CRUCIBLE FOR MELTING A THERMIT MATERIAL HAVING A GLASS OR METAL LAYER THERMIT WELDING DEVICE WITH SUCH CRUCIBLE

TECHNICAL FIELD

The present invention relates to a crucible employed in thermite welding and a thermite welding device by which such a crucible is utilized, specifically, a crucible which can protect a thermite material being utilized as the welding material inside the crucible for thermite welding from external humidity or oil, etc., and the welding device by which such a crucible is utilized.

BACKGROUND ART

Thermite welding is welding technology in which a mixed powder

(hereinafter, referred to as "thermite material") of aluminum and copper oxide (or iron oxide) is combusted in the vicinity of the surface of a base metal, and welding is performed by melting a portion of the surface of the base metal by introducing copper (or iron) that is melted via exothermic heat generated by a chemical reaction indicated by the chemical formula mentioned below onto the surface of the base metal.

2AI+3CuO → 3Cu+AI ₂ O ₃ +δQ (exothermic heat) (2AI+3FeO → 3Fe+AI ₂ O ₃ +δQ (exothermic heat))

The combustion of the thermite material, conventionally, is performed by packing the thermite material inside a furnace (hereinafter, referred to as "crucible") consisting of a highly thermal-resistant graphite together with the ignition material (ignition powder), etc., and igniting the ignition material. In the chemical reaction mentioned above, Cu (copper) and AI ₂ O ₃ (aluminum oxide) are separated, and the aluminum oxide, which has a lower specific gravity, is laminated onto the surface of the molten copper in a liquid state. Subsequently, it

flows from the lower layer of molten copper towards a weld portion of the surface of the base metal, until finally, the molten copper is welded to the base metal as the thermite welded weld metal. The AI2O3 (aluminum oxide), which is the unnecessary portion (hereinafter, referred to as "slag"), is accumulated on the outer periphery of the weld metal.

Hereinafter, a thermite welding process and a structure of a thermite welding device employed in conventional thermite welding will be explained with reference to Figure 3.

Fig. 3 (a) shows a condition before packing the thermite material and the ignition material; and Fig. 3 (b) shows a condition of the thermite material, ignition material, and a conductive rod connected to a terminal, etc., after being placed.

A thermite welding device 61 consists of: a crucible 65 for storing a thermite welding material 62 and ignition material 63 therewithin, and combusting these materials by igniting the ignition material; a passageway 67 for allowing the molten thermite material 62 to flow thereby after combustion; a concave portion 68 for forming a welding portion on the surface of the base metal, into which the molten thermite material flows via the passageway 67; and an insertion portion 69 for inserting a terminal 71 , etc., connected to conductive rod, welded together with the weld portion. In a pre-combusted state, the bottom portion inside the crucible 65 is blocked by a steel disc 64.

Subsequently, the surface of the base metal which is not illustrated in Fig. 3 (b) is brought into close contact with a surface 70, so that the concave portion 68 is tightly sealed. Then, in order to perform thermite welding, the ignition material 63 is ignited, and the thermite material 62 is combusted and melted. The steel disc 64 is also melted, along with the thermite material, and the molten metal thereof flows into the concave portion 68 via the passageway 67. Next, the molten metal melts a portion of the surface of the base metal abutted with the surface 70 having an opening portion, and a welded portion which corresponds to the shape of the inner portion of convex portion 68 is formed on the surface of the base metal.

[Patent Document 1] Japanese Patent No. 3619168

DISCLOSURE OF THE INVENTION

Problem(s) to be Solved A conventional thermite welding device, as mentioned above, is one having a configuration in which a crucible 65 is integrally formed within a structure thereof, or one having a configuration in which only the crucible is formed as a separate member of the structure, for example, a cartridge type crucible packed with a thermite material and ignition material, which can be exchanged by being attachable/detachable to/from a thermite welding device main body portion.

In the former configuration, in addition to the abovementioned graphite, the crucible may also be made of highly thermal-resistant ceramics; and in the later configuration, generally, the cartridge type crucible is made of highly thermal- resistant ceramics, and the thermal welding device main body portion is made of graphite or ceramics.

