JPWO2018030231A1 - Method of manufacturing pure titanium metal sheet and method of manufacturing speaker diaphragm - Google Patents

Abstract

Multi-axial forging, one of the giant straining methods, is applied to a pure titanium metal material, and then rolled to form a fine-grained titanium metal sheet, which does not start recrystallization beyond room temperature A thin plate manufacturing method for inexpensively manufacturing a titanium metal thin material plate having a curved surface shape which maintains high strength and is excellent in processability by stretch forming in the following.

Description

  The present invention relates to a method of manufacturing a titanium metal material thin plate, and more particularly to a method of manufacturing a titanium metal material thin plate having high strength and high ductility and made of pure titanium having a purity of 99% or more and having a curved surface.

  From the dynamic mechanical properties of titanium metal materials, it has attracted attention as a diaphragm member such as a musical instrument or a speaker relating to acoustics, and research on manufacturing technology has been advanced. Specifically, the thickness required for the diaphragm is usually 200 μm or less, and for the tweeter in particular, a thickness of several tens of μm or less is required. Since pure titanium metal materials are difficult to meet the required specifications in terms of workability and strength, studies have been conducted to meet the requirements with alloys with other metal materials, but in comparison with pure titanium, It has not been put to practical use due to inferior characteristics and cost increase.

  Also, from the viewpoint of biocompatibility, titanium metal materials are expected to be applied to artificial bones, but like titanium diaphragms, titanium alloy materials in which other metal materials are added to pure titanium materials to improve processability Has been proposed. However, depending on the metal material to be added, there is a concern about the influence on the living body.

  In applications such as these diaphragms and artificial bones, it is desirable from the viewpoint of cost and biocompatibility not to solve the problem by addition of other metal materials, but to approach the problem solving by the manufacturing method using pure titanium material. Therefore, the prior art will be described focusing on the processability of the pure titanium thin plate to the curved surface.

  Conventional pure titanium thin sheets have been considered to suffer from severe forming cracking near the deformation limit. In Non-Patent Document 1, it is experimentally confirmed that the lower the oxygen content and the larger the crystal grain size, the better the stretchability and formability for a titanium thin plate of about 0.6 mm to 1.0 mm. There is.

  Non-Patent Document 2 reports that the workability is high when the grain size is 4 μm, for a titanium thin plate material having a thickness of 25 μm. Specifically, cold rolling of a pure titanium thin plate equivalent to JIS type 1 to a plate thickness of 25 μm is repeated at different temperatures up to 620 to 740 ° C. in a continuous annealing facility to control the crystal grain size, and Erichsen is controlled. As a result of conducting the test, it is shown that when the crystal grain size exceeds 80 μm, the formability is reduced.

  Patent Document 1 discloses a titanium thin plate having a surface of 200 μm or less and having a hard surface and a soft inside, and a method of manufacturing the same. Specifically, iron in the bulk is 0.1 mass% or less, oxygen is 0.1 mass% or less, plate thickness (mm) / particle diameter (mm) ≧ 3 and particle diameter ≧ 2.5 μm are satisfied, and the surface is Discloses a material having a hardened layer of 200 nm to 2 .mu.m. As a manufacturing method, after performing the cold rolling and intermediate | middle annealing of the pure titanium material prescribed | regulated to JISH4600, the crystal grain was controlled by further annealing by Ar atmosphere. In addition, the hardened layer on the surface is formed by concentrating oxygen, nitrogen, or carbon by a rolling oil or a gas atmosphere of an annealing furnace.

  Although a technology developed by the inventor of the present application is disclosed in Patent Document 2, in this technology, rolling ratio is obtained after multi-axial forging (MDF) using a block-shaped pure titanium material as a starting material. By rolling at 65% or more, a titanium plate with an average crystal grain size of 500 nm and a thickness of several mm is realized. In multi-axis forging, ultrafine particles with an average value of the crystal grain size of 500 nm or less can be obtained by repeating a pass of sequentially forging a work piece on a pure titanium rectangular from the respective axial directions of three axes a plurality of times Organization is obtained. It is shown that the rolling process is performed to further increase the strength of the workpiece after multi-axis forging, and the rolling ratio is 65% or more under the temperature condition of room temperature or less.

