Machining method for reducing extrusion forming metal stripping

Abstract

The invention belongs to the technical field of plastic processing, and discloses a processing method for reducing extrusion forming metal peeling, which comprises the following steps: plugging one end of a to-be-formed area of a pipe, performing shot blasting treatment on the to-be-formed area of the pipe, spraying a water-based colloidal graphite lubricant on the to-be-formed area of the pipe, and performing extrusion forming on the to-be-formed area of the pipe; and the pipe end sprayed with the water-based colloidal graphite lubricant is dried, a graphite dry film is formed outside a to-be-formed area, the pipe end of the to-be-formed area of the pipe is extruded into a high-temperature forming mold, in the pipe shrinking process, pits formed through shot blasting are gradually deformed, the graphite dry film is gradually discharged out of the pits, and supplement of the lubricant is formed. According to the method, the pipe end lubricating form is improved, the improved lubricating performance is improved, the metal stripping condition in the extrusion forming process is basically eliminated, and the product percent of pass is increased. In the implementation process, all the steps are simple and practical technological methods, implementation is easy through automatic and integrated means, efficiency can be improved for mass production, and cost can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of plastic processing, and relates to a plastic processing method through extrusion deformation, and in particular to a processing method for reducing extrusion-formed metal peeling. Background Art

[0002] A tubular part is often used in aircraft control and lift systems. The structural characteristics of this part are that the outer diameter is thin and the wall is thick at both ends, the outer diameter is thick and the wall is thin in the middle, the inner cavity is hollow, and the appearance is shuttle-shaped. Generally, the internal thread is processed by using the thicker tube wall at both ends. Parts with this structure have the characteristics of light weight, high strength, and resistance to tension, compression, twisting, and bending. It can withstand static and dynamic loads during use. Since such parts are often used for flight attitude control and directly affect flight safety during flight, they are often defined as key or important parts.

[0003] Based on the closed cavity-like structure of this part, traditional machining methods cannot reach the inner surface of the part, and the tissue fibers are cut off during the machining process, which is not conducive to the parts achieving excellent mechanical properties. The ideal part performance can be more easily obtained by plastic processing, which generally adopts hot extrusion or cold rotary forging process methods. Compared with the two methods, the dynamic load performance of the parts processed by hot extrusion will be better. However, the hot extrusion method also has certain technical bottlenecks. That is, during the hot extrusion process, if the lubrication effect is poor, the pipe and the mold are prone to adhesion, and the outer surface of the pipe is partially peeled off. After the pipe is peeled off, the size of the subsequent processing blank is insufficient; the peeled metal has a high bonding strength with the mold. During reprocessing, the peeled metal hinders the flow of the pipe in the mold, and the pipe cannot be reshaped into a qualified size part. Therefore, the use of lubricants is related to the extrusion forming effect and the continuous service life of the mold.

[0004] There are two commonly used high temperature extrusion lubrication methods:

[0005] One is to use graphite powder-mineral oil lubricant. The advantage is that the materials involved are simple and easy to obtain. The disadvantage is that mineral oil produces a large amount of irritating gas in a high temperature environment, and it is also easy to produce open flames, which leads to a poor working environment and low production safety. Abrasive texturing does not improve the adhesion of the lubricant much. The metal of the parts often peels off at the beginning of the extruded parts and sticks to the mold, which shows that the lubricant fails to form an effective and complete isolation layer between the parts and the mold.

[0006] The second is to use glass composite lubricants. The advantage is good lubrication effect, but the disadvantage is that composite lubricants produce a certain amount of irritating gas in a high temperature environment. After cooling, the composite lubricant forms residues, which contain sharp structures of broken glass, which can easily cause personal injury. The working environment is also poor and production safety is low. In the high-speed extrusion process, the limited fluidity of glass can also easily cause metal peeling of parts. Summary of the invention

[0007] In order to solve the above problems, the present invention provides a processing method for reducing metal peeling during extrusion forming. By using automated equipment for pre-processing before forming, an excellent graphite coating effect is obtained, the metal peeling during extrusion forming is reduced, and a low-cost, high-quality extrusion forming effect is achieved.

