A forming method for improving the inner surface quality of a copper-clad steel liner

Abstract

The present application discloses a forming method for improving the inner surface quality of a copper drug-former, belonging to the technical field of plastic processing of metal materials. The method includes preparing a bar blank made of copper; extruding the bar blank with large deformation to prepare a conical preform; placing the conical preform into the cavity of the extrusion die of an extrusion device, and performing cold extrusion forming on the conical preform for three to five passes. The deformation rate for each pass of cold extrusion forming is 5 mm / s to 10 mm / s, and the deformation amount is controlled to be 10% to 30%. Before odd-numbered cold extrusion forming, lubricant is applied to the surface of the conical preform and the inner surface of the cavity of the extrusion die. Stress-relieving annealing is performed on the formed part to obtain an annealed part; the annealed part is placed into the cavity of the extrusion die for at least one cold sizing forming until a copper drug-former with a taper angle deviation ≤ 2°, a wall thickness difference ≤ 0.08 mm, and an inner surface roughness Ra ≤ 0.2 μm is obtained. The inner surface quality of the drug-former prepared by the present application is good.

Description

Technical Field

[0001] This application relates to the technical field of plastic processing of metal materials, and particularly to a forming method for improving the inner surface quality of a copper-clad liner. Background Art

[0002] The liner is a key component of a shaped charge warhead, which is used to converge the detonation wave energy generated by the shaped charge explosion, and then form a high-speed metal jet to achieve penetration and destruction of the target, playing an important role in the petroleum industry and other fields.

[0003] Copper is a tough, soft and ductile purple-red and shiny metal, which has a high density (8.9 g / cm 3 ), high sound velocity (4.7 km / s) and high melting point (1085 °C), and shows good plastic deformation ability in both hot and cold states. Using copper material to form the liner can not only reduce the production cost, but also obtain a continuous jet with high penetration performance, meeting the high-performance requirements of the warhead. The penetration ability of the copper-clad liner mainly depends on grain size, surface roughness and tissue uniformity, etc. Among them, rough inner surface quality is likely to cause local fracture of the copper jet, poor jet stability and small penetration depth. The requirement for high penetration performance of the copper-clad liner determines that the inner surface quality is one of the key factors affecting its high-efficiency service. Therefore, improving the inner surface quality of the copper-clad liner is an important goal in forming the liner component.

[0004] At present, turning forming is the mainstream process for manufacturing copper-clad liners. This process has the characteristics of simple and easy operation, but it is prone to tool sticking during the forming process, resulting in poor inner surface quality of the liner. In addition, due to the geometric characteristics of the liner such as deep cone and thin wall, problems such as wall thickness difference and large cone angle deviation will inevitably occur during the processing using plastic deformation processes such as stamping and spinning. The surface roughness generally exceeds 1 μm, which will also lead to poor inner surface quality of the liner. Summary of the Invention

[0005] The embodiments of this application solve the problem that the forming method of the liner in the prior art results in poor inner surface quality of the liner by providing a forming method for improving the inner surface quality of a copper-clad liner.

[0006] To achieve the above object, the technical solution of the embodiments of the present invention is as follows:

[0007] The embodiments of the present invention provide a forming method for improving the inner surface quality of a copper-clad liner, including:

[0008] Preparing a bar blank made of copper;

[0009] Extruding and greatly deforming the bar blank to prepare a conical preform;

[0010] Place the conical preform into the cavity of the extrusion die of the extrusion device, and perform cold extrusion forming on the conical preform in three to five passes. The deformation rate of each cold extrusion forming is 5 mm / s to 10 mm / s, and the deformation amount is controlled to be 10% to 30%, until a medium-formed part with a cone angle deviation ≤ 3°, a wall thickness difference ≤ 0.1 mm, and no obvious pits or scratches on the surface is obtained. Among them, before odd-numbered cold extrusion forming, lubricant is applied to the surface of the conical preform and the inner surface of the cavity of the extrusion die;

[0011] Perform stress relief annealing on the medium-formed part to obtain an annealed part;

[0012] Place the annealed part into the cavity of the extrusion die and perform at least one cold sizing forming until a copper liner for shaped charge with a cone angle deviation ≤ 2°, a wall thickness difference ≤ 0.08 mm, and an inner surface roughness Ra ≤ 0.2 μm is obtained.

[0013] In a possible implementation manner, when the deformation amount is controlled to be 10% to 30%, it further includes:

[0014] The deformation amount of each pass gradually decreases.

[0015] In a possible implementation manner, before odd-numbered cold extrusion forming, when lubricant is applied to the surface of the conical preform and the inner surface of the cavity of the extrusion die, it further includes:

[0016] Before even-numbered cold extrusion forming, wipe the inner surface of the cavity of the extrusion die clean.

[0017] In a possible implementation manner, the preparation of the bar stock made of copper includes:

[0018] Calculate the volume of the bar stock using the structure diagram of the liner for shaped charge, and obtain a bar stock with a height-to-diameter ratio of 1.2 to 1.5 by cutting and turning the copper raw material.

