A T-joint self-propagating deflagration friction pressure welding-mortise composite connection method

Abstract

The present invention discloses a self-propagating deflagration friction pressure welding-mortise composite connection method for a T-joint. The method belongs to the field of welding. The method comprises: machining a spherical interlocking groove on the bottom plate surface of the T-joint; machining a spherical connector that matches the interlocking groove on the lower end surface of the web; the connector is slightly smaller than the interlocking groove; and nano self-propagating powder is added between the connector and the interlocking groove. Pressure is applied downward to the web, and at the same time, two pendulums are used to hammer the web back and forth, so that the web spherical connector and the nano self-propagating powder slide a short distance. When the sliding friction heat reaches the ignition temperature, a self-propagating reaction of the powder is triggered to generate molten steel and molten aluminum oxide. The surface of the ball head and the spherical interlocking groove is heated and melted. Under the action of high temperature and pressure, the reaction products, molten steel and aluminum oxide, are squeezed out, and the ball head is welded to the spherical interlocking groove to form a weld-mortise composite connection T-joint. The joint not only has high bonding strength, but also can improve connection efficiency and reduce welding processing costs.

Description

Technical Field

[0001] The present application belongs to the field of welding technology, and specifically relates to a T-joint self-propagating deflagration friction pressure welding-mortise composite connection method. Background Art

[0002] This T-shaped welded joint refers to a joint formed by welding two steel plates into shapes that are perpendicular to each other. The shape of the joint is similar to the letter "T", so it is called a "T-shaped joint". In the prior art, the T-shaped joints of CN218777592U and CN115719343A steel plates are usually welded by electric welding or laser welding. During the electric welding process, it is necessary to first machine grooves on both sides of the steel plate ends, and then perform multiple passes of multi-layer welding to achieve the connection of two ultra-thick steel plates in the form of a T-shaped joint. Among them, the welding materials required for multi-pass multi-layer welding are large, and the welds need to be cleaned and polished many times during the welding process. The welding process is cumbersome, the welding quality control is difficult, and the weld strength and toughness are poor, which cannot meet the current demand for high efficiency and high quality of the welding process. Summary of the Invention

[0003] Based on this, the present application provides a T-joint self-propagating deflagration friction pressure welding-mortise composite connection method.

[0004] A first aspect of the present invention provides a T-joint self-propagating deflagration friction pressure welding-mortise composite joining method, comprising: machining a spherical mating groove on the bottom surface of the T-joint; machining a spherical connector head on the lower end surface of the web to mate with the mating groove; wherein the dimensions of the connector head are smaller than those of the mating groove; after the connector head is inserted into the mating groove, nano-self-propagating powder is added to the gap formed between the connector head and the mating groove. A hydraulic press continuously applies downward pressure to the web, while simultaneously hammering the web back and forth with two pendulums, causing the spherical connector head at the lower end of the web to slide relative to the spherical mating groove in a short reciprocating motion along the length of the groove. When the frictional heat generated by the sliding friction reaches the ignition temperature of the nano-self-propagating powder, a strong self-propagating exothermic reaction occurs instantaneously. After ignition, hammering ceases. The reaction produces molten steel and molten alumina, accompanied by a large amount of high-temperature gas. The high temperature melts the spherical connector head at the lower end of the web and the surface of the spherical mating groove, which are in contact with the powder. Under the action of the deadweight of the web and the continuous downward force of the hydraulic press on the web, the molten steel and alumina at the bottom of the ball head are squeezed into the side gap along the surface of the ball head along with the high-temperature gas. Due to the low density of alumina, it floats on the surface and is squeezed out of the fitting groove. As a result, the spherical connector with a molten surface is in direct contact with the surface of the spherical fitting groove and is welded together. After maintaining the pressure for a few minutes, the longitudinal pressure is released. A metallurgical bond is formed. Thus, a T-joint is formed by a self-propagating deflagration friction pressure welding-mortise and tenon composite connection. In this connection structure, the fitting groove has a limiting section, which is used to limit the connector from falling out of the fitting groove. The orthographic projection of the limiting section on the bottom of the fitting groove is covered by the bottom of the groove. The orthographic projection of the notch of the fitting groove on the bottom of the groove is covered by the orthographic projection of the limiting section on the bottom of the fitting groove. Four triangular limiting blocks are symmetrically positioned on either side of the notch of the mating groove on the bottom plate surface to ensure the bottom plate and web surface remain perpendicular during up, down, and forward, and backward movement. The chemical composition of the molten steel generated by the self-propagating exothermic reaction is identical to that of the bottom plate and / or web. A gap of 5mm-10mm is provided between the bottom surface of the connector and the bottom surface of the mating groove, which is filled with nano self-propagating powder.

