3D data generation method for screws for 3D additive manufacturing

Abstract

Provided is a three-dimensional data generation method for screws for three-dimensional laminate shaping, the three-dimensional data generation method comprising: a procedure (S102) for generating first screw part data (310) by magnifying three-dimensional data of a screw part (3) of a standard screw by 1.0-2.5 times along an axial direction of the screw part; a procedure (S103) for generating second screw part data (320) by duplicating the first screw part data; a procedure (S104) for generating third screw part data (330) by coaxially arranging the first screw part data and the second screw part data so that one screw thread (321) in the second screw part data is interposed between two adjacent screw threads (311) in the first screw part data; and a procedure (S105) for generating fourth screw part data (340) by extracting an intended length portion from a portion in which the first screw part data overlaps the second screw part data in the third screw part data.

Description

[Technical Field]

[0001] The present invention relates to a method for generating three-dimensional data for a screw for three-dimensional additive manufacturing. [Background technology]

[0002] Layered objects manufactured using three-dimensional additive manufacturing devices, commonly known as 3D printers, may have overhangs that protrude significantly outward relative to the stacking direction. To achieve a smooth finish on the surface of these overhangs without using support materials, it is effective to set the angle between the stacking direction and the overhang (hereinafter referred to as the "overhang angle") to 50 degrees or less, and more preferably 45 degrees or less.

[0003] For example, JP 2019-90066 A discloses a three-dimensional additively manufactured product comprising a main body portion and a male thread portion integrally protruding from the surface of the main body portion, the male thread portion having a trailing flank that forms a first flank angle with respect to a plane perpendicular to the axis of the male thread portion, and the first flank angle being 45 degrees or more (less than 45 degrees according to the definition of the overhang angle above). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-90066 Summary of the Invention [Problem to be solved by the invention]

[0005] Screws conforming to the standards used in various countries (hereinafter referred to as "standard screws") often have thread angles of 60 degrees or 55 degrees. When such standard screws are additively manufactured along the axial direction (pushing direction) of the screw, the thread overhang angle exceeds 50 degrees, not 45 degrees. In other words, it is not easy to additively manufacture standard screws smoothly without support materials. Therefore, screws with specially shaped male threads, such as those disclosed in JP 2019-90066 A, have been developed for 3D additive manufacturing. However, such specially shaped male threads have completely different shapes from those of standard screws. Therefore, if a male thread with a different nominal diameter (outer diameter of the male thread) is required, for example, 3D data for the male thread must be newly created, which is extremely time-consuming. Furthermore, the direction of engagement between the male and female threads is unique, which can cause problems when manufacturing the entire object, as the manufacturing of the thread takes priority. Although the male thread portion has been mentioned up to this point, the same can be said for the female thread portion provided on a nut or the like.

[0006] The present invention has been made in consideration of the above circumstances, and its purpose is to provide a method for generating 3D data for screws for 3D additive manufacturing, which can easily create 3D data for a screw portion with a thread that can be smoothly additively manufactured using a 3D additive manufacturing device without using support material. [Means for solving the problem]

[0007] The present application includes multiple means for solving the above-mentioned problems, and one example thereof includes a first step of generating first thread portion data by enlarging three-dimensional data of the thread portion of a standard screw by 1.0-2.5 times along the axial direction of the thread portion; a second step of generating second thread portion data by duplicating the first thread portion data; a third step of generating third thread portion data by arranging the first thread portion data and the second thread portion data coaxially so that one thread in the second thread portion data is located between two adjacent threads in the first thread portion data; and a fourth step of generating fourth thread portion data by extracting a portion of a desired length from the portion in the third thread portion data where the first thread portion data and the second thread portion data overlap. [Effects of the Invention]

[0008] According to the present invention, it is possible to easily create three-dimensional data for a screw for three-dimensional additive manufacturing, which has a screw portion with threads that can be smoothly additively manufactured without support material, based on three-dimensional data for the screw portion of a standard screw that is relatively easy to obtain. [Brief explanation of the drawings]