WO 2014/027657 WO2014 / 038487

Sawaya Masaki, I-City Yu, Ishiyama Seiji, Iron and Steel 72nd No. 6 115-122 (1986) Kei Matsumoto, Yuto Kita, Shin Nippon Steel & Sumikin Technique, No. 396, 117-122 (2013)

  However, in Non-Patent Documents 1 and 2 and Patent Documents 1 and 2 described above, no curved surface is provided with a thickness of about 10 μm to 200 μm, and necessary mechanical characteristics such as hardness and Young's modulus are used as a diaphragm of a speaker. It has not been possible to provide a thin sheet that can be developed. Moreover, although the speaker diaphragm is published as a processing example in the nonpatent literature 2, it is not disclosed at all about the manufacturing method, The evaluation about the workability of the curved surface shape by the titanium metal material in the said plate thickness is also carried out As it has not been done, it has not been established how to process it into a good curved surface shape.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a manufacturing method for inexpensively manufacturing a curved surface titanium metal thin plate having high strength and excellent workability. It is in the place to offer.

  In order to achieve this object, the first invention according to the method for producing a pure titanium metal thin plate comprises a pre-processing step of subjecting a pure titanium metal material to strong strain processing, and the pure titanium metal processed in the pre-processing step Multi-axis forging in which forging is performed at least once each in a three-dimensional direction with a strain amount falling within a range of 0.1 to 0.8. The method includes a processing step and a rolling step of rolling at a rolling ratio of 65% or more, and the deformation processing step includes a forming step of stretch forming at a temperature of room temperature or more and 400 ° C. or less.

  A second invention according to the method for manufacturing a pure titanium metal thin plate is the method according to the first invention, wherein the deformation processing step further includes a heat treatment step of heating to a temperature at which titanium does not recrystallize.

  According to a third invention of the method of manufacturing a pure titanium metal thin plate, in the first or second invention, the forming step is performed by stretch forming under conditions of 100 ° C. or more and 300 ° C. or less.

  According to a fourth invention of the method of manufacturing a pure titanium metal thin plate, in the first or second invention, the deformation processing step maintains a state in which the mold and the die are heated to room temperature or more and 400 ° C. or less It is a thing.

  The fifth invention according to the method for producing a pure titanium metal thin plate is the third invention wherein in the deformation processing step, a state in which the mold and the die are heated to 100 ° C. or more and 300 ° C. or less is maintained. is there.

  The sixth invention according to the method for manufacturing a pure titanium metal thin plate according to the first to fifth inventions is characterized in that the preliminary processing step comprises processing the pure titanium metal material manufactured in the multiaxial forging step by the rolling step. The thickness is set to 10 μm to 300 μm, and the forming process is to deform the thick titanium metal material into a curved surface.

  A seventh invention according to a method of manufacturing a pure titanium metal thin plate according to the sixth invention, wherein the processing method includes a ratio of a length in the overhanging direction to a length of a range in which the curved surface is processed by the overhang forming. Is transformed to 1/16 to 1/4.

  The invention according to the method for manufacturing a speaker diaphragm is processed into a spherical shape by processing a pure titanium metal thin film having a thickness of 10 μm to 300 μm by the manufacturing method according to the sixth or seventh method for manufacturing a pure titanium metal thin plate. It is characterized by

  According to the processing method of a titanium metal material thin plate having a curved surface of the present invention, there is an effect that titanium metal material having strength and ductility can be manufactured inexpensively by controlling crystal structure using pure titanium metal material. .