[0019] In a possible implementation manner, the extrusion of the bar stock with large deformation to prepare a conical preform includes:

[0020] Place the bar stock into the cavity of the extrusion die. Under dry friction conditions, control the punch of the extrusion device to move downward to make the bar stock in the cavity of the extrusion die be compressed and deformed. Among them, the deformation rate of the compression deformation is 5 mm / s to 10 mm / s, and the deformation amount is controlled to be 30% to 45%, to obtain a conical preform with a cone angle deviation ≤ 4°, a wall thickness difference ≤ 0.3 mm, and no obvious pits or scratches on the surface.

[0021] In a possible implementation, in the process of stress-relieving annealing the middle-shaped part to obtain an annealed part, the heat treatment temperature is 300°C to 350°C, and the holding time is 50 min to 90 min.

[0022] In a possible implementation, the holding time is calculated according to the following formula:

[0023] T = 40 + aDn,

[0024] where T is the holding time, a is the holding time coefficient, D is the wall thickness, and n ranges from 1.2 to 2.2.

[0025] In a possible implementation, putting the annealed part into the cavity of the extrusion die for at least one cold sizing forming includes:

[0026] Putting the annealed part into the cavity of the extrusion die, performing one or two passes of cold sizing forming on the annealed part, and the deformation rate of each pass of the cold sizing forming is 2 mm / s to 5 mm / s, and the deformation amount is controlled to be 0.5% to 3%.

[0027] In a possible implementation, before putting the annealed part into the cavity of the extrusion die, it further includes:

[0028] Coating the surfaces of the annealed part and the inner surface of the cavity of the extrusion die with a lubricant.

[0029] In a possible implementation, the lubricant includes rapeseed oil, TR2-drawing oil, and castor oil.

[0030] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0031] The embodiments of the present invention provide a forming method for improving the inner surface quality of a copper liner. The method includes preparing a bar blank made of copper. Extruding the bar blank with large deformation to prepare a conical preform. Putting the conical preform into the cavity of the extrusion die of an extrusion device, performing three to five passes of cold extrusion forming on the conical preform, and the deformation rate of each pass of the cold extrusion forming is 5 mm / s to 10 mm / s, and the deformation amount is controlled to be 10% to 30%, until a middle-shaped part with a cone angle deviation ≤ 3°, a wall thickness difference ≤ 0.1 mm, and no obvious pits or scratches on the surface is obtained. Among them, before odd-numbered cold extrusion forming, the surfaces of the conical preform and the inner surface of the cavity of the extrusion die are both coated with a lubricant. Stress-relieving annealing the middle-shaped part to obtain an annealed part. Putting the annealed part into the cavity of the extrusion die for at least one cold sizing forming until a copper liner with a cone angle deviation ≤ 2°, a wall thickness difference ≤ 0.08 mm, and an inner surface roughness Ra ≤ 0.2 μm is obtained.

[0032] Before the odd-numbered cold extrusion forming of this application, lubricant is applied to the surface of the conical preform and the inner surface of the extrusion die cavity, which can reduce the friction force between the surface of the conical preform and the inner surface of the extrusion die cavity. By means of the relative sliding of the contact surface, micro hydrodynamic lubrication is formed, and the lubricating oil accumulated in the closed lubricating oil pit is led out to form a lubricating oil film with a uniform thickness, reducing the friction coefficient to avoid phenomena such as adhesion and scratches, reducing the surface roughness, and thus improving the surface quality of the obtained intermediate formed part. After the odd-numbered cold extrusion forming, since the surface topography of the conical preform is micro-protrusions, the lubricating oil will be stored in the concave areas between the micro-protrusions. After completing the odd-numbered cold extrusion forming, the conical preform for the next even-numbered cold extrusion forming is directly placed into the extrusion die cavity for even-numbered cold extrusion forming without applying lubricant to the surface of the conical preform and the inner surface of the extrusion die cavity, reducing the harmful friction force during the even-numbered cold extrusion forming while taking into account weakening the hindering effect of the lubricant on the surface flattening effect of the conical preform. The surface roughness of the conical preform after multi-pass cold extrusion forming is greatly reduced. Before the odd-numbered and even-numbered multi-pass cold extrusion forming, different lubrication conditions are selected to optimize the interface state between the conical preform and the extrusion die cavity, further reducing the surface roughness of the liner and improving the uniformity and forming stability of its surface quality. At the same time, the forming method for improving the inner surface quality of the copper liner provided by the embodiments of this application has the characteristics of simple operation, high process stability, and wide applicability. It simplifies the quality control of the inner surface of the copper liner and improves the forming accuracy. In addition, the forming method of this application is near-net-shape forming, with high material utilization rate. The intermediate formed part is prepared by multi-pass cold extrusion forming, and the required time cost is relatively low. Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments of the present invention. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0034] Figure 1 It is a flowchart of the forming method for improving the inner surface quality of the copper liner provided by the embodiments of this application;

