TW201819782A - Double screw structure having a loosening prevention function and allowing the screw portion to have sufficient strength - Google Patents

Abstract

According to a double screw structure 1 of the present invention, a first screw (S1) and a second screw (S2) having different leads are formed on a double screw portion. The double screw structure 1 has a loosening prevention function and allows the screw portion to have sufficient strength. The screw portion includes the first screw (S1) composed of a coarse screw having a standard pitch P, and the special second screw (S2). The second screw (S2) is continuously formed on the thread of the first screw (S1). The cross-sectional shape of a screw groove has the same or substantially the same shape as that of the first screw (S1), and has the same twist direction. The second screw is selected from a group of multiple screws, which have a lead L containing predetermined n times the standard pitch p (i.e., L=n*p) and a triangular cross section, and the number of the second screw is at least one less than the number of said multiple screws.

Description

Double screw structure

The present invention relates to a double screw structure having a loosening prevention function and the like. More specifically, the dual screw structure (male screw) is a first screw (S1) having a triangular cross-sectional shape and a second screw (S1) formed on a thread of the first screw (S1). S2) Two structures. The second screw (S2) is a plurality of screws having a lead different from the first screw (S1), and is a double screw structure having the same triangular thread as the first screw (S1) having the same cross-sectional shape. . The double screw structure is a double screw structure that can be used in fasteners having sufficient strength and having a loosening prevention function, a lead cam device, and the like.

Regarding the fastening structure of a screw having a loosening prevention function, various structures have been proposed in the past. A common method is a method called ｢double nut｣. The tightening method is to tighten the nut 1 of the female screw on the screw part of the double screw structure (male screw), and then tighten the nut 2 of the female screw to contact with the nut 1 to stretch A method in which a force (axial force) acts between two nuts. The mutual tightening of the nut 1 and the nut 2 prevents loosening of the screw due to vibration or the like of a structure using the nut. The ｢double nut｣ is usually a nut 1 for a loose nut (thin nut), and a nut 2 to be tightened later is a nut (thick nut) for fastening.

As one of the techniques for improving the above-mentioned technology, it has been proposed to form screws (for example, coarse-tooth screws and fine-tooth screws) having different pitches in the screw portion (male screw), and use nuts for coarse-tooth screws and fine-tooth screws. The nut is tightened, and the technology of anti-loosing function is provided by the difference between the two. As a method for producing a bolt used therein, a method for producing a multi-bolt in which a coarse screw and a fine screw are formed is known (for example, refer to Patent Document 1). Further, a related art is also known in which any one of a coarse tooth screw and a fine tooth screw is a lock bolt of a plurality of screws (for example, refer to Patent Documents 2 and 3).

In addition, in order to equalize the plastic deformation during rolling, that is, the rolling load, rolling has been proposed that includes a coarse screw with a standard first pitch and a fine screw with a second pitch smaller than the first pitch. Related technology for manufacturing the shape of a screw thread of a bolt (see Patent Document 4). [Prior Art Literature] [Patent Literature]

[Patent Literature 1] Japanese Patent No. 3546211 [Patent Literature 2] Japanese Patent Laid-Open Publication No. 2003-184848 [Patent Literature 3] Japanese Patent Laid-Open Publication No. 2003-220438 [Patent Literature 4] Japanese Patent Laid-Open No. 2010- 014226

[Problems to be Solved by the Invention] As described above, a conventional bolt having a loosening prevention function as a double screw structure is used in a screw portion of a bolt including a coarse screw and a fine screw, and a nut of the coarse screw 3, the principle of different pitches of the nuts of the fine screw. That is, two nuts are tightened separately, and when the two screws are tightened, a difference in tightening torque occurs due to a difference in screw pitch. Looseness is mainly prevented by the difference in the torque. However, most of such bolts are bolts having a structure in which the screw portion is a fine-pitch screw having the same triangular thread on a coarse-pitch screw with a triangular cross-sectional shape.

The screw portion of the bolt has a structure in which a fine screw is formed on the thread of the coarse screw. The fine screw has a small pitch and threads with shallow grooves are periodically formed protrusions (the cross-sectional shape is substantially triangular). Therefore, the bolts including coarse screws and fine screws described in Patent Documents 1 to 4 described above have a small cross-sectional shape (area) of the fine screws, and therefore have insufficient strength when tightening the screws (shearing of threads). Damage, insufficient allowable contact surface pressure, etc.). That is, the triangular cross-sectional area of the fine screw is small, so that the strength of the screw portion is weakened. For example, if a large axial force is applied to the fine screw through the nut, the fine screw may have a short shear length (the length of the bottom side of the thread), which may cause deformation or shear failure. In addition, the rolling mold for manufacturing the screw also has a small cross-sectional area that constitutes a triangle, so that there may be problems such as a part of a protrusion of the rolling mold for forming a fine screw being defective. A rolling die having a defect in a part of the protrusion becomes a defective product, and an operation of replacing the rolling die with a new one is required, thereby reducing the productivity of the bolt rolling operation.

On the other hand, the double-screw structure (male screw) is formed with a coarse-pitch screw with a standard pitch and a plurality of screws with a coarse-neck screw with n times the lead of the standard pitch on the thread of the coarse-pitch screw. The structure is also considered to have a locking effect due to the difference between the two leads. However, in the double screw structure, the height of the thread is periodically changed, and at a certain angular position, a low-thread continuous portion is formed, and the volume of the thread (or the cross-sectional area of the cut surface) is less than Usual screws. Therefore, in the screw portion of the double screw structure, the area where the screwed nut is engaged (contacted) with the thread is small, and the strength of the screw portion (shear failure of the thread, contact surface pressure, etc.) may be insufficient. On the other hand, in anti-loosening bolts including a double-screw structure, for example, in infrastructure facilities such as bridges, there is a demand for high strength in the screw portion. Therefore, it is desirable to improve the development without the use of fine-head screws. Double screw structure with tightening strength of screws.

The present invention has been made to solve the existing problems as described above, to achieve the following objects. An object of the present invention is to provide a double screw structure formed with a first screw of a general design specification and a special second screw, which can be used as a locking fastener with sufficient strength at a screw portion. The lead of the first screw has a different lead from the first screw and deforms a plurality of screws. Another object of the present invention is to provide a double screw structure which can be used as a lead cam device for converting rotation into a linear motion, and the double screw structure is formed with a first design specification. 1 screw and a special second screw, the second screw is on the thread of the first screw, the lead is different from the first screw, and a plurality of screws are deformed. [Means to solve the problem]

In order to achieve the object, the present invention adopts the following means. In the double screw structure of the present invention 1, two kinds of screws are formed on a screw shaft. The double screw structure is characterized in that it includes: a first screw (S1) formed on the screw shaft (3); The cross-sectional shape of the thread is a screw having a triangular shape and a pitch (P); and the second screw (S2) is a screw formed in a continuous shape on the thread and having a triangular cross-section and has the same twisting direction as the thread And is one screw less than a plurality of screws having a lead (Ln) of a predetermined multiple (n) of the pitch (P) of the threads.