It is the figure which showed the manufacturing process of the titanium metal material thin plate. It is a schematic diagram of the pure titanium metal material thin plate which has the shape | molded curved surface. (A) is a diaphragm formed for a speaker tweeter, and (b) is an artificial bone used for a skull. It is an example of the structure | tissue photograph (TEM image) before heat processing. It is the figure which showed the relationship between overhang molding temperature and an Erichsen value. It is a figure showing change of temperature at the time of stretch forming using a 20 micrometer thin sheet, T.D. surface hardness, and Young's modulus. It is the relationship between the thickness of the thin plate and the Erichsen value. It is thickness distribution of the deformation | transformation part after an overstretching formation process. It is an example of the structure | tissue photograph (TEM image) after heat processing (temperature 300 degreeC x 1 h). It is an example of the structure | tissue photograph (TEM image) after heat processing (temperature 350 degreeC x 1 h). It is an example of the structure | tissue photograph (TEM image) after heat processing (temperature 400 degreeC x 1 h). It is an example of the structure | tissue photograph (TEM image) after heat processing (temperature 500 degreeC x 1 h). It is the relationship between the temperature of the heat treatment process and the average grain size. It is a figure showing change of hardness and Young's modulus in heat treatment temperature.

  Hereinafter, embodiments of the present invention will be described in detail.

  The titanium metal material used in the present invention may be a titanium material having few impurities (two types of CP titanium of JIS), and any shape may be used, for example, a block shape such as a rod or a round bar may be used . Generally, the average crystal grain size of crystals of titanium metal material used as a raw material is about 33 μm and the Young's modulus is 106.4 GPa.

  One embodiment of the manufacturing method is shown in FIG. The S1 process is a multiaxial forging process. After the step S1, the sheet is rolled to a predetermined thickness in the rolling step S2. The step S3 is a stretch forming step. Step S4 is a heat treatment step of the molded article. Here, the steps S1 and S2 are referred to as a preliminary processing step, and the step S3 is referred to as a deformation processing step. The heat treatment in the step S4 can be omitted according to the required characteristics of the processed product.

  The multi-axial forging (MDF) method of step S1 will be described. The multi-axial forging method is a method of applying a predetermined forging strain to a block-shaped workpiece and rotating a sample by 90 degrees for each forging pass. Specifically, first, a rectangular workpiece is prepared. The workpiece is forged along the first direction (first pass). Next, it is forged along a second direction which is a direction perpendicular to the first direction of the workpiece (a second pass). Furthermore, the workpiece is forged along a third direction perpendicular to the first and second directions (third pass). After three passes, the workpiece returns in appearance to substantially the same shape as the initial one. The amount of processing strain applied to the workpiece by forging (in each pass) in each direction may be the same or different. Moreover, in order to make it easier to forge during the forging process, the workpiece may be cut. By sequentially repeating the forging pass from each direction by such multiaxial forging, a large amount of strain can be introduced as a result to the workpiece. It is known that a pure titanium material has low plastic formability because there is less active slip system at room temperature, and if it is attempted to introduce a large strain in one pass, a crack or a defect easily occurs. For this reason, the amount of strain introduced in each one forging pass is reduced and forging in each direction is performed. The amount of strain given in one pass is in the range of 0.1 to 0.8, and preferably in the range of 0.2 to 0.4. This process makes it possible to make the material structure ultrafine and to make the average grain size of the titanium metal material smaller. By multi-axis forging, large strains are accumulated and introduced into the workpiece. The accumulated strain amount introduced into the workpiece after the step S1 is, for example, in the range of 1.0 to 40. The accumulated strain amount is preferably 2.0-10.

  The multi-axial forging process is performed at room temperature (about 300 K), but may be performed at a temperature lower than room temperature such as, for example, -196 ° C. (77 K: liquid nitrogen atmosphere). At low temperature forging, more deformation-induced structures (deformation twins, shear bands, micro bands, deformation bands, dislocations, etc.) are introduced to a workpiece by a single forging, and crystal grains are refined more quickly There is a merit that can be done. In the present invention, the temperature of the multiaxial forging treatment mainly refers to the temperature of the environment to which the workpiece is exposed. This is because the temperature of the object to be processed rises to a certain extent by the execution of forging, so if the temperature is defined by the temperature of the object to be processed, the value becomes ambiguous.