[0035] Figure 2 It is the copper liner obtained in Embodiment 1 of this application;

[0036] Figure 3 It is the SEM morphology diagram of the inner surface of the copper liner obtained in Embodiment 1 of this application: (a) at point a in the core; (b) at point b in the radial direction; (c) at point c in the radial direction;

[0037] Figure 4The white light interference morphology map of the inner surface of the copper liner obtained in the first embodiment of this application: (a) at point a in the core; (b) at point b in the radial direction; (c) at point c in the radial direction;

[0038] Figure 5 The copper liner obtained in the second embodiment of this application;

[0039] Figure 6 The SEM morphology map of the inner surface of the copper liner obtained in the second embodiment of this application: (a) at point a in the core; (b) at point b in the radial direction; (c) at point c in the radial direction;

[0040] Figure 7 The white light interference morphology map of the inner surface of the copper liner obtained in the second embodiment of this application: (a) at point a in the core; (b) at point b in the radial direction; (c) at point c in the radial direction;

[0041] Figure 8 The copper liner obtained in the third embodiment of this application;

[0042] Figure 9 The SEM morphology map of the inner surface of the copper liner obtained in the third embodiment of this application: (a) at point a in the core; (b) at point b in the radial direction; (c) at point c in the radial direction;

[0043] Figure 10 The white light interference morphology map of the inner surface of the copper liner obtained in the third embodiment of this application: (a) at point a in the core; (b) at point b in the radial direction; (c) at point c in the radial direction. Detailed implementation manners

[0044] Next, the technical solutions in the embodiments of this application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0045] In the relevant descriptions of this embodiment, terms such as "include, contain, have" are all open terms, generally preferably understood as including but not limited to; the term "at least one" is generally preferably understood as one or more, where "multiple" means two or more; the term "at least one (item) of the following" or its similar expression refers to any combination of these items, including any combination of single item (item) or plural items (items). For example, "at least one (item) of a, b or c", or, "at least one (item) of a, b and c" can all represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, where a, b, c can be single or multiple respectively; the symbol "A / B" is used to describe the selection relationship of associated objects, generally representing an "or" relationship before and after.

[0046] In the following description of this embodiment, the terms used in the embodiments of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms "a" and "the" used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly dictates otherwise.

[0047] Those skilled in the art should understand that in the following description of the embodiments of this application, the sequence numbers do not imply the order of execution, and some or all of the steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of this application.

[0048] Those skilled in the art should understand that the numerical ranges in the embodiments of this application should be understood to specifically disclose each intermediate value between the upper and lower limits of the range. Each intermediate value within any stated value or range of values, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0049] Unless otherwise specified, the technical / scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs. Although this application only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of this application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0050] An embodiment of the present invention provides a forming method for improving the inner surface quality of a copper drug form cover, as Figure 1 shown, including steps 101 to 105:

[0051] Step 101: Prepare a bar blank made of copper.

[0052] Step 101 specifically includes calculating the volume of the bar blank using the structure diagram of the drug form cover, and obtaining a bar blank with a height-to-diameter ratio of 1.2 to 1.5 by cutting and turning the copper raw material. Specifically, according to the principle of constant volume in plastic forming and the principle of near-uniform plastic deformation, select appropriate dimensions of the copper raw material, and obtain a bar blank with a height-to-diameter ratio of 1.2 to 1.5 by fine wire electrical discharge machining and turning the outer surface of the copper raw material. The bar blank is cylindrical. The height-to-diameter ratio of the bar blank being 1.2 to 1.5 is based on considering the shape and stress state of the drug form cover, which can reduce the deformation resistance of the drug form cover, increase the plastic deformation amount, refine the surface layer grains, and thus reduce the surface roughness.

[0053] Step 102: Extrude the bar billet with large deformation to prepare a conical preform.

[0054] Among them, Step 102 includes putting the bar billet into the cavity of the extrusion die, and under dry friction conditions, controlling the punch of the extrusion device to move downward to make the bar billet in the cavity of the extrusion die be compressed and deformed. Among them, the deformation rate of the compression deformation is 5 mm / s to 10 mm / s, and the deformation amount is controlled to be 30% to 45%, so as to obtain a conical preform with a cone angle deviation ≤ 4°, a wall thickness difference ≤ 0.3 mm, and no obvious pits or scratches on the surface. The setting of this deformation rate and deformation amount can obtain a conical preform with better quality, thus laying a good foundation for the next step.