The double screw structure according to the second aspect of the present invention is the first aspect of the present invention, wherein the predetermined multiple (n) is an integer multiple of the pitch (P). The double screw structure according to the third aspect of the present invention is the first or second aspect of the present invention, wherein the lead (Ln) is twice the pitch (P) of the thread in the second screw (S2). The number of the plurality of screws is two, and one of the screws is formed.

The double screw structure according to the fourth aspect of the present invention is the first or second aspect of the present invention, wherein the lead (Ln) in the second screw (S2) is three times the pitch (P) of the thread. The number of the plurality of screws is three, and one or two of the screws are formed.

The double screw structure according to the fifth aspect of the present invention is the first or second aspect of the present invention, wherein the lead (Ln) in the second screw (S2) is four times the pitch (P) of the thread. The number of the plurality of screws is four, and two of the screws are formed.

The double screw structure according to the sixth aspect of the present invention is the first or second aspect of the present invention, wherein the first screw (S1) and the second screw (S2) are located on a center line including the double screw structure. In the cross section, the valleys of the hill-like threads appearing at specific angular positions are filled with the base metal.

The double screw structure of the seventh aspect of the present invention is the sixth aspect of the present invention, wherein the outer diameter of the groove is the effective diameter of the first screw (S1). The dual screw structure according to the eighth aspect of the present invention is the first or second aspect of the present invention, characterized in that the first screw (S1) and the second screw (S2) are raw fiber tissues that are continuous along the thread Ground flowing rolled screws. The dual screw structure according to the ninth aspect of the present invention is the first or second aspect of the present invention, wherein the first screw (S1) is a metric coarse tooth screw.

The dual screw structure according to the tenth aspect of the present invention is the first or the second aspect of the present invention, wherein the dual screw structure is the screw shaft (3) is a bolt (81), and includes screwing into the first screw. The first nut (82) of (S1) and the second nut (94) screwed into the thread of the second screw (S2) and having a triangular cross-sectional shape are used to fasten and fix parts and components. Parts of fasteners (80).

The double screw structure according to the eleventh aspect of the present invention is the invention 1 or the second aspect, wherein the double screw structure is the screw shaft (3) is a lead cam (91), including the first screw (S1) Parts of the first cam follower (94) engaged and the lead cam device (90) of the second cam follower (92) engaged with the second screw (S2). [Effect of the invention]

The double screw structure of the present invention includes a first screw (S1) and a second screw (S2), and the reference mountain shape can be formed continuously or at predetermined intervals at various angular positions in the circumferential direction of the axis of the screw shaft portion. Threads having a shape similar to the reference mountain shape can increase the strength of the screw portion. In addition, the double screw structure increases the volume of the thread, improves the contact surface pressure applied to the nut, and improves the thread's resistance compared with the existing lock bolts including coarse screws and fine screws. Resistant to shear failure stress. In addition, since the double screw structure of the present invention does not use the existing fine-tipped screws, the grooves of the threads are not filled with, for example, molten tin in the dipping process for plating. As a result, it can also be used for infrastructure equipment, such as a bridge, using a large-diameter bolt with a thick plating process for the said thread.

Hereinafter, each embodiment of the double screw structure of this invention is demonstrated based on drawing. 1 (a) and 1 (b) show an embodiment of a double screw structure. FIG. 1 (a) is a front view, and FIG. 1 (b) is a side view.

[Double Screw Structure 1] Hereinafter, the outline of the double screw structure of the present invention will be described first. Double screw pitch P 1 in the structure of the outer periphery of the screw shaft 3 having a triangular cross-sectional shape of the threads, in this embodiment, corresponding to a nominal diameter of normalized standard (lead L = _1), there is formed a metric The first screw (S1) of the coarse screw (hereinafter also referred to as ｢coarse screw｣). A second screw (S2), which is a screw having a lead L _n (= n * P) that is a predetermined multiple (n) of the pitch P of the coarse screw, is formed on the thread of the first screw (S1). The second screw (S2) is a screw (thread and screw groove) formed continuously and spirally on the thread of the first screw (S1) and having a triangular cross-sectional shape. The screw direction of the second screw (S2) is the same torsion direction as the screw of the first screw (S1), and is a screw having a lead (nP) that is a multiple (n) of the pitch (P) of the screw. Or multiple screws. However, to be precise, the second screw (S2) is a screw that is one or more fewer than the original multiple screws. That is, it is a plurality of original screws, and one or more screws are removed from the number of the plurality of screws (also referred to as “new multiple screws”). In addition, although one or more screws are removed from the original number of the plurality of screws, depending on the number of the removed screws, there may be cases where the number of screws is not one and the result is one screw.

The lead L _{1 of the} first screw (S1) is smaller than the lead L _{n of} the second screw (S2). The shape and pitch P of the first screw (S1) is determined by a screw-related specification (for example, the International Standardization Organization (ISO)), and in this example, it is a standard specification such as a metric coarse screw. However, the pitch P of the first screw (S1) may be a screw having a pitch different from the standard size. In addition, in FIGS. 1 (a) and 1 (b), only the double screw structure and its vicinity are shown with respect to the double screw structure 1, but the double screw structure 1 is formed on a screw shaft and a bolt ( For example, hexagon bolt, hexagon socket bolt, eyebolt, studbolt, anchor bolt, set screw, wing bolt, U-bolt, ceiling bolt (Ceiling bolt)) and so on.

When the double-screw structure 1 is used as a double nut for locking, for example, a first nut 82 (a tightening nut) as a female screw is screwed into the first screw (S1) (metric coarse tooth screw). Cap), and the second screw (S2) is screwed into a second nut 84 (a lock nut) as a female screw (see FIG. 24 (a) and FIG. 24 (b)). With the configuration described above, a large tightening force is generated by the first nut 82 screwed into the first screw (S1), and the second nut 84 is tightened as a lock nut. As the lead angles of the two nuts are different, a locking effect is produced. In other words, the double-screw structure 1 can provide a large size to the screw shaft 3 by tightening the fastened body with the first screw 82 of the first screw (S1) screwed into the double-screw portion 2. Preload. As a result, the fastened state can be maintained even when an external force is applied to the fastened member 86 from the axial direction.