[0009] [Figure 1] 1A to 1C are diagrams showing a procedure for generating 3D shape data of a thread portion of a screw for 3D additive manufacturing according to an embodiment of the present invention. [Figure 2] Side view of the 3D data of the standard screw (hexagon bolt) 1 that has been obtained. [Figure 3] 3 is a side view of three-dimensional data of the threaded portion 3 of the standard screw 1 in FIG. 2. [Figure 4] FIG. 10 is a side view of the three-dimensional data of the first screw portion data 310. [Figure 5] FIG. 10 is a side view of the three-dimensional data of the third screw portion data 330. [Figure 6] FIG. 10 is a side view of three-dimensional data of a hexagonal bolt 10 using fourth thread portion data 340 generated according to an embodiment of the present invention. [Figure 7] FIG. 10 is a side view of three-dimensional data of a hexagonal bolt 10A using fourth thread portion data 340A generated when the shape of the thread is trapezoidal. [Figure 8] 10 is a cross-sectional view of the three-dimensional data of the nut 20 using the fourth thread portion data 440 of the female thread portion. [Figure 9] FIG. 1 is a diagram showing an example of a male screw produced according to an embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing an example of a female screw created according to an embodiment of the present invention. [Figure 11] 1 is a diagram showing an example of a member fastened with a male screw and a female screw, which is produced according to an embodiment of the present invention; [Figure 12] Side view of 3D data of thread portion 4 of a metric forming standard screw. [Figure 13] FIG. 10 is a side view of the three-dimensional data of the first screw portion data 312. [Figure 14] FIG. 10 is a side view of the three-dimensional data of the third screw portion data 332. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Example 1 1 is a diagram showing the procedure for generating 3D shape data of the thread portion of a screw for 3D additive manufacturing according to an embodiment (Example 1) of the present invention. Each of the steps shown in the figure can be performed, for example, by operating 3D CAD software installed on a computer. Each step will be described in detail below.

[0011] First, in S101, three-dimensional data of the thread portion of a standard screw is prepared.

[0012] One way to prepare 3D data for a screw part is to use 3D data for a standard screw that you have already obtained. 3D data for standard screws is often easily available for free download from the web, for example.

[0013] FIG. 2 is a side view of three-dimensional data of a standard screw (hexagonal bolt) 1 that has been obtained. The standard screw 1 in FIG. 2 has a head 2 that is roughly hexagonal prism-shaped, and a threaded portion (external threaded portion) 3 where the head 2 is attached to the base end and has a male thread on the outer periphery. Note that while FIG. 2 shows a hexagonal bolt 1 with a hexagonal prism-shaped head 2, there is no particular limitation on the shape of the head 2. There is also no particular limitation on the shape of the threads in the threaded portion 3, and it may be trapezoidal, for example. The shape of the threaded portion 3 may also be that of a tapping screw or wood screw, which does not require a nut.

[0014] (Step S101) To prepare the 3D data of the threaded portion 3 in S101, for example, the head 2 can be removed from the 3D data of the standard screw 1 in Figure 2. Figure 3 shows the standard screw 1 with the head 2 removed, leaving only the threaded portion 3.

[0015] Figure 3 is a side view of the three-dimensional data of the threaded portion 3 of the standard screw 1 in Figure 2. Note that the same parts as in the previous figures are given the same reference numerals and their explanations may be omitted. This also applies to subsequent figures.

[0016] The threaded portion 3 is a single-start screw having one spiral thread 31 per pitch (denoted as P1), and the length of the threaded portion 3 is denoted as L1.

[0017] The angle (thread angle) φ1 of each thread 31 is 60 degrees. If the stacking direction of the 3D additive manufacturing device is from bottom to top in Figure 3, then each thread 31 becomes an overhanging portion, and the angle (overhang angle) θ1 that the lower flank 31a of each thread 31 makes with the stacking direction is 60 degrees, the same as the thread angle φ1. In other words, because the overhang angle of the thread 31 in this case is greater than 45 degrees, it is difficult to smoothly finish the lower flank (chasing flank) 31a in the 3D additive manufacturing device without support.

[0018] Incidentally, the threaded portion of a standard screw can also be created using 3D CAD software. Many commercially available 3D CAD software programs come with pre-installed commands for creating the threaded portion of a standard screw. If this type of command exists in the 3D CAD software, the user can easily create 3D data for the threaded portion of a standard screw by selecting, for example, the screw standard and size (thickness (nominal diameter) and length).

[0019] (Step S102) In S102, the three-dimensional data of the thread portion 3 prepared in S101 is enlarged along the axial direction of the thread portion 3 by a predetermined magnification (magnification rate) r (r is a real number greater than 1) while maintaining the radial dimension (nominal diameter) of the thread portion 3. Here, the three-dimensional data of the thread portion after enlargement is referred to as "first thread portion data 310" and is shown in FIG.

[0020] Figure 4 is a side view of the three-dimensional data of the first thread portion data 310. The first thread portion data 310 is data obtained by multiplying the thread portion 3 of Figure 3 by r along the axial direction while maintaining the radial dimension. The first thread portion data 310 has a plurality of threads 311 with a pitch of P2 (P2 = P1 × r) and a thread angle of φ2, and the overhang angle of the lower flank 311a of each thread 311 is θ2. The length of the thread portion 310 is L2 (L2 = L1 × r).

