A flask 7 made of a light alloy and divided into at least two parts having a diameter of 1.a is arranged so that the injection port 7b and the injection port at the lower end of the cylinder coincide with each other. In order to tightly fit this flask 7 to the lower end of the cylinder 1, the frame 4 is attached to the supports 3 and 3.
Adjustment can be made by moving the table 8 up and down along the line a or by moving the table 8 up and down in the same way.

Inside this flask 7, a plaster mold 7c is arranged, and in this mold 7c, there is a negative pressure ventilation passage 7d connected to another negative pressure tank (not shown) in order to make the mold space 7a negative pressure. It is provided.

As shown in FIG. 3, the resin capsule 10 loaded into the cylindrical hole 1b provided in the center of the cylinder 1 is composed of a bottomed cylindrical body 11a for filling the resin 9 and a crown-shaped lid 11b. At the center of the bottom of the main body 11a, there is a thin-walled part 1 that can be easily destroyed by pressure and inject the molten resin inside.
0a is provided. The thin portion 10a can be formed into any shape such as circular or polygonal. This thin wall portion 10a is formed by making the wall thickness of that portion thinner than that of the outer peripheral portion, or by cutting grooves in at least a portion thereof.

In the resin capsule of the present invention, it is important to fit the crown-shaped lid 11b into the inside diameter of the main body 11a.

The main body 11a and the lid 11b of the resin capsule 10 are made of metal or high melting point resin, but in general, from the viewpoint of cost and ease of handling, aluminum is preferable. Coronal lid 11
If b is constructed with a thin wall at the lower end and a thick wall at the upper surface and the periphery near the upper surface, the piston 6 will be connected to the lid 11.
When pressing b, the thin walled portion at the lower end tends to expand outward due to the internal pressure, so the resin capsule 1
In addition to preventing the melted resin 9 from leaking from the inner periphery of the piston 0, by making the upper surface and the surrounding area near the upper surface thicker, the downward pressure of the piston 6 may break through the ceiling or buckle the surrounding area. It is possible to prevent this.

The lid 11b may be plate-shaped or cylindrical in addition to the illustrated crown-shaped lid.

In addition, the lid 11b can be provided with a small hole (not shown) for discharging air and moisture inside the capsule, so that when the piston 6 pushes the lid 11b, the air stagnant in the upper part of the capsule 10 can be removed. Water can be drained. That is, in this case, when the lower surface of the lid 11b comes into contact with the melted resin, the resin contacts the piston 6 through the small hole,
As a result, the resin solidifies and closes the small holes, allowing injection to be performed without any problems.

In addition, since the thickness of the thin part 10a of the resin capsule 10 is for destructive injection, it is necessary to set it to an appropriate thickness, but as a result of experiments, when using rolled aluminum material, the thickness is about 0.1 mm to 0.6 mm. It was appropriate. Furthermore, in relation to the fact that the lid 11b is fitted into the inner diameter of the main body 11a in the resin capsule 10, in a molding apparatus using this, it is necessary to prevent the head of the piston 6 from pressing the main body 11a of the resin capsule 10. The diameter thereof may be made equal to or less than the inner diameter of the main body 11a.

In the molding apparatus using the resin capsule of the present invention, before installing the flask 7, the clamping device 5 of the cylinder 1 is removed, and as shown by the imaginary line in FIG. It is preferable that the upper end of the cylinder 1 is tilted forward by the same amount. In this case, it becomes easy to insert the resin capsule 10 into the central cylindrical hole 1b, and it is also possible to check the melting state of the resin.

On the other hand, place the flask in at least two parts prepared in advance and tightened with bolts on the table 8, lower the frame 4, or lift the table 8 and
The frame 4 or the table 8 is fixed to the supports 3, 3a with b aligned with the thin wall portion 10a of the resin capsule 10. Then, by operating pneumatic or hydraulic pressure to lower the piston 6 and press down the lid 11 of the resin capsule to pressurize the melted resin 9, the thin wall portion 10a at the bottom of the resin capsule is ruptured and the melted resin 9 is transferred to the flask 7. injection port 7b
Then, the liquid is injected into the mold space 7a. At this time, the mold space 7a
Since the interior is under negative pressure by suction from the outside through the negative pressure ventilation path 7d, the injected resin is sufficiently filled in every corner.