In addition, the second screw (S2) of this example includes screws (threads and screw grooves) having a triangular cross-sectional shape similar to the coarse-threaded screws, and fine-threaded screws are not used. Therefore, the double-screw structure 1 can increase the contact area between the screw and the nut, and the volume of the screw can be increased compared with the existing bolts and the like including the fine screw. Therefore, since the area to be engaged with the second screw nut can be increased, the allowable shear failure stress of the thread can be increased, and the allowable contact surface pressure resistance can be increased, so that insufficient strength of the screw portion does not occur. In addition, the second screw (S2) of this embodiment is preferably a lead having a predetermined multiple of the lead of the first screw (S1) or more. However, it is considered that it is actually used in general metal materials as a double nut. , It is preferably a screw with a lead of 4 times or less. The reason is that if the lead screwed into the second screw (S2) is increased in lead length, it is necessary to make the screw thread at least 1 turn or longer, so that the length in the axial direction of the nut is extended. Therefore, when a nut is produced by tapping, processing becomes difficult, so it is preferably 4 times or less the lead.

As described above, the embodiment of the first screw (S1) of the present invention is a metric coarse tooth screw. The second screw (S2) is a screw that is one or more fewer than the original multiple screws. The inventors have removed one from the second screw (S2) (multiple screws) formed on the coarse screw (first screw (S1)) based on the coarse screw (first screw (S1)). As mentioned above, the double screw structure 1 with a reduced number is repeatedly researched and developed. As a result, the double screw structure of the present invention was found to have both the strength improvement and the locking effect of the double screw portion 2. Hereinafter, the double screw structure 1 of the present invention will be described in detail for each combination of the first screw (S1) and the second screw (S2), which are preferable as the double screw portion 2.

[Embodiment 1] [Dual screw structure including coarse screw and 牙 3 times lead 2 screws]] Hereinafter, a specific description will be given with reference to FIGS. 2 (a) and 2 (b). The double screw structure of the first embodiment described in FIG. 2 (a) and FIG. 2 (b) is a first screw (S1) including a thread and a screw groove formed on the double screw portion 2 of the screw shaft 3. . The thread is a standard 凖 metric coarse screw ｣(hereinafter also referred to as a｢ coarse screw ｣) specified in the ISO (the International Organization for Standardization), and a first screw having a triangular cross-sectional shape ( S1). The first screw (S1) is screwed into a nut, which is a normal female screw for metric coarse teeth. In addition, a second screw (S2) is formed on the thread of the first screw (S1) so that the thread appears to be cut (wall-cut). The second screw (S2) is a special screw, and one of the three screws is removed without forming the removed screws (threads and screw slots). That is, in this example, one screw is removed from the original three screws (hereinafter also referred to as "3 times lead 2 screws").

2 (a) and 2 (b) are for explaining the structure of the double screw structure 10 (｢3 times lead 2 screws｣) of the first embodiment, and are cut by a plane passing through the center line of the screw shaft 3. 2 (a) shows the cross-sectional shape of the double screw portion 2 of the ｢0 ° angular position of the double screw structure 10, and FIG. 2 (b) shows the double screw portion 2 of the｢ 90 ° angular position. Section shape. The double screw structure 10 shown in FIGS. 2 (a) and 2 (b) is formed with a first screw (S1) as a metric coarse screw and a second screw having the same metric coarse screw as a reference mountain shape. (S2). In this example, the second screw (S2) is two screws (one is called “3 times lead 2 screws”), and one is removed from the original three screws. The first screw (S1) in this example is a metric coarse-pitch screw with a standardized pitch P (lead L ₁ = P). The second screw (S2) is 3 times (integer multiple) the pitch P of the metric coarse screw having a lead L ₃ (= 3P) of the two screws. The second screw (S2), which is the two screws, is formed by reducing two screws (removing one) from the original three screws (hereinafter referred to as “three well-known screws”) to the first screw. The screw on the screw (S1).

As a first screw (S1) metric coarse screw threads of the pitch P and the lead L same as a screw _1, h _1, a fixed pitch is formed along the helix (Helix) has a screw groove g ₀ and thread R & lt (hatching section). As the second screw (S2), ｢3 times the lead 2 screws｣ (the gray part in Figure 2 (a) and Figure 2 (b) refers to the nut screwed in here) is the lead L ₃ (= 3P ), Two screw grooves g ₁ and g ₂ are formed along the spiral line h ₃ . In addition, in the description of the first embodiment, for convenience of explanation, the cross-sectional shape of the screw groove g ₀ of the coarse screw and the screw groove g ₁ and screw groove g ₂ of ｢3 times the lead 2 screws｣ The angular position where the cross-sectional shapes overlap is described as "0 ° angular position" in Fig. 2 (a).

In FIGS. 2 (a) and 2 (b), the first screw (coarse screw) S1 is a cross section of the first thread r at a pitch P (= lead L ₁ ) indicated by a contour line (solid line) Q1. Triangular shaped screws. ｢3 times lead 2 screws｣ The second screw (S2) is a screw that removes one thread from three well-known screws. In other words, it is a contour line (two-point chain line) without forming one screw (slot). ) The so-called ｢new 2 screws｣ in the present invention indicated by Q3-1. The new two screws have a portion where two screw grooves g ₁ and g ₂ are continuously formed at a fixed pitch, and one screw is not formed adjacent to the screw groove g ₂ (or the screw groove g ₁ ). Part of the slot de. That is, the two new screws are alternately formed at the portion (the portion that is the outer peripheral surface of the screw shaft portion and is flat in cross-section) and the screw grooves g ₁ and g _{2 that} are a group. Three screws with a lead L ₃ (= 3P) produce two screws with variations. As described above, the gray portions shown in Figs. 2 (a) and 2 (b) refer to the threads of the second nut (S2) which is screwed into the second screw (S2) which is ｢3 times the lead 22. Section shape.

At ｢0 ° angular position 图 in FIG. 2 (a), there is a first thread r (hatched portion) formed as a reference mountain shape (triangular shape) as an original coarse screw. The first thread r has a triangular reference mountain shape (triangular shape) formed continuously and regularly at regular intervals of a fixed pitch P. However, at the ｢90 ° angle position 图 in FIG. 2 (b), the top of the first thread r, which is the reference mountain shape of the original coarse screw, appears to be cut off, and the thread height is lower than that described above. The hill-shaped second thread r _s of the first thread r. At the above-mentioned angular position, the second thread r _{s is} formed into a screw shape in which four mountains are continuous in a mountain-like outline. That is, the first thread r, which is the reference mountain shape (triangular shape) of the coarse screw, is cut, and the second thread r _{s is} reduced, and the shear failure stress of the thread is lower than that of the reference mountain shape (the original triangular shape). However, as will be described later, in the double screw structure 10 according to the first embodiment, the 螺丝 new plurality of screws ｢, which are the second screws (S2), have portions where the screws (grooves) are not formed regardless of the angular position ( 0 ° angle, 180 ° angle position, etc.), so the original triangular mountain shape of the thread of the coarse screw must be left.