[0021] The expansion ratio r is determined taking into consideration the overhang angle θ2 of the lower flank 311a of the expanded thread portion 310 and the spacing of the threads 311 when threads 311 of the same dimensions are arranged between two adjacent threads 311 in the expanded thread portion 310 (i.e., the pitch of the third thread portion data 330 generated in step S104), and it is preferable to select any value from the range of 1.5-2.5, for example. The lower limit of the expansion ratio r is determined based on the overhang angle θ2 of the lower flank 311a. When θ1 is 60 degrees, θ2 is expressed as r, and θ=tan -1(√3 / r). Specifically, the lower limit of the magnification factor r is determined to be the value at which the overhang angle θ2 is 50 degrees or less, preferably 45 degrees or less. For example, in the above formula, θ2 is 45 degrees when r is the square root of 3 (√3). The upper limit of the magnification factor r can be determined based on whether the pitch of the third thread portion data 330 generated in step S104 falls within the user's acceptable range. This is because, if the length of the generated screw is predetermined, an increase in the pitch reduces the number of threads and reduces the binding strength of the screw. Note that, in the range of 1.5-2.5, the magnification factor r is preferably 2; the following description will be given assuming r = 2. When r = 2 and θ1 = 60 degrees, θ2 is approximately 41 degrees, which is less than 45 degrees.

[0022] (Step 103) In S103, the first screw portion data 310 generated in S102 is duplicated (copied and pasted), and the duplicated data is set as second screw portion data 320 (see FIG. 5).

[0023] (Step 104) In S104, the two pieces of thread data 310, 320 are arranged coaxially so that one thread 321 in the second thread data 320 generated in S103 is located between two adjacent threads 311 in the first thread data 310, and the two pieces of thread data 310, 320 are combined to generate third thread data 330. This third thread data 330 is shown in FIG.

[0024] 5 is a side view of the three-dimensional data of the third thread portion data 330. In the figure, the first thread portion data 310 is shown by a solid line, and the second thread portion data 320 is shown by a dashed line. In the third thread portion data 330, the thread 321 of the second thread portion data 320 is positioned between two adjacent threads 311 in the first thread portion data 310, and further, the first thread portion data 310 and the second thread portion data 320 are arranged coaxially. As a result, the portion in the third thread portion data 330 where the first thread portion data 310 and the second thread portion data 320 overlap forms a double-thread thread, with two thread spirals per pitch.

[0025] In the example of FIG. 5, the positions of the first thread portion data 310 and the second thread portion data 320 are shifted in the axial direction by P2 × 0.5 so that the pitch P3 of the third thread portion data 330 is half the pitch P2 of the first thread portion data 310 and the second thread portion data 320. When the magnification factor n is 2, the pitch P3 matches the pitch P1 of the original thread portion 3 (FIGS. 2 and 3). However, the axial shift between the two thread portion data 310 and 320 is not limited to P2 × 0.5. Any value (shift amount) can be selected as long as the condition that the thread thread 321 of the second thread portion data 320 is located between two adjacent thread threads 311 in the first thread portion data 310 is satisfied. If a value other than P2 × 0.5 is selected, two types of pitch will appear in the third thread portion data.

[0026] (Step 105) In S105, fourth thread portion data 340 (see FIG. 6) is generated by extracting a portion of the third thread portion data 330 that corresponds to a desired length (for example, length L1 of standard thread 1 shown in FIG. 5) from the overlapping portion of the first thread portion data 310 and the second thread portion data 320. This completes the generation of the fourth thread portion data 340.

[0027] (Step 106) Although the desired male thread can be designed using the fourth thread portion data 340 generated in S105, it is preferable to reduce or expand the fourth thread portion data 340 in the radial direction in S106 to facilitate engagement with the mating female thread (fifth step). To facilitate engagement of the male thread and female thread, the outer diameter of the male thread (D1 in FIG. 6) must be slightly smaller than the root diameter of the female thread (D2 in FIG. 8). However, the "reduction or expansion" in this step is sufficient if either the male thread is reduced or the female thread is expanded. When reducing the male thread, it is preferable to reduce the fourth thread portion data 340 in the radial direction by, for example, 0.85 to 0.90 times. When expanding the female thread, it is preferable to expand the fourth thread portion data 440 (FIG. 8) in the radial direction by, for example, 1.1 to 1.2 times. However, when the female thread is enlarged, the flank 441a of the thread becomes shallower, and the angle θ2 (overhang angle: FIG. 8) between the flank 441a and the axis of the thread becomes larger. Therefore, it is more desirable to reduce the male thread than to enlarge the female thread. In one embodiment of the present invention, the male thread (fourth thread portion data 340) is reduced in the radial direction by 0.88 times so that it can mesh with the female thread (fourth thread portion data 440 (FIG. 8)). Note that, as is clear from the arrow in FIG. 1 that goes directly from S105 to S107 without passing through S106, S106 can be omitted.