[0055] When there is no lubricant between two friction surfaces, the ridge-like protrusions (called profile peaks) on the surfaces of the two objects are in direct contact, and this friction state is called dry friction. In the embodiment of the present application, the bar billet is put into the cavity of the extrusion die, and under dry friction conditions, by controlling the punch of the extrusion device to move downward, the bar billet in the cavity of the extrusion die is compressed and deformed. The ridge-like protrusions on the surface of the billet first come into contact with the die, and the mutual sliding effect is strong. The ridge-like convex bodies are directly affected by the pressure of the cavity of the extrusion die and expand to form small planes. The material of the liner of the present application is copper. Due to the excellent plastic deformation ability and good self-lubricating property of copper, under dry friction conditions, the bar billet is extruded with large deformation, so that the flattening effect of the ridge-like convex bodies on the surface of the bar billet during the forming process is maximized. More and more metal fills the concave areas, making the small planes connect with each other. The flattening effect of the ridge-like protrusions on the contact surface between the bar billet and the cavity of the extrusion die is significant, and thus the surface roughness of the prepared conical preform is greatly reduced, and the inner surface quality is significantly improved.

[0056] Step 103: Prepare an intermediate formed part by multi-pass cold extrusion forming: Put the conical preform into the cavity of the extrusion die of the extrusion device, and perform three to five passes of cold extrusion forming on the conical preform. The deformation rate of each pass of cold extrusion forming is 5 mm / s to 10 mm / s, and the deformation amount is controlled to be 10% to 30%. Further, the deformation amount of each pass gradually decreases, and the difference in the amount of decrease can be the same or different, until an intermediate formed part with a cone angle deviation ≤ 3°, a wall thickness difference ≤ 0.1 mm, and no obvious pits or scratches on the surface is obtained. Among them, before the odd-numbered cold extrusion forming, the surface of the conical preform and the inner surface of the cavity of the extrusion die are both coated with lubricant.

[0057] Further, before the odd-numbered cold extrusion forming, coating the surface of the conical preform and the inner surface of the cavity of the extrusion die with lubricant also includes: wiping the inner surface of the cavity of the extrusion die clean before the even-numbered cold extrusion forming.

[0058] Exemplarily, before the first-pass cold extrusion forming, lubricant is applied to both the surface of the conical preform and the inner surface of the extrusion die cavity, and the deformation amount of the first-pass cold extrusion forming is controlled to be 30%. Before the second-pass cold extrusion forming, lubricant is no longer applied to the surface of the conical preform and the inner surface of the extrusion die cavity, and the inner surface of the extrusion die cavity is wiped clean. The deformation amount of the second-pass cold extrusion forming is controlled to be 25%. Before the third-pass cold extrusion forming, lubricant is applied to both the surface of the conical preform and the inner surface of the extrusion die cavity, and the deformation amount of the third-pass cold extrusion forming is controlled to be 19%, and so on.

[0059] Before odd-numbered cold extrusion forming, lubricant is applied to both the surface of the conical preform and the inner surface of the extrusion die cavity, which can reduce the friction force between the surface of the conical preform and the inner surface of the extrusion die cavity. By means of the relative sliding of the contact surface, micro hydrodynamic lubrication is formed, the lubricating oil accumulated in the closed lubricating oil pit is led out and a lubricating oil film with uniform thickness is formed, the friction coefficient is reduced to avoid phenomena such as adhesion and scratches, the surface roughness is reduced, and thus the surface quality of the obtained intermediate formed part can be improved.

[0060] After odd-numbered cold extrusion forming, since the surface topography of the conical preform is micro-protrusions, the lubricating oil will be stored in the concave areas between the micro-protrusions. After the odd-numbered cold extrusion forming is completed, the conical preform for the next even-numbered cold extrusion forming is directly placed into the extrusion die cavity for even-numbered cold extrusion forming without applying lubricant to the surface of the conical preform and the inner surface of the extrusion die cavity, and the inner surface of the extrusion die cavity is wiped clean. There is lubricant residue on the surface of the conical preform and no lubricant on the inner surface of the extrusion die cavity, which reduces the harmful friction force during the even-numbered cold extrusion forming and at the same time weakens the hindering effect of the lubricant on the surface flattening effect of the conical preform. The surface roughness of the conical preform after multi-pass cold extrusion forming is greatly reduced. Before odd-numbered and even-numbered multi-pass cold extrusion forming, different lubrication conditions are selected to optimize the interface state between the conical preform and the extrusion die cavity, further reducing the surface roughness of the liner and improving the uniformity and forming stability of its surface quality.

[0061] In step 103, the number of passes of the cold extrusion forming of the conical preform and the deformation amount of each pass are designed according to the requirements of the cone angle deviation, wall thickness difference and surface roughness of the liner.

[0062] The deformation amount per pass gradually decreases, while the total deformation amount gradually increases. The expanding extrusion forming of the conical preform is controlled by step - increment deformation, thereby realizing the forming of the copper - clad explosive liner and controlling the surface quality. This application utilizes the sensitive mechanism of the surface roughness during the cold extrusion forming process of the copper - clad explosive liner on the interface pressure and lubrication conditions. Through the step - increment forming method, the inner surface quality of the copper - clad explosive liner is effectively improved, overcoming the problems of high surface roughness and difficult control of surface uniformity of the copper - clad explosive liner in the conventional forming method. At the same time, it has the advantages of low production cost, high material utilization rate, and good process stability.

