JPH076984Y2 - Denture base coining machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a device for coining a denture base using a superplastic metal plate.

[Conventional technology]

As a device for coining a denture base, Japanese Patent Laid-Open No. 1-91919 discloses that a mold for forming a denture base is housed in one of the furnaces that can be divided into two, and a superplastic metal plate is placed facing the molding surface of the mold. An apparatus is disclosed which sandwiches an annular seal member between both furnaces and deforms a superplastic metal plate heated to a superplastic temperature range along a molding surface of a mold by gas pressure. In a device for coining a denture base from a superplastic metal plate using such a gas pressure, a seal member for maintaining airtightness in the furnace is important from the viewpoint of securing the formability of the denture base and preventing oxidation. Become. As this seal member, the device disclosed in the above publication is Ni-Cr
Heat resistant alloys such as

On the other hand, it is not an apparatus for coining a denture base, but the use of a highly malleable metal for a gas seal member during superplastic metal forming is disclosed in Japanese Patent Laid-Open No. 61-238423. On the other hand, since the denture base is used after being molded and placed in the oral cavity, it cannot be altered by oxidation or the like and must have a perfect metal surface. As a method that enables such processing, there is a pack molding method as disclosed in Japanese Patent Laid-Open No. 1-150419.

[Problems to be solved by the device]

As a sealing member that maintains the airtightness in the furnace, a denture base coining machine using a heat-resistant alloy such as Ni-Cr is considered to be due to poor sealing even though the sealing member itself has excellent heat resistance. Occasionally bad accidents occurred. This is because due to the deformation of the mating surface of the furnace that can be divided into two parts, the distortion of the superplastic metal plate, etc., a sealing failure occurs in the intervening part of the seal member
It is probable that the superplastic metal sheet could not be maintained in the superplastic temperature range due to insufficient heating of the superplastic metal plate due to the gas cooling action caused by the outflow of the pressurized gas for forming.

In addition, since oxides may be generated and adhere to the part where the heat-resistant furnace metal object and the superplastic metal plate directly contact with each other at high temperature, it is necessary to apply a release material (inorganic refractory material) in advance. There is. In the case of the above-mentioned denture base forming device, the mold release material is applied to the downward sealing surface of the upper furnace, but there is a problem that this work is extremely difficult.

On the other hand, the gas seal member made of a highly malleable metal is soft and is deformed along with the modification of the mating surface of the furnace, and therefore, it is considered to be effective in eliminating the sealing failure. However, ordinary soft metals such as Al have a low melting point and melt when heated to a high temperature such as superplasticity temperature (800-900 ° C for Ti system), resulting in denture base imprinting. It cannot be used as a sealing member for molding equipment. On the other hand, a metal with a high melting point and a soft metal is extremely expensive because it is a noble metal, and is also unsuitable as a seal member for a denture base coiner.

The pack molding method does not have the risk of oxidative deterioration due to poor sealing, but has the drawback of lacking general versatility, such as packing being a special processing method such as beam welding in vacuum. It is also unsuitable for molding.

The present invention has been made in view of such circumstances, and in coining molding from a highly versatile superplastic metal plate, denture base coining molding that can eliminate a sealing defect that is a problem in the molding at low cost. The purpose is to provide a device.

[Means for Solving the Problems]

The denture base coining apparatus of the present invention accommodates a mold for molding a denture base in one of the furnaces which can be divided into two, and a superplastic metal plate is provided between the two furnaces so as to face the molding surface of the mold. In the denture base coining molding device that sandwiches via, and deforms the superplastic metal plate heated to the superplastic temperature range along the molding surface of the mold by gas pressure, the sealing member is made from an expansive graphite sheet with a purity of 99% or more. It becomes a feature.