[0008] The technical solution of the present invention is as follows:

[0009] A processing method for reducing extrusion metal peeling comprises the following steps:

[0010] S1, plugging one end of the area to be formed of the pipe;

[0011] S2, shot peening the area of ​​the pipe to be formed;

[0012] S3, spraying a water-based colloidal graphite lubricant on the area to be formed of the pipe;

[0013] S4, drying the tube end sprayed with the water-based colloidal graphite lubricant to form a graphite dry film outside the area to be formed;

[0014] S5, the end of the tube in the area to be formed is squeezed into a high-temperature forming die. During the shrinkage of the tube, the pits formed by shot peening are gradually deformed, and the graphite dry film is gradually discharged from the pits to form a lubricant supplement.

[0015] Furthermore, in S1, after the pipe is sealed, the pipe is placed vertically, and a low-melting-point alloy with a melting point of 85° C. is injected, the injection amount exceeds the height of the forming zone, and the pipe is cooled to room temperature.

[0016] Furthermore, in S4, after drying, the low melting point alloy melts and falls off.

[0017] Furthermore, in S2, cast steel shots with a diameter of 0.58 mm to 1.17 mm are used to spray around the surface of the to-be-formed area of ​​the pipe, forming dense and uniform pits on the surface of the pipe.

[0018] Further, in S3, the sprayed water-based graphite lubricant coating completely covers the pipe metal, and then the plugging of the pipe end is removed.

[0019] Furthermore, in S4, the end of the tube in the area to be formed is placed in a 200° C. heating coil for low-temperature drying for 5 minutes.

[0020] Furthermore, in S5, the end of the tube is squeezed into the high-temperature forming die at a speed of 1 mm / s to 3 mm / s.

[0021] Furthermore, in S5, the temperature of the high temperature forming mold is 500°C to 550°C.

[0022] The beneficial effects of the present invention are as follows:

[0023] 1. The processing method for reducing metal peeling during extrusion molding described in the present invention improves the lubrication form of the pipe end, and the improved lubrication performance is enhanced, which basically eliminates the metal peeling during the extrusion molding process and improves the product qualification rate.

[0024] 2. The processing method for reducing extrusion metal peeling described in the present invention is a simple and practical process method in each step during implementation, which is easy to implement through automation and integration, and can improve efficiency and reduce costs for mass production.

[0025] 3. The processing method for reducing extrusion-molded metal peeling described in the present invention has no irritating gas release, no open flame, no sharp residue generation, and is environmentally friendly and safe during use.

[0026] 4. After pouring the low melting point alloy, the inner wall of the tube is supported, which reduces the vibration of the tube during the outer surface processing and prevents the lubricant from being sprayed on the inner wall of the tube.

[0027] 5. The shot peening process of the present invention is to form pits on the surface of the pipe, to provide support for the adhesion of the water-based graphite lubricant coating, and more importantly, to provide a storage place for the graphite dry film; when the pipe enters the extrusion processing stage, the stored graphite dry film is softened by the high temperature mold, and the pits are squeezed out at the same time, providing timely and effective supplement for lubrication.

[0028] 6. When the low-temperature pipe end is squeezed into the high-temperature mold, the surface of the high-temperature mold first contacts the graphite dry film, forming heat conduction, and then the heat is conducted from the graphite dry film and the outside of the pipe end to the inside. Since the heat is conducted from the outside to the inside, the metal temperature on the outside is higher and the metal temperature on the inside is lower, the metal strength on the outside is reduced, and the pits on the outer surface gradually collapse under the extrusion force of the mold. The graphite dry film lubricant in the pits overflows one by one, and the lubricating layer of the graphite dry film is continuously replenished, which promotes the barrier effect between the mold and the outer surface of the pipe and reduces the risk of metal adhesion or even peeling.

[0029] 7. Since the forming process is gradual, the temperature of the outer metal and the inner metal are both rising, but a certain temperature difference is always maintained, so the strength of the inner material is relatively high, providing better support stability for the forming process.

[0030] 8. During the forming process, the pipe end is subjected to the radial force provided by the high-temperature mold, and the pipe end is formed into a narrowing state; after the pipe end forming purpose is achieved, the pipe is pulled out of the forming mold, and all the remaining pits are greatly reduced by the extrusion depth, which can be removed in the subsequent necessary mechanical polishing process of the pipe surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solution of the implementation method of the patent of the present invention, the following is a brief introduction to the drawings required for use in the implementation method. It should be understood that the following drawings only show certain embodiments of the patent of the present invention and should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A schematic diagram of the low melting point alloy infusion process of the invention;

[0033] Figure 2 A schematic diagram of the inventive pit processing and water-based graphite spraying process;

[0034] Figure 3 It is a schematic diagram of the low melting point alloy removal and graphite dry film drying process of the invention;

[0035] Figure 4 It is a schematic diagram of the hot extrusion forming process of the invention;

[0036] Figure 5 Schematic diagram of the graphite relubrication process in the pits of the invention.

