Press machine and pressing method

Abstract

To provide a press machine and a press method capable of applying a desired pressure to a sample without increasing the size and with reduced vibration of the pressure shaft. [Solution] The press is a press 10 that applies pressure to a sample while heating it. It includes a frame 14 composed of an upper frame 11, a bottom frame 12, and a side frame 13 that connects the upper frame 11 and the bottom frame 12, a wire 15 that is wound around the outer periphery of the frame 14 to apply compressive stress to the side frame 13, a pressure unit 16 provided on the bottom frame, a container 17 placed on the top surface 16a of the pressure unit 16, a chamber 18 that is housed in the container 17 and has an anvil that clamps a pressure medium containing the sample, and a heating unit that heats at least the chamber 18 and the sample.

Description

[Technical Field]

[0001] The present invention relates to a press and a pressing method for performing high-pressure pressing under high temperatures. [Background technology]

[0002] The high-temperature, high-pressure method has been known as a conventional method for producing synthetic diamond. This method synthesizes diamond by exposing a carbon material as a carbon source to high temperature and high pressure together with a metal catalyst.

[0003] The synthesis conditions used in the high-pressure / high-temperature method are determined by a carbon equilibrium diagram, with the horizontal axis representing temperature and the vertical axis representing pressure. The carbon-diamond equilibrium line obtained from the carbon equilibrium diagram serves as the standard for producing synthetic diamonds. The pressure and temperature used in the high-pressure / high-temperature method are selected from pressures that are higher than the carbon-diamond equilibrium line and temperatures that are higher than the carbon-diamond equilibrium line.

[0004] The pressures used in the high-temperature, high-pressure method are typically around 5.0 to 10 GPa, and in order to synthesize large diamonds, the press must be able to apply extremely high pressure. When pressing at pressures exceeding GPa, compressive stress is applied to the sample, and the reaction force generates tensile stress in the frame of the press. When tensile stress is applied to the frame, the compressive stress applied to the sample is alleviated, and it may not be possible to apply sufficient pressure to the sample.

[0005] Therefore, for example, Patent Document 1 discloses a technique in which a wire is wound around the outer periphery of a frame to apply a compressive stress to the frame in advance. With this technique, it is said that the reaction force generated in the frame when pressure is applied to the sample cancels out the compressive stress that has been applied in advance, making it possible to apply a desired pressure to the sample.

[0006] The press described in Patent Document 1 is composed of an upper yoke and a lower yoke fixed to a frame, a die fixed to the lower yoke, a ram fixed to the upper yoke, etc. For example, when compressing powder, the powder is generally filled into a sample introduction hole provided in a die indirectly fixed to the frame, and the powder is compressed by an upper punch. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 48-63372 Summary of the Invention [Problem to be solved by the invention]

[0008] Patent Document 1 states that the 2 A pressure of about 500 MPa is assumed. Furthermore, normally, the anvil is indirectly fixed to the frame with bolts or the like. Furthermore, when bolts or the like are used to fix the device, a clearance is provided between the fixed table of the press and the anvil. Thus, assuming a pressure of about 500 MPa and pressing at room temperature, even if a clearance is provided, damping due to misalignment of the press axis caused by gaskets or the like provided between the anvil and the chamber will not be a major problem in the press.

[0009] However, when a high pressure of 5.5 to 10 GPa, which is the pressure used in synthesizing diamond, is applied at a high temperature of 1000°C or higher, the pressure applied to the sample is attenuated due to misalignment of the press axis. For this reason, when a wire is wound around the frame, as in the invention described in Patent Document 1, attenuation of the pressure due to the reaction force of the frame can be avoided, but the desired pressure may not be applied to the sample due to misalignment of the press axis.

[0010] One way to avoid the attenuation of pressure due to misalignment of the press axis is to increase the size of the press machine, but even if a larger press machine is used, the pressure will still be attenuated, and a significant increase in costs will be unavoidable.

[0011] Therefore, an object of the present invention is to provide a press and a pressing method that can apply a desired pressure to a sample without increasing the size and with reduced vibration of the pressure axis. [Means for solving the problem]

[0012] To apply high pressure to a sample at high temperatures, the inventors first decided to use a device with a wire wound around a frame, as described in Patent Document 1. They then investigated a configuration that would prevent the press axis from wobbling due to clearance.

[0013] Typically, when using the high-temperature, high-pressure method, a sample is inserted into a designated position, and then pressure is applied while an electric current is passed through the sample to heat it. However, if the anvil is fixed with a fixture such as a bolt, the pressure axis will be misaligned due to the clearance between the fixture and the anvil. Furthermore, to synthesize large diamonds, it is inevitable that the jig that holds the sample will become larger. In addition, as the number of press cycles increases, distortion will occur in the jig and the press device itself, making fine adjustment of the pressure axis even more difficult.

[0014] Furthermore, when pressing is performed at pressures of 5.5 GPa or greater and heating temperatures exceeding 1000 °C, it is not possible to fine-tune the misalignment of the pressure axis using mechanical adjustment devices or software, as is the case when pressing at pressures of around MPa. Furthermore, if wire is wound around the frame, it is thought that the misalignment of the pressure axis can be somewhat suppressed. However, as mentioned above, when a pressure of GPa is applied to the sample, the anvil itself is thick and heavy, making fine adjustments after it is fixed with bolts or other fasteners difficult. Even if the position is fine-tuned before it is fixed with bolts or other fasteners, slight misalignment of the anvil that occurs when the bolts are fastened is unavoidable.

[0015] Therefore, the inventors decided to simply place a chamber equipped with an anvil on the top surface of a pressurizing unit such as a hydraulic press, unlike conventional methods. They then came up with the idea of ​​performing the press without fixing it to a frame or the like with bolts or other fasteners. As a result, they discovered that the position of the anvil spontaneously fine-tunes during pressing, thereby reducing the wobble of the pressing axis and enabling the desired pressure to be applied to the sample. It is believed that this is because, when the tensile stress on the frame is offset by the compressive stress applied by winding the wire before pressing, the chamber equipped with the anvil is not fixed to the frame, so that equilibrium between the frame and the chamber is achieved, allowing the sample to be pressed by hydrostatic pressure.

[0016] In addition to the above, the inventors came up with the idea of ​​housing the anvil in a container to maintain a high pressure applied to the sample, in addition to the function of automatically fine-tuning the pressure axis during pressure application. As a result, even if the pressure medium sandwiched between the anvil and the chamber is crushed during pressure application, the side walls of the container prevent crushed pieces of the crushed pressure medium and other fragments from escaping to the outside, and a high pressure can be maintained. The present invention, which was made based on this finding, is as follows.

[0017] (1) A press that applies pressure to a sample while heating it, a frame including an upper frame, a bottom frame, and a side frame connecting the upper frame and the bottom frame; a wire wound around the outer periphery of the frame to apply compressive stress to the side frame; a pressure unit provided on the bottom frame; a container placed on the top surface of the pressurizing unit; a chamber accommodated in the container and having an anvil between which a pressure medium containing a sample is clamped; a heating unit that heats at least the chamber and the sample by passing current through the chamber; A press machine comprising:

[0018] (2) The press according to (1) above, wherein the anvil has a shape of a Czechvitsa type or a toroidal type.