The double screw structure 11 shown in Figs. 3 (a) and 3 (b) is a modification of the double screw structure 10 shown in Figs. 2 (a) and 2 (b), and is a double screw structure (｢ Modification of 3 times lead 2 screws ｣) 11 cross-sectional view. That is, the double-screw structure 11 is a structure in which the angle phases of the two screws of the double-screw structure 10 are changed. 3 (a) and 3 (b) are cross-sectional views cut by a plane passing through the screw shaft, and FIG. 3 (a) is a partial view showing a cross-sectional shape of the double screw portion 2 at an angle position of 0 °. FIG. 3 (b) is an explanatory view partially showing a cross-sectional shape of the double screw portion 2 at ° 90 ° angular position. That is, 图 3 times lead 2 screws 所示 shown in FIG. 2 (a) and FIG. 2 (b) are simply removing one screw from the original three screws, so the angle phase of the thread is variability. Therefore, it is a screw that changes the angular position of the two screws and makes the arrangement of the two screws equal.

The ｢3 times lead 2 screws｣ in the modified example (the gray parts in Figs. 3 (a) and 3 (b) refer to the cross section of the nut screwed in here) is the lead L ₃ (= 3P ) Screws. The screw has two screw grooves g ₁₁ and g ₁₂ formed at equal intervals between the leads L ₃ and ｢3 times the lead 2 shown in FIGS. 2 (a) and 2 (b). ｣2 different screws. That is, the deformation of the ｢3 times lead 2 screws｣ is, for example, shown by the outline Q3-1 ′ between the screw groove g ₁₁ and the screw groove g _{12 and} between the screw groove g ₁₂ and the screw groove g ₁₁ A portion where a screw groove is not formed on the thread of the coarse-screw (a portion that is flat on the cross-section as the outer peripheral surface of the screw shaft) is formed.

The coarse tooth screw is a screw having the same pitch P and lead L ₁ , and a screw groove g _{0 is} formed along the spiral line h ₁ (if viewed from the nut, the thread g ₀ ). 3 (a) and 3 (b) ｢3 times lead 2 screws (modified example)｣ are 2 screws of lead L ₃ , formed at a predetermined interval along the spiral h ₃ Two screw grooves g ₁₁ and g ₁₂ (gray area). In the cross-sectional shape of the double screw structure 11 at ｢0 ° angular position｢ and ｢90 ° angular position｣, between the first thread r (hatched portion) and the first thread r of the reference mountain shape, Two hill-shaped second threads r _s ′ are formed in a mountain shape, and the height of the second threads r _s ′ is lower than the first thread r. As shown in Fig. 2 (b), the hill-shaped continuous mountain is 2 mountains, so the shear failure strength is stronger than that of the 4 continuous mountains.

[Double Screw Structure Containing Coarse Screws and ｢3 Leads One Screw｣] FIGS. 4 (a) and 4 (b) show the double screw structure 12 according to the first embodiment. Fig. 4 (a) is an explanatory view partially showing the cross-sectional shape of the double screw portion 2 at ｢0 ° angular position ，, and Fig. 4 (b) is a partially cross-sectional shape of the double screw portion 2 at｢ 90 ° angular position Illustration. Figure 2 (a), Figure 2 (b), Figure 3 (a), and Figure 3 (b) show the second screw (S2), which is two screws removed from the original three screws. The double screw structure 12 shown in 4 (a) and FIG. 4 (b) is a structure formed by removing two screws and forming one screw. Therefore, regardless of the cross-sectional angle, a considerable amount of the thread of the coarse screw remains.

That is, the double-screw structure 12 is formed with a coarse-pitch screw having a pitch P (lead L ₁ = P) and a lead L ₃ (= 3P) which is three times (integer multiple) the pitch P of the coarse-pitch screw. ) 1 screw (hereinafter referred to as ｢3 times lead 1 screw｣). In the cross-sectional views of FIGS. 4 (a) and 4 (b), the coarse screw is a triangular screw with a pitch P indicated by the outline Q1. The "3 times lead 1 screw" is a screw that has not been formed (removed) 2 of the 3 known screws, and is a screw indicated by outline Q3-2. The special one screw is a portion where one screw groove g ₂₁ is formed, and a portion provided adjacent to the screw groove g ₂₁ (gray portion) without forming two screw grooves (as an outer peripheral surface of the screw shaft portion and One screw with a lead L ₃ (= 3P) formed alternately in a flat portion when viewed in cross section. The coarse tooth screw is a screw having the same pitch P and the same lead L ₁ , and a screw groove g ₀ and a thread r are formed along the spiral line h ₁ .

｢1 screw with 3 times lead｣ is a screw with lead L ₃ (3P), and one screw groove g ₂₁ (gray part) is formed along the spiral line h ₃ . At ｢0 ° angular position｣ in FIG. 4 (a), a cross-sectional shape of a double screw in which the first thread r (hatched portion) formed in a reference mountain shape is continuous is formed. In the cross-sectional shape at ｢90 ° angular position｣ of FIG. 4 (b), the first thread r having a reference mountain shape is continuous with the second thread r _s (hatched portion) of two mountains of a continuous mountain, and The height of the second thread r _s is lower than that of the first thread r.

FIG. 5 is a list of cross-sectional views showing a cross-sectional shape at each position of each angular position of the screw of the double screw portion 2 of the screw shaft 3. FIG. 5 is a view of each of the double-screw structure 10, the double-screw structure 11, and the double-screw structure 12 when one or two screws are formed on the coarse screw. Partial cross-sectional view of the plane cut. FIG. 6 is a graph showing the relationship between the angular position and the area ratio of the screw shaft of the double screw portion 2 of each screw shaft 3 shown in FIG. 5. In addition, the area ratio (%) in FIG. 6 refers to the area of the original coarse screw with a triangular cross-sectional shape of the thread and each angle of the double screw structure 10, the double screw structure 11, and the double screw structure 12. The proportion (%) of the cross-sectional area of the position. FIG. 7 is a diagram for explaining a state in which a raw material to be rolled is filled in a recess of a round rolling die at each position of each angular position when the double screw structure 11 according to the first embodiment is rolled. Illustration. FIG. 8 is a graph showing a relationship between a plugging amount and a filling rate (%) at each angular position of the circular rolling die when the double screw structure 11 of Embodiment 1 is rolled using the circular rolling die. From this relationship, it can be understood that the double screw structure 11 of the first embodiment can be smoothly rolled.