[0063] Step 104: Stress relief annealing is performed on the centered formed part to obtain an annealed part, that is, the centered formed part is subjected to vacuum heat treatment in a vacuum heat treatment furnace. Among them, the heat treatment temperature is 300°C - 350°C, and the holding time is 50 min - 90 min. The annealing treatment eliminates the fibrous structure through recrystallization, reduces the deformation resistance, and improves the surface quality.

[0064] Furthermore, the holding time is calculated according to the following formula:

[0065] T = 40 + aDn,

[0066] where T is the holding time, with the unit of min; a is the holding time coefficient, generally taking a value of 4 min / mm; D is the wall thickness, with the unit of mm; n takes a value of 1.2 - 2.2, which is related to the hardness of the material. The calculation formula for the holding time provided in the embodiments of this application can accurately calculate the holding time according to materials with different hardnesses, making the effect of stress relief annealing better.

[0067] Step 105: The annealed part is placed into the cavity of the extrusion die for at least one cold sizing forming until a copper - clad explosive liner with a cone angle deviation ≤ 2°, a wall thickness difference ≤ 0.08 mm, and an inner surface roughness Ra ≤ 0.2 μm is obtained.

[0068] Furthermore, placing the annealed part into the cavity of the extrusion die for at least one cold sizing forming includes:

[0069] The annealed part is placed into the cavity of the extrusion die, and one to two passes of cold sizing forming are performed on the annealed part. The deformation rate of each pass of cold sizing forming is 2 mm / s - 5 mm / s, and the deformation amount is controlled at 0.5% - 3%. Among them, the number of passes of cold sizing forming is determined according to the cone angle deviation, wall thickness difference, and inner surface roughness of the explosive liner. Cold sizing forming can achieve the high - surface - quality forming of the copper - clad explosive liner.

[0070] Optionally, before placing the annealed part into the cavity of the extrusion die, it further includes: applying lubricant to both the surface of the annealed part and the inner surface of the cavity of the extrusion die.

[0071] Among them, the lubricant includes rapeseed oil, TR2-drawing oil and castor oil. Rapeseed oil and castor oil are vegetable oils, which are easy to obtain and harmless to the human body. The drawing oil is made by blending high-quality mineral base oil, compounding high-performance sulfurized lard and sulfurized fatty acid ester as the main agents. It is dedicated to metal stamping and drawing processing, has excellent anti-wear and extreme pressure properties, will not cause workpiece hair pulling or scratching, improves the surface finish of the workpiece, effectively extends the service life of the punching die, is easy to clean, has no peculiar smell, and does not irritate the skin.

[0072] The forming method for improving the inner surface quality of the copper-clad explosive liner provided by the embodiment of the present application can effectively improve the inner surface quality of the copper-clad explosive liner, and has the characteristics of simple operation, high process stability and wide applicability. It simplifies the quality control of the inner surface of the copper-clad explosive liner and improves the forming accuracy. In addition, the forming method of the present application is near-net forming, with high material utilization rate. The formed parts are prepared by multi-pass cold extrusion forming, and the required time cost is relatively low.

[0073] The following provides a specific embodiment of a forming method for improving the inner surface quality of the copper-clad explosive liner of the present application.

[0074] Example 1

[0075] Taking a copper-clad explosive liner with equal wall thickness as an example, the caliber size of the copper-clad explosive liner is Ф158mm, the height is 172mm, the inner cone depth is 152mm, the maximum wall thickness is 3mm, and the inner cone angle is 54°. The specific process is as follows:

[0076] Step 101: Prepare a bar blank made of copper.

[0077] Calculate the volume of the bar blank using the structure diagram of the explosive liner. According to the principle of constant volume in plastic forming and the principle of near-uniform plastic deformation, select a copper bar with a size of Ф50mm. Obtain a bar blank with a diameter of 48mm and a height of 70mm by fine wire electrical discharge machining and turning the outer surface of the original copper material.

[0078] Step 102: Extrude the bar blank with large deformation to prepare a conical preform.

[0079] Place the bar blank into the cavity of the extrusion die. Under dry friction conditions, the extrusion die is installed in a 1600-ton hydraulic press. The bar blank in the cavity of the extrusion die is compressed and deformed by controlling the downward movement of the punch of the extrusion device. The deformation rate is 10mm / s, and the deformation amount is controlled at 45%. Obtain a conical preform with a cone angle deviation ≤4°, a wall thickness difference ≤0.3mm, and no obvious pits or scratches on the surface.

[0080] Step 103: Prepare the intermediate formed part by multi-pass cold extrusion forming.