  In the rolling step of the S2 step, since the plastic formability of the material is improved by the MDF step, rolling can be performed at a low temperature, and it is preferable to carry out at room temperature to a temperature at which recrystallization does not start. Preferably, the temperature is 400 ° C. or less. More preferably, the temperature is 300 ° C. or less. If the rolling temperature is higher than 300 ° C., the crystal grain size tends to be large, and in some cases, it is not preferable because of recrystallization (see FIGS. 8 to 12 described later).

  The overhang forming method in step S3 will be described in detail. Since temperature control is an important factor in the step of forming the thin plate manufactured up to the S2 step of the preliminary processing step into a curved surface with a uniform thickness, the punch / die and die of the die for forming the curved surface The thin plate is heated to a predetermined temperature determined as a molding temperature using a heating furnace before the start of molding, and is sufficiently held until each reaches a predetermined temperature. The temperature of the extrusion molding step is equal to or less than the temperature at which recrystallization does not start from room temperature. Preferably it is 400 degrees C or less. More preferably, it is 300 ° C. or less. At temperatures above 300 ° C., grain growth of the ultrafine-crystallized titanium metal material begins in the preliminary processing step, and recrystallization begins in the high temperature range, which is not preferable. In forming a thin plate, the stress state, deformed shape, and fracture mode show various changes depending on the mechanical forming conditions such as the size of the molded product, the shape and the mold, so it is necessary to think separately for each forming method. In the present invention, a stretch forming method, which is one of the forming methods applied to metal materials, is applied, but in this method, it tends to break from the largest part of the elongation deformation. In order to improve the fracture limit, it is necessary to improve the ductility of the thin plate and to ensure the uniformity of the strain distribution. That is, it is necessary to avoid the concentration of deformation locally, and to apply the condition to disperse as much as possible across the thin plate. In order to apply it as a diaphragm of a speaker tweeter, uniformity of thickness distribution after molding is also required. The overhang property is usually formed by overhang using a rigid body punch in an overhang test, and the amount of overhang when a crack occurs is displayed as an Erichsen value. The Erichsen value is a crack limit value under deformation of approximately equal strain with respect to two axes of rolling direction and its perpendicular direction on a thin plate.

  Step S4 is a heat treatment step. The heat treatment temperature is 400 ° C. (573 K), preferably 300 ° C. (573 K) or less, so that both the strength (hardness) and the workability are not deteriorated with respect to those before the heat treatment. Since plastic deformation is possible, the processability after forming on a curved surface in the overhang forming step of S3 is improved. At a temperature of 400 ° C. or more, the crystal grain size rapidly increases, which is not preferable.

  FIG. 2 shows a perspective view of an artificial bone which is a thin plate of titanium metal material having a curved surface manufactured through the steps S1 to S4 and which is used as a part of a diaphragm and a skull of a tweeter of a speaker. Fig.2 (a) is a diaphragm used for the tweeter of a speaker, FIG.2 (b) is a schematic diagram of the artificial bone of a skull. The diaphragm of the tweeter has a thickness in the range of about 10 μm to 300 μm, and the ratio of the length in the extension direction to the diameter of the processed range can be realized to 1/16 to 1/4.

  The evaluation test will be described. In the evaluation test, the crystal structure is observed by transmission electron microscopy (TEM) from the ND (rolled surface normal direction) of the test material. In the stretch test performed as a mechanical property, Young's modulus and Erichsen value are investigated to evaluate ductility, and in the strength test, Vickers hardness is evaluated.