In the abovementioned thermite welding device configurations, since a mixed powder of the thermite material and ignition material (ignition powder, etc.) may be packed inside either of the abovementioned crucibles, it is desirable that a uniformly low moisture content is maintained inside the crucible, so as not to be susceptible to moisture, etc.

However, the cartridge-type crucible or thermite welding device consisting of ceramics absorbs moisture and oil easily, due to its porosity. Moreover, the moisture content within the crucible fluctuates in accordance with the moisture content of the external environment, and there is a potential for oil adhering to the outer surface of the cartridge-type crucible or thermite welding device, during the process of thermite welding, etc., to seep inside the crucible and be absorbed. When the moisture content within the crucible fluctuates, for example, in cases where there is a cartridge type crucible, into which the thermite welding material and ignition material have been packed and stored for a long duration of time, the ignition powder becomes moist and cannot function properly as the ignition material. Otherwise, when oil is absorbed within the crucible, there is a potential

for poor welds to occur due to the abovementioned oil, which adversely effects thermite welding.

Means for Solving the Problem(s) Accordingly, the present invention aims to provide a thermite welding device or ceramic crucible within which the thermite welding material and ignition material can be stored for a long time before thermite welding, even in a packed condition, by having a liquid tightness which is high enough to prevent contamination by oil, etc., and maintaining a uniform low moisture content therewithin.

In a first embodiment, in order to achieve the abovementioned aim, the crucible of the present invention is characterized as being a crucible for melting a thermite material, in which a metallic layer or glass layer is formed on an exterior surface or interior surface thereof. In a second embodiment of the crucible of the present invention, the crucible is further characterized as being a tubular crucible for thermite welding having a bottom portion provided with a through portion communicating with an exteriror, in which a metallic layer or glass layer is formed on an exterior surface or interior surface of the tubular crucible. In a third embodiment, the metallic layer of the crucible of the present invention preferably consists of copper, aluminum, nickel, zinc or an alloy thereof. In a fourth embodiment, when the crucible of the present invention is formed with a glass layer, a mass of the glass incorporated during thermite welding is preferably no more than 1/45 of a mass of the thermite material. In a fifth embodiment, the crucible of the present invention is preferably moisture resistant in an inner portion thereof.

In a sixth embodiment, the thermite welding device of the present invention comprises: the crucible described in any of second to fifth embodiments; a main body portion having a cavity portion forming a welding portion; and a passageway communicating with the through portion at one opening portion, and communicating the cavity portion at another opening portion.

In a seventh embodiment of the present invention, the thermite welding device is preferably one in which the crucible is universally attachable/detachable to/from the main body portion.

Summary of the Invention

According to the first embodiment of the present invention, since a metallic layer or glass layer is formed, the inner portion of the crucible is capable of being air-tightly maintained with uniformly low moisture content, for example, in cases where a cartridge type crucible having an inner portion packed with a thermite material and ignition material is employed, the abovementioned cartridge type crucible can be stored for a long period of time, without dampening the ignition material, etc.,. Furthermore, the inside of the crucible exhibits high liquid- tightness, and thus, is capable of preventing contamination by moisture and oil from the exterior. According to the second embodiment of the present invention, since a tubular crucible having a bottom portion provided with a through portion communicating with an exterior is employed as the crucible for thermite welding, a cartridge type crucible can be provided, in which a molten metal is capable of flowing to a predetermined position of a base metal surface during thermite welding.

Moreover, since the metallic layer or glass layer is formed, as described in a first embodiment of the present invention, the inner portion of the crucible is capable of being air-tightly maintained at uniformly low moisture content, for example, in cases where a cartridge type crucible having an inner portion packed with the thermite material and ignition material is employed, the abovementioned cartridge type crucible can be stored for a long period of time, without dampening the ignition material, etc.,. Furthermore, the inside of the crucible exhibits high liquid-tightness, and thus, is capable of preventing contamination by moisture and oil from the exterior. According to the third embodiment of the present invention, since the metallic layer consists of copper, aluminum, nickel, zinc, or an alloy thereof, the inner portion of the crucible is liquid-tightly protected from moisture or oil

penetration, etc., from the external environment before thermite welding. Moreover, a thermite welding process can be performed, in which the metallic material is melted together with the thermite material during thermite welding, and the metal of the metallic layer is deposited as a portion of the weld metal, or becomes slag, after thermite welding.