[0028] (Step 107) Furthermore, in S107, 3D data of a desired additively shaped object having the fourth thread portion data 340 generated in S105 as a thread portion may be generated. In this procedure, desired processing may be applied to the tip or base end of the fourth thread portion data 340. Also, desired processing may be applied to the tip or base end of data obtained by reducing or enlarging the fourth thread portion data 340 in the radial direction in S106. Figure 6 shows an example of generating a hexagonal bolt as an additively shaped object having the fourth thread portion data 340 as a thread portion.

[0029] FIG. 6 is a side view of three-dimensional data of a hexagon bolt 10 using fourth thread data 340 generated according to an embodiment of the present invention. The bolt 10 comprises fourth thread data (thread portion) 340 having a chamfered portion 345 at its tip, and a head portion 2 attached to the base end side of the fourth thread data 340. Note that the example in FIG. 6 is merely an example, and the shapes of the chamfered portion 345 and the head portion 2 can be changed as desired. Furthermore, the chamfered portion 345 and the head portion 2 are not essential elements.

[0030] The pitch of the fourth thread portion data 340 is P3, the same as that of the third thread portion data 330, and the length of the fourth thread portion data 340 is L1, the same as that of the thread portion 3 of the standard screw in FIGS.

[0031] As mentioned above, the shape of the thread of the screw portion 3 prepared in S101 is not limited to the triangle described above, but may be, for example, trapezoidal. Figure 7 shows a hexagonal bolt 10A that uses the fourth screw portion data 340A generated when the thread shape is trapezoidal.

[0032] (effect) As described above, in this embodiment, when generating three-dimensional data of a screw for three-dimensional additive manufacturing, the process includes a first step (S102) of generating first screw portion data 310 by enlarging the three-dimensional data of the screw portion 3 of a standard screw by 1.5-2.5 times along the axial direction of the screw portion 3, a second step (S103) of generating second screw portion data 320 by duplicating the first screw portion data 310, a third step (S104) of generating third screw portion data 330 by arranging the first screw portion data 310 and the second screw portion data 320 coaxially so that one screw thread 321 in the second screw portion data 320 is located between two adjacent screw threads 311 in the first screw portion data 310, and a fourth step (S105) of generating fourth screw portion data 340 by extracting a portion of the desired length from the overlapping portion of the third screw portion data 330 where the first screw portion data 310 and the second screw portion data 320 overlap.

[0033] The angle θ2 between the lower flank 341a of each thread of the fourth thread portion data 340 generated in this manner and the axis of the fourth thread portion data 340 is each 50 degrees or less. Therefore, when a part (e.g., the hexagonal bolt 10 in FIG. 6) including a shape defined by the fourth thread portion data 340 is additively manufactured from the bottom to the top in the axial direction of the fourth thread portion data 340 using a 3D additive manufacturing device, the lower flank 341a can be smoothly manufactured without support materials. In particular, the only 3D data required to generate the 3D data of the fourth thread portion data 340 is the 3D data of the thread portion 3 of a standard screw, which is easily available. The fourth thread portion data 340 can be generated simply by applying simple operations (such as enlarging, copying, pasting, and moving) to the 3D data of the thread portion 3 using 3D CAD software. In other words, according to this embodiment, it is possible to easily create 3D data of a thread portion having a thread that can be smoothly additively manufactured using a 3D additive manufacturing device without support materials. In addition, the manufacturing cost of screws using additive manufacturing can be reduced, and the variation in the quality of screws manufactured using additive manufacturing can be reduced, thereby improving yield.

[0034] Furthermore, the threads of the fourth thread portion data 340 generated by the above method have the same angle θ2 between the lower flank (chasing flank) 341a and the upper flank (leading flank) of the fourth thread portion data 340, allowing for lamination in either axial direction. In contrast, the male thread portion of Patent Document 1 (JP 2019-90066 A) has an overhang angle of 45 degrees or less for the trailing flank located at the rear in the screw insertion direction (advancement direction), while the overhang angle of the leading flank located at the front in the same direction is, for example, 90 degrees. Therefore, to manufacture this male thread portion without support material, it must be laminated (molded) in a position where the leading flank is located at the top and the trailing flank is located at the bottom (i.e., the screw insertion direction is vertically upward). In other words, the lamination direction of this male thread portion is essentially limited to one.