As described above, the double screw structure 10, the double screw structure 11, and the double screw structure 12 shown in FIGS. 2 (a) and 2 (b) to 4 (a) and 4 (b) include: The first screw (coarse screw) (S1), and 螺丝 3 times the lead screw 2 as the second screw (S2) (see Figure 2 (a) and Figure 2 (b), Figure 3 (a), and Figure 3 (b)) or ｢3x lead 1 screw｣ (see Figures 4 (a) and 4 (b)). 2 (a) and FIG. 2 (b) to FIG. 4 (a) and FIG. 4 (b), in order to explain the structure of the double screw structure 10, the double screw structure 11, and the double screw structure 12, respectively, are shown. The cross-sectional shape of each thread at 0 ° angle position ｣,｢ 90 ° angle position ｣. Based on FIGS. 5 and 6, another angular position of the double screw structure 10, the double screw structure 11, and the double screw structure 12 will be described. 5 and 6 also show a double screw structure including a coarse tooth screw and three well-known screws ｣, and a coarse tooth screw including the first embodiment described above and a plurality of new screws (｢ 3 times lead 1). Modifications of two screws ｣,｢ 3 times lead 2 screws ｣, and｢ 3 times lead 2 screws ｣) Double screw structure 10, double screw structure 11, and double screw structure 12 are compared.

That is, FIG. 5 is a diagram showing the relationship between the angular position of each 30 ° in the circumferential direction of the axis of the screw shaft 3 where the double screw portion 2 shown in FIG. 1A is formed and the cross-sectional shape of the double screw portion 2. FIG. 6 is a graph showing the area ratio of the cross-sectional area of each double angular portion (see FIG. 1 (a) and FIG. 1 (b)) to the angular position of the screw shaft 3 in the circumferential direction of the axis of the screw shaft 3. As shown in FIG. 5, the double screw structure repeatedly exhibits the same combined cross-sectional shape at every predetermined cycle. For example, in ｢3 times lead 2 screws 所示 shown in FIG. 2 (a) and FIG. 2 (b), the two leads are combined in each cycle of 3 times the pitch of the coarse screw. Repeat the same shape. FIG. 5 is a diagram showing an area of a cross-sectional area of the double screw portion 2. FIG. 6 is a diagram showing an area ratio of a cross-sectional area of the double screw portion 2, and a sum of a cross-sectional area of a triangular thread at each angular position and a cross-sectional area of a reference mountain shape of a coarse screw is 100%, A diagram showing the comparison at each of the angular positions.

As shown in FIG. 5, the double screw structure including the coarse screw and the three well-known three screws 由于 has the same mountain shape and pitch as the coarse screws and the three well-known three screws 故, so they are at predetermined angular positions. The mountain shape causes interference, and there is an angular position where the mountain shape is hardly left (refer to the left end of FIG. 5). The double screw structure may deform the screw from the angular position where the mountain shape does not remain and its vicinity, thereby causing insufficient strength of the screw shaft portion and the screw portion. For example, the double screw structure is formed at an angular position other than ｢0 ° angular position｣, ｢180 ° angular position｣, especially ｢90 ° angular position ，, the height of the thread is lower than that of the reference mountain-shaped thread, The cross-sectional shape of a double screw in which the hill-shaped thread continuously appears in the axial direction. In addition, from ｢60 ° angular position｣ to ｢120 ° angular position｣, the area ratio was reduced to 42% or less. That is, the double screw structure including the coarse screw and three well-known three screws 存在 has an angular position where the strength of the double screw portion is insufficient.

In contrast, in the double screw structure 10, the double screw structure 11, and the double screw structure 12 according to the first embodiment, there is a portion (0 °) where no screw groove is formed on a plurality of new screws as the second screw (S2). Angle, 180 ° angle position, etc.) to increase the volume of the thread, so that the situation of no mark mountain shape is not left at any angle. For example, a double screw structure (coarse screw and ｢3 times lead 2 screws｣) 10 is a 双重 90 ° angle position ｣, and is also a double screw portion formed to show a 凖 -shaped thread at predetermined intervals. The cross-sectional shape of 2 also increased the area ratio to about 56%. In addition, the double screw structure (coarse screw and ｢3 times lead 1 screw 12) 12 is also a double screw portion 2 formed at a 是 90 ° angle position 部 to show a 凖 mountain-shaped thread per 1 mountain. The cross-sectional shape and area ratio also increased to about 78%. In addition, the double screw structure (a modified example of a coarse screw and ｢3 times lead 2 screws）) 11 does not have a continuous angular position of a standard 凖 -shaped thread, but is formed continuously or at predetermined intervals. The cross-sectional shape of the double-screw portion 2 exhibiting a ridge-shaped thread has an area ratio that is a stable large value of about 70% to about 78% throughout all angular positions. That is, the double screw structure 10, the double screw structure 11, and the double screw structure 12 are formed so that the strength of the screw portion is sufficient.

Regarding the rolling processing method of the double screw structure, a double screw structure (a modified example of a coarse screw and ｢3 times lead 2 screws｣) 11 will be described as an example. FIG. 7 shows ｢0 ° angular position｣, ｢90 ° angular position｣, ｢180 ° angular position｣ when the screw rolling die D is inserted into the screw material M and the double screw structure 11 is rolled. Graph of the filled results. The angular position is a part of the double-screw structure 10 in which the shape of the double-screw part is greatly different, and is shown as a representative example. FIG. 8 is a diagram showing a relationship between a plugging amount and a filling rate during the screw rolling process. As shown in FIGS. 7 and 8, it has been confirmed that, at each angular position, the screw material M is plastically deformed at substantially the same filling rate, and is reliably filled in the rolling surface formed in the screw rolling mold D. In the space between the rolled material M and the rolled surface, the double screw portion 2 is continuously rolled.

[Embodiment 2] The double screw structure 20 of Embodiment 2 shown in Figs. 9 (a) and 9 (b) is a first screw (S1) (metric coarse screw) formed on the screw shaft 3, and formed in the coarse pitch P of the thread on the screw 4 times the lead L ₄ (= 4P) a second screw (S2) (screw Article 2). The two screws are formed by reducing two screws (two in the middle of the four) from four ordinary screws (threads and screw grooves) (hereinafter referred to as “well-known four screws”) to form two screws. The new multiple screws (hereinafter referred to as "4 times lead 2 screws") are double screw structures 20 in which double screw portions 2 are formed.

9 (a) and 9 (b) are cross-sectional views for explaining the structure of the double screw structure 20 according to the second embodiment, and FIG. 9 (a) is a double screw portion 3 partially showing ｢0 ° angular position｣ FIG. 9 (b) is an explanatory view partially showing the cross-sectional shape of the double screw portion 3 at an angle position of 90 °. FIG. 10 shows a double screw structure 20 according to the second embodiment, and a double screw structure including a coarse screw and a thread of a well-known four screws ｣(commonly four screws), and partially shows each angular position. A cross-sectional view of the cross-sectional shape of the double screw portion at each position. FIG. 11 shows the area ratio (%) of the double screw structure 2 according to the second embodiment and the double screw structure including the coarse screw and the well-known four screws at each position of each angular position. Graph. FIG. 12 is an explanatory diagram for explaining a filling condition at each of the angular positions of the double screw structure of the second embodiment.

