Thermal action solid joining method for metal materials

Abstract

Welding is a technique for joining two or more metallic materials together. To solve the problem that the strength of a joining part is insufficient in conventional welding. Further, it is technically difficult to manufacture a metal plate material having a large size and a large thickness, and when necessary, a plurality of plate materials are stacked and joined by bolts and nuts or rivets. However, since the work process is complicated, a simpler method has been required.SOLUTION: As a material property of metal, there is a property that an object to be joined is joined by being melted (in a liquid state), and a joining method using this property is welding. Metals also have the property of being joined by atomic bonding of the contact surfaces even when the joining targets are at a temperature immediately before melting (in a solid state). When this is used in the bonding method, it is not necessary to melt the bonding target, and the bonding portion can be bonded on a solid surface instead of a conventional linear or dotted shape. By this method, the problems of the insufficient strength of the joined part and the thickness working of the sheet material are solved.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to the material properties of metals and the application of welding technology. [Background technology]

[0002] Material properties of metals (atomic bonding due to heat)

[0003] Metal material welding technology Summary of the Invention [Problem to be solved by the invention]

[0004] (Task 1) There is a technique called welding that is used to join metal materials. Welding technology is a technique for joining two or more metal materials into one metal material by melting the joint, cooling it, and solidifying it. There are three methods: fusion welding, which uses heat from a gas flame, arc discharge, laser, etc. to melt the contact surfaces of the base metal and filler metal to be joined, and join them; pressure welding, which applies frictional heat or pressure to the joint area of ​​the metals to be joined, and joins them; and brazing, which fills the gap between the base metals to be joined with an alloy with a lower melting point than the base metals, and joins them. Conventional welding methods have the problem that the strength of the joint, which is formed by melting and then cooling and hardening the metal, is weaker than that of the unmelted portion. Once melted and cooled, the molecular bonding structure of the joint changes, even if the metal is the same type as the other parts, so the properties are different and the strength is weaker. (Task 2) Conventional welding methods involve melting lines or points to join materials, but because the area ratio of the joining area to the entire material is small, there are issues with low joint stability and reduced strength. (Assignment 3) It was technically difficult to manufacture a metal plate (single plate) that was large in size and thick (tall). (The temperature of the surface and interior of the plate cools down at different times after production, which means there is a time difference in cooling shrinkage, making deformation and warping more likely to occur, and making quality control difficult.) When a thick, large plate material is required, multiple plates are stacked and joined together to increase the thickness. Welding technology is suitable for joining both ends of plates to increase their length, but it is not suitable for stacking plates to increase their thickness, so bolts, nuts, and rivets were used to join them. This joining method involves complicated steps, so a simpler method was needed. [Means for solving the problem]

[0005] (Solution 1) Welding, a conventional joining technique, involves melting the joint between base materials to be joined, or between a filler metal and the base material, and then allowing it to cool and harden. Metals have the property of being joined (integrated) when the objects to be joined are at a temperature above their melting point (in a molten liquid state), and also have the property of being atomically bonded (integrated) at the contact surface when the objects to be joined are at a temperature just below their melting point (in a solid state just before melting). When this property of metals is utilized in joining techniques, an electrode is attached to the base metal or filler metal and an electric current is passed through it from an external power source. This generates Joule heat within the metal material, causing it to reach a high temperature. (If the dimensions of the base material to be joined are small, heat the entire base material; if the dimensions of the base material are large, heat the area around the joint.) When the temperature reaches just below the melting point, the base material or filler material is joined in a solid state at the contact surface. Since the base material or filler metal is joined (integrated) with other base materials without melting, the molecular bonding structure remains unchanged, solving the problem of insufficient strength seen in conventional welding. (Solution 2) The joints between the base materials to be joined are arranged so that the joint surfaces are in contact with each other without any gaps. Then, a plate made of the same type of metal as the base material is placed at a position that overlaps the joint (the boundary between the base materials) (a position that covers the outside of the boundary between the base materials), electrodes are attached to this plate, and an electric current is passed through it from an external power source. Then, solid bonding is performed at a temperature just below melting. This allows the plate material to function as a filler material in welding, and the plate material and the base material are joined (integrated) at the surface area of ​​the plate material. The two base materials are joined by joining (integrating) the surface area of ​​the plate material at a position where the plate material straddles the junction of the base materials to be joined (the boundary between the base materials). Conventional welding creates a linear joint, but this method, which uses plate-shaped solid joining, solves the problem of insufficient strength in conventional welding by joining the entire surface area of ​​the plate, which acts as a filler metal. (Solution 3) The joining method described in Solution 2 is not used to connect (join) the base materials to be joined horizontally, but rather to stack the base materials to increase their thickness, thereby simplifying the work process compared to conventional joining methods that use bolts, nuts, or rivets, and solving the problem. The problem is solved by a method of manufacturing thick plates (single plates) by repeatedly layering base materials on top of each other and creating solid bonds that utilize the properties of metals.