[0019] (3) A press according to (1) or (2) above, wherein the inner diameter of the container is larger than the outer diameter of the chamber.

[0020] (4) The container consists of an upper container and a bottom container. The press machine according to (3) above, wherein the upper container is fixed to the upper frame, and the bottom container is fixed to the top surface of the pressing unit.

[0021] (5) The press machine according to any one of (1) to (4) above, further comprising a measuring unit for measuring the current value and voltage value of the current flowing through the chamber.

[0022] (6) further comprising a control unit; The control unit a resistance value acquisition unit that acquires a resistance value from the measurement unit at predetermined time intervals; a resistance difference calculation unit that calculates a resistance difference by subtracting a resistance value immediately before the latest resistance value is obtained from a latest resistance value obtained by the resistance value obtaining unit; a resistance difference sign confirmation unit that confirms the sign of the resistance difference calculated by the resistance difference calculation unit; a second or more negative resistance difference value checking unit that checks whether the resistance difference is a negative value for the second or more times when the resistance difference sign checking unit checks that the sign of the resistance difference is negative; a heating end signal transmitting unit that transmits a heating end signal to the heating unit when the second or more negative resistance difference value confirming unit confirms that the negative resistance difference value is a negative value for the second or more times; a pressurization end signal transmitting unit that transmits a pressurization end signal to the pressurizing unit after the heating end signal transmitting unit transmits the heating end signal; The press machine according to (5) above, comprising:

[0023] (7) A press machine as described in (6) above, which is provided with a resistance difference two consecutive negative value confirmation unit that confirms whether the second or more negative value confirmed by the resistance difference second or more negative value confirmation unit is a negative value calculated immediately after the negative value calculated by the resistance difference calculation unit immediately before the negative value is calculated.

[0024] (8) a threshold calculation unit that, when the resistance difference sign confirmation unit confirms that the sign of the resistance difference is negative, calculates a threshold value that is 1% or more of the resistance value immediately before obtaining the latest resistance value used to calculate the resistance difference with a negative sign; a negative value confirmation unit above threshold that confirms whether the absolute value of the resistance value confirmed to have a negative sign by the resistance difference sign confirmation unit, or the absolute value of the negative value confirmed by the resistance difference second or more negative value confirmation unit or the resistance difference two consecutive negative value confirmation unit, is a value above the threshold calculated by the threshold calculation unit; The press machine according to (7) above, comprising:

[0025] (9) A pressing method using the pressing machine according to any one of (1) to (8), The pressure medium containing the sample is clamped by an anvil provided in the chamber, The chamber holding the pressure medium is housed in a container; The container is placed on the top surface of the pressurizing unit, Applying a desired pressure to the container; After applying the pressure, at least the chamber and the sample are heated. A pressing method characterized by: [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a schematic perspective view showing an example of a press machine according to this embodiment. [Figure 2] FIG. 2 is a perspective view of a container that houses the chamber. [Figure 3] FIG. 3 is a partial cross-sectional view showing an example of a press machine according to this embodiment. [Figure 4] FIG. 4 is a perspective view showing an anvil that can be used in the press machine according to this embodiment and a pressure medium held between the anvils, where FIG. 4(a) is a Czechwitz type and FIG. 4(b) is a toroid type. [Figure 5] FIG. 5 is a phase equilibrium diagram for carbon. [Figure 6] FIG. 6 is a block diagram showing a hardware configuration as an example of a control unit used in the press machine according to this embodiment. [Figure 7] FIG. 7 is a block diagram showing the functional configuration of an example control unit used in the press machine according to this embodiment. [Figure 8] FIG. 8 is a flowchart showing an example of a control unit used in the press machine according to this embodiment. [Figure 9] FIG. 9 is a block diagram showing the functional configuration of another example of a control unit used in the press machine according to this embodiment. [Figure 10] FIG. 10 is a flowchart of another example of the control unit used in the press machine according to this embodiment. [Figure 11] FIG. 11 is a graph showing the changes over time in pressure, temperature, and resistance value in a diamond generation (synthesis) program for generating or synthesizing diamond by another example of a control unit used in the press machine according to this embodiment. [Figure 12] FIG. 12 is a block diagram showing the functional configuration of another example of a control unit used in the press machine according to this embodiment. [Figure 13] FIG. 13 is a flowchart of another example of the control unit used in the press machine according to this embodiment. [Figure 14] FIG. 14 is a partial cross-sectional view showing an example of a press machine using a convex anvil. DETAILED DESCRIPTION OF THE INVENTION

[0027]

[0023] The following embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are merely examples of the present invention, and the present invention is not limited to the following embodiments. Furthermore, combinations of the embodiments may also be implemented.

[0028] 1. Press machine FIG. 1 is a schematic perspective view showing an example of a press according to this embodiment. The press 10 according to this embodiment includes a frame 14 composed of an upper frame 11, a bottom frame 12, and a side frame 13 connecting the upper frame 11 and the bottom frame 12. The frame 14 also includes a recess on its outer periphery, and a wire 15 wound around the recess to apply compressive stress to the side frame 13. The press also includes a pressure unit 16 provided on the bottom frame 12, a container 17 placed on the top surface 16a of the pressure unit 16, and a chamber 18 accommodated in the container 17 and equipped with an anvil for clamping a pressure medium containing a sample. The press also includes a heating unit (not shown) for heating the container 17, the chamber 18, the pressure medium, and the sample.

[0029] 1, the frame 14 is formed by connecting an upper frame 11 and a bottom frame 12 via a pair of side frames 13. The upper frame 11, the bottom frame 12, and the side frames 13 may be separate members or may be integral.

[0030] The shapes of the upper frame 11 and the bottom frame 12 are not particularly limited, but are preferably semicircular or semi-elliptical when viewed from the front, as in the upper frame 11 shown in Fig. 1. The bottom frame 12 shown in Fig. 1 is rectangular when viewed from the front, but the portion between the two bases 12a and 12b that make up the bottom frame 12, i.e., the portion around which the wire 15 is wound, may be semicircular or semi-elliptical when viewed from the front, as shown by the dotted line portion 12c. With such a shape, the compressive stress from the wire 15 can be efficiently applied to the side frame 13.

[0031] A recess is provided on the side surface of the frame 14, and a wire 15 is wound around the recess. The wire 15 applies a compressive stress to the pair of side frames 13 via the upper frame 11 and the bottom frame 12.

[0032] The compressive stress applied to the frame 14 by the wire 15 is offset by the reaction force generated in the side frame 13 when the chamber 18 is pressurized via the container 17. Therefore, the desired pressure can be applied to the sample without attenuation of the pressure.

[0033] In the press 10 according to this embodiment, when the pressurizing unit 16 rises and pressurizes the container 17 with the upper frame 11 and the bottom frame 12, a reaction force is applied to the frame 14. This reaction force occurs in the direction opposite to the direction of pressure application. Therefore, if the compressive stress applied to the frame 14 in advance by the wire 15 and the reaction force are balanced, the pressure force is applied without attenuation to the sample contained in the anvil held by the chamber 18.