Figures 9 (a) and 9 (b) show the 螺丝 0 ° angular position ｣and｢ 90 ° angular position ｣double screws in a double screw structure 20 including a coarse screw and｢ 4 times the lead 2 screws ｣ The cross-sectional shape of the portion 2. The double screw structure 20 includes a coarse screw having a pitch P (lead L ₁ = P) and a lead L ₄ (= 4P) of 4 times (integer multiple) the pitch P of the coarse screw. Thread of the screw. However, the two screws are four screws (known as four screws), two of which are ｢4 times the lead and two screws. The coarse tooth screw is a screw having the same pitch P and the lead L ₁ , and a screw groove g ₀ (or a thread) is formed along the spiral line h ₁ . ｢2 screws with 4 times lead｣ are screws with lead L ₄ (= 4P), and two screw grooves g ₃₁ and g ₃₂ are formed along the spiral line h ₄ . In addition, in the description of the second embodiment, for convenience of explanation, the cross-sectional shape of the screw groove g ₀ of the coarse screw and the screw groove g ₃₁ and screw groove g ₃₂ of ｢4 times the lead 2 screws｣ are used. The angular position where the cross-sectional shapes overlap is set to ｢0 °｣ for explanation.

In FIGS. 9 (a) and 9 (b), the cross-sectional shape of the coarse screw is a triangular screw with a pitch P indicated by the outline Q1. 24 times lead 2 screws ｣is a screw which removes 2 of 4 well-known 4 screws｣. ｢2 screws with 4 times lead｣ are the screws indicated by outline Q4-2 without screw groove g ₃₁ and screw groove g ₃₂ (the gray part refers to the nut screwed in here). ｢4 times lead 2 screws｣ Between the screw slot g ₃₁ and the screw slot g _32, between the screw slot g ₃₂ and the screw slot g ₃₁ , there is a portion where no screw is formed (as a screw shaft portion) The outer peripheral surface is flat at the cross section), and the lead L ₄ (= 4P) of the deflected two screws. At ｢0 ° angular position 所示 shown in FIG. 9 (a), a double screw shape marked with 凖 is formed, that is, a first thread r and a screw groove formed in a reference mountain shape are continuously formed. At ｢90 ° angle position｣ shown in FIG. 9 (b), the first thread r having a reference mountain shape and the second thread r _s1 and the third thread having a hill shape lower than the first thread r are formed. r _s2 is a double screw shape that forms a continuous contour of 2 mountains.

In the description of FIGS. 9 (a) and 9 (b), ｢0 ° angular position｣ and ｢90 ° angular position｣ in the double screw structure 20 have been described, but based on FIGS. 10 and 11, The double screw structure 20 will be further described. FIGS. 10 and 11 show a double screw structure including coarse screws and four well-known four screws ｣(normally four screws), and coarse screws and｢ 4 times lead 2 including the second embodiment. Comparison of the double screw structure 20 of the screw ｣. FIG. 10 is a diagram showing a relationship between an angular position every 30 ° in the circumferential direction of the axis of the double screw portion shown in FIG. 1 (a) and the cross-sectional shape of the double screw portion 2. FIG. 11 is a graph showing an area ratio of an angular position per 30 ° in the circumferential direction of the axis of the screw shaft 3 to the cross-sectional area of the double screw portion 2. The area ratio of the cross-sectional area of the double screw portion is a sum of the cross-sectional area in one cycle of the reference mountain shape of the coarse screw and 100%, and the cross-sectional area of one cycle at each position of each angular position. And are compared.

The double screw structure 20 including the coarse screw and the four well-known four screws ｣has the same size and pitch as the ridges of the coarse screw and the four well-known screws ，, so the mountain shape will interfere at a predetermined angular position. On the other hand, there are locations where there is almost no mountain shape remaining. The double screw structure 20 may deform the screw from the angular position where the mountain shape does not remain and its vicinity, so that the strength of the screw portion is insufficient. For example, the double-screw structure 20 is formed in a cross-sectional shape of a double-screw with a continuous low thread at ｢60 ° angular position｣. Therefore, at the angular position, the strength of the screw portion tends to be significantly insufficient. Regarding the ratio of the cross-sectional area to each angular position, when the cross-sectional area of ｢0 ° angular position 设为 is set to 100%,｢ 60 ° angular position ｣,｢ 180 ° angular position ｣,｢ 300 ° angular position ｣ The cross-sectional area (not shown) significantly decreased to about 35%, and the strength of the double screw portion was insufficient.

In contrast, the double screw structure (coarse screw and ｢4 times lead 2 screws｣) 20 of the second embodiment is located on ｢4 times lead 2 screws 存在, as shown in FIG. 10. The part where the screw groove is not formed increases the volume of the thread without causing a mountain shape. For example, the double-screw structure 20 is formed in a cross-sectional shape of the double-screw portion 2 in which a reference mountain-shaped thread is inevitably formed continuously or at predetermined intervals regardless of the angular position. When the area ratio of the ｢0 ° angular position 100 is set to 100%, the area ratio of｢ 60 ° angular position ｣,｢ 180 ° angular position ｣, etc. becomes as shown in FIG. 11. About 68%. Therefore, the double-screw structure 20 has a cross-sectional shape of the double-screw portion 2 in which a reference mountain-shaped thread is inevitably formed continuously or at predetermined intervals, so that the strength of the screw portion is sufficient.

FIG. 12 shows ｢0 ° angular position｣, ｢60 ° angular position｣, ｢90 ° angular position when the double-screw structure 20 is rolled into the screw material M in the screw rolling mold D Graph of padding results on. The angular position is a portion of the double screw structure 20 in which the shape of the double screw portion is greatly different, and is shown as a representative example. 13 is a diagram showing a relationship between a plugging amount and a filling rate in the screw rolling process. As shown in FIGS. 12 and 13, it has been confirmed that, at each angular position, the screw material M is plastically deformed at approximately the same filling rate, and is reliably filled into the rolling surface formed in the screw rolling mold D. In the space between the rolled material M and the rolled surface, the double screw portion 2 is continuously rolled.

Furthermore, the double screw structure may also be a double screw structure including a coarse tooth screw and a 4 times lead 1 screw or a 4 times lead 3 screws, the 4 times lead 1 screw or 4 times The lead of 3 screws is 4 times as long as the pitch P of the coarse screw, and includes one or three screw slots.