[Action]

The expansive graphite sheet is obtained by expanding scaly graphite with acid and heat treatment, and then forming it into a sheet by compression molding.The raw material price is low, so the cost is low, and the characteristic is 200-300 ° C. It expands by heating at a relatively low temperature and exhibits sufficient heat resistance up to the superplastic temperature range of the superplastic metal sheet. Therefore, by using this expansive graphite sheet as a seal member of the denture base coining device targeted by the present invention, the expansive graphite sheet expands along the deformation of the mating surface of the furnace and the distortion of the superplastic metal plate in the initial heating stage. The expandable graphite sheet expands, and the seal portion is provided with sufficient airtightness.

Thus, the flaky graphite which is the material of the expandable graphite sheet contains compounds such as Si, Al, Ca, K, Fe and Ti as impurities. Further, the treatment with an acid (usually sulfuric acid) for expansion causes a small S content to remain. Therefore, the expandable graphite sheet contains some impurities.

When the expandable graphite sheet used as a seal member in the denture base coining apparatus of the present invention has a low purity, the ash content of the portion of the outer peripheral portion of the sheet that contacts the atmosphere is burned by the heating of the furnace. Adheres to the superplastic metal plate and also partially to the mating surface of the furnace. This ash adhesion is considered to be caused by the metal content as an impurity contained in the expansive graphite sheet, which is reduced and attached to the surroundings when the graphite is burned off, which makes it difficult to remove the denture base from the furnace. Further, it is very difficult to care for the adhered substances, and there is concern about the sealing property in the molding after the next time. Therefore, it is necessary not to generate such deposits.

In that respect, if the expansive graphite sheet has a purity of 99% or more, even when the outer peripheral portion of the sheet is burnt out, no deposits, deposits, etc. are formed in the vicinity thereof, and even if the release agent is not used, It is taken out smoothly, and there is no concern that the sealing property will deteriorate in the molding after the next time. Therefore, the expanded graphite sheet used as a seal member in the denture base coining apparatus of the present invention has a purity of 99% or more.

Note that as the expandable sheet, there is also a ceramic type. However, since the organic sheet is a composite for expansion, the organic sheet has a low heat resistant temperature and is expensive. On the other hand, a pure ceramic sheet made of ceramic short fibers has excellent heat resistance and is relatively flexible. However, if the superplastic metal plate is distorted, there will be insufficient sealing between the two furnaces until it is heated to approximately 800 ° C. Therefore, none of them can be sealed with an expansive graphite sheet.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
FIG. 1 is a vertical cross-sectional view schematically showing the structure of an example of a denture base coining device embodying the present invention.

The furnace 1 is composed of an upper furnace 1a and a lower furnace 1b which can be freely connected and separated. In the lower furnace 1b, a denture base coining mold 2 is housed with its molding surface 2a facing upward. In the lower furnace 1b containing the mold 2,
The superplastic metal plate 3 is placed so as to face the molding surface 2a of the mold 2. Then, for example, the lower furnace 1b is raised so as to hermetically cover the lower furnace 1b with the superplastic metal plate 3 and the annular seal member 4 placed thereon.

The superplastic metal plate 3 has, for example, a superplastic temperature range of 800 to 900 ° C.
It is a Ti-based material (Ti-9.5V-2.5Mo-3Al etc.) and has a thickness suitable for a denture base. The seal member 4 is made of an expansive graphite sheet having a purity of 99% or more, has an inner diameter d substantially the same as the inner diameter of the furnace 1, and a width w is preferably 7 to 10 mm. Also, the wall thickness t
Is preferably 0.38 to 0.43 mm. In the furnace 1, for example, Japanese Patent Laid-Open No.
The structure disclosed in Japanese Patent No. 91919 is adopted.

