Method for manufacturing ceramic structures

Abstract

This improves the efficiency of inserting inserts into screw holes formed in a ceramic substrate. [Solution] The method for manufacturing a ceramic structure according to the present disclosure includes the steps of: preparing a substrate made of ceramic having a screw hole and an insert to be screwed into a helical screw groove located on the side wall of the screw hole; holding the insert using a holding part of an insert insertion machine; moving the insert directly above the screw hole using the moving mechanism of the insert insertion machine; and inserting the insert into the screw hole while rotating it using the rotating mechanism of the insert insertion machine. When the region of the screw hole where the screw groove is located is defined as the screw portion, the screw portion includes a first region and a second region located on the opening side of the screw hole than the first region. When the inner diameter of the first region is defined as the first inner diameter and the inner diameter of the second region is defined as the second inner diameter, the difference in inner diameter, which is the value obtained by subtracting the first inner diameter from the second inner diameter, is greater than 0.05 mm.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a ceramic structure.

Background Art

[0002] Conventionally, inserts may be used to adjust the dimensions or improve the strength of threaded holes provided in a substrate. For example, a coil-type insert is attached to an internal thread by being screwed into the threaded hole (see Patent Document 1).

[0003] Inserts are generally used for substrates that are equivalent to or softer than the insert, such as light metals, resins, or woods, but in recent years, they have also been used for ceramics, which are brittle materials.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure provides a technique capable of improving the efficiency of the operation of inserting an insert into a threaded hole formed in a ceramic substrate.

Means for Solving the Problems

[0006] A method for manufacturing a ceramic structure according to one aspect of the present disclosure includes the steps of: preparing a substrate made of ceramic having a screw hole and an insert to be screwed into a helical screw groove located on the side wall of the screw hole; holding the insert using a holding part of an insert insertion machine having a holding part for holding the insert, a moving mechanism for moving the holding part, and a rotating mechanism for rotating the holding part; moving the insert held in the holding step directly above the screw hole using the moving mechanism; and inserting the insert held in the holding step into the inside of the screw hole using the moving mechanism while rotating it using the rotating mechanism. When the region of the screw hole where the screw groove is located is defined as the screw portion, the screw portion includes a first region and a second region located on the opening side of the screw hole than the first region. When the inner diameter of the first region is defined as the first inner diameter and the inner diameter of the second region is defined as the second inner diameter, the difference in inner diameter, which is the value obtained by subtracting the first inner diameter from the second inner diameter, is greater than 0.05 mm. [Effects of the Invention]

[0007] According to this disclosure, the process of inserting an insert into a screw hole formed in a ceramic substrate can be made more efficient. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic cross-sectional view of the area around a screw hole in a ceramic structure according to the first embodiment. [Figure 2] Figure 2 is an enlarged view of section H shown in Figure 1. [Figure 3] Figure 3 is a schematic perspective view showing an example of an insert insertion machine. [Figure 4] Figure 4 is a flowchart showing an example of the procedure for insert insertion using an insert insertion machine. [Figure 5] Figure 5 is a schematic cross-sectional view showing an example of the operation of an insert insertion machine during the holding process. [Figure 6] Figure 6 is a schematic cross-sectional view showing an example of the operation of an insert insertion machine during the moving process. [Figure 7]Figure 7 is a schematic cross-sectional view showing an example of the operation of an insert insertion machine during the insertion process. [Figure 8] Figure 8 is a schematic cross-sectional view of the area around a screw hole in a ceramic structure according to the second embodiment. [Figure 9] Figure 9 is a schematic cross-sectional view of the area around a screw hole in a ceramic structure according to the third embodiment. [Figure 10] Figure 10 is a schematic cross-sectional view of the area around a screw hole in a ceramic structure according to the fourth embodiment. [Modes for carrying out the invention]

[0009] The embodiments for carrying out the method for manufacturing ceramic structures according to this disclosure (hereinafter referred to as "embodiments") will be described in detail below with reference to the drawings. However, this disclosure is not limited by these embodiments. Furthermore, each embodiment can be combined as appropriate, provided that the processing content is not inconsistent. Also, the same parts are denoted by the same reference numerals in each of the following embodiments, and redundant descriptions are omitted.