  The crystal structure is observed by TEM observation, and the average grain size is determined from the TEM image by the line intercept method. The strength test measures the hardness of a 20 μm thin plate to the T.D. surface (the surface in the direction perpendicular to the rolling surface) with a dynamic microhardness tester. In order to measure the hardness of a 20 μm thin plate with respect to the T.D. surface, a 20 μm thin plate is embedded in a resin and embedded, and then emery paper polishing and buff polishing are sequentially performed to prepare a test sample. In emery paper polishing, water resistant paper is placed on a rotary polishing machine, and mechanical polishing is performed while sequentially changing the particle size from # 180 to # 4000. Also, the mechanical polishing direction is adjusted so that the # 4000 polishing direction is parallel to the RD direction (rolling direction). In the subsequent buffing, a buff is placed on a rotary polishing machine, and polishing is performed using an alumina paste with a particle size of 0.1 μm until the mirror surface becomes parallel to the N.D. direction (the rolling surface normal direction). . In the hardness test, the dynamic hardness test is performed at the mirror surface with the test force set to 10 mN or 20 mN, the load holding time 5 seconds, and the unloading holding time 5 seconds.

  Hereinafter, experimental examples for verifying the manufacturing method and the effect of the present invention will be described.

  The starting material is a commercially available round rod-shaped pure titanium sample (2 types of CP titanium of JIS) having a diameter of about 60 mm. The average grain size is about 33 μm, and the Young's modulus is 106.4 GPa. Here, the chemical compositions of two types of pure titanium specified in JISH4600 are shown in Table 1.

  After cutting the starting material into a rectangular workpiece, multiaxial forging was performed by the MDF method in step S1.

The conditions of the MDF method will be described. The workpiece was forged (first pass) at room temperature along the first direction (X direction, mainly the longitudinal direction of the starting material) of the workpiece. The strain amount Δε introduced by the first pass is 0.2. Next, the workpiece was forged along the second direction (Y direction) of the workpiece (second pass). The strain amount Δε introduced by the second pass is 0.2. Next, the workpiece was forged (third pass) along the third direction (Z direction) of the workpiece. The strain amount Δε introduced by the third pass is 0.2. Thus, cumulative strain 鍛造 Δε = 2.0 was introduced into the workpiece by repeating the forging process 10 times in total (10 passes) in the order of X direction → Y direction → Z direction. In the present invention, the strain rate in each pass is preferably in the range of 1 × 10 ⁻³ / sec to 10 / sec. In addition, generation | occurrence | production of a crack or defect was not recognized by the to-be-processed body after multi-axial forging processing.

  Next, the rolling process of S2 process was implemented at room temperature with respect to the rectangular to-be-processed object which gave the multi-axial forging process. The rolling ratio of the object to be processed by rolling was 95% or more, and rolling was repeated a plurality of times to produce thin plates (foils) of five thicknesses of 13 μm, 20 μm, 30 μm, 50 μm, and 100 μm. It is called 13 μm foil, 20 μm foil, 30 μm foil, 50 μm foil and 100 μm foil, respectively. In the thin sheet after the rolling process, cracks and cracks were observed at the foil end, but were cut and removed.

  FIG. 3 is a TEM observation image of the crystal structure of a 20 μm foil produced by the steps S1 → S2. As a result of measuring an average crystal grain size by the line intercept method, it was 69 nm. It is observed that there are a plurality of black contrast parts, and that the substructure of dislocation is developed by MDF. The tissue is not necessarily equiaxed, and a lamellar structure remains in part, but it can be seen that it is a fine grain structure. In the upper left of FIG. 3, a SAD (selected area diffraction) pattern is also described. As a result of microscopic texture observation, the presence of tangles and dislocation cells of dislocation was clearly observed.