[0034] The compressive stress caused by winding the wire 15 can be determined, for example, as follows. First, the pressure applied to the dummy sample is set on the equipment side and applied without winding the wire 15. Then, the difference between the pressure actually applied to the sample and the pressure set on the equipment side is calculated as the reaction force. The wire 15 can be wound around the frame 14 so that this reaction force is equal to the compressive stress.

[0035] Because the reaction force varies depending on the rigidity of the frame 14, it is necessary to measure the reaction force before winding the wire 15. Because the reaction force is roughly equal to the pressure applied to the sample, the compressive stress due to the wire 15 can be estimated and adjusted.

[0036] As shown in Figure 1, the pressure unit 16 is provided on the bottom frame 12. The pressure unit 16 can raise a container 17 containing a chamber 18, for example, by using a hydraulic cylinder. This action causes the anvil to pressurize the sample contained in the pressure medium via the container 17 and the chamber 18. The hydraulic cylinder may have a configuration similar to that of a conventional hydraulic cylinder.

[0037] The pressure may be about 100 to 10,000 tons, but it may also be possible to apply a larger pressure. Depending on the pressure of the press, the size of the sample is determined so that a pressure of about 5.5 to 10 GPa, for example, is applied to the sample, which is a pressure above the graphite-diamond equilibrium line.

[0038] 2 is a perspective view of a container 17 that houses a chamber 18. The container 17 is composed of a bottom container 17a and an upper container 17b. The inner diameter D1 of the container 17 is preferably larger than the outer diameter D2 of the chamber 18.

[0039] Due to this relationship between D1 and D2, the chamber 18 is not fixed as in the past, and it is possible to some extent to prevent chamber collapse fragments from being pushed out in the direction perpendicular to the press axis during collapse. Therefore, it is possible to minimize the attenuation of the pressure on the sample contained in the anvil provided in the chamber 18. Furthermore, if D1 is not too larger than D2, it is possible to suppress the attenuation of the pressure on the sample. A more preferable range for D2 is 0.70 × D1 to 0.99 × D1.

[0040] Furthermore, from the viewpoint of improving the positioning accuracy of the chamber 18 during pressing, it is preferable that the container 17 is fixed to the frame 14. For example, the bottom container 17a may be fixed to the top surface 16a of the pressurizing part 16, and the upper container 17b may be fixed to the surface of the upper frame 11 that abuts against the upper container 17b. There are no particular limitations on the fixing method, and it is sufficient that they are fixed with bolts or the like.

[0041] In the presses 10 and 30 shown in FIGS. 1 and 3, the heating unit (not shown) is a device that applies electricity between the bottom container 17a and the upper container 17b, between the bottom chamber 18a and the upper chamber 18b, and to the sample. To apply electricity to the sample, the heating unit may be electrically connected to the container 17, and only needs to be connected to at least the chamber 18. The heating device that constitutes the heating unit may be any conventional power source. The heating device generally includes an electrical signal control unit (not shown) that is connected to the container 17 or the chamber 18. The output can be controlled based on information from the electrical signal control unit.

[0042] As will be described later, when observing the state of the sample 22 by observing the resistance value of the sample 22, it is preferable to keep the output of the heating unit constant. For example, the output of the heating unit may be set to an output that synthesizes or generates diamond from a dummy sample using the sample. The heating temperature may be 1000°C or higher, and may be a temperature above the graphite-diamond equilibrium line.

[0043] Fig. 3 is a partial cross-sectional view showing an example of a press machine 30 according to this embodiment. The side frames 13 shown in Fig. 1 are omitted from Fig. 3. Also, the upper frame 11 and a portion of the bottom frame 12 are omitted. As shown in Fig. 3, a pressure unit 16 is provided on the bottom frame 12, and a container 17 that accommodates a chamber 18 is placed on a top surface 16a of the pressure unit 16.

[0044] The chamber 18 is composed of a bottom chamber 18a and an upper chamber 18b. The bottom chamber 18a and the upper chamber 18b are each equipped with anvils 19a and 19b. The anvils 19a and 19b may be made of carbide or the like and may be fitted into the bottom chamber 18a and the upper chamber 18b, respectively. As shown in FIG. 3, the anvils 19a and 19b that come into contact with the sample 22 are preferably concave. In the concave anvils 19a and 19b, as shown in FIG. 3, the recesses are curved, such as substantially spherical, allowing for quick and uniform pressure application to the entire sample 22.

[0045] However, it is not impossible to apply pressure to the sample 32 using convex anvils. FIG. 14 is a partial cross-sectional view of an example of a press using convex anvils 29a and 29b. The frame and pressure unit are omitted from FIG. 14, and a cross-sectional view of the anvils 29a and 29b, the chamber 28, and the pressure medium 33 containing the sample 32 is shown. The convex anvils 29a and 29b shown in FIG. 14 are truncated cones and apply pressure to the sample 32 contained in the pressure medium 33 from above and below. However, because the sample 32 is pressed by the surfaces of the anvils 29a and 29b, it is susceptible to axial wobble and other factors. Furthermore, it takes time for the desired pressure to be applied uniformly to the sample 32. For this reason, the present embodiment does not require the use of convex anvils.

[0046] As shown in Figure 3, a pressure medium 23 containing a sample 22 is sandwiched between the bottom chamber 18a and the upper chamber 18b. There are no particular limitations on the pressure medium, as long as it is made of oxide powder or the like. The shape of the pressure medium 23 is preferably a sphere so that the pressure force does not attenuate, such as a chechewica or toroidal shape. The toroidal shape shown in Figure 3 is particularly preferred.

[0047] Figure 4 is a perspective view showing anvils and a pressure medium sandwiched between the anvils that can be used in the press according to this embodiment. Figure 4(a) shows a Czechievica type, and Figure 4(b) shows a toroidal type. As shown in Figure 4(a), in the Czechievica type, a pressure medium 70 is sandwiched between upper and lower anvils 72 and 73 in a central recess 71. When pressurized, the pressure medium is appropriately crushed within the recess, preventing a decrease in the pressure applied to the raw material. Note that the sample contained in the pressure medium 70 is omitted from Figure 4(a).

[0048] As shown in Figure 4(b), the toroidal type has a central recess 81 surrounded by an annular recess 82. The annular recess 82 is formed in a ring shape when viewed from above. If the pressure medium 80 collapses, it will tend to leak out of the recess 81 in the left-right direction of Figure 4(b). However, the annular recess 82 prevents the collapsed pressure medium from flowing, thereby suppressing a decrease in pressure even after the pressurization time has elapsed. Although Figure 4(b) shows one annular recess 82, another annular recess may be formed around it. Note that the sample contained in the pressure medium 80 is also omitted from Figure 4(b).