[0010] Furthermore, in the embodiments described below, expressions such as "constant," "orthogonal," "perpendicular," or "parallel" may be used, but these expressions do not require strict adherence to "constant," "orthogonal," "perpendicular," or "parallel" conditions. In other words, each of the above expressions allows for deviations, for example, in manufacturing accuracy or installation accuracy.

[0011] The purpose of applying an insert to a ceramic substrate is, for example, to reduce the risk of cracks forming in the threaded hole when a male screw is inserted into the threaded hole of the substrate. These cracks can then propagate and cause chipping or other damage to the ceramic.

[0012] However, when an insert is applied to a ceramic substrate, when inserting the insert into the screw hole in the manufacturing process, a large load is applied near the thread of the screw hole opening end, which may cause cracks at the screw hole opening end. In addition, there is a risk that the smooth insertion of the insert may be hindered by the thread at the screw hole opening end. To improve the efficiency of the insert insertion operation, it is conceivable to introduce an automatic machine for inserting the insert into the screw hole. However, due to the above circumstances, it is difficult to introduce an automatic machine for the operation of inserting the insert into the screw hole formed in the ceramic substrate, and it has been carefully performed by hand.

[0013] Therefore, there is an expectation for providing a technology to improve the efficiency of the insert insertion operation for the screw hole formed in the ceramic substrate.

[0014] (First Embodiment) First, the configuration of the ceramic structure according to the first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic cross-sectional view of the periphery of the screw hole in the ceramic structure according to the first embodiment. FIG. 2 is an enlarged view of the H portion shown in FIG. 1. As shown in FIG. 1, the ceramic structure 1 according to the first embodiment includes a substrate 10, a screw hole 20, and an insert 30.

[0015] The substrate 10 is made of ceramic. The ceramic constituting the substrate 10 is not particularly limited. For example, the ceramic constituting the substrate 10 may be alumina (Al2O3), silicon nitride (Si3N4), cordierite (2MgO·2Al2O3·5SiO2), or the like. Also, the shape of the substrate 10 is not particularly limited. For example, although the shape of the substrate 10 is assumed to be plate-shaped, the shape of the substrate 10 is not limited to plate-shaped.

[0016] The screw hole 20 is provided in the base body 10. For example, when the base body 10 is plate-shaped, the screw hole 20 may have an opening 21 on one plate surface 11 of the base body 10 and extend in the depth direction of the base body 10 from this opening 21. The screw hole 20 may penetrate the base body 10. That is, the screw hole 20 may also open to the surface located opposite to the plate surface 11. In FIG. 1, one screw hole 20 is shown, but the base body 10 may have a plurality of screw holes 20.

[0017] On the side wall of the screw hole 20, a spiral screw groove is located. Hereinafter, the region in the screw hole 20 where the screw groove is located is referred to as a screw portion 50. The screw portion 50 does not necessarily need to be located over the entire depth direction of the screw hole 20. That is, the screw portion 50 may be located in at least a part of the screw hole 20.

[0018] The insert 30 is screwed into the screw groove of the screw hole 20. The insert 30 is formed of, for example, metal. Also, the insert 30 may be formed of a material other than metal, such as resin or the like.

[0019] The insert 30 may be, for example, a coil-type insert. In this case, on the outer periphery of the insert 30, a screw groove that is screwed into the screw groove of the screw hole 20 is located, and on the inner periphery of the insert 30, a screw groove that is screwed into a screw groove of a male screw (not shown), such as a bolt or a screw, is located.

[0020] In the ceramic structure 1 according to the first embodiment, the screw portion 50 may include a first region 51 and a second region 52 located closer to the opening 21 side of the screw hole 20 than the first region 51. In the first embodiment, the second region 52 is a region including the opening 21 of the screw hole 20, and the first region 51 is continuous with the second region 52.