[0081] Place the conical preform into the cavity of the extrusion die, and perform three cold extrusion forming operations on the preform under the condition of a deformation rate of 5 mm / s. Before the first cold extrusion forming, apply TR-2 stretching oil lubricant to the surface of the conical preform and the inner surface of the extrusion die cavity, and control the deformation amount of the first cold extrusion forming to 30%. Subsequently, wipe the inner surface of the extrusion die cavity clean, and directly place the conical preform after the first cold extrusion forming into the extrusion die cavity for the second cold extrusion forming, and control the deformation amount of the second cold extrusion forming to 28%. Then, apply rapeseed oil lubricant to the surface of the conical preform after the second cold extrusion forming and the inner surface of the extrusion die cavity, place the conical preform after the second cold extrusion forming into the extrusion die cavity for the third cold extrusion forming, and control the deformation amount of the third cold extrusion forming to 24%, obtaining a medium-formed part with a cone angle deviation ≤ 3°, a wall thickness difference ≤ 0.1 mm, and no obvious pits or scratches on the surface.

[0082] Step 104: Perform stress relief annealing on the medium-formed part to obtain an annealed part.

[0083] Place the medium-formed part into a vacuum heat treatment furnace for stress relief annealing. The heat treatment temperature is 350 °C, the holding time is 65 min, and the vacuum degree is not less than 2.5×10 -3 Pa.

[0084] Step 105: Place the annealed part into the cavity of the extrusion die for at least one cold sizing forming.

[0085] Place the annealed part into the cavity of the extrusion die, and perform two cold sizing forming operations on the annealed part under the condition of a deformation rate of 2 mm / s.

[0086] Before each cold sizing forming, apply rapeseed oil lubricant to the surface of the annealed part and the inner surface of the extrusion die cavity, and control the deformation amounts of the first and second cold sizing forming operations to 2% and 0.5% respectively, obtaining a copper liner with a cone angle deviation ≤ 2°, a wall thickness difference ≤ 0.08 mm, and an inner surface roughness Ra ≤ 0.2 μm.

[0087] Perform surface topography observation and surface roughness measurement on the copper liner prepared in Example 1. Select three different positions along the radial direction of the copper liner component from the center to the inner diameter edge as the detection positions (as Figure 2 shown). The results show that the height of the micro-protrusions on the inner surface decreases significantly, and the surface topography is flat (as Figure 3 and Figure 4 shown). The surface roughness values at the three positions from the center to the inner diameter edge are 0.15 μm, 0.13 μm, and 0.18 μm respectively, and the inner surface quality of the copper liner is significantly improved.

[0088] Example 2

[0089] Taking an equal-wall-thickness copper liner as an example, the caliber size of the copper liner is Ф140mm, the height is 143mm, the inner cone depth is 118mm, the maximum wall thickness is 4mm, and the inner cone angle is 60°. The specific process is as follows:

[0090] Step 101: Prepare a bar blank made of copper.

[0091] Calculate the volume of the bar blank using the structure diagram of the liner. According to the principle of constant volume in plastic forming and the principle of near-uniform plastic deformation, select a copper bar with a size of Ф50mm. Obtain a bar blank with a diameter of 48mm and a height of 60mm by precision wire electrical discharge machining and turning the outer surface of the original copper material.

[0092] Step 102: Extrude the bar blank with large deformation to prepare a conical preform.

[0093] Place the bar blank into the cavity of the extrusion die. Under dry friction conditions, the extrusion die is installed in a 1600-ton hydraulic press. Press the bar blank in the cavity of the extrusion die to deform by controlling the downward movement of the punch of the extrusion device. The deformation rate is 8mm / s, and the deformation amount is controlled at 35%. Obtain a conical preform with a cone angle deviation ≤4°, a wall thickness difference ≤0.3mm, and no obvious pits or scratches on the surface.

[0094] Step 103: Prepare an intermediate formed part by multi-pass cold extrusion forming.

[0095] Place the conical preform into the cavity of the extrusion die, and perform five-pass cold extrusion forming on the preform under the condition that the deformation rate is 5 mm / s. Before the first-pass cold extrusion forming, apply TR-2 stretching oil lubricant to both the surface of the conical preform and the inner surface of the extrusion die cavity, and control the deformation amount of the first-pass cold extrusion forming to 28%. Subsequently, wipe the inner surface of the extrusion die cavity clean, and directly place the conical preform after the first-pass cold extrusion forming into the extrusion die cavity for the second-pass cold extrusion forming, and control the deformation amount of the second-pass cold extrusion forming to 24%. Then, apply rapeseed oil lubricant to both the surface of the conical preform after the second-pass cold extrusion forming and the inner surface of the extrusion die cavity, and place the conical preform after the second-pass cold extrusion forming into the extrusion die cavity for the third-pass cold extrusion forming, and control the deformation amount of the third-pass cold extrusion forming to 18%. Then, wipe the inner surface of the extrusion die cavity clean, and directly place the conical preform after the third-pass cold extrusion forming into the extrusion die cavity for the fourth-pass cold extrusion forming, and control the deformation amount of the fourth-pass cold extrusion forming to 14%. Finally, apply TR-2 stretching oil lubricant to both the surface of the conical preform after the fourth-pass cold extrusion forming and the inner surface of the extrusion die cavity, and place the conical preform after the fourth-pass cold extrusion forming into the extrusion die cavity for the fifth-pass cold extrusion forming, and control the deformation amount of the fifth-pass cold extrusion forming to 10%, to obtain a medium-formed part with a cone angle deviation ≤ 3°, a wall thickness difference ≤ 0.1 mm, and no obvious pits or scratches on the surface.