According to a fourth embodiment of the present invention, since the mass of glass incorporated during thermite welding is no more than 1/45 the mass of the thermite material, even if the glass formed as a layer on the inner surface of the crucible is incorporated into molten metal during thermite welding, for example, the glass becomes a portion of the weld metal after thermite welding without effecting the separation of the aluminum oxide and copper, and thus, the aim of the present is still achieved.

According to the fifth embodiment of the present invention, since the inner portion of the crucible is moisture resistant, superior thermite welding can be performed without becoming damp and having any moisture absorbed into the ignition material.

According to a sixth embodiment of the present invention, a thermite welding device equipped with the crucible having the abovementioned characteristics is provided, such that the required thermite welding can be performed.

According to a seventh embodiment of the present invention, since the crucible is universally attachable/detachable to/from the main body portion, for example, a thermite welding device constructed of a cartridge type crucible and thermite welding main body portion as separate members can be employed, and the thermite welding device main body portion may be reused, with only the cartridge type crucible being exchanged each time thermite welding is performed.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a cross-sectional diagram of a thermite welding device sectioned in a longitundial direction;

Fig. 2 (a) is cross-sectional diagram of a cartridge type crucible having a layer 11 consisting of glass or metal formed on an outer and inner surface thereof; Fig. 2 (b) is cross-sectional diagram of a cartridge type crucible having the layer 11 formed only on an outer surface thereof; and Fig. 2 (c) is cross-sectional diagram of a cartridge type crucible having the layer 11 formed only on an inner surface thereof; and

Fig. 3 is a diagram showing a thermite welding device structure employed in conventional thermite welding; Fig. 3 (a) shows a condition before packing the thermite welding material and ignition material; and Fig. 3 (b) shows a condition of the thermite welding material, ignition material and a conductive rod attached to a terminal, etc., after being positioned.

PREFERRED MODE FOR CARRYING OUT THE INVENTION

Example(s) of preferred embodiment(s) of the present invention shall be explained below with reference to the drawings. Moreover, in each drawing, the same constituents shall be designated by the same reference numerals, and when appropriate explanations thereof shall be omitted.

Example(s)

Example 1

Fig. 1 shows a perspective view of a thermite welding device 1 of the present invention containing a cartridge type crucible 3 and a thermite welding device main body portion 2, and a longitudinally sectioned cross-sectional phase diagram of the cartridge type crucible 3 attached to the thermite welding main body portion 2 of the thermite welding device 1.

The cartridge type crucible 3, which is attachable/detachable to/from the thermite welding main body portion 2, so as to be exchangeable after each use, is formed of a tubularly shaped highly thermal resistant ceramic, etc., preferably a cylindhcally shaped and highly thermal resistant ceramic containing a bottom

portion, and provided with a through portion 6 communicating a bottom portion thereof to an exterior. Furthermore, a steel disc 8 is arranged in the inner portion of the cartridge type crucible 3 to liquid-tightly and air-tightly seal the through portion 6, and a mixed powder of the thermite material 5 and the ignition material 4 is packed inside the crucible (refer to Fig. 2). Moreover, the cartridge type crucible 3 may be stored for a long period of time by having the inner portion liquid-tightly or air-tightly sealed by a lid, etc., (not illustrated), before being attached to the thermite welding main body portion 2.