[0021] The screw hole 20 in the second region 52 is larger than the screw hole in the first region 51. For example, as shown in Figure 2, in a cross-sectional view, the thread 521 of the second region 52 may be located between the thread 511 of the first region 51 and the thread root 512 of the first region 51. In other words, the thread 521 of the second region 52 may be located radially outward of the screw hole 20 than the thread 511 of the first region 51, and radially inward of the screw hole 20 than the thread root 512 of the first region 51. Also, the thread root 522 of the second region 52 may be located radially outward of the screw hole 20 than the thread root 512 of the first region 51.

[0022] The position of the thread root 512 in the first region 51 is approximately the same as the position of the thread on the insert 30. Therefore, the thread 521 in the second region 52 is located radially inward of the screw hole 20 compared to the thread on the insert 30. When the insert 30 is screwed into the screw hole 20, the insert 30 moves in the depth direction of the screw hole 20 while rotating along the thread groove of the second region 52, loosely fitted to the thread groove of the second region 52. Subsequently, the insert 30 moves in the depth direction of the screw hole 20 while rotating along the thread groove of the first region 51, more tightly fitted to the thread groove of the second region 52 than to the thread groove of the first region 51. As a result, the insert 30 is screwed into the first region 51 and fixed in the screw hole 20.

[0023] Thus, the second region 52 is formed to be larger than the first region 51 to the extent that it loosely fits with the insert 30.

[0024] Specifically, as shown in Figure 1, if the inner diameter of the first region 51 is defined as the first inner diameter B1 and the inner diameter of the second region 52 is defined as the second inner diameter B2, then the first inner diameter B1 is smaller than the second inner diameter B2. Here, the inner diameter refers to the nominal diameter. That is, the inner diameter is the diameter of the threads 511 and 521 in the screw groove of the threaded portion 50. Also, if the outer diameter of the first region 51 is defined as the first outer diameter D1 and the outer diameter of the second region 52 is defined as the second outer diameter D2, then the first outer diameter D1 is smaller than the second outer diameter D2.

[0025] More specifically, the difference in inner diameter, which is the value obtained by subtracting the first inner diameter B1 from the second inner diameter B2, is greater than 0.05 mm. In this way, because the second inner diameter B2 is 0.05 mm greater than the first inner diameter B1, stress is less likely to be generated in the second region 52 when the insert 30 is inserted into the screw hole 20, thereby reducing the occurrence of cracks near the opening 21 of the screw hole 20.

[0026] Furthermore, since the second inner diameter B2 is 0.05 mm larger than the first inner diameter B1, the process of fitting the insert 30 into the opening 21 becomes easier. Therefore, the workability when inserting the insert 30 into the screw hole 20 can be improved.

[0027] The difference in inner diameter between the first inner diameter B1 and the second inner diameter B2 may be 1 mm or less. With this configuration, the insert 30 can be properly guided to the first region 51 while reducing the occurrence of cracks near the opening 21 of the screw hole 20.

[0028] The second outer diameter D2, that is, the diameter of the thread root 522 in the second region 52, may be set to a size of, for example, the outer diameter of the insert 30 + 0.1 mm. The outer diameter of the insert 30 may be referred to as the outer diameter of the first region 51, that is, the first outer diameter D1.

[0029] For example, if the distance from one thread 521 to the next thread 521 is considered as one pitch, the number of thread groove pitches in the second region 52 may be 4 or less. Since the second region 52 does not contribute to the fastening force of the insert 30, setting the number of thread groove pitches in the second region 52 to 4 or less reduces the occurrence of cracks near the opening 21 of the screw hole 20 while also reducing the complexity of the work of inserting the insert 30 into the screw hole 20. In other words, although the number of rotations of the insert 30 increases due to the presence of the second region 52, setting the number of thread groove pitches in the second region 52 to 4 or less reduces the increase in the effort required for this work while also reducing the occurrence of cracks near the opening 21 of the screw hole 20. Furthermore, if the number of thread groove pitches in the second region 52 is less than 1 pitch, it becomes difficult to insert the insert 30, and the insert is positioned close to the plate surface 11, making it easier for the insert 30 to be pulled out when the screw is fastened. For this reason, the number of thread groove pitches in the second region 52 may be 1 or more. In other words, the number of screw groove pitches in the second region 52 may be between 1 and 4. Furthermore, the distance from one screw root 522 to the next screw root 522 may be considered as one pitch.