  It shape | molded in the cone-shaped curved-surface shape of the speaker by the extrusion molding process of S3 process. The size of the workpiece was 30 mm × 18 mm in length in the rolling direction (R.D.) × vertical direction (T.D.), and a steel ball with a diameter of 8 mm was used for the extrusion-formed male punch. The female mold is a metallic mold having a hemispherical recess having a diameter of 8 mm in diameter, which is twice the thickness of the thin sheet to be molded. These male and female molds and thin plates were placed in the tank of a small-sized furnace, and heated for 5 minutes at a predetermined molding temperature and maintained, and it was confirmed that the mold and the workpiece were at a predetermined temperature. The extrusion was performed to the design depth without cracking, and the pressing was performed manually. For a thin plate of 20 μm, the depth of the curved surface (recess deformation depth) was 0.5 mm to 2 mm for a diameter of 8 mm. The ratio of the indentation deformation depth to this diameter could be formed to 1/4 to 1/16.

  An overhang test was performed to determine the forming conditions of the overhang forming process. The measurement results of temperature and Erichsen value at the time of stretch forming using a 20 μm thin plate are shown in FIG. Since the Erichsen value indicates the amount of extrusion forming at the fracture limit, the temperature of the forming conditions can be determined. The Erichsen value indicating the overhang formability increases with the temperature rise, and the formability is improved by the temperature. In particular, the rise of the Erichsen value at 300 ° C. (573 K) is remarkable, which is a sufficiently large value for the production of the tweeter diaphragm used for the speaker. It is thought that the main reason is that the MDF has been applied to refine the crystal grains and grain boundary slip has occurred, and the increase of the active slip system by warm forming. Moreover, the hardness and Young's modulus of the hollow deformation portion after the overhang forming step are shown in FIG. There was no significant drop in strength due to deformation after stretch forming. It was found that the Young's modulus decreased most at 300 ° C. (573 K), and there was a tendency for a minimum of Young's modulus to be present between 77 ° C. (350 K) and 177 ° C. (450 K). From these results, the overhang forming temperature at which thin plate processing can be performed as a speaker tweeter is 300 ° C. (573 K) to 27 ° C. (300 K). However, if slight crystal grain growth is allowed (see FIG. 12 described later), it is considered to be 400 ° C. or less from the viewpoint of increase in grain boundary sliding and active slip system.

  The relationship between the thickness of the thin plate before forming and the Erichsen value is shown in FIG. The Erichsen value at 300 ° C. (573 K) showed an Erichsen value of about 2.3 or more times that of room temperature 27 ° C. (300 K). In particular, the 13 μm foil exhibited an Erichsen value of about 3.6 times. In addition, it was found that an Erichsen value of 0.5 mm equivalent to 13 μm was obtained even with a thin plate with a thickness of 50 μm, and a diaphragm of a speaker tweeter can be formed even with a thickness of 50 μm.

  The distribution of the thickness of the depressed portion after overhang forming is shown in FIG. The two ends of the line passing through the center of the depressed portion of the test piece are 0 and 11, and equally divided into 11. The points between the line segments were sequentially 1 to 10 from the left, and the thickness of the portion of these 10 points was measured. Although there is a slight decrease in thickness near both ends which are 1 and 10 of the measurement point, no remarkable thickness variation is observed in the molding temperature range of 27 ° C to 300 ° C.

  Heat treatment in step S4 was performed. In order to determine the optimum range of the heat treatment temperature in vacuum, the test was performed in the range from room temperature to 500 ° C. (773 K). The photograph which observed the structure | tissue of the test piece after heat processing at 300 degreeC, 350 degreeC, 400 degreeC, and 500 degreeC by TEM is shown in FIGS. In the upper left of the figure, the SAD (selected area differential) pattern is also described. Before heat treatment and at a heat treatment temperature of 300 ° C., the presence of dislocation tangles and dislocation cells is remarkably observed, and there is no influence of heat treatment. In the structures after heat treatment at 350 ° C., 400 ° C., and 500 ° C., many crystal grain structures that appeared to be recrystallized were observed. From the relationship between the heat treatment temperature in FIG. 12 and the average crystal grain size, the crystal grain size shows a value of 69 nm to 100 nm in heat treatment at 300 ° C. (573 K) or less. The From this, the heat treatment temperature in the step S4 is preferably 300 ° C. or less which does not affect the crystal grain size. However, even at a heat treatment temperature of 500 ° C., the average crystal grain size is 1 μm or less, and it has an ultrafine grain structure, which is extremely fine compared to a normal titanium structure.