[Embodiment 3] The double screw structure 30 according to Embodiment 3 shown in Figs. 14 (a) and 14 (b) is formed on the screw shaft 3, and includes a metric coarse screw (first screw) and a guide. The process L ₂ is a double screw of the double screw portion 2 of a new multiple screw (hereinafter referred to as ｢2 times lead 1 screw｣) having a pitch P which is twice the pitch P of the coarse-threaded screw. Structure 30. That is, the “2 times lead 1 screw” means that the first screw (S1) is a coarse tooth screw, and the second screw (S2) has twice the lead of the coarse tooth screw, and is removed from the original two screws 1 screw of 1 screw.

14 (a) and 14 (b) show） 0 ° angular position 角度, ｢90 of a double screw structure 30 including a coarse screw and｢ 2 lead 1 screw ｣(second screw (S2)) The cross-sectional shape of the double screw portion 2 at the angle position ｣. For example, the double screw structure 30 includes a coarse-pitch screw having a pitch P (lead L ₁ = P) and ｢2 lead 1 screw｣, which is a lead L ₂ ( = 2P) is twice the pitch P of the coarse screw, and includes one screw that is two screws (known as two screws) and one screw that is less than one known. The coarse tooth screw is a screw having the same pitch P and the lead L ₁ , and a screw groove g ₀ (or a thread) is formed along the spiral line h ₁ . ｢1 screw with 2 times lead｣ is a screw with lead L ₂ and 1 screw groove g _{41 is} formed along the spiral line h ₂ . In addition, in the description of the third embodiment, for convenience of explanation, the angle at which the cross-sectional shape of the screw groove g ₀ of the coarse tooth screw coincides with the cross-sectional shape of the screw groove g ₄₁ of ｢2 lead 1 screw｣ The position is set to ｢0 °｣ for explanation.

In FIG. 14 (a) and FIG. 14 (b), the coarse-pitch screw is a screw of the pitch P shown by the outline Q1. ｢One screw with 2 times lead｣ is a screw that is not formed with one of the two well-known two screws ｣and is formed with one screw indicated by the outline Q2-1, and is provided in the screw groove g A screw with a lead L ₂ (= 2P) at a portion where no screw is formed between ₄₁ and the screw groove g ₄₁ (the portion that is the outer peripheral surface of the screw shaft portion and is flat in cross-section). FIG. 14 (a) shows the cross-sectional shape of the double screw portion 2 at ｢0 ° angular position 角度 of the double screw structure 30, and FIG. 14 (b) shows the double screw at｢ 90 ° angular position ｣of the double screw structure 30. The cross-sectional shape of the portion 2. A first thread r (or a screw groove) formed in a reference mountain shape is continuously formed at ｢0 ° angular position｣. At the ｢90 ° angle position ，, a double screw shape with a contour line Q2-1 is formed, that is, a first thread r having a reference mountain shape is formed, and the height of the thread is slightly lower than that of the first thread r. , The second thread r _{s1 of the} middle thread, and the third thread r _{s2 of the} hill-shaped thread formed to have a height lower than that of the second thread r _s1 .

The double screw structure 30 according to the third embodiment has been described with respect to ｢0 ° angle position｣ and ｢90 ° angle position｣. However, the double screw structure 30 will be further described based on FIGS. 15 and 16. . 15 and 16 show a double screw structure including a coarse tooth screw and two well-known screws ｣, and a double screw structure including a coarse tooth screw of the second embodiment and a double-lead screw｣ Figure 30 for comparison. FIG. 15 is a diagram showing a relationship between an angular position every 30 ° in the circumferential direction of the screw shaft 3 and a cross-sectional shape of the double screw portion 2. FIG. 16 is a diagram showing an area ratio of an angular position per 30 ° of the double screw portion 2 and a cross-sectional area of the double screw portion 2. The ratio of the cross-sectional area of the double screw portion 2 is a sum of the cross-sectional area in one cycle of the reference mountain shape of the thread of the coarse screw with a triangular thread, that is, a reference mountain shape. The sum of the cross-sectional areas of one cycle is shown in comparison.

The double screw structure including the coarse screw and the two well-known screws ｣has the same size and pitch as the ridges of the coarse screws and the two well-known screws ，. Therefore, the mountain shape interferes at a predetermined angular position, and there is The position of the mountain is hardly left. The double screw structure may deform the screw from the angular position where the mountain shape does not remain and the vicinity thereof, so that the strength of the screw portion is insufficient. For example, the double-screw structure has a cross-sectional shape of a double-screw with low-thread continuity at a screw position of ｢180 ° angular position｣ and its vicinity (refer to 180 ° in FIG. 15). Therefore, at the angular position, the strength of the screw portion tends to decrease significantly. Regarding the ratio of the cross-sectional area to each angular position, when ｢0 ° angular position｣ is set to 100%, the cross-sectional area ranges from ｢120 ° angular position｣ to ｢220 ° angular position｣ (not shown). Significantly decreased to about 40% or less, and the strength of the double screw portion was insufficient.

In contrast, in the double-screw structure 30 of the third embodiment, there is a portion where no screw groove is formed on the ｢2 times lead 1 screw｣, so that the volume of the thread is increased, and no mountain shape is left. . Regardless of the angular position of the double-screw structure 30, the cross-sectional shape of the double-screw portion 2 in which a reference mountain-shaped thread is inevitably formed continuously or at predetermined intervals is formed. Therefore, the strength of the screw portion is sufficient. When the area ratio of the ｢0 ° angular position 所述 is set to 100% in the double screw structure 30, the area ratio is about 65% or more regardless of the angular position.

[Tensile Strength of Double Screw Structure] The tensile strength of the double screw structure according to the first to third embodiments was confirmed. FIG. 17 is a schematic diagram showing an outline of a test device for measuring a tensile strength of a screw including a double screw structure of the present invention, and a tensile test is performed using the test device. The data shown in FIG. 18 is a double screw structure 11 (refer to FIG. 3 (a) and FIG. 3) showing a common coarse screw and the first embodiment (as a modified example of ｢3 times lead 2 screws｣). (B)) A graph of the tensile test results. In addition, the tensile strength is mainly related to the shear fracture stress of the thread in the axial direction of the double screw structure.

The second screw nut 53 and the first screw nut 54 are screwed into the bolt 50 including the head 50a and the double-screw structure 11 is formed, and the first screw nut 53 and the second screw are screwed. The nut 54 is tightened so as to have a double nut structure. For example, the first screw nut 54 is a nut of a female screw having a coarse screw. The second screw nut 53 is a nut on which a female screw having a plurality of new screws is formed. The bolt 50 is inserted into a bolt hole formed in the fixed-side clamp member 51 and the moving-side clamp member 52, and the lower surface of the head 50 a of the bolt 50 is brought into contact with the fixed-side clamp member 51. The moving-side clamp member 52 is moved in a direction away from the fixed-side clamp member 51 (direction of arrow F), and a load is applied to the bolt 50. In other words, a tensile load F is applied between the head 50 a of the bolt 50 and the first screw nut 53 and the second screw nut 54 to measure the tensile strength of the bolt 50 (see FIG. 17). The measurement is performed until the screw shaft of the screw shaft body 50 is broken or the thread is broken, and the nut is detached.