[0030] When the depth of the first region 51 is defined as the first depth and the depth of the second region 52 is defined as the second depth, the first depth may be longer than the second depth. With this configuration, the insert 30 can be properly fastened to the screw hole 20 compared to the case where the first depth is the same as or shorter than the second depth.

[0031] The pitch, which is the distance from one thread to the next, may be the same in the first region 51 and the second region 52. Also, the thread angle may be the same in the first region 51 and the second region 52.

[0032] Next, an example configuration of an automatic insert insertion machine (hereinafter referred to as the "insert insertion machine") will be described with reference to Figure 3. Figure 3 is a schematic perspective view showing an example of an insert insertion machine.

[0033] As shown in Figure 3, the insert insertion machine 100 may have a holding section 110, a rotating mechanism 120, and a first moving mechanism 130. Alternatively, the insert insertion machine 100 may have a mounting table 140, a second moving mechanism 150, and an insert holder 160.

[0034] The retaining portion 110 holds the insert 30. The retaining portion 110 may, for example, have a male thread shape. In this case, the retaining portion 110 can be screwed into a thread groove located on the inner circumference of the insert 30.

[0035] The holding portion 110 may be attached, for example, to the rotating mechanism 120. In this case, the holding portion 110 may be detachably attached to the rotating mechanism 120.

[0036] The rotation mechanism 120 includes a motor and the like, and rotates the holding part 110 around a vertical axis. The rotation mechanism 120 may be capable of rotating the holding part 110 in both forward and reverse directions. Specifically, the rotation mechanism 120 may be configured to rotate the holding part 110 in a first rotational direction and also to rotate the holding part 110 in a second rotational direction opposite to the first rotational direction.

[0037] The first moving mechanism 130 moves the holding part 110. For example, the first moving mechanism 130 may have a base part 131, a moving part 132, an arm part 133, and a support column 134.

[0038] The base section 131 fixes the rotation mechanism 120. The movable section 132 includes a motor and the like, and raises and lowers the base section 131 vertically. The movable section 132 also moves horizontally along the arm section 133, which will be described later. Specifically, the arm section 133 extends along a first horizontal direction, and the movable section 132 is movable along the arm section 133 along the first horizontal direction. In this way, the movable section 132 can move the base section 131 along the first horizontal direction and the vertical direction. The support column 134 supports the arm section 133 at a predetermined height.

[0039] The mounting base 140 is located below the arm portion 133. The ceramic structure 1 is placed on the mounting base 140. An insert holder 160, described later, may also be placed on the mounting base 140. The second moving mechanism 150 includes a motor and moves the mounting base 140 in the horizontal direction. For example, the second moving mechanism 150 may move the mounting base 140 along a second horizontal direction perpendicular to the first horizontal direction, which is the direction of movement of the holding portion 110. The insert holder 160 has multiple holes capable of accommodating multiple inserts 30.

[0040] The insert insertion machine 100 may include an operating unit (not shown), a storage unit, and a control unit. The operating unit accepts various operations from the operator, including the input of teaching data. The storage unit stores, for example, teaching data input via the operating unit, as well as a program for operating the insert insertion machine 100. The control unit controls the rotating mechanism 120, the first moving mechanism 130, and the second moving mechanism 150 based on the program and teaching data stored in the storage unit.

[0041] The configuration of the insert insertion machine 100 is not limited to that shown in the figures. For example, in the example shown in Figure 3, the insert insertion machine 100 is shown to have a configuration comprising a first moving mechanism 130 that moves the holding part 110 along a first horizontal direction and a second moving mechanism 150 that moves the mounting table 140 along a second horizontal direction. The insert insertion machine 100 is not limited to this configuration, and may, for example, have a configuration in which the support column 134 is moved in a second horizontal direction using the second moving mechanism 150. In this configuration, the holding part 110 can be moved in the first horizontal direction using the first moving mechanism 130, and the holding part 110 can be moved in the second horizontal direction using the second moving mechanism 150.