Furthermore, when the cylinder 1 and flask 7 of the molding device are installed in a vacuum device (not shown), the air and moisture inside the resin capsule 10 are also exhausted, and the air and moisture in the mold space 7a are also exhausted through the injection hole. Therefore, there is no need to provide a negative pressure ventilation path 7d in the plaster mold, and since the surroundings of the flask 7 are also under negative pressure, there is no need for the mold space 7a to be airtight, making it easier to create and handle the mold 7c.

When injecting and inserting the resin into the resin capsule 10, it is desirable that the resin has good fluidity, and heating is performed at as high a temperature as possible to increase fluidity. , discoloration, discoloration, strength deterioration, etc. may occur due to heating temperature,
I am limited by time.

However, by placing cylinder 1 in a vacuum chamber and applying negative pressure, the amount of oxygen decreases, and even if the heating temperature is raised, the resin inside the capsule will not decompose, discolor, discolor, or deteriorate in strength, and molding can be performed under free heating conditions. It can be carried out.

The resin-based dentures and crowns molded in this way are cooled to room temperature while in the flask 7, and then annealed with a warm bath agent such as glycerin to remove distortion and internal stress caused by molding, and then the flask is disassembled. After the molded product is removed and polished, it is coated with resin for a manicure finish to produce a product.

As explained above, when molding resin-based dentures and crowns, the present invention is extremely effective by preparing resin capsules filled with various colors in dental-specific moldings that differ each time. This resin capsule can be easily molded, and since the resin capsule body is not crushed by simply pressing the lid when molding, the molding power is small and the molding is smooth. The aluminum of the resin capsule does not stick to the cylinder, and the resin does not adhere to the cylinder, so there is no need to clean the cylinder every time. It is very efficient in molding, which is unique to dentistry, where molding is often performed, and since the resin capsule is used, there is no wear on the cylinder.

In addition, by making the upper end of the vertical cylinder tiltable forward, it is easy to fill resin capsules and resin, and it is also convenient to check the dissolution state of the resin, which makes it easier than the conventional horizontal cylinder. It is extremely easy to operate, and because it is vertical, the air inside the resin capsule and cylinder is discharged upwards, preventing air from entering the melted resin and therefore preventing air bubbles from entering the product, improving quality. A high quality product is obtained, and there are almost no defective products.

The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the gist of the present invention. For example, as the resin, injection moldable dental thermosetting resins such as AMA resin other than thermoplastic resins can also be used. In this case, in order to heat the flask after injection and harden the resin, a hot plate may be attached to an appropriate location on the flask and the flask may be heated.

Furthermore, the shape of the resin may be a thin rod instead of a pellet, or a solid resin that matches the shape of the capsule body 11a.

[Brief explanation of the drawing]

The attached drawings show embodiments of the present invention, and the first
The figure is a perspective view of the molding device, Figure 2 is a central cross-sectional view of the cylinder holding part in Figure 1, also showing the forward tilted state, and Figure 3 is a vertical cross-section of the main part of the molding device using resin capsules. FIG. 4 is a partially cutaway side view of the resin capsule. 1...Cylinder, 1a...Heating device, 1b...
Cylindrical hole, 2, 2a... fulcrum, 3, 3a... pillar,
4... Frame, 5... Clamp device, 6... Piston, 7... Flask, 7a... Mold space, 7b
...Injection port, 7c...Gypsum mold, 7d...Negative pressure air passage, 8...Table, 9...Resin, 10...Resin capsule, 10a...Thin wall part of resin capsule, 11a... Main body, 11b...
...Resin capsule lid.

Claims (1)

[Claims] 1. In a resin capsule that is loaded inside a cylinder for injecting resin into a flask that has a molding space of a desired shape inside, the bottom of the bottomed cylindrical main body that houses the resin is lower than the cylindrical part. For molding resin-based dentures or crowns, which is formed thin and has a crown-shaped lid fitted inside the mouth of the main body, with the circumference becoming thinner toward the lower end. resin capsule.