[0037] Among them, 1. pipe; 2. plug; 3. low melting point alloy; 4. injection height; 5. forming area height; 6. cast steel projectile; 7. pit; 8. water-based colloidal graphite lubricant; 9. heating coil; 10. graphite dry film; 11. forming mold. DETAILED DESCRIPTION

[0038] This section is an embodiment of the present invention, which is used to explain and illustrate the technical solution of the present invention. In the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0039] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate directions or positional relationships as given in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or case referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implying the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0040] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be interpreted in a broad sense, for example, it can be a fixed connection, a detachable connection or an integrated connection; it can be a mechanical connection or a point connection; it can be a direct connection or a connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0041] Embodiment 1:

[0042] A processing method for reducing extrusion metal peeling comprises the following steps:

[0043] S1, plugging one end of the area to be formed of the pipe;

[0044] S2, shot peening the area of ​​the pipe to be formed;

[0045] S3, spraying a water-based colloidal graphite lubricant on the area to be formed of the pipe;

[0046] S4, drying the tube end sprayed with the water-based colloidal graphite lubricant to form a graphite dry film outside the area to be formed;

[0047] S5, the end of the tube in the area to be formed is squeezed into a high-temperature forming die. During the shrinkage of the tube, the pits formed by shot peening are gradually deformed, and the graphite dry film is gradually discharged from the pits to form a lubricant supplement.

[0048] In S1, after the pipe is sealed, the pipe is placed vertically, and a low melting point alloy with a melting point of 85°C is injected, the injection amount exceeds the height of the forming area, and cooled to room temperature.

[0049] In S4, after drying, the low melting point alloy melts and falls off.

[0050] In S2, cast steel shots with a diameter of 0.58 mm to 1.17 mm are used to spray around the surface of the to-be-formed area of ​​the pipe, forming dense and uniform pits on the surface of the pipe.

[0051] In S3, a sprayed coating of water-based graphite lubricant completely covers the pipe metal, and then the pipe end plugging is removed.

[0052] In S4, the end of the tube in the area to be formed is placed in a 200° C. heating coil for low-temperature drying for 5 minutes.

[0053] In S5, the end of the tube is squeezed into a high temperature forming die at a speed of 1 mm / s to 3 mm / s.

[0054] In S5, the temperature of the high temperature forming die is 500°C to 550°C.

[0055] Embodiment 2:

[0056] The purpose of the present invention is to provide a processing method for reducing the peeling of extruded metal. The pipe end is sealed with a rubber plug or a wooden plug, the pipe is placed vertically, and a low-melting-point alloy with a melting point of 85°C is injected. The injection amount exceeds the height of the forming area, generally 80mm to 100mm, and then cooled to room temperature. After the low-melting-point alloy is poured, the inner wall of the pipe is supported, which reduces the vibration of the pipe during the outer surface processing and prevents the lubricant from being sprayed on the inner wall of the pipe. Shot peening technology is used to process the forming area of ​​the pipe end, that is, the area where the lubricant needs to be coated. Cast steel shots are generally selected for shot peening, and the shot diameter is 0.58mm to 1.17mm. By adjusting the air flow velocity and the spraying distance, dense and uniform pits with a maximum diameter of 0.4mm to 0.5mm are formed on the surface. In the forming area, a water-based colloidal graphite lubricant is sprayed, and the lubricant coating is preferably used to completely cover the metal, and the rubber plug or wooden plug is removed. The tube end sprayed with water-based colloidal graphite lubricant is placed in a 200℃ heating coil for 5 minutes for drying. After drying, the low melting point alloy melts and falls off, and the area to be formed is adhered by a graphite dry film. During forming, the tube end is squeezed into a 500℃ to 550℃ high-temperature forming mold at a speed of 1mm / s to 3mm / s. The high temperature reduces the strength of the metal. Under the action of the radial component force, the material shrinks with the mold surface. During the shrinking process, the surface graphite lubrication layer isolates the tube from the mold surface. The pit gradually deforms as the material is squeezed. The volume of the pit decreases during the deformation process, and the graphite is gradually discharged from the pit, forming a supplement for the lubricant, which can greatly improve the integrity of the lubrication layer, reduce the probability of contact and adhesion between the tube end material and the mold surface, and thus reduce the possibility of metal peeling during the extrusion forming process.