[0042] Furthermore, the insert insertion machine 100 may be configured to include an articulated robot, such as a horizontal articulated robot or a vertical articulated robot. In this case, the holding part 110 and the rotating mechanism 120 may be attached to the tip of the articulated robot.

[0043] Next, the insertion operation of the insert 30 using the insert insertion machine 100 described above will be explained with reference to Figures 4 to 7. Figure 4 is a flowchart showing an example of the procedure for insert insertion using the insert insertion machine 100. Figure 5 is a schematic cross-sectional view showing an example of the operation of the insert insertion machine 100 in the holding process. Figure 6 is a schematic cross-sectional view showing an example of the operation of the insert insertion machine 100 in the moving process. Figure 7 is a schematic cross-sectional view showing an example of the operation of the insert insertion machine 100 in the insertion process.

[0044] As shown in Figure 4, first, a preparation step is performed (step S101). In the preparation step, the operator prepares the ceramic structure 1 and a plurality of inserts 30. Specifically, the operator places the ceramic structure 1 on the mounting table 140 of the insert insertion machine 100. At this time, the ceramic structure 1 may be fixed in a predetermined position on the mounting table 140 by a jig (not shown). The operator also sets the plurality of inserts 30 into the insert holder 160 placed on the mounting table 140. If the ceramic structure 1 has one screw hole 20, the operator only needs to set at least one insert 30 into the insert holder 160.

[0045] Subsequently, the operator initiates the work using the control unit (not shown) of the insert insertion machine 100. Upon receiving the command to start the work, the control unit of the insert insertion machine 100 controls the rotation mechanism 120, the first movement mechanism 130, and the second movement mechanism 150 based on the teaching data stored in the memory unit, thereby executing the steps S102 to S104 shown below. Although Figure 4 shows the process up to inserting an insert 30 into one screw hole 20, if the ceramic structure 1 has multiple screw holes 20, the insert insertion machine 100 repeats the steps S102 to S104 multiple times according to the teaching data.

[0046] First, the insert insertion machine 100 performs a holding process (step S102). In the holding process, the insert insertion machine 100 positions the holding part 110 directly above the insert 30 set in the insert holder 160 and rotates the holding part 110 in the first rotational direction. After that, the insert insertion machine 100 lowers the holding part 110.

[0047] As the retaining part 110 rotates during descent, the female threaded portion on the inside of the insert 30 engages with the male threaded portion on the retaining part 110 (see Figure 5). As a result, the retaining part 110 holds the insert 30.

[0048] Next, the insert insertion machine 100 performs a moving process (step S103). During the moving process, the insert insertion machine 100 stops the rotation of the holding part 110 and raises the holding part 110. After that, the insert insertion machine 100 moves the holding part 110 to directly above the screw hole 20 formed in the ceramic structure 1 (see Figure 6).

[0049] Next, the insert insertion machine 100 performs the insertion process (step S104). During the insertion process, the insert insertion machine 100 rotates the holding part 110 in the first rotational direction. After that, the insert insertion machine 100 lowers the holding part 110. At this time, the control unit of the insert insertion machine 100 lowers the holding part 110 to a depth where the insert 30 reaches the first region 51 of the threaded portion 50, based on the teaching data stored in the memory unit. In this way, the insert insertion machine 100 moves the insert 30 held in the holding part 110 into the inside of the threaded hole 20, specifically to the first region 51 of the threaded portion 50, using the first moving mechanism 130 while rotating it using the rotation mechanism 120 (see Figure 7).

[0050] As described above, when the insert 30 is screwed into the screw hole 20, the insert 30 moves in the depth direction of the screw hole 20 while rotating along the screw groove of the second region 52, loosely fitted into the screw groove of the second region 52. Subsequently, the insert 30 moves in the depth direction of the screw hole 20 while rotating along the screw groove of the first region 51, tighter fitted into the screw groove of the second region 52 than the screw groove of the first region 51. As a result, the insert 30 is screwed into the first region 51 and fixed in the screw hole 20.