[0049] The sample 22 shown in Figure 3 is not particularly limited, as long as it is used to produce a material that requires high-temperature, high-pressure processing. For example, HPHT single-crystal diamond can be obtained by using a sample that mixes predetermined amounts of amorphous carbon such as carbon black and a carbon compound such as pentaerythritol. When using such samples, high-temperature, high-pressure synthesis in a short period of time is required. For this reason, it is preferable to use concave anvils 19a and 19b, as shown in Figure 3.

[0050] Alternatively, samples containing graphite mixed with various metal catalysts may be used. Examples of metal catalysts that can be used include resin-type NiMn and metal-type NiFe(Co). When using these samples, it is recommended to use convex anvils 29a and 29b, as shown in Figure 14. HPHT single-crystal diamonds can also be obtained using these samples.

[0051] The timing of the start and end of heating and the start and end of pressurization is preferably controlled by the control unit 24. The control unit 24 sends a signal to the pressurization unit 16 to apply a preset pressure, and after the pressure reaches or exceeds the graphite-diamond equilibrium line, sends a signal to the heating unit to heat. In particular, after the start of pressurization and heating in this order, the timing of the end of heating is preferably controlled by the control unit 24 based on predetermined information, as will be described in detail later. The pressurization rate is preferably 0.5 to 1.5 GPa / sec, and the heating rate is preferably 500 to 1000°C / sec.

[0052] Considering these pressurization and heating rates, it is preferable that heating begin 5 to 100 seconds after the start of pressurization. This is because the desired pressure is reached 5 to 100 seconds after the start of pressurization. Thereafter, heating is continued, for example, for a heating time in the range of 1 to 1800 seconds. After heating is completed, the material is cooled to a temperature below the graphite rearrangement temperature, and then the pressurization is terminated. The cooling method is not particularly limited, and various methods such as air cooling or cooling with a cooling medium may be used.

[0053] After the desired pressure is reached after the start of pressure application, the pressure unit 16 continues pressure application by maintaining the hydraulic cylinder at the same elevated position for several tens of seconds to several minutes. The sample is then heated to a temperature above the graphite-diamond equilibrium line, and the appropriate pressure and heating conditions are established, resulting in the synthesis of diamond from the sample, resulting in a slight reduction in pressure. However, since the presses 10 and 30 according to this embodiment are primarily devices for producing or synthesizing diamond, a slight reduction in pressure is acceptable. For example, a reduction of approximately 1 to 10% from the maximum pressure is acceptable. Naturally, a pressure above the graphite-diamond equilibrium line obtained from the graphite phase equilibrium diagram shown in Figure 5 must be maintained.

[0054] Furthermore, the pressure in the bottom chamber 18a and the upper chamber 18b is preferably reduced after the heating unit has finished heating for a predetermined period of time. That is, the heating and cooling of the sample is preferably performed while the pressure is being applied. By applying pressure and heating at this timing, carbonization of the sample can be more reliably suppressed.

[0055] The timing for depressurizing is preferably after heating is completed and chamber 18 has cooled to a temperature at which re-transition to graphite does not occur. For example, depressurizing may be performed 5 to 30 seconds after heating is completed. The above-mentioned pressurization and heating may be performed in the atmosphere.

[0056] Considering the above, we considered the axial runout, pressure velocity, pressure release, and sample volume of the press according to this embodiment and other presses outside the scope of this embodiment, and performed a comprehensive evaluation of the press. The press used was the press 10 shown in Figure 1, which has a maximum pressure of 1500 tons. A wire was wound around the recessed outer periphery of the frame 14, applying compressive stress to the side frame 13. The anvil shape, pressure medium shape, whether or not the anvil chamber is fixed, and whether or not a container is used were set as shown in Table 1. The sample was then subjected to high-temperature, high-pressure treatment at a pressure and heating temperature equal to or higher than the graphite-diamond equilibrium line shown in Figure 5. The treatment environment was atmospheric air. These conditions are summarized in Table 1.

[0057] [Table 1]

[0058] In Table 1, axial runout is an evaluation to confirm the influence of whether or not the chamber 18 is fixed. Pressurization speed is an evaluation to confirm the influence of the shape of the anvil 19 and the presence or absence of the container 17. Pressure release is an evaluation to confirm the influence of whether or not the chamber 18 is fixed, the presence or absence of the container 17, and the shape of the pressure medium (shape of the anvil). Sample volume is an evaluation to confirm the influence of the presence or absence of the container and the shape of the pressure medium (shape of the anvil).

[0059] In order to confirm Table 1 above, an embodiment using convex anvils 29a, 29b shown in Fig. 14 is assumed in addition to the concave anvils 19a, 19b shown in Fig. 3. Also, when a container 17 is used as shown in Fig. 3, an embodiment is assumed in which the bottom container 17a is fixed to the top surface 16a of the pressurizing unit 16 and the upper container 17b is fixed to the upper frame 11. Furthermore, when no container is used or when the container 17 cannot be used, an embodiment is assumed in which the anvils 29a, 29b are fixed to the pressurizing unit in Fig. 14 and an embodiment in which the chamber is directly fixed to the pressurizing unit in Fig. 3.

[0060] In Table 1, "convex," "frustum," "fixed," and "Yes (x)" indicate that anvils 29a and 29b shown in FIG. 14 are fixed to the top surface of the frame and the pressurizing unit, respectively, and therefore a container cannot be used. Also, "concave," "Czechvita," or "toroid," "fixed," and "Yes (x)" indicate that the bottom chamber shown in FIG. 3 is fixed to the top surface of the pressurizing unit with bolts or the like, and therefore a container cannot be used. Because these cannot be implemented, they are marked with "-" in Table 1.

[0061] The present embodiment, which is "concave," "Czechvitsa" or "toroid," "free," and "present," is excellent in all evaluations, and therefore receives an overall rating of "9" or "10." On the other hand, other examples that deviate from the present embodiment receive an overall rating of "6" at best, which is not as good as the present embodiment. It is also believed that the same tendency will occur regardless of which of the samples listed above is used as the sample.

[0062] As mentioned above, the heating unit is energized with an output that will reach a temperature above the graphite-diamond equilibrium line. When diamond is generated or synthesized, the area where the diamond appears is essentially insulated, and the resistance between the upper chamber 18b and the bottom chamber 18a increases as the amount of diamond synthesized or generated increases. Furthermore, since current flows through the sample but not through the pressure medium, the resistance value is essentially the resistance value of the sample. Therefore, by monitoring the resistance value, the status of diamond generation or diamond synthesis can be monitored in real time.

[0063] In this way, it is preferable to monitor the state of the sample by determining the resistance value from the current value and voltage value between the bottom chamber 18a and the upper chamber 18b.

[0064] To confirm that diamond has been synthesized, a press 30, such as that shown in FIG. 3, is preferably provided with a measuring unit 20 that measures the current and voltage between the upper chamber 18b and the bottom chamber 18a at predetermined intervals. The measuring unit 20 may also include a pressure gauge 21 for measuring the pressure of the pressurizing unit 16. The resistance value can be obtained from the current and voltage values ​​measured by the measuring unit 20. Even if the output from the heating unit is constant, the resistance value changes when the sample synthesizes or generates diamond or retransforms into graphite. Therefore, in the press 30 shown in FIG. 3, it is possible to observe changes in the sample's resistance value while passing current through the sample using the output from the heating unit.