[0035] As described in the above embodiment, if the magnification factor r in S102 is set to 2 and the first thread portion data 310 and the second thread portion data 320 are arranged in S104 so as to be shifted in the axial direction by 0.5 times the pitch P2 of the first thread portion data 310, the angles θ2 formed between the two flanks of the threads of the third thread portion data 330 and the fourth thread portion data 340 and the axis of the screw will each be less than 45 degrees, and the pitch P3 of the third thread portion data 330 and the fourth thread portion data 340 will both match the pitch P1 of the original thread portion 3. In other words, it is easy to generate three-dimensional data for screws 330, 340 that have the same pitch and length as the original thread portion 3 but with θ2 less than 45 degrees. Furthermore, this method makes it easy to standardize screws because three-dimensional data for screws can be generated using standard screws in a set procedure. In addition, since the screw manufactured by additive manufacturing using the fourth screw portion data 340 will be a double-thread screw, the lead (the distance the screw advances in one rotation) will be twice that of the original screw portion 3.

[0036] As mentioned above, the magnification ratio r of S102 is preferably selected so that the angle θ2 formed between the axis of the first screw portion data 310 (screw portion) and the two flanks (lower flank and upper flank) associated with one screw thread 311 in the first screw portion data 310 is each 50 degrees or less, so that the screw thread (flank) defined by the fourth screw portion data 340 can be smoothly additively manufactured using a 3D additive manufacturing device, and more preferably so that the angle θ2 is each 45 degrees or less.

[0037] Example 2 In this example, a metric forming screw with a wide pitch interval is used as the standard screw, and the procedure for generating 3D shape data of the thread portion of the screw for 3D additive manufacturing is shown. The procedure for generating 3D shape data in this example is generally the same as in Example 1, so it will be explained with reference to Figure 1. However, because the shape of the screw is different, different drawings (Figures 12-14) from Example 1 will be used to explain each step. Note that explanations of steps S106 and S107 are omitted because they do not use different drawings from Example 1, and steps S101 to S105 will be explained here.

[0038] (Step S101) To prepare the 3D data of the screw portion 4 in S101, for example, just as the head 2 was removed from the 3D data of the standard screw 1 in Figure 2, the head 2 is removed from the 3D data of the metric forming screw that complies with the standard, leaving only the screw portion 4. The screw portion 4 is shown in Figure 12.

[0039] Figure 12 uses a metric forming screw as the standard screw and shows a side view of the 3D data of the thread portion 4, with the head removed from the 3D data of the standard screw. The thread portion 4 may also be created using 3D CAD software. If commercially available 3D CAD software is pre-installed with a command for creating the thread portion 4 of a metric forming screw, the user can easily create 3D data for the thread portion 4 of a standard metric forming screw by selecting, for example, the screw standard and size (thickness (nominal diameter) and length).

[0040] The thread portion 4 is a single-start thread, with one spiral thread 32 per pitch (referred to as P4). The thread portion 4 in FIG. 12 has a wider pitch and fewer threads than the thread portion 3 in FIG. 3 (Example 1). In FIG. 12, L4 denotes the length of the thread portion 4, W4 denotes the thread width, φ4 denotes the angle of the thread 32, and θ4 denotes the overhang angle. The overhang angle is the angle between the lower flank 32a of each thread 32 and the lamination direction (bottom-to-top direction in FIG. 12). The metric forming screw in this example is intended for screws with a pitch interval P4 that is at least twice the thread width W4.

[0041] (Step S102) In S102, the three-dimensional data of the thread portion 4 prepared in S101 is enlarged along the axial direction of the thread portion 4 by a predetermined magnification (magnification rate) r (r is a real number equal to or greater than 1) while maintaining the radial dimension (nominal diameter) of the thread portion 4. Here, the three-dimensional data of the thread portion after enlargement is referred to as "first thread portion data 312" and is shown in FIG.

[0042] FIG. 13 is a side view of the three-dimensional data of the first thread portion data 312. The first thread portion data 312 is data obtained by multiplying the thread portion 4 of FIG. 12 by r along the axial direction while maintaining the radial dimension. The first thread portion data 312 has a plurality of threads 313 with a pitch of P5 (P5 = P4 × r) and a thread angle of φ5. The overhang angle of the lower flank 313a of each thread 313 is θ5. The length of the thread portion 312 is L5 (L5 = L4 × r), and the thread width is W5 (W4 × r).