When the lower furnace 1b containing the mold 2 is hermetically covered with the superplastic metal plate 3 and the seal member 4, the upper furnace 1a and the lower furnace 1b are replaced with an inert gas. When this replacement is completed, the furnace 1 is heated, and from the time when the inside of the upper furnace 1a and the inside of the lower furnace 1b reach the superplastic temperature range of the superplastic metal plate 3, the upper furnace 1a
The internal gas thickness is increased to a predetermined pressure. By holding this state for a predetermined time, the superplastic metal plate 3 is deformed along the molding surface 2a of the mold 2 and molded into a denture base.

Thus, the seal member 4 begins to expand when the furnace temperature reaches 200 to 300 ° C. and deforms along the deformation of the mating surface of the upper furnace 1a and the distortion of the superplastic metal plate 3. Therefore, when heated to the superplastic temperature range, the outer peripheral portion of the seal member 4 in contact with the outside air is burnt off, but the other portion completely seals the upper furnace 1a and the superplastic metal plate 3. Therefore, it is possible to avoid the situation where the inert gas injected into the upper furnace 1a at a high pressure flows out, the amount of gas used is reduced, the cooling of the furnace 1 due to the outflow of gas is prevented, and the defective molding is prevented. Of course, the shortening of the molding time is also achieved.

Further, due to the sealing due to the expansion, the airtight holding work at the start of the work can be roughly performed, and the release material becomes unnecessary, so that the work time can be shortened. Further, in the work for taking out the denture base after the completion of molding, since no deposits are generated between the upper furnace 1a and the superplastic metal plate 3, the work can be performed easily. In addition, since the mating surface of the upper furnace 1a is kept clean, there is no fear that the sealing property will be deteriorated in the subsequent molding.

The seal member 4 can also be interposed between the superplastic metal plate 3 and the lower furnace 1b.

When the seal member made of Ni-Cr heat-resistant alloy was changed to the seal member made of expandable graphite sheet whose specification characteristics are shown in Table 1, the airtight maintenance work at the beginning of work, which took an average of 12 minutes, became unnecessary. The average time required for actual molding from the start of heating is 3
The average time was reduced from 48 minutes to 3 hours and 33 minutes by 15 minutes. The amount of Ar used as the inert gas was drastically reduced from 767 l to 103 l per molding. No molding failure or oxidative deterioration was observed in the molded denture base.

[Effect of device]

As is clear from the above description, the denture base coining apparatus of the present invention is remarkably excellent in gas sealability when forming a superplastic metal plate into a denture base by gas pressure, and contributes to high quality of the denture base. At the same time, the gas cost and the molding time are reduced. In addition, the seal member is inexpensive, and there is no possibility of causing harmful effects such as the formation of deposits. Further, it is possible to significantly reduce the time required for the airtight maintenance work.

[Brief description of drawings]

FIG. 1 is a vertical sectional view schematically showing the structure of an example of a denture base coining device embodying the present invention. 1: Furnace, 2: Mold, 2a: Forming surface, 3: Superplastic metal plate, 4: Seal member.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hirokazu Hokatsu, Hikazu, 3rd light, Oshima, Kashima-machi, Kashima-gun, Ibaraki Sumikin Kashima General Service Co., Ltd. (72) Junichi Yamada, 3rd light, Oshima, Kashima-machi, Kashima-gun, Ibaraki Prefecture Sumikin Kashima Comprehensive Service Co., Ltd. (72) Inventor Kenzo Maezono 3 Hikari, Kashima Town, Kashima Town, Ibaraki Prefecture Sumikin Kashima Comprehensive Service Co., Ltd. (56) Reference JP-A-1-91919 (JP, A) Special Kai 61-238423 (JP, A) JP-A-1-150419 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A mold for molding a denture base is housed in one of two furnaces which can be divided into two, and a superplastic metal plate is sandwiched between the two furnaces so as to face the molding surface of the mold with an annular seal member interposed therebetween. In a denture base coining apparatus for deforming a superplastic metal plate heated to a plastic temperature range along a molding surface of a mold by gas pressure, the seal member is made of an expansive graphite sheet having a purity of 99% or more, Denture base coining and forming device.