[0051] Subsequently, the insert insertion machine 100 raises the holding part 110 while rotating it in the second rotational direction. This releases the screw connection between the holding part 110 and the insert 30, and only the holding part 110 rises while the insert 30 remains in the ceramic structure 1.

[0052] Subsequently, the insert insertion machine 100 stops rotating the holding part 110. This completes the process of inserting one insert 30 into one screw hole 20. If there are other screw holes 20, the insert insertion machine 100 repeats steps S102 to S104 for the remaining screw holes 20. When inserts 30 have been inserted into all screw holes 20, the insert insertion machine 100 completes the series of insert insertion operations for the ceramic structure 1.

[0053] As described above, the threaded portion 50 is formed such that the difference in inner diameter, which is the difference between the inner diameter of the second region 52 (second inner diameter B2) and the inner diameter of the first region (first inner diameter B1), is greater than 0.05 mm (see Figure 1). In this way, because the second inner diameter B2 is 0.05 mm greater than the first inner diameter B1, stress is less likely to occur in the second region 52 when the insert 30 is inserted into the threaded hole 20, thereby reducing the occurrence of cracks near the opening 21 of the threaded hole 20. By providing the threaded hole 20 in the ceramic structure 1 with the above configuration, the insertion of the insert 30 into the threaded hole 20 of the ceramic substrate 10 can be automated using the insert insertion machine 100. In other words, by providing the threaded hole 20 with the above configuration, it is possible to insert the insert 30 without causing cracks in the opening 21, even when using the insert insertion machine 100.

[0054] Thus, according to the ceramic structure 1 of the first embodiment, the insertion of the insert 30 into the screw hole 20 formed in the ceramic base 10 can be made more efficient.

[0055] (Second Embodiment) Figure 8 is a schematic cross-sectional view of the area around a screw hole in a ceramic structure according to the second embodiment. As shown in Figure 8, the screw portion 50 of the ceramic structure 1 according to the second embodiment may have a third region 53 between the first region 51 and the second region 52. In this case, the third region 53 may expand in diameter from the first region 51 toward the second region 52.

[0056] If the inner diameter changes discontinuously from the second region 52 to the first region 51, when the insert 30 is inserted into the screw hole 20, the insert 30 may get stuck midway through the screw hole 20, and stress may concentrate at that point, potentially causing a crack.

[0057] The third region 53 functions as a guide to move the insert 30 from the second region 52 to the first region 51. Having this third region 53 makes it less likely for the insert 30 to get stuck in the middle of the screw hole 20, compared to the case where the inner diameter changes discontinuously from the second region 52 to the first region 51. Therefore, it is possible to reduce the occurrence of cracks in the middle of the screw hole 20. In addition, it is possible to improve the workability when inserting the insert 30 into the screw hole 20.

[0058] (Third embodiment) Figure 9 is a schematic cross-sectional view of the area around a screw hole in a ceramic structure according to the third embodiment. As shown in Figure 9, the screw portion 50 of the ceramic structure 1 according to the third embodiment may have a fourth region 54. The fourth region 54 is located closer to the opening 21 of the screw hole 20 than the second region 52. If the inner diameter of the fourth region 54 is the fourth inner diameter B4, the fourth inner diameter B4 may be larger than the second inner diameter B2.

[0059] Thus, the presence of a fourth region 54, which has a larger diameter than the second region 52, on the opening 21 side of the screw hole 20 makes it even easier to fit the insert 30 into the opening 21. Therefore, the workability when inserting the insert 30 into the screw hole 20 can be further improved.

[0060] (Fourth Embodiment) Figure 10 is a schematic cross-sectional view of the area around a screw hole in a ceramic structure according to the fourth embodiment. In the third embodiment described above, an example was given in which the fourth region 54 is part of the threaded portion 50, that is, an example in which a screw groove is located in the fourth region 54. However, the fourth region 54 does not have to have a screw groove. For example, as shown in Figure 10, the fourth region 54 may taper towards the opening 21 of the screw hole 20.

[0061] Thus, the position of the fourth region 54, which tapers and expands toward the opening 21 of the screw hole 20, on the opening 21 side of the screw hole 20 makes it even easier to fit the insert 30 into the opening 21. Therefore, the workability when inserting the insert 30 into the screw hole 20 can be further improved.