[0057] The technical solution of the present invention is a processing method for reducing extrusion metal peeling, comprising the following specific steps:

[0058] 1. Seal the end of the pipe 1 with a plug 2, place the pipe 1 vertically, inject a low-melting-point alloy 3 with a melting point of 85°C, and the injection height 4 is generally 80mm to 100mm. The injection height 4 is required to exceed the forming area height 5, and cool to room temperature.

[0059] 2. Cast steel shots 6 with a diameter of 0.58 mm to 1.17 mm are used to spray around the surface of the forming area of ​​the pipe 1, and dense and uniform pits 7 with a maximum diameter of 0.4 mm to 0.5 mm are formed on the surface of the pipe 1 within the spraying range.

[0060] 3. Spray water-based colloidal graphite lubricant 8 around the surface of the forming area of ​​the pipe 1. The coating of water-based graphite lubricant 8 is preferably enough to completely cover the metal of the pipe 1. Remove the plug 2.

[0061] 4. The end of the pipe 1 sprayed with the water-based colloidal graphite lubricant 8 is placed in a 200° C. heating coil 9 for 5 minutes for drying. After low-temperature heating, the low-melting-point alloy 3 melts and falls off, and a graphite dry film 10 is formed on the end of the pipe 1.

[0062] 5. During forming, the end of the pipe 1 is squeezed into a high-temperature forming die 11 at 500°C to 550°C at a speed of 1mm / s to 3mm / s. The high temperature reduces the strength of the metal. Under the action of the radial force, the end of the pipe 1 shrinks along with the surface of the forming die 11.

[0063] 6. During the shrinking process, the lubricating layer of the graphite dry film 10 on the end surface of the tube 1 isolates the tube 1 from the molding surface of the forming die 11. The pit 7 is gradually deformed as the tube 1 is squeezed. The volume of the pit 7 decreases during the deformation process, and the graphite dry film 10 is gradually discharged from the pit 7, forming a supplement to the lubricating layer of the graphite dry film 10.

[0064] 7. After the end of the pipe 1 is formed, the pipe 1 is pulled out from the forming die 11. The depth of all remaining pits 7 is greatly reduced after extrusion, and can be removed in the subsequent necessary mechanical polishing process of the surface of the pipe 1.

Claims

1. A processing method for reducing extrusion metal peeling, characterized in that: The following steps are involved: S1, plugging one end of the area to be formed of the pipe; S2, shot peening the area of ​​the pipe to be formed; S3, spraying a water-based colloidal graphite lubricant on the area to be formed of the pipe; S4, drying the tube end sprayed with the water-based colloidal graphite lubricant to form a graphite dry film outside the area to be formed; S5, the end of the tube in the area to be formed is squeezed into a high-temperature forming die. During the shrinkage of the tube, the pits formed by shot peening are gradually deformed, and the graphite dry film is gradually discharged from the pits to form a lubricant supplement.

2. A method for reducing extrusion metal peeling according to claim 1, characterized in that: In S1, after the pipe is sealed, the pipe is placed vertically, and a low melting point alloy with a melting point of 85°C is injected, the injection amount exceeds the height of the forming area, and cooled to room temperature.

3. A method for reducing extrusion metal peeling according to claim 2, characterized in that: In S4, after drying, the low melting point alloy melts and falls off.

4. A method for reducing extrusion metal peeling according to claim 1, characterized in that: In S2, cast steel shots with a diameter of 0.58 mm to 1.17 mm are used to spray around the surface of the to-be-formed area of ​​the pipe, forming dense and uniform pits on the surface of the pipe.

5. A method for reducing extrusion metal peeling according to claim 1, characterized in that: In S3, a sprayed coating of water-based graphite lubricant completely covers the pipe metal, and then the pipe end plugging is removed.

6. A method for reducing extrusion metal peeling according to claim 1, characterized in that: In S4, the end of the tube in the area to be formed is placed in a 200° C. heating coil for low-temperature drying for 5 minutes.

7. A method for reducing extrusion metal peeling according to claim 1, characterized in that: In S5, the end of the tube is squeezed into a high temperature forming die at a speed of 1 mm / s to 3 mm / s.

8. A method for reducing extrusion metal peeling according to claim 1, characterized in that: In S5, the temperature of the high temperature forming die is 500°C to 550°C.

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