[0065] 3 may also include a control unit 24 that receives measurements from the measurement unit 20 and the pressure gauge 21, and controls the timing of depressurization of the pressurizing unit 16 and the timing of heating termination of a heating unit (not shown). The control unit 24 that monitors changes in the sample in this manner will be described in detail below.

[0066] 6 is a block diagram showing an example of the hardware configuration of the control unit 24 used in the press machine according to this embodiment. The control unit 24 includes a CPU (Central Processing Unit) 51 that performs various processes, a memory 52, a nonvolatile storage device 53, an input means 54, a monitor 55, and an input / output interface 56.

[0067] The CPU 51 loads a program stored in the storage device 53 into the memory 52 and executes it. Each function described below is executed by the CPU 51. The storage device 53 stores various data in addition to the program. The storage device 53 is a non-volatile memory such as a ROM (Random Access Memory), an externally connectable HDD, or the like. Any medium capable of storing a program may be used, including magnetically or optically storing media such as a floppy (registered trademark) disk, a hard disk, an optical disk, a CD-ROM, a DVD-ROM, a ROM, etc.

[0068] The recording medium on which the program is recorded may be any medium capable of storing the program, including magnetically or optically memorizing media such as floppy disks, hard disks, optical disks, CD-ROMs, DVD-ROMs, ROMs, etc. The recording medium can be connected to the input / output interface 56 of the control unit 24 to cause the computer 50 to function.

[0069] The program according to this embodiment stored in the storage device 53 is loaded into the memory 52. ​​The input means 54 is a device for inputting information. The execution results of the CPU 51 are displayed on the monitor 55. The input / output interface 56 is an interface for transmitting and receiving data and signals to and from external devices such as a measurement unit, a heating unit, and a pressurizing unit.

[0070] The input means 54 is a keyboard, a mouse, or the like, and is used to select various options displayed on the monitor 55, and to input the output of the heating unit, the pressure of the pressure unit, and the like into the input items.

[0071] 7 is a block diagram showing the functional configuration of an example control unit 24 used in the press machine according to this embodiment. The control unit 24 can cause the program according to this embodiment to function using a computer. The same applies to control units 34 and 44, which will be described in detail below.

[0072] The control unit 24 includes a resistance value acquisition unit 24a, a resistance difference calculation unit 24b, a resistance difference sign confirmation unit 24c, a resistance difference negative value confirmation unit 24d for the second or subsequent time, a heating end signal transmission unit 24e, and a pressurization end signal transmission unit 24f. These functions will be described using FIG. 8. FIG. 8 is a flowchart of the control unit 24, showing an example used in the press machine according to this embodiment. In the following description, the hardware configuration shown in FIGS. 3 and 6 will be used as appropriate.

[0073] First, a predetermined pressure is applied to the sample, and when current begins to flow from the heating unit to the sample, the resistance value acquisition unit 24a acquires resistance values ​​at predetermined time intervals from the resistance meter 20a of the measurement unit 20 shown in FIG. 3 (S20). This resistance value is calculated at predetermined time intervals by multiplying the current by the voltage. The predetermined time may be approximately 0.1 to 1 second. The resistance difference calculation unit 24b calculates the resistance difference between the latest resistance value acquired by the resistance value acquisition unit 24a and the resistance value immediately before acquiring the latest resistance value (S21), and stores the calculation result in the storage device 53 and / or memory 52 shown in FIG. 6. Immediately after current begins to flow, the sign of the resistance difference remains positive because diamond is synthesized or generated by the current flowing through the sample.

[0074] Next, the resistance difference sign checking unit 24c checks the sign of the resistance difference calculated by the resistance difference calculating unit 24b (S22). If the sign of the resistance difference is not negative, that is, if the resistance difference is zero or a positive value (S22, no), the process returns to S11.

[0075] On the other hand, if the sign of the resistance difference is negative (S22, yes), second or more negative resistance difference value checking unit 24d reads the calculation result of the resistance difference stored in storage device 53 or memory 52 in Fig. 6 and checks whether the negative value checked by resistance difference sign checking unit 24c is the second negative value (S23). In detail, it checks whether there is a calculation result indicating a negative value among the calculation results of the resistance difference read from storage device 53 or memory 52 in Fig. 6. If the negative value is the first negative value (S23, no), the process returns to S11.

[0076] On the other hand, if the negative value is the second negative value (S23, yes), the heating end signal transmitting unit 24e transmits a signal to the heating unit to terminate heating (S24). After that, the pressurization end signal transmitting unit 24f transmits a pressurization end signal to the pressurization unit 16 after a predetermined time has elapsed since the heating end signal transmitting unit 24e transmitted the heating end signal (S25).

[0077] In this embodiment, when the resistance difference sign confirmation unit 24c confirms that the resistance difference has a positive sign, this indicates that diamond synthesis or generation has begun. Therefore, according to this embodiment, the diamond synthesis process or diamond generation process can be monitored in situ, which leads to further improvements in diamond synthesis or diamond generation. Furthermore, if the start of re-transition to graphite is determined based on only one negative value, if a negative value is obtained for some reason, it will be erroneously determined that re-transition to graphite has begun. In this case, diamond synthesis or generation will stop midway. However, as in this embodiment, by ending heating when a second negative value is calculated, re-transition to graphite can be accurately determined.

[0078] Fig. 9 is a block diagram showing the functional configuration of another example of a control unit 34 used in the press machine according to this embodiment. Compared to the control unit 24 shown in Fig. 7, the control unit 34 shown in Fig. 9 includes a resistance difference two consecutive negative value checking unit 34g. This function will be described with reference to Fig. 10.

[0079] FIG. 10 is a flowchart of another example of the control unit 34 used in the press machine according to this embodiment. Steps S30 to S33, S35, and S36 in FIG. 10 are the same as steps S20 to S25 in FIG. 8, and therefore will not be described further. As shown in FIG. 10, if the resistance difference second-time negative value checking unit 34d determines that the resistance difference is a negative value for the second time (S33, yes), the resistance difference two-time consecutive negative value checking unit 34g determines whether the resistance difference is a negative value for two consecutive times (S34). If the resistance difference is not a negative value for two consecutive times (S34, no), the process returns to S31. On the other hand, if the resistance value is a negative value for two consecutive times (S34, yes), steps S35 and S36 are performed.

[0080] In this way, when the resistance difference indicates a second negative value, the control unit 34 checks whether the second negative value occurs twice in a row, thereby enabling more accurate monitoring of the timing of the end of diamond synthesis or diamond generation, as well as the timing of re-transition to graphite.