Claims

1. There is a joining technique called welding that is used when joining metal materials (such as plates) to make products. Welding technology is a technique for joining (integrating) two or more metal materials by melting the joints of the materials, cooling them, and solidifying them into a single material. Welding can be divided into three methods: fusion welding, which uses heat from a gas flame, arc discharge, laser, etc. to melt and join the joint between the base materials (metal materials to be joined) and filler metal (metal material sandwiched between the base materials for connection purposes); pressure welding, which applies frictional heat, pressure, electric current, etc. to the joint between the base materials to melt and join them; and brazing, which fills the gap between the base materials with an alloy with a lower melting point than the base materials and joins them. Of these three, brazing uses an alloy with a lower melting point than the base material as the joining material, so naturally the strength of the joint is weak, but the other two, fusion welding and pressure welding, also have insufficient joint strength. The reason for this is due to the concept of welding, which involves melting the joints (both ends) of the materials to be joined, then letting them cool and harden to join them. If a part of a completed metal material (such as a sheet metal) is melted, even if it is made of the same metal (molecules) as the unmelted part, the molecular bonding structure changes, resulting in different properties and a weaker strength. In addition to the property that metals bond to other objects when the temperature of the objects to be joined exceeds their melting point (when they are in a molten liquid state), they also have the property that they form atomic bonds at the contact surface with other objects to be joined when the temperature of the objects to be joined is just below their melting point (when they are in a solid state just before they melt). By applying this property to joining technology, it is possible to prevent a decrease in strength due to changes in the molecular bonding structure. An electrode is attached to the base materials to be joined, or to a filler metal that is a member for connecting the base materials, and a current is passed through it from an external power source. This causes Joule heat to be generated within the metal material (electrical energy is converted into thermal energy within the metal material). (If the dimensions of the base materials to be joined are small, the entire base material is heated with electric current; if the dimensions of the base materials are large, the heating is centered around the joint). When the current continues to flow and the temperature reaches just before the melting point, the material remains in a solid state at the joint (contact surface) because it has not yet exceeded the melting point. Since the base material or filler metal is not melted, the molecular bonding structure does not change, preventing a decrease in strength. This is a joining method that utilizes the properties of metals, in which an electric current is passed through the base materials to be joined, or the filler metal, which is the material used to connect the base materials, generating Joule heat and joining them at a high temperature (solid state) just before melting. This method prevents a lack of strength at the joint by bonding at a temperature just before the melting point (when the material is in a solid state just before melting) rather than at a temperature above the melting point (when the material is in a molten liquid state).This method does not change the molecular bonding structure and prevents a lack of strength at the joint.

2. Welding, a conventional joining technique, melts and joins lines or points, so the area ratio of the joint to the entire base material to be joined is narrow and small, which results in low joint stability and insufficient strength. In contrast to this, the characteristics of the metal used in the method described in claim 1 (if it is the same metal, atoms bond at the contact surface at a temperature just before the melting point) are utilized, and the base materials are lined up and a plate of the same type of metal as the base materials is placed at a position overlapping the joint (the boundary between the base materials), and electrodes are attached to this plate and current is passed through it from an external power source. This generates Joule heat within the metal material, and when the temperature reaches just below melting point, the plate material is bonded to the base material across the entire contact surface. As a result, the plate material located at a position overlapping the joint (boundary line) between the base materials functions as a joining material (filler metal in welding) that joins the two base materials. Conventional welding joins two base materials in a long, thin line, but with this method, the base materials are joined in a planar manner by placing plates across the boundary between them, improving the stability of the joint and preventing a lack of strength. In this way, an electric current is passed through plates placed at the joint (contact surface) between the base materials to be joined, generating Joule heat and joining them at a high temperature (solid state) just before melting. This is a method of joining base materials at the surface area of ​​the plates used to join base materials. Rather than joining the base materials at their contact surfaces, the plate material that straddles the joining point of both base materials is joined to both base materials, resulting in the two base materials being joined together (the plate material placed so that it overlaps the joining point of both base materials is joined to both base materials, thereby fulfilling the joining function between the base materials), and because the plates are joined across their entire surfaces, the area ratio of the joint is larger and wider than with conventional welding, preventing a decrease in the strength of the joint.

3. It was technically difficult to manufacture a metal plate (single plate) that was large in size and thick (height). (The surface and interior of the plate material take different amounts of time to cool after production, which means there is a time difference in cooling shrinkage, making deformation and warping more likely and making quality control more difficult.) When a thick plate was required, the thickness was increased by stacking and joining multiple plates. Welding technology is suitable for joining both ends of plate material and connecting them horizontally, but it is not suitable for stacking plate material to increase thickness. Therefore, bolt nuts and rivets were used to join the plates, which made the process complicated. This method simplifies the process compared to conventional methods by increasing the thickness of the plate material using the same method as that described in claim 2, in which a metal plate material is heated with an electric current and joined to a base material at the surface area of ​​the plate material. A method for improving strength by applying the joining method utilizing the properties of metals described in claim 2 to a technique for joining metal plates in layers to increase their thickness.

4. Capital materials (construction materials, etc.) and durable consumer goods (ships, aircraft, etc.) manufactured using the methods of claims 1, 2, and 3.

5. A service or business using the capital goods or durable consumer goods according to claim 4.