[0043] The expansion rate r is determined taking into consideration the overhang angle θ5 of the lower flank 313a of the expanded thread portion 312 and the spacing of the threads 313 when threads 313 of the same dimensions are arranged between two adjacent threads 313 in the expanded thread portion 312 (i.e., the pitch of the third thread portion data 332 generated in step S104).Unlike in the first embodiment, it is preferable to select any value from the range of, for example, 1.0-2.5.The lower limit of the expansion rate r is determined based on the overhang angle θ5 of the lower flank 313a.When θ4 is 55 degrees, θ5 is expressed as r, and θ5=tan -1 The magnification factor r is (tan(55) / r), and specifically, the value at which the overhang angle θ5 is 50 degrees or less, preferably 45 degrees or less, is determined as the lower limit of the magnification factor r. For example, in the above formula, θ5 is 45 degrees when r is tan(55)=1.4. The upper limit of the magnification factor r can be determined based on whether the pitch of the third thread portion data 332 generated in step S104 falls within the user's acceptable range. This is because, if the length of the screw to be generated is predetermined, an increase in the pitch reduces the number of threads and reduces the binding strength of the screw. Note that if the overhang angle θ4 of the thread portion 4 of the metric forming screw is 45 degrees or less, the magnification factor r can also be set to 1. In this case, step S102 is omitted, and the three-dimensional data of the thread portion 4 becomes the first thread portion data 312 (in other words, in step S202, the three-dimensional data of the thread portion 4 is magnified by 1.0 times along the axial direction to generate the first thread portion data 312). However, the following description will be given assuming that r = 1.5. When r = 1.5 and θ4 = 55 degrees, θ5 becomes approximately 44 degrees, which is less than 45 degrees.

[0044] (Step 103) In S103, the first screw portion data 312 generated in S102 is duplicated (copied and pasted), and the duplicated data is set as second screw portion data 322 (see FIG. 14).

[0045] (Step 104) In S104, the two pieces of thread data 312, 322 are arranged coaxially so that one thread 323 in the second thread data 322 generated in S103 is located between two adjacent threads 313 in the first thread data 312, and the two pieces of thread data 312, 322 are combined to generate third thread data 332. This third thread data 332 is shown in FIG.

[0046] 14 is a side view of the three-dimensional data of the third thread portion data 332. In the figure, the first thread portion data 312 is shown by a solid line, and the second thread portion data 322 is shown by a dashed line. In the third thread portion data 332, the thread 323 of the second thread portion data 322 is positioned between two adjacent threads 313 in the first thread portion data 312, and further, the first thread portion data 312 and the second thread portion data 322 are arranged coaxially. As a result, the portion in the third thread portion data 332 where the first thread portion data 312 and the second thread portion data 322 overlap forms a double-thread thread, with two spiral threads per pitch.

[0047] In the example of FIG. 14, the positions of the first thread portion data 312 and the second thread portion data 322 are shifted in the axial direction by P5×0.5 so that the pitch P6 of the third thread portion data 332 is half the pitch P5 of the first thread portion data 312 and the second thread portion data 322. When the magnification factor n is 1.5, the pitch P6 is half the value obtained by multiplying the pitch P4 (FIG. 12) of the original thread portion 4 by 1.5. However, the axial shift between the two thread portion data 312, 322 can be any value (amount of shift) as long as it satisfies the condition that the thread thread 323 of the second thread portion data 322 is located between two adjacent thread threads 313 of the first thread portion data 312. In this case, two types of pitches appear in the third thread portion data.

[0048] (Step 105) In S105, fourth thread portion data (not shown) is generated by extracting a portion of the third thread portion data 332 that corresponds to a desired length (for example, length L4 shown in FIG. 14) from the overlapping portion of the first thread portion data 312 and the second thread portion data 322. This completes the generation of the fourth thread portion data.

[0049] (effect) As described in Example 2 above, if the magnification factor r in S102 is set to 1.5 and the first thread portion data 312 and the second thread portion data 322 are arranged in S104 so that they are offset in the axial direction by 0.5 times the pitch P5 of the first thread portion data 312, the angle θ5 between the two flanks of the thread of the third thread portion data 332 and the axis of the thread will be less than 45 degrees, and the pitch P6 of the third thread portion data 332 will be half the value obtained by multiplying the pitch P4 of the original thread portion 4 by 1.5. In other words, it is easy to generate 3D data for a screw that has the same length as the original thread portion 4, a pitch 0.75 times larger, and an overhang angle less than 45 degrees. Furthermore, this method facilitates standardization of screws because 3D data for the screw can be generated using a standard screw according to a set procedure. Furthermore, if a metric forming screw is used as the standard screw, the pitch interval P4 is more than twice the thread width W4, so the magnification factor in S102 can be reduced. When the expansion rate is reduced, the increase in the thread angle φ5 after expansion relative to the thread angle φ4 before expansion can be reduced, so the thread angle can be maintained shallow and a decrease in the thread binding strength can be suppressed. Note that the thread shape of a metric forming screw is not limited to the triangular shape described above, and it can also be trapezoidal, for example, as shown in Figure 7. Even when the thread shape of a metric forming screw is trapezoidal, the expansion rate in S102 can be reduced, so the thread angle (the base angle of the trapezoid) can be maintained shallow and a decrease in the thread binding strength can be suppressed.