  The measurement results of the hardness and Young's modulus of a thin plate of 20 μm heat treated at different heat treatment temperatures are shown in FIG. When the heat treatment temperature was in the range of 27 ° C. (300 K) to 500 ° C. (773 K), the Young's modulus was 68 GPa to 90 GPa. Also, in this temperature range, the strength (hardness) shows a high value. When used as a diaphragm for a speaker, the higher the specific modulus (E / ρ, E: Young's modulus, ρ: density), the lower the noise due to material division vibration, so the same material is used for Young The higher the rate, the better. It was found that the hardness and the Young's modulus increased up to 300 ° C. (573 K), and the hardness and the Young's modulus decreased with the increase of the heat treatment temperature, with the peak at 300 ° C. (573 K). It can be said that, at a heat treatment temperature of 300 ° C. (573 K) or more, grain growth and recrystallization proceed as shown in the TEM photograph.

  The pure titanium metal thin plate manufactured according to the present invention according to the method for manufacturing a pure titanium metal thin plate has an Erichsen value of 0.5 mm or more at a plate thickness of 13 μm to 50 μm, and therefore becomes excellent in formability. It can be used as a speaker diaphragm (tweeter) or for artificial bones for skulls, and also has an advantage of having a metallic luster for aesthetics, and it can also be used as a casing for mobile phones using thin plates and casings for other various products. It can be used and, furthermore, from the viewpoint of biocompatibility, it can be used for artificial joints and the like.

  In addition, because it is made of pure titanium metal, it can be used for heat transfer tubes, heat exchangers, engine peripheral parts, etc. made of thin plates, considering corrosion resistance and thermal conductivity, and can also be used for IT equipment .

Claims (8)

A method of manufacturing a pure titanium metal thin plate,
A preliminary processing step of subjecting a pure titanium metal material to strong strain processing;
And d) deforming the pure titanium metal thin plate processed in the preliminary processing step into a predetermined shape;
The pre-machining step is a multi-axial forging treatment step in which forging is performed at least once each in a three-dimensional direction with a strain amount in a range of 0.1 to 0.8;
And a rolling process for rolling at a rolling ratio of 65% or more,
The method of manufacturing a pure titanium metal thin plate, wherein the deformation processing step includes a forming step of forming by stretching under conditions of room temperature or more and 400 ° C. or less.   The method according to claim 1, wherein the deformation processing step further includes a heat treatment step of heating to a temperature at which titanium does not recrystallize.   The method for producing a pure titanium metal thin plate according to claim 1, wherein the forming step is performed by stretch forming under conditions of 100 ° C. or more and 300 ° C. or less.   The method for producing a pure titanium metal thin plate according to claim 1 or 2, wherein the deformation processing step maintains a state in which the mold and the die are heated to room temperature or more and 400 ° C or less.   The method of manufacturing a pure titanium metal thin plate according to claim 3, wherein the deformation processing step maintains a state in which the mold and the die are heated to 100 ° C to 300 ° C.   The preliminary processing step is to make the pure titanium metal material manufactured in the multi-axial forging step 10 μm to 300 μm in thickness by the rolling step, and the forming step is a pure titanium metal material having the thickness The method for producing a pure titanium metal thin plate according to any one of claims 1 to 5, wherein the flat plate is deformed into a curved surface.   The pure titanium metal thin plate according to claim 6, wherein the curved surface is such that the ratio of the extension direction length to the length of the range processed by the extension forming is changed to 1/16 to 1/4. Manufacturing method.   A method of manufacturing a speaker diaphragm using pure titanium, comprising: forming a pure titanium metal thin film having a thickness of 10 μm to 300 μm into a spherical shape by the manufacturing method according to claim 6 or 7 Method of manufacturing diaphragm.

Images