The thermite welding device main body portion 2 consists of graphite, ceramics or another material having high thermal resistance, and includes a cavity portion 10, a passageway 11 and a passageway 9. The passageway 11 and the passageway 9 are formed with a connected passageway, so that when the cartridge type crucible 3 is attached to the thermite welding main body portion 2, the through portion 6 is arranged in the proximity of one opening portion of the passageway 11. The through portion 6 is formed to communicate with passageway 11 when unobstructed by steel disc 8. Moreover, the passageway 9 is formed to communicate with cavity portion 10 at one opening portion thereof. However, the passageway to the cavity portion 10, as shown in Fig. 1 , may be formed so that the vicinity flowing into the cavity portion may be visible from the exterior, or may be formed with through holes which are completely internal until reaching the cavity portion, so as to be non-visible.

Fig. 2 shows a cross-sectional diagram of the cartridge type crucible 3 of the present invention. In Fig. 2 (a), a layer 14 consisting of glass or metal is formed on an inner and outer surface of the cartridge type crucible 3, and the inside of the cartridge type crucible 3 becomes air-tight and liquid-tight. Accordingly, the inner portion of the cartridge type crucible 3 is moisture resistant, and prevents contamination by water or oil droplets, etc. The thickness of the layer 14, as described hereinafter, is preferably a thickness that is just thin enough to retain the air-tight and liquid-tight capabilities. Moreover, the glass of the present invention may be an amorphous or non-crystalline solid body exhibiting a glass transition phenomenon via a rise in temperature, or a substance in a state which is no more than a temperature of the

glass transition (glass state), for example, a silicate based silicate glass (quartz glass), or a non-silicate based acrylic glass, organic glass, chalcogen glass, metallic glass, inorganic glass, etc., in glassy state may be exemplified.

The metallic layer may be generated by employing a conventional evaporation coating method or a non-electrolytic plating method, and the glass layer may be generated by immersing the crucible in molten glass via a dipping method, or via a spray method, for example, utilizing a material which modifies a highly purified silica glass film by initiating a chemical reaction between the moisture in room temperature air and the spray covering a desired surface of the crucible.

Figs. 2 (b) and 2 (c) show examples of variations of Fig. 2 (a). In Fig. 2 (b), the layer 14 is only formed on the outer surface of the cartridge type crucible 3; and in Fig. 2 (c) the layer 14 is only formed on the inner surface of the cartridge type crucible 3. Examples of the metallic layer of layer 14 in Figs. 2 (a) to (c) may include, for example, aluminum, copper, nickel, zinc, or any alloy thereof, or additionally, any metal that can be selected from a metal which can be melted as the weld metal together with the thermite material. In the embodiment(s) of either Fig. 2 (b) or 2 (c), the air-tight and liquid-tight capabilities of the inner portion of the cartridge type crucible 3 are achieved, and the moisture resistant capability for maintaining a uniform moisture content is present. Accordingly, the ignition material 4 and the thermite material 5, which are packed within the inner portion of the cartridge type crucible 3, may be kept in a uniformly low moisture state.

Subsequently, a process for performing thermite welding using the thermite welding device of the present invention will be explained hereinafter. First, the cartridge type crucible 3 of the present invention is attached to the thermite welding device main body portion 2 (refer to Fig. 1 ). Next, a terminal, etc., (not illustrated) connected to a conductive rod, etc., for conducting thermite welding on the base metal surface is positioned in an insertion portion 7. The terminal has a dome-contouring shape, so as to closely contact the inner surface of the insertion portion 7, and is formed to have a flat surface portion being flush with surface 12. The terminal is located with at least an end portion thereof inside the cavity portion 10, and positioned in the insertion portion 7 so as to be

enveloped within the welded portion after thermite welding. Consequently, the space between the cavity portion 10 and the insertion portion 7 is in a tightly sealed state. Therefore, the cavity portion 10 is tightly sealed by abutting the surface 12 and the flat-surface portion of the terminal to the base metal surface (not illustrated). Once the abovementioned preparatory steps are completed, the lid (not illustrated) of the cartridge type crucible 3 is removed, and the thermite material 5 combusted by igniting the ignition material 4 in the crucible 3 via a predetermined method is melted together with the steel disc 8 arranged at the bottom portion of the cartridge type crucible 3. Here, in cases where the cartridge type crucible 3 of Figs. 2 (a) and 2 (c) is employed, since layer 14 of the inner surface of crucible 3 is in close contact with the thermite material 5, when the thermite material 5 is melted, the layer 14 is also melted via the heat therefrom.