[0081] The operation of the control unit 34 will be described in detail with reference to FIG. 11. FIG. 11 is a graph showing the changes in pressure, temperature, and resistance over time in a diamond generation (synthesis) program generated or synthesized by another example of the control unit 34 used in the press according to this embodiment. The elapsed time rate represents the elapsed time rate (%) when the time from the start of pressure application to the end of pressure application is set to 100%. Also, while the pressure and temperature are constant in FIG. 11, some fluctuations are allowed as long as they are within a range above the graphite-diamond equilibrium line.

[0082] As shown in Figure 11, after the pressure reaches the desired value, heating begins when the elapsed time rate is around 40%, and the resistance value rises sharply from 39% to 50%. The resistance difference at this elapsed time rate is positive. It is presumed that diamond is being generated or synthesized from the sample during this period.

[0083] Then, because the resistance value decreases significantly between 50% and 51% of the elapsed time, it is calculated that the resistance difference between 50% and 51% of the elapsed time is a negative value. This negative value is the first time. In other words, S32 in Figure 10 is yes. It is estimated that during this period, some of the diamond begins to rearrange into graphite.

[0084] The resistance value does not change between 51 and 55% of the elapsed time, so the resistance difference is zero. In other words, the resistance difference does not show a negative value between 51 and 55% of the elapsed time, so S32 in Figure 10 is no. It is presumed that during this period, diamond generation or diamond synthesis continues, and re-transposition to graphite also occurs in parallel.

[0085] When the elapsed time rate is between 55% and 56%, the resistance value decreases, so the resistance difference shows a negative value. This corresponds to the second negative value, so S32 in FIG. 10 is yes, and S33 in FIG. 10 is also yes. However, although the negative value during this period is the second negative value, it is not continuous from the first negative value. For this reason, S34 in FIG. 10 is no.

[0086] Even when the elapsed time rate is 56-57%, the resistance value drops, so the resistance difference shows a negative value. This is the third negative value, so S32 and S33 in Figure 10 are yes. Furthermore, the third negative value is the second consecutive negative value, so S34 is also yes. After that, the process immediately proceeds to S35 and S36 in Figure 10, where heating and pressurization are completed. This completes diamond generation or diamond synthesis.

[0087] In this way, the control unit 34 stops heating and pressurizing when the resistance difference shows a consecutive negative value, so it is possible to grasp the timing to end heating more accurately. As a result, diamond synthesis and generation can be carried out until the last possible moment, thereby improving the diamond yield.

[0088] Furthermore, even for samples that take a long time to calculate consecutive negative resistance difference values, as shown in Figure 11, the resistance value can be continuously monitored until two consecutive negative resistance difference values ​​are confirmed. This makes it possible to confirm two consecutive negative values ​​for various samples with different behaviors of retransposition to graphite.

[0089] In the case of the control unit 24 shown in Figures 7 and 8, the elapsed time rate in Figure 11 indicates a second negative value at 55 to 56%, so the process immediately proceeds to S24 and S25 in Figure 8, where the heating and pressurization are terminated. This terminates the diamond generation or diamond synthesis.

[0090] Fig. 12 is a block diagram showing the functional configuration of another example of a control unit 44 used in the press machine according to this embodiment. Compared to the control unit 34 shown in Fig. 9, the control unit 44 shown in Fig. 12 includes a threshold value calculation unit 44h and a threshold value or greater negative value confirmation unit 44i. These functions will be described using Fig. 13.

[0091] 13 is a flowchart of another example of the control unit 44 used in the press machine according to this embodiment. S40 to S42 and S45 to S48 are the same as S30 to S36 in FIG. 11, respectively, and therefore description thereof will be omitted.

[0092] If the resistance difference sign checker 44c confirms that the sign of the resistance difference is negative (S42, yes), the threshold calculator 44h calculates a threshold value that is 1% or more of the resistance value immediately before obtaining the latest resistance value used to calculate the negative resistance difference (S43). Then, the threshold or greater negative value checker 44i checks whether the absolute value of the resistance difference with a negative sign confirmed by the resistance difference sign checker 44c is a value greater than or equal to the threshold calculated by the threshold calculator 44h (S44). If the absolute value is smaller than the threshold (S44, no), the process returns to S41. On the other hand, if the absolute value is greater than or equal to the threshold (S44, yes), steps S45 to S48 are executed.

[0093] In this way, when the resistance difference sign confirmation unit 44c confirms that the sign of the resistance difference is negative, the control unit 44 compares the resistance difference with the threshold value. Therefore, when the two consecutive negative resistance difference confirmation unit 44g confirms that there are two consecutive negative resistance differences, the absolute value of at least the second consecutive negative value among the calculated negative values ​​is equal to or greater than the threshold. Therefore, it is possible to more accurately monitor the timing of the end of diamond generation or diamond synthesis.

[0094] For example, if the first negative value is smaller than the threshold, the answer is no in S44 in Fig. 13. If the second consecutive negative value immediately thereafter is equal to or greater than the threshold, the answer is yes in S42 and S44 to S46.

[0095] If the first negative value is equal to or greater than the threshold, S42 and S44 answer yes, but S45 answers no. If the consecutive negative values ​​immediately thereafter are equal to or greater than the threshold, S42 and S44 to S46 answer yes. In addition, as shown in FIG. 11, for example, even if the second negative value after a period of time has elapsed since the first negative value is either equal to or greater than the threshold or less than the threshold, if the third consecutive negative value immediately thereafter is equal to or greater than the threshold, S42 and S44 to S46 answer yes.

[0096] 13, S43 and S44 are provided after S42, but similar results can be obtained by moving S43 and S44 after S45 or after S46. Furthermore, similar results can be obtained by moving S43 and S44 after S45 or after S46 instead of after S42. That is, the negative value above threshold value checking unit 44i may check whether the absolute value of the resistance difference whose sign has been confirmed to be negative by the resistance difference sign checking unit 44c, or the absolute value of the negative resistance difference confirmed by the second or more negative resistance difference value checking unit 44d or the two consecutive negative resistance difference checking unit 44g, is a value greater than or equal to the threshold.

[0097] By comparing the resistance difference with a threshold, minute negative values ​​due to noise and the like can be excluded, allowing for a more accurate determination of re-transposition to graphite. When calculating the threshold, a value 1% or more of the resistance value immediately before obtaining the latest resistance value used to calculate the resistance difference is calculated as the threshold because, if a negative value is calculated, the immediately preceding resistance value is greater than the latest resistance value, allowing for a higher threshold value to be used to determine the resistance difference. It is preferable to calculate this percentage as a threshold value of 2% or more, as necessary, and it is even more preferable to calculate a threshold value of 3% or more.

[0098] 2. Pressing method The pressing method according to this embodiment is a pressing method using the above-mentioned press machine, and will be described with reference to FIG.

[0099] First, the pressure medium 23 containing the sample 22 is clamped between the anvils 19 provided in the chamber 18. The chamber 18 clamping the pressure medium 23 is housed in the container 17. The container 17 housing the chamber 18 is placed on the top surface 16a of the pressurizing unit 16. The pressurizing unit 16 is raised, thereby pressurizing the container 17. Accordingly, the chamber 18, the pressure medium 23, and the sample 22 are also pressurized. The pressure need only be equal to or greater than the graphite-diamond equilibrium line.