[0050] (others) Although the fourth thread portion data 340 in each of the above-described embodiments was for a male thread portion, the fourth thread portion data for a female thread portion can also be generated in a similar manner using the procedure shown in FIG. 1. FIG. 8 is a cross-sectional view of three-dimensional data of a nut 20 using the fourth thread portion data 440 for the female thread portion. However, when performing S106 (radial expansion) of FIG. 1 on the fourth thread portion data 440 for the female thread portion, the fourth thread portion data 340 for the male thread may remain at the size at the end of S105 (the fourth thread portion data 340 for the male thread is not reduced by omitting S106). Conversely, when performing S106 (radial reduction) of FIG. 1 on the fourth thread portion data 340 for the male thread portion, the fourth thread portion data 440 for the female thread may remain at the size at the end of S105 (the fourth thread portion data 440 for the female thread is not increased by omitting S106).

[0051] In particular, the three-dimensional data of this nut 20 has the advantage that the angles that the two flanks 441a, 441b that form each thread 441 in the fourth thread portion data 440 make with the axis of the fourth thread portion data 440 are the same θ2, so all flanks can be smoothly finished regardless of the axial direction from which additive manufacturing is performed. Another advantage is that the nut 20 can be inserted into a bolt from either axial direction.

[0052] While the above describes examples of additively manufactured objects using the fourth thread data, the method described above can be applied to 3D data of various additively manufactured objects (e.g., joints used in piping, etc.) as long as they have a thread (male thread or female thread), and can also be applied to a method for manufacturing such additively manufactured objects using a 3D additive manufacturing device that uses the 3D data. For example, the method can be applied to a male screw having a shape like that shown in FIG. 9 or a female screw having a shape like that shown in FIG. 10. The threads of both the male screw in FIG. 9 and the female screw in FIG. 10 have fourth thread data 340 or 440 generated using the present invention. Furthermore, the male screw in FIG. 9 and the female screw in FIG. 10 can be used as the fastening member shown in FIG. 11 by fastening them together. In this way, the 3D data of the thread portion to which the present invention is applied can also be applied to male screws and female screws having complex shapes.

[0053] In addition, in the above, we have explained the case where the fourth screw portion data 340 is generated by combining two screw portion data 310, 320 obtained by enlarging the screw portion 3 of a standard screw to generate a double-thread screw, but it is also possible to create a triple-thread screw by combining three screw portion data obtained by enlarging the screw portion 3 of a standard screw.

[0054] The present invention is not limited to the above-described embodiments, and includes various modifications within the scope of the gist thereof. For example, the present invention is not limited to those having all of the configurations described in the above-described embodiments, and includes those in which some of the configurations are omitted. Furthermore, some of the configurations of one embodiment can be added to or replaced with configurations of other embodiments. For example, the present invention may include the following inventions (1) to (9).

[0055] (1) a first step of generating first screw portion data by enlarging three-dimensional data of a screw portion of a standard screw by 1.0-2.5 times along the axial direction of the screw portion; a second step of generating second thread portion data by duplicating the first thread portion data; a third step of generating third thread portion data by coaxially arranging the first thread portion data and the second thread portion data so that one thread in the second thread portion data is located between two adjacent threads in the first thread portion data; and a fourth step of generating fourth screw portion data by extracting a portion of a desired length from the portion of the third screw portion data where the first screw portion data and the second screw portion data overlap.

[0056] (2) In (1) above, A method for generating 3D data for a screw for 3D additive manufacturing, comprising a fifth step of reducing or enlarging the fourth screw portion data in the radial direction.

[0057] (3) In (1) or (2) above, In the first step, the first screw portion data is generated by enlarging three-dimensional data of the screw portion of the standard screw by two times along an axial direction of the screw portion of the standard screw; A method for generating 3D data of a screw for 3D additive manufacturing, in which the third step generates the third screw portion data by arranging the first screw portion data and the second screw portion data so that they are shifted in the axial direction by 0.5 times the pitch of the first screw portion data.

[0058] (4) In any one of (1) to (3) above, A method for generating 3D data for a screw for 3D additive manufacturing, wherein in the first screw portion data, the angle formed between the axis of the screw portion and two flanks relating to one thread is each 50 degrees or less.

[0059] (5) In any one of (1) to (3) above, A method for generating 3D data for a screw for 3D additive manufacturing, wherein in the first screw portion data, the angle formed between the axis of the screw portion and two flanks relating to one thread is each 45 degrees or less.