Accordingly, in cases where the layer 14 consists of a metal, even if the thermite material 5 is contaminated by copper, aluminum, nickel, zinc or an alloy thereof, the nickel, the zinc or alloy thereof is incorporated into the welded metal of a copper thermite material; the aluminum or alloy thereof is incorporated into the slag (aluminum oxide); and the copper or alloy thereof is incorporated into a portion of the welded metal, since a main ingredient, or the copper or alloy thereof is identical to thermite material. In such cases, if the layer 14 is a layer of nickel, zinc or an alloy thereof which is thinly formed, as mentioned above, the metal mass of the layer is extremely small with respect to the mass of thermite material, and therefore, even if the molten thermite material 5 is mixed with any of the abovementioned metals, there is no deterioration in the weld performance of the welded metal of the thermite material welded to the surface of the base metal.

Moreover, in cases where the layer 14 is glass, when thermite welding was performed with 67 g of copper thermite material into which quartz glass is incorporated, the results showed that the molten copper and slag were favorably separated when the glass mass was no more than 1.5 g. That is, if the mass of glass incorporated into the thermite material 5 is no more than approximately 1/45 (1.5 g/ 67 g) of the mass of the thermite material, there are no adverse effects on the separation of the thermite material and slag during thermite welding.

Moreover, similar to cases where layer 14 is a metal, there is no deterioration in the weld performance of the welded metal of the thermite material 5 welded to the surface of the base metal. Accordingly, the glass layer is relatively thinly formed on the inner surface of the crucible 3, such that the mass of the portion melted together with the thermite material is no more than 1/45 the mass of the thermite material.

Subsequently, after the thermite material 5 is melted within the crucible 3, the molten thermite material 5 flows through the through portion 6, and into passageway 11 and passageway 9, to enter into and fill the inside of the cavity portion 10, via the force of gravity. The filled molten metal of the thermite material 5 melts a portion of the surface of the base metal not illustrated, and welds the surface of the base metal as a weld portion having the shape of cavity portion 10 after cooling. Finally, since the slag following the molten thermite also flows into cavity portion 10 to adhere to the surface of the weld portion, the slag is removed by employing a predetermined tool therefor, and the weld portion is arranged in the predetermined form via the impact, etc., to complete the thermite welding.

INDUSTRIAL APPLICABILITY

As described above, since the attachable/detachable cartridge type crucible of the present invention is formed with a metal layer or glass layer on the inner or outer surface thereof, the thermite material and the ignition material can be stored at a uniform moisture content in a packed state, with the inside of the crucible being air-tight and liquid-tight before thermite welding, such that thermite welding can be performed without any deterioration in the weld performance of the weld metal, even if thermite material is contaminated by the metal or glass forming such a layer during thermite welding.

In the Example(s), the attachable/detachable cartridge type crucible employed in the thermite welding device main body portion 2 is described.

However, it should be obvious to one who is skilled in the art that remarkable effects of the present invention can be achieved even if the metal layer or glass layer is formed on the inner surface of a crucible that is intregrally formed with the thermite welding device main body portion 2.

Moreover, while preferred embodiments of the present invention have been described and illustrated above, it is to be understood that they are exemplary of the invention and are not to be considered to be limiting. Additions, omissions, substitutions, and other modifications can be made thereto without departing from the spirit or scope of the present invention. Accordingly, the invention is not to be considered to be limited by the foregoing description and is only limited by the scope of the appended claims.

EXPLANATION OF THE REFERENCE NUMERALS 1 Thermite welding device

2 Thermite welding device main body portion

3 Cartridge type crucible

4 Ignition material

5 Thermite material 6 Through portion

7 Insertion portion

8 Steel disc

9 Passageway

10 Cavity portion 11 Passageway

12 Surface 14 Layer

61 Thermite welding device

62 Thermite material 63 Ignition material

64 Steel disc

65 Crucible

67 Passageway

68 Concave portion 69 Insertion portion

70 Surface

71 Flat surface portion