[0096] Step 104: Perform stress relief annealing on the medium-formed part to obtain an annealed part.

[0097] Place the medium-formed part into a vacuum heat treatment furnace for stress relief annealing. The heat treatment temperature is 320 °C, the holding time is 90 min, and the vacuum degree is not less than 2.5×10 -3 Pa.

[0098] Step 105: Place the annealed part into the cavity of the extrusion die for at least one cold sizing forming.

[0099] Place the annealed part into the cavity of the extrusion die, and perform one-pass cold sizing forming on the annealed part under the condition that the deformation rate is 3 mm / s.

[0100] Before the cold sizing forming, apply castor oil lubricant to both the surface of the annealed part and the inner surface of the extrusion die cavity, and control the deformation amount to 2%, to obtain a copper liner with a cone angle deviation ≤ 2°, a wall thickness difference ≤ 0.08 mm, and an inner surface roughness Ra ≤ 0.2 μm.

[0101] Perform surface topography observation and surface roughness measurement on the copper liner prepared in Example 2. The selected detection positions are three different positions along the radial direction of the copper liner component from the core to the inner diameter edge (such as Figure 5As shown, the results show that the height of the micro - protrusions on the inner surface has decreased significantly, and the surface topography is flat (as Figure 6 and Figure 7 shown). The surface roughness at three positions from the core to the edge of the inner diameter is 0.12μm, 0.09μm, and 0.15μm respectively. The quality of the inner surface of the copper liner has been significantly improved.

[0102] Example 3

[0103] Taking an equal - wall - thickness copper liner as an example, the diameter of the copper liner is Ф100m, the height is 120mm, the inner - cone depth is 92mm, the maximum wall - thickness is 2mm, and the inner - cone angle is 50°. The specific process is as follows:

[0104] Step 101: Prepare a bar blank made of copper.

[0105] Calculate the volume of the bar blank using the structure diagram of the liner. According to the principle of constant volume in plastic forming and the principle of near - uniform plastic deformation, select a copper bar with a size of Ф35mm. Obtain a bar blank with a diameter of 33mm and a height of 43mm by fine wire - cut electrical discharge machining and turning the outer surface of the original copper material.

[0106] Step 102: Extrude the bar blank with large deformation to prepare a conical preform.

[0107] Place the bar blank into the cavity of the extrusion die. Under dry - friction conditions, the extrusion die is installed in a 1600 - ton hydraulic press. Press the bar blank in the cavity of the extrusion die to deform by controlling the downward movement of the punch of the extrusion device. The deformation rate is 5mm / s, and the deformation amount is controlled at 30%. Obtain a conical preform with a cone - angle deviation ≤4° and a wall - thickness difference ≤0.3mm, and no obvious pits or scratches on the surface.

[0108] Step 103: Prepare an intermediate formed part by multi - pass cold extrusion forming.

[0109] Place the conical preform into the cavity of the extrusion die, and perform four-pass cold extrusion forming on the preform under the condition that the deformation rate is 10 mm / s. Before the first-pass cold extrusion forming, apply castor oil lubricant to the surface of the conical preform and the inner surface of the extrusion die cavity, and control the deformation amount of the first-pass cold extrusion forming to 25%. Then wipe the inner surface of the extrusion die cavity clean, and directly place the conical preform after the first-pass cold extrusion forming into the extrusion die cavity for the second-pass cold extrusion forming, and control the deformation amount of the second-pass cold extrusion forming to 20%. After that, apply castor oil lubricant to the surface of the conical preform after the second-pass cold extrusion forming and the inner surface of the extrusion die cavity, and place the conical preform after the second-pass cold extrusion forming into the extrusion die cavity for the third-pass cold extrusion forming, and control the deformation amount of the third-pass cold extrusion forming to 15%. Finally, wipe the inner surface of the extrusion die cavity clean, and directly place the conical preform after the third-pass cold extrusion forming into the extrusion die cavity for the fourth-pass cold extrusion forming, and control the deformation amount of the fourth-pass cold extrusion forming to 10%, to obtain a medium-formed part with a cone angle deviation ≤ 3°, a wall thickness difference ≤ 0.1 mm, and no obvious pits or scratches on the surface.

[0110] Step 104: Perform stress relief annealing on the medium-formed part to obtain an annealed part.

[0111] Place the medium-formed part into a vacuum heat treatment furnace for stress relief annealing. The heat treatment temperature is 300 °C, the holding time is 50 min, and the vacuum degree is not less than 2.5×10 -3 Pa.