[0100] After a predetermined time has passed since the application of pressure, at least the chamber 18 and the sample 22 are heated by passing an electric current through them. The heating temperature may be any temperature above the graphite-diamond equilibrium line. In FIG. 3, the container 17, the chamber, and the sample are heated by passing an electric current through them. After a predetermined time has passed since the start of heating, the heating is stopped. After the temperature of the container 17 has cooled to a temperature at which the produced or synthesized diamond does not retransform to graphite, the pressure application is stopped. The temperature at which retransformation to graphite does not occur is a temperature range below the graphite-diamond equilibrium line shown in FIG. 5.

[0101] In the pressing method according to this embodiment, the chamber 18 is not fixed but is housed in the container 17. This prevents the pressure medium or the like from collapsing and being pushed out to the side when pressure is applied, so the pressure applied to the sample is maintained.

[0102] Furthermore, in the pressing method according to this embodiment, the above-mentioned control unit can be used to adopt, for example, the following pressing method. First, a predetermined pressure is applied to the sample, and when current begins to flow from the heating unit to the sample, resistance values ​​are acquired at predetermined time intervals. Among the acquired resistance values, a resistance difference is calculated by subtracting the resistance value immediately before acquiring the latest resistance value from the latest resistance value.

[0103] Next, it is checked whether the sign of the calculated resistance difference is negative. If it is confirmed that the sign is negative, it reads out the calculation results up to that point and checks whether the resistance difference is a negative value for the second or more times. If it is confirmed that the negative value is a negative value for the second or more times, it sends a heating end signal to the heating unit, sends the heating end signal, and after a predetermined time has passed, it sends a pressurization end signal to the pressurization unit.

[0104] According to this manufacturing method, the timing of the re-transition from single crystal diamond to graphite can be accurately grasped by in-situ monitoring during the production of single crystal diamond. Therefore, a high yield of single crystal diamond can be obtained. Furthermore, since the re-transition to graphite can be grasped regardless of the sample, there is no need to measure reference data in advance as in the past, and it can also handle variations between samples and various samples. [Explanation of symbols]

[0105] 10, 30 press machine, 14 frame, 15 wire, 16 pressure unit, 17 container, 18 chamber, 19 anvil, 20 measurement unit, 21 pressure gauge, 22, 32 sample, 23, 33 pressure medium, 24, 34, 44 control unit

Claims

1. A press that applies pressure to a sample while heating it, a frame including an upper frame, a bottom frame, and a side frame connecting the upper frame and the bottom frame; a wire wound around the outer periphery of the frame to apply a compressive stress to the side frame; a pressure unit provided on the bottom frame; a container placed on the top surface of the pressurizing unit; a chamber accommodated in the container and including an anvil between which a pressure medium containing the sample is clamped; a heating unit that heats at least the chamber and the sample by passing current through the chamber; Equipped with The sample contained in the pressure medium is pressurized by the anvil through the container and the chamber. A press characterized by:

2. The press according to claim 1 , wherein the anvil has a shape of a Czechwitz type or a toroidal type.

3. 3. The press according to claim 1, wherein the inner diameter of the container is larger than the outer diameter of the chamber.

4. The container is composed of an upper container and a bottom container, 4. The press machine according to claim 3, wherein the upper container is fixed to the upper frame, and the bottom container is fixed to the top surface of the pressure section.

5. The apparatus further includes a control unit and a measurement unit for measuring a current value and a voltage value of a current flowing through the chamber and the sample, The control unit a resistance value acquiring unit that acquires a resistance value from the measuring unit at predetermined time intervals; a resistance difference calculation unit that calculates a resistance difference by subtracting the resistance value immediately before acquiring the latest resistance value from the latest resistance value acquired by the resistance value acquisition unit; a resistance difference sign confirmation unit that confirms the sign of the resistance difference calculated by the resistance difference calculation unit; a second or more negative resistance difference value checking unit that checks whether the resistance difference is a negative value for the second or more times when the resistance difference sign checking unit checks that the sign of the resistance difference is negative; a heating end signal transmitting unit that transmits a heating end signal to the heating unit when the second or more negative resistance difference value confirming unit confirms that the negative resistance difference is a negative resistance difference for the second or more times; a pressurization end signal transmitting unit that transmits a pressurization end signal to the pressurizing unit after the heating end signal transmitting unit transmits the heating end signal; The press according to claim 1 or 2, comprising:

6. 6. The press according to claim 5, further comprising a resistance difference two consecutive negative value confirmation unit that confirms whether the second or more negative value confirmed by the resistance difference second or more consecutive negative value confirmation unit is a negative value calculated immediately after the negative value calculated by the resistance difference calculation unit immediately before the negative value was calculated.

7. a threshold calculation unit that, when the resistance difference sign confirmation unit confirms that the sign of the resistance difference is negative, calculates a threshold value that is 1% or more of the resistance value immediately before obtaining the latest resistance value used to calculate the resistance difference having the negative sign; a negative value confirmation unit above threshold that confirms whether the absolute value of the resistance value whose sign has been confirmed to be negative by the resistance difference sign confirmation unit, or the absolute value of the negative value confirmed by the resistance difference second or more negative value confirmation unit or the resistance difference two consecutive negative value confirmation unit, is a value above the threshold calculated by the threshold calculation unit; The press of claim 6 , comprising:

8. A pressing method using the press machine according to claim 1 or 2, The pressure medium containing the sample is clamped by the anvil provided in the chamber; The chamber holding the pressure medium is housed in the container; The container is placed on the top surface of the pressurizing unit; applying a desired pressure to the container; heating at least the chamber and the sample after applying the pressure; Pressurizing the sample contained in the pressure medium by the anvil through the container and the chamber. A pressing method characterized by:

9. The method further comprises a control unit and a measurement unit for measuring a current value and a voltage value of a current flowing through the chamber and the sample, The control unit a resistance value acquiring unit that acquires a resistance value from the measuring unit at predetermined time intervals; a resistance difference calculation unit that calculates a resistance difference by subtracting the resistance value immediately before acquiring the latest resistance value from the latest resistance value acquired by the resistance value acquisition unit; a resistance difference sign confirmation unit that confirms the sign of the resistance difference calculated by the resistance difference calculation unit; a second or more negative resistance difference value checking unit that checks whether the resistance difference is a negative value for the second or more times when the resistance difference sign checking unit checks that the sign of the resistance difference is negative; a heating end signal transmitting unit that transmits a heating end signal to the heating unit when the second or more negative resistance difference value confirming unit confirms that the negative resistance difference is a negative resistance difference for the second or more times; a pressurization end signal transmitting unit that transmits a pressurization end signal to the pressurizing unit after the heating end signal transmitting unit transmits the heating end signal; The press of claim 3 , comprising:

10. A press machine as described in Claim 9, which is equipped with a resistance difference two consecutive negative value confirmation unit that confirms whether the second or more negative value confirmed by the resistance difference second or more negative value confirmation unit is a negative value calculated immediately after the negative value calculated by the resistance difference calculation unit immediately before the negative value is calculated.