[0060] (6) In (1) above, A method for generating 3D data for a screw for 3D additive manufacturing, wherein the standard screw is a screw whose pitch interval is at least twice as wide as the width of the thread.

[0061] (7) In any one of (2) to (5) above, A method for generating 3D data for a screw for 3D additive manufacturing, wherein the standard screw is a screw whose pitch interval is at least twice as wide as the width of the thread.

[0062] (8) In (6) or (7) above, When the angle between the axis of the thread portion of the standard screw and two flanks relating to one thread is 45 degrees or less, the first step is a method for generating 3D data of a screw for 3D additive manufacturing, in which the 3D data of the thread portion is enlarged by 1.0 times along the axial direction of the thread portion.

[0063] (9) In any one of (1) to (8) above, A method for manufacturing a layered object, which uses a three-dimensional layered manufacturing device to manufacture a layered object based on the fourth screw portion data. [Explanation of symbols]

[0064] 1...Standard screw (hexagon bolt), 3...Thread portion of standard screw (male thread portion), 4...Thread portion of standard metric forming screw (male thread portion), 10...Hexagon bolt, 20...Nut, 31...Thread, 31a...Lower flank (chasing flank), 32...Thread, 32a...Lower flank, 310...First thread portion data, 311...Thread, 311a...Lower flank, 312...First thread portion data, 313 ...Thread, 320...Second thread data, 321...Thread, 322...Second thread data, 323...Thread, 330...Third thread data, 332...Third thread data, 340...Fourth thread data, 340A...Fourth thread data, 345...Chamfered portion, 341a...Lower flank (chasing flank), 440...Fourth thread data, 441...Thread, 441a...Flank, 441b...Flank

Claims

1. a first step of generating first thread portion data by enlarging three-dimensional data of a thread portion of a standard screw by 1.0 to 2.5 times along an axial direction of the thread portion; a second step of generating second thread portion data by duplicating the first thread portion data; a third step of generating third thread portion data by coaxially arranging the first thread portion data and the second thread portion data so that one thread in the second thread portion data is located between two adjacent threads in the first thread portion data; and a fourth step of generating fourth screw portion data by extracting a portion of a desired length from the portion of the third screw portion data where the first screw portion data and the second screw portion data overlap.

2. The method for generating three-dimensional data of a screw for three-dimensional additive manufacturing according to claim 1, A method for generating three-dimensional data for a screw for three-dimensional additive manufacturing, comprising a fifth step of reducing or enlarging the fourth screw portion data in the radial direction.

3. The method for generating three-dimensional data of a screw for three-dimensional additive manufacturing according to claim 1, In the first step, the first thread portion data is generated by enlarging three-dimensional data of a thread portion of the standard screw by two times along an axial direction of the thread portion of the standard screw; In the third step, the method for generating three-dimensional data of a screw for three-dimensional additive manufacturing generates the third screw portion data by arranging the first screw portion data and the second screw portion data so that they are shifted in the axial direction by 0.5 times the pitch of the first screw portion data.

4. The method for generating three-dimensional data of a screw for three-dimensional additive manufacturing according to claim 1, A method for generating three-dimensional data for a screw for three-dimensional additive manufacturing, wherein in the first screw portion data, the angle formed between the axis of the screw portion and two flanks relating to one thread is each 50 degrees or less.

5. The method for generating three-dimensional data of a screw for three-dimensional additive manufacturing according to claim 1, A method for generating three-dimensional data for a screw for three-dimensional additive manufacturing, wherein in the first screw portion data, the angle formed between the axis of the screw portion and two flanks relating to one thread is each 45 degrees or less.

6. The method for generating three-dimensional data of a screw for three-dimensional additive manufacturing according to claim 1, A method for generating three-dimensional data for a screw for three-dimensional additive manufacturing, wherein the standard screw is a screw whose pitch interval is at least twice as wide as the width of the thread.

7. The method for generating three-dimensional data of a screw for three-dimensional additive manufacturing according to claim 2, A method for generating three-dimensional data for a screw for three-dimensional additive manufacturing, wherein the standard screw is a screw whose pitch interval is at least twice as wide as the width of the thread.

8. The method for generating three-dimensional data of a screw for three-dimensional additive manufacturing according to claim 6, When the angle between the axis of the thread portion of the standard screw and two flanks relating to one thread is 45 degrees or less, the first step is a method for generating three-dimensional data of a screw for three-dimensional additive manufacturing, in which the three-dimensional data of the thread portion is enlarged by 1.0 times along the axial direction of the thread portion.

9. A method for manufacturing a layered object, comprising the steps of: forming a layered object using a three-dimensional layered manufacturing device based on the fourth screw portion data according to claim 1 ;

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