[0005] The present invention changes the traditional T-joint connection method, shortens the connection process, and at the same time forms a weld-mortise composite connection method through self-propagating friction pressure welding and the mutual interlocking of the interlocking groove and the connector, thereby ensuring the connection strength between the base plate and the web. It is an efficient, high-quality, and low-cost connection method. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0007] Figure 1 Schematic diagram of the self-propagating deflagration friction pressure welding-mortise composite connection process of a T-joint provided in an embodiment of the present invention;

[0008] Figure 2 2. This is a schematic structural diagram of a T-joint provided in an embodiment of the present invention after self-propagating deflagration friction pressure welding-mortise composite connection is completed;

[0009] Reference numerals:

[0010] 1-base plate, 2-triangular limiting block, 3-web, 4-nano self-propagating powder, 5-molten steel. DETAILED DESCRIPTION

[0011] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0012] The process of T-joint self-propagating deflagration friction pressure welding-mortise composite connection is as follows: Figure 1 As shown: Length and width are 1000mm, thickness is 300mm, material is 45 # The surface of the steel T-joint bottom plate 1 is processed with a spherical fitting groove with a diameter of 130-140 mm; the length and width are 1000 mm, the thickness is 80 mm, and the material is 45 #The lower end surface of the steel web 3 is machined with a spherical connector that mates with the slot. The connector is smaller than the slot, resulting in a gap of 5-10 mm between the two. After the connector is inserted into the slot, the gap between the connector and the slot is filled with nano self-propagating powder 4 with a particle size of 50-80 nm, and pressure is applied from the side to compact the powder 4. The main formula of the self-propagating powder is configured according to the equation 8Al + 3Fe3O4 = 4Al2O3 + 9Fe, and appropriate alloying elements are added to ensure that the composition of the molten steel generated by the self-propagating reaction is the same as that of the connected plates. Four triangular limiting blocks are symmetrically spot-welded on either side of the notch of the bottom plate to ensure that the bottom plate surface and the web surface remain perpendicular during up, down, and forward and backward movement. They are removed after welding. A hydraulic press applies a continuous downward pressure of 200 MPa to the web 3. Simultaneously, two pendulum hammers strike the front and rear ends of the web, causing it to slide a short distance back and forth. The spherical connector at the lower end of the web and the spherical groove, under positive pressure, generate sliding friction. When the heat generated by friction reaches the ignition temperature of the nano-SPP powder, approximately 500°C, the powder undergoes a strong, self-propagating, exothermic reaction (explosion). Ignition is followed by the hammering, which ceases. This reaction produces molten steel and molten aluminum oxide, with the same chemical composition as the connected plates, accompanied by a large amount of high-temperature gas. The high temperature causes the spherical connector at the lower end of the web and the surface of the spherical groove on the bottom plate to instantly melt. Under the weight of the web and the continuous downward pressure of the hydraulic press, the molten steel and aluminum oxide at the bottom of the spherical connector, along with the high-temperature gas, are squeezed along the surface of the spherical connector into the side gap. Due to its low density, the aluminum oxide floats to the surface and is squeezed out of the groove, leaving the molten steel in the groove. As a result, the spherical connector and the surface of the spherical groove are welded together, forming a metallurgical bond. After maintaining the pressure for 5 minutes, longitudinal pressure is ceased. Complete the self-propagating deflagration friction pressure welding-mortise composite connection to form a T-shaped joint. Figure 2 It is a schematic diagram of the structure of the T-joint after the self-propagating deflagration friction pressure welding-mortise composite connection is completed provided by an embodiment of the present invention. In this connection structure, the fitting groove has a limiting section, and the limiting section is used to limit the connector from falling out of the fitting groove. Optionally, the orthographic projection of the limiting section on the bottom of the fitting groove is covered by the bottom of the groove. Optionally, the orthographic projection of the notch of the fitting groove on the bottom of the groove is covered by the orthographic projection of the limiting section on the bottom of the fitting groove. The depth of the fitting groove should be greater than one-third of the thickness of the base plate and less than or equal to two-thirds of the thickness of the base plate 1, so as to ensure that the fitting groove fully exerts its fitting effect without affecting the strength of the base plate, and to prevent the base plate from being significantly deformed during the casting mortise composite connection process, thereby affecting the connection effect.