11. A threshold calculation unit that, when the resistance difference sign confirmation unit confirms that the sign of the resistance difference is negative, calculates a threshold value that is 1% or more of the resistance value immediately before obtaining the latest resistance value used to calculate the resistance difference whose sign is negative; and a negative value confirmation unit above threshold that confirms whether the absolute value of the resistance value whose sign has been confirmed to be negative by the resistance difference sign confirmation unit, or the absolute value of the negative value confirmed by the resistance difference second or more negative value confirmation unit or the resistance difference two consecutive negative value confirmation unit, is a value above the threshold calculated by the threshold calculation unit; The press of claim 10, comprising:

12. The method further comprises a control unit and a measurement unit for measuring a current value and a voltage value of a current flowing through the chamber and the sample, The control unit a resistance value acquiring unit that acquires a resistance value from the measuring unit at predetermined time intervals; a resistance difference calculation unit that calculates a resistance difference by subtracting the resistance value immediately before acquiring the latest resistance value from the latest resistance value acquired by the resistance value acquisition unit; a resistance difference sign confirmation unit that confirms the sign of the resistance difference calculated by the resistance difference calculation unit; a second or more negative resistance difference value checking unit that checks whether the resistance difference is a negative value for the second or more times when the resistance difference sign checking unit checks that the sign of the resistance difference is negative; a heating end signal transmitting unit that transmits a heating end signal to the heating unit when the second or more negative resistance difference value confirming unit confirms that the negative resistance difference is a negative resistance difference for the second or more times; a pressurization end signal transmitting unit that transmits a pressurization end signal to the pressurizing unit after the heating end signal transmitting unit transmits the heating end signal; The press of claim 4 , comprising:

13. A press machine as described in claim 12, which is equipped with a resistance difference two consecutive negative value confirmation unit that confirms whether the second or more negative value confirmed by the resistance difference second or more negative value confirmation unit is a negative value calculated immediately after the negative value calculated by the resistance difference calculation unit immediately before the negative value is calculated.

14. A threshold calculation unit that, when the resistance difference sign confirmation unit confirms that the sign of the resistance difference is negative, calculates a threshold value that is 1% or more of the resistance value immediately before obtaining the latest resistance value used to calculate the resistance difference whose sign is negative; and a negative value confirmation unit above threshold that confirms whether the absolute value of the resistance value whose sign has been confirmed to be negative by the resistance difference sign confirmation unit, or the absolute value of the negative value confirmed by the resistance difference second or more negative value confirmation unit or the resistance difference two consecutive negative value confirmation unit, is a value above the threshold calculated by the threshold calculation unit; The press of claim 13, comprising:

15. A pressing method using the press machine according to claim 3, The pressure medium containing the sample is clamped by the anvil provided in the chamber; The chamber holding the pressure medium is housed in the container; The container is placed on the top surface of the pressurizing unit; applying a desired pressure to the container; heating at least the chamber and the sample after applying the pressure; Pressurizing the sample contained in the pressure medium by the anvil through the container and the chamber. A pressing method characterized by:

16. A pressing method using the press machine according to claim 4, The pressure medium containing the sample is clamped by the anvil provided in the chamber; The chamber holding the pressure medium is housed in the container; The container is placed on the top surface of the pressurizing unit; applying a desired pressure to the container; heating at least the chamber and the sample after applying the pressure; Pressurizing the sample contained in the pressure medium by the anvil through the container and the chamber. A pressing method characterized by:

17. A pressing method using the press machine according to claim 5, The pressure medium containing the sample is clamped by the anvil provided in the chamber; The chamber holding the pressure medium is housed in the container; The container is placed on the top surface of the pressurizing unit; applying a desired pressure to the container; heating at least the chamber and the sample after applying the pressure; Pressurizing the sample contained in the pressure medium by the anvil through the container and the chamber. A pressing method characterized by:

18. A pressing method using the press machine according to claim 6, The pressure medium containing the sample is clamped by the anvil provided in the chamber; The chamber holding the pressure medium is housed in the container; The container is placed on the top surface of the pressurizing unit; applying a desired pressure to the container; heating at least the chamber and the sample after applying the pressure; Pressurizing the sample contained in the pressure medium by the anvil through the container and the chamber. A pressing method characterized by:

19. A pressing method using the press machine according to claim 7, The pressure medium containing the sample is clamped by the anvil provided in the chamber; The chamber holding the pressure medium is housed in the container; The container is placed on the top surface of the pressurizing unit; applying a desired pressure to the container; heating at least the chamber and the sample after applying the pressure; Pressurizing the sample contained in the pressure medium by the anvil through the container and the chamber. A pressing method characterized by:

20. A pressing method using the press machine according to claim 9, The pressure medium containing the sample is clamped by the anvil provided in the chamber; The chamber holding the pressure medium is housed in the container; The container is placed on the top surface of the pressurizing unit; applying a desired pressure to the container; heating at least the chamber and the sample after applying the pressure; Pressurizing the sample contained in the pressure medium by the anvil through the container and the chamber. A pressing method characterized by:

21. A pressing method using the press machine according to claim 10, The pressure medium containing the sample is clamped by the anvil provided in the chamber; The chamber holding the pressure medium is housed in the container; The container is placed on the top surface of the pressurizing unit; applying a desired pressure to the container; heating at least the chamber and the sample after applying the pressure; Pressurizing the sample contained in the pressure medium by the anvil through the container and the chamber. A pressing method characterized by:

22. A pressing method using the press machine according to claim 11, The pressure medium containing the sample is clamped by the anvil provided in the chamber; The chamber holding the pressure medium is housed in the container; The container is placed on the top surface of the pressurizing unit; applying a desired pressure to the container; heating at least the chamber and the sample after applying the pressure; Pressurizing the sample contained in the pressure medium by the anvil through the container and the chamber. A pressing method characterized by:

23. A pressing method using the press machine according to claim 12, The pressure medium containing the sample is clamped by the anvil provided in the chamber; The chamber holding the pressure medium is housed in the container; The container is placed on the top surface of the pressurizing unit; applying a desired pressure to the container; heating at least the chamber and the sample after applying the pressure; Pressurizing the sample contained in the pressure medium by the anvil through the container and the chamber. A pressing method characterized by:

24. A pressing method using the press machine according to claim 13, The pressure medium containing the sample is clamped by the anvil provided in the chamber; The chamber holding the pressure medium is housed in the container; The container is placed on the top surface of the pressurizing unit; applying a desired pressure to the container; heating at least the chamber and the sample after applying the pressure; Pressurizing the sample contained in the pressure medium by the anvil through the container and the chamber. A pressing method characterized by:

25. A pressing method using the press machine according to claim 14, The pressure medium containing the sample is clamped by the anvil provided in the chamber; The chamber holding the pressure medium is housed in the container; The container is placed on the top surface of the pressurizing unit; applying a desired pressure to the container; heating at least the chamber and the sample after applying the pressure; Pressurizing the sample contained in the pressure medium by the anvil through the container and the chamber. A pressing method characterized by:

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