[0062] (Other embodiments) In the second embodiment described above, an example was given in which the screw hole 20 has a first region 51, a second region 52, and a third region 53. In the third and fourth embodiments, an example was given in which the screw hole 20 has a first region 51, a second region 52, and a fourth region 54. However, the screw hole 20 may have a first region 51, a second region 52, a third region 53, and a fourth region 54.

[0063] (Examples) Screw holes with outer diameters of M3, M4, M5, and M12 were formed in a ceramic plate. Specifically, for each of the M3, M4, M5, and M12 screw holes, a comparative example screw hole with a constant inner diameter and an example screw hole in which the inner diameter for the first two pitches from the opening was formed to be 0.1 mm larger than the inner diameter for the third pitch and beyond were formed in the ceramic plate. Subsequently, the shape of each screw hole was molded using resin, and the maximum inner diameter of the molded resin was measured using a projector. The projection magnification was 10x. The results are shown in Table 1. Note that three of each screw hole were made using the same procedure, and Table 1 shows the average value of the measurement results of those three screw holes.

[0064] [Table 1]

[0065] As shown in Table 1, the difference in maximum inner diameter between the examples and comparative examples for M3, M4, M5, and M12 screw holes was 0.121 mm, 0.095 mm, 0.066 mm, and 0.128 mm, respectively, all of which rounded to 0.1 mm.

[0066] The ease of inserting inserts into M3, M4, M5, and M12 screw holes was evaluated on a 5-point scale: 1: Very poor, 2: Poor, 3: Average, 4: Good, 5: Very good. The results are shown in Table 2. Table 2 also shows the average evaluation results for three screw holes fabricated using the same procedure.

[0067] [Table 2]

[0068] As shown in Table 2, for each of the M3, M4, and M5 screw holes, it was confirmed that the screw holes in the embodiment showed improved insert insertion workability compared to the screw holes in the comparative examples. Furthermore, it was found that the improvement in insertion workability was more pronounced for screw holes with smaller inner diameters. Specifically, in the screw holes in the comparative examples, the smaller the inner diameter, the more difficult it was to insert the insert for the first rotation, but in the screw holes in the embodiment, this first rotation was easier compared to the comparative examples.

[0069] The time required for inserting inserts was measured for M3, M4, M5, and M12 screw holes. The results are shown in Table 3. Table 3 shows the average measurement results for three screw holes fabricated using the same procedure.

[0070] [Table 3]

[0071] As shown in Table 3, for M3, M4, M5, and M12 screw holes, the time required for inserting the insert into the screw holes according to the embodiment was shorter than the time required for inserting the insert into the screw holes according to the comparative example. Furthermore, for M3, M4, and M5 screw holes, the reduction in working time was found to be more pronounced for screw holes with smaller inner diameters.

[0072] In this way, the improved ease of inserting the insert makes it possible to insert the insert into the screw hole smoothly.

[0073] Torque tests were performed on M3, M4, M5, and M12 screw holes with inserts using a preset torque driver. The results are shown in Table 4.

[0074] [Table 4]

[0075] As shown in Table 4, there was no difference in the torque test results between the comparative example and the embodiment for each of the M3, M4, M5, and M12 screw holes. This confirmed that forming the inner diameter for the first two pitches from the opening 0.1 mm larger than the inner diameter for the third pitch and beyond did not affect the tightening torque value. The results shown in Tables 1 to 4 were obtained by manually inserting the inserts into the substrate. Next, using the substrates and inserts of the embodiment and comparative example described in Tables 1 to 4, tests were conducted using an insert insertion machine. In the embodiment, inserts could be inserted more easily than in the comparative example. On the other hand, in the case of the comparative example, cracks frequently occurred in the substrate.