[0112] Step 105: Place the annealed part into the cavity of the extrusion die for at least one-pass cold sizing forming.

[0113] Place the annealed part into the cavity of the extrusion die, and perform one-pass cold sizing forming on the annealed part under the condition that the deformation rate is 5 mm / s.

[0114] Before the cold sizing forming, apply castor oil lubricant to the surface of the annealed part and the inner surface of the extrusion die cavity, and control the deformation amount to 3%, to obtain a copper liner with a cone angle deviation ≤ 2°, a wall thickness difference ≤ 0.08 mm, and an inner surface roughness Ra ≤ 0.2 μm.

[0115] Perform surface topography observation and surface roughness measurement on the copper liner obtained in Example 3. Select three different positions along the radial direction of the copper liner component from the center to the inner diameter edge as the detection positions (as Figure 8 shown). The results show that the height of the micro-protrusions on the inner surface decreases significantly, and the surface topography is flat (as Figure 9 and Figure 10As shown, the surface roughness at three positions from the core to the inner diameter edge is 0.12 μm, 0.10 μm, and 0.14 μm respectively, and the inner surface quality of the copper liner is significantly improved.

[0116] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments.

[0117] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present application.

Claims

1. A forming method for improving the inner surface quality of a copper drug form cover, characterized in that, Including: Preparing a bar blank made of red copper; Extruding the bar blank with large deformation to prepare a conical preform, including: placing the bar blank into the cavity of an extrusion die, and under dry friction conditions, making the bar blank in the cavity of the extrusion die be deformed under pressure by controlling the downward movement of the punch of the extrusion device, wherein the deformation rate of the deformation under pressure is 5 mm / s to 10 mm / s, the deformation amount is controlled to be 30% to 45%, and a conical preform with a cone angle deviation ≤ 4°, a wall thickness difference ≤ 0.3 mm, and no obvious pits or scratches on the surface is obtained; Placing the conical preform into the cavity of the extrusion die of the extrusion device, and performing cold extrusion forming on the conical preform for three to five passes. The deformation rate of each pass of the cold extrusion forming is 5 mm / s to 10 mm / s, and the deformation amount is controlled to be 10% to 30% until a medium-formed part with a cone angle deviation ≤ 3°, a wall thickness difference ≤ 0.1 mm, and no obvious pits or scratches on the surface is obtained. Among them, before the odd-numbered cold extrusion forming, lubricant is applied to the surface of the conical preform and the inner surface of the cavity of the extrusion die, and before the even-numbered cold extrusion forming, the inner surface of the cavity of the extrusion die is wiped clean; Performing stress relief annealing on the medium-formed part to obtain an annealed part; Placing the annealed part into the cavity of the extrusion die and performing at least one cold sizing forming until a red copper liner with a cone angle deviation ≤ 2°, a wall thickness difference ≤ 0.08 mm, and an inner surface roughness Ra ≤ 0.2 μm is obtained.

2. The forming method for improving the inner surface quality of a copper drug form cover according to claim 1, characterized in that, The deformation amount is controlled to be 10% to 30%, and it also includes: The deformation amount of each pass gradually decreases.

3. The forming method for improving the inner surface quality of a copper drug form cover according to claim 1, characterized in that, The preparing of the bar blank made of red copper includes: Calculating the volume of the bar blank by using the structure diagram of the liner, and obtaining a bar blank with a height-diameter ratio of 1.2 to 1.5 by cutting and turning the red copper raw material.

4. The forming method for improving the inner surface quality of a copper drug form cover according to claim 1, characterized in that, In the performing stress relief annealing on the medium-formed part to obtain an annealed part, the heat treatment temperature is 300°C to 350°C, and the holding time is 50 min to 90 min.

5. The forming method for improving the inner surface quality of a copper drug form cover according to claim 4, characterized in that, The holding time is calculated according to the following formula: T = 40 + aDn, wherein T is the holding time, a is the holding time coefficient, D is the wall thickness, and n takes a value of 1.2 to 2.

2.

6. The forming method for improving the inner surface quality of a copper drug form cover according to claim 1, characterized in that, The placing the annealed part into the cavity of the extrusion die and performing at least one cold sizing forming includes: Placing the annealed part into the cavity of the extrusion die, and performing cold sizing forming on the annealed part for one to two passes. The deformation rate of each pass of the cold sizing forming is 2 mm / s to 5 mm / s, and the deformation amount is controlled to be 0.5% to 3%.

7. The forming method for improving the inner surface quality of a copper drug form cover according to claim 6, characterized in that, Before placing the annealed part into the cavity of the extrusion die, it also includes: Applying lubricant to the surface of the annealed part and the inner surface of the cavity of the extrusion die.

8. The forming method for improving the inner surface quality of a copper drug form cover according to claim 7, characterized in that, The lubricant includes rapeseed oil, TR2-drawing oil, and castor oil.

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