[0013] The length of the interlocking groove should be less than or equal to the length of the base plate, and one end face thereof should be aligned with the end face of the base plate 1 to form a groove body with an opening at least at one end. Optionally, in order to reduce the difficulty of processing and improve the versatility between the connecting parts, the interlocking groove and the connector can be selected to meet the standards of the mechanical industry, in addition to the spherical shape. During the design process, the dovetail-shaped interlocking groove size parameters that are compatible with the thickness of the base plate can be selected by looking up a table or other methods. The interlocking groove of the base plate can be formed on the plate surface of the base plate using common mechanical processing methods. Specifically, multi-step grooving, insert turning or ramping is usually used for processing. The web is an extra-thick steel plate, and its thickness is usually greater than 20mm. A connector that is compatible with the interlocking groove can be processed on the main body of the web by methods such as hot forging and hot piercing. Among them, the width and depth of the connector should be less than the width and depth of the interlocking groove, and the length of the connector can be less than or equal to the length of the interlocking groove. In this process, the present invention reduces the steps of conventional welding and shortens the welding process. At the same time, the mutual engagement of the engaging grooves and the connecting heads ensures the connection strength between the bottom plate and the web, which is an efficient and high-quality welding method.

[0014] The embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from the other embodiments. References to the common and similar parts between the various embodiments are sufficient. Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they understand the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as covering the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0015] Finally, it should be noted that, in this document, relational terms such as base plate and web are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises", "includes" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, an element defined by the sentence "comprises a..." does not exclude the presence of other identical elements in the process, method, article or terminal device that includes the element.

[0016] The above is a detailed introduction to the self-propagating deflagration friction pressure welding-mortise composite connection method of a T-joint provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A T-joint self-propagating deflagration friction pressure welding-mortise composite connection method, characterized in that a spherical fitting groove is machined on the bottom plate surface of the T-joint, and a spherical connector that matches the fitting groove is machined on the lower end surface of the web, wherein the size of the connector is smaller than the size of the fitting groove, and after the connector is inserted into the fitting groove, the gap between the connector and the fitting groove is filled with nano self-propagating powder and compacted, and pressure is continuously applied downward to the web while two pendulums are used to hammer the web back and forth so that the spherical connector of the web and the nano self-propagating powder slide back and forth in the fitting groove along the length direction of the groove. When the sliding friction heat reaches the ignition temperature of the nano self-propagating powder, self-propagation is triggered. The powder undergoes a self-propagating high-temperature exothermic reaction. After ignition, the hammering is stopped and the reaction generates molten steel, molten alumina and high-temperature gas. The high temperature causes the surface of the spherical connector at the lower end of the web and the surface of the spherical fitting groove of the bottom plate to melt due to the heat. Under the action of the web's own weight and the pressure continuously applied downward to the web, the molten steel and molten alumina at the bottom of the ball head are squeezed to the side of the fitting groove along the surface of the ball head along with the high-temperature gas. Due to the low density of alumina, it floats on the surface and is squeezed out of the fitting groove. The spherical connector with the melted surface is in direct contact with the surface of the spherical fitting groove and is welded together. After maintaining the pressure for a few minutes, the longitudinal pressure is released to complete the self-propagating deflagration friction pressure welding-mortise composite connection of the T-joint.

2. According to the connection method of claim 1, the fitting groove has a limiting section, which is used to limit the connecting head from escaping from the fitting groove, and the orthographic projection of the notch of the fitting groove on the bottom of the groove is covered by the orthographic projection of the limiting section on the bottom of the fitting groove.

3. The method according to claim 1, characterized in that Triangular limiting blocks are respectively provided on both sides of the engaging groove on the plate surface of the bottom plate, and their function is to keep the plate surface of the bottom plate and the plate surface of the web plate always perpendicular during the upward, downward, forward and backward movement.

4. The method according to claim 1, characterized in that The chemical composition of the molten steel generated by the self-propagating exothermic reaction is the same as the chemical composition of the bottom plate and / or web.

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