[0076] Furthermore, this technology can take the following configuration. (1) A step of preparing a ceramic substrate having a screw hole, and an insert that is screwed into a helical screw groove located on the side wall of the screw hole, An insert insertion machine having a holding part for holding the insert, a moving mechanism for moving the holding part, and a rotating mechanism for rotating the holding part, the process of holding the insert using the holding part, Using the aforementioned moving mechanism, a step is made to move the insert held in the holding step directly above the screw hole, The process of moving the insert held in the holding step into the screw hole using the moving mechanism while rotating it using the rotating mechanism, Includes, When the region of the screw hole in which the screw groove is located is defined as the threaded portion, the threaded portion includes a first region and a second region located on the opening side of the screw hole, A method for manufacturing a ceramic structure, wherein, when the inner diameter of the first region is defined as the first inner diameter and the inner diameter of the second region is defined as the second inner diameter, the inner diameter difference, which is the value obtained by subtracting the first inner diameter from the second inner diameter, is greater than 0.05 mm. (2) The method for manufacturing a ceramic structure according to (1), wherein the difference in inner diameter is 1 mm or less. (3) The method for manufacturing a ceramic structure according to (1) or (2), wherein the number of screw groove pitches in the second region is 1 or more and 4 or less. (4) A method for manufacturing a ceramic structure according to any one of (1) to (3) above, wherein, when the depth of the first region is defined as the first depth and the depth of the second region is defined as the second depth, the first depth is longer than the second depth. (5) The threaded portion has a third region between the first region and the second region. The method for manufacturing a ceramic structure according to any one of (1) to (4), wherein the third region expands in diameter from the first region to the second region. (6) The screw hole has a fourth region located on the opening side of the screw hole, A method for manufacturing a ceramic structure according to any one of (1) to (5), wherein the inner diameter of the fourth region is defined as the fourth inner diameter, and the fourth inner diameter is larger than the second inner diameter. (7) The method for manufacturing a ceramic structure according to (6), wherein the fourth region tapers in diameter toward the opening of the screw hole.

[0077] The embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. Indeed, the embodiments described above can be embodied in a variety of forms. Furthermore, the embodiments described above may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of Symbols]

[0078] 1. Ceramic structure 10 Base 11 Board surface 20 screw holes 21 Aperture 30 inserts 50 Threaded part 51 First area 52 Second area 53 Third area 54 4th area B1 First inner diameter B2 2nd inner diameter B4 4th inner diameter

Claims

1. A step of preparing a ceramic substrate having a screw hole, and an insert that is screwed into a helical screw groove located on the side wall of the screw hole, An insert insertion machine having a holding part for holding the insert, a moving mechanism for moving the holding part, and a rotating mechanism for rotating the holding part, the process of holding the insert using the holding part, Using the aforementioned moving mechanism, a step is made to move the insert held in the holding step directly above the screw hole, The process of moving the insert held in the holding step into the screw hole using the moving mechanism while rotating it using the rotating mechanism, Includes, When the region of the screw hole in which the screw groove is located is defined as the threaded portion, the threaded portion includes a first region and a second region located on the opening side of the screw hole, A method for manufacturing a ceramic structure, wherein, when the inner diameter of the first region is defined as the first inner diameter and the inner diameter of the second region is defined as the second inner diameter, the inner diameter difference, which is the value obtained by subtracting the first inner diameter from the second inner diameter, is greater than 0.05 mm.

2. The method for manufacturing a ceramic structure according to claim 1, wherein the difference in inner diameter is 1 mm or less.

3. The method for manufacturing a ceramic structure according to claim 1, wherein the number of screw groove pitches in the second region is 1 or more and 4 or less.

4. A method for manufacturing a ceramic structure according to claim 1, wherein, when the depth of the first region is defined as the first depth and the depth of the second region is defined as the second depth, the first depth is longer than the second depth.

5. The threaded portion has a third region between the first region and the second region. The method for manufacturing a ceramic structure according to claim 1, wherein the third region expands in diameter from the first region toward the second region.

6. The screw hole has a fourth region located on the opening side of the screw hole, The method for manufacturing a ceramic structure according to claim 1, wherein, when the inner diameter of the fourth region is defined as the fourth inner diameter, the fourth inner diameter is larger than the second inner diameter.

7. The method for manufacturing a ceramic structure according to claim 6, wherein the fourth region tapers in diameter toward the opening of the screw hole.

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