The double screw structure 11 (a modification of the first embodiment) is a representative example, and the results of the tensile test will be further described. In FIG. 18, bolts (for example, hexagon bolts) B0 (for example, hex bolts) formed with metric coarse screws with a nominal diameter of M16 formed with ｢screws, and bolts having two types of double screw structures 11 ( For example, hex bolt) B11 is the result of a tensile test. It should be noted that in the description, the second screw nut 53a and the first screw nut 54 are screwed into the double screw structure 11 as a double nut, and are shown as the bolt body B11-2. In Figure 18. In addition, a nut 53b serving as the first screw nut and a nut 54 serving as the second screw are screwed into the double screw structure 11 as a double nut. The bolt body B11-1 is shown in FIG. 18. The nut 53a is a nut having a standard height of ｢M16, a normal hexagonal nut (JIS B 1181), and a height h (for example, 13 mm). The nut 53b is a nut having a height 2h (for example, 26 mm) that is twice the height h (for example, 13 mm) of the nut 53a.

In FIG. 18, the vertical axis represents the tensile load (KN), and the horizontal axis represents the stroke (mm) of the tensile test. As a result, it was confirmed that the tensile strength of the bolt body B11-1 and the bolt body B11-2 in which the double structure 11 was formed showed a strength of 90% or more with respect to the tensile strength of the normal bolt B0 of M16. That is, it was confirmed that the strength of the double screw structure 11 formed on the bolt body B11-1 and the bolt body B11-2 did not cause a problem in practical application. The strength of the double screw structure 11 was confirmed to be sufficiently higher than the guaranteed load (48,700 N) of the strength level 4.8 of the coarse screw of M16. In the above embodiment, the double screw structure 11 as a modification of the first embodiment will be described as a representative example. However, it is confirmed that the same test can be obtained in the double screw structure of other embodiments. result.

[Nut Screw Cutting Torque Test] For the double screw structure of the first embodiment to the third embodiment, tests related to the screw cutting torque were performed to confirm the strength of the double screw structure. FIG. 19 is a schematic diagram showing an outline of a test apparatus for performing a comparative test of a screw cutting torque (maximum tightening torque) of a screw including a double screw structure of the present invention. FIG. 20 shows the double of a conventional coarse screw, a conventional lock bolt including a fine screw and a coarse screw, and a 、 3 times lead 2 screws 倍 (modification) including a modification of the first embodiment. Histogram of test results of screw cutting torque of the screw structure 11.

As shown in FIG. 19, in the test device, the nut 58 is screwed into a bolt 55 inserted into a block 56, and the nut 58 is tightened until the tightening torque does not increase, and a torque wrench (torque wrench (not shown) measures the maximum tightening torque at this time (see Figure 19). In the nut screw cutting torque test, in order to compare and confirm the strength of the double-screw structure, a conventional bolt B0 having a metric coarse screw and a conventional lock bolt including a coarse screw and a fine screw are included. B01. Bolts B11 having the double screw structure 11 as a modification of the first embodiment are tested separately to compare the maximum tightening torque values.

As shown in FIG. 20, regarding the maximum tightening torque value, the second screw (S2) serving as the double screw structure 11 is not inferior to the bolt B0 of the ordinary coarse tooth screw. That is, it has been confirmed that, when the bolt B11 as the double screw structure 11 is tightened by a nut that is a female screw having a plurality of new screws formed therein, it can be tightened to a conventional nut for a coarse screw. In the case of tightening the bolt B0 of a normal coarse screw, the maximum tightening torque value is approximately the same. In addition, if the height (thickness) of the nut of the thread on which a plurality of new screws are formed is increased, the maximum tightening torque is increased. In addition, the double-screw structure 11 corresponds to the ｢fine nut｣ (49 Nm) for the fine screw compared with the existing lock bolt B01 including the fine screw and the coarse screw. The coarse nut ｢(162 Nm) for coarse screws and the new multiple screws｢ (218 Nm to 293 Nm) corresponding to the nuts of the coarse screws are the maximum tightening. As the value of the torque increases, it can be confirmed that the maximum tightening torque value of the double screw structure 11 increases. In the above-mentioned embodiment, the double screw structure as a modification of the first embodiment will be described as a representative example. However, the double screw structure of other embodiments is also confirmed to obtain the same test. result.

[Locking effect of the double screw structure] The locking effect of the double screw structure 11 of the first embodiment to the third embodiment was confirmed. 21 (a) and 21 (b) are test apparatuses (manufactured by Nissei Co., Ltd. (Head Office: Yamanashi, Japan) showing a test device for confirming the locking effect of a screw including the double screw structure of the present invention. ) An overview of the figure. Fig. 21 (a) is a front view schematically showing a main part of the test device, and Fig. 21 (b) is an A-A cross-sectional view of Fig. 21 (a) cut by a line A-A. FIG. 22 is a diagram showing a conventional coarse screw (B0), a conventional lock bolt (B01) including a fine screw and a coarse screw, and a modification of the first embodiment (as a ｢3x lead 2 screws｣)变形 Modified Example of Double Screw Structure ｣) A graph of comparative test results of the locking effect of the double screw structure 11 (B11). FIG. 23 is a diagram showing the results of a comparison test of the locking effect between a normal coarse screw and a modification example ｢of a double screw structure according to the first embodiment. FIG.

The lock test apparatus 70 includes a first member 72 that swings with a fulcrum 71 as a fulcrum, a weight 73 provided at a predetermined distance from the fulcrum 71, a second member 75 including an excitation point 74, and the like. The first member 72 and the second member 75 are connected by a bolt 60, a first nut (fastening nut) 61, and a second nut (loosening nut) 62. Reference numeral 65 is a sensor for measuring the axial force of the bolt 60, and an axial force is displayed on a measuring instrument body (not shown). The first nut 61 and the second nut 62 constitute a so-called double nut. After the shaft portion of the bolt 60 is inserted into the bolt hole of the first member 72 and the bolt hole of the second member 75, the first nut 61 and the second nut 62 are tightened and fixed to a predetermined axial force. An excitation force F2 of a predetermined condition (frequency: 713 min ^-1 , amplitude: 11 mm) is applied to the excitation point 74 of the lock tester 70 to swing the second member 75 in the direction of the arrow θ, and the sensor 65 is used. Measure how the axial force of the bolt 60 changes at this time.

The above-mentioned locking test is performed on a bolt B0 having a common coarse screw formed with M16, a conventional lock bolt B01 including a coarse screw and a fine screw, and a bolt B11 having a double screw structure 11 formed. The bolt B0 on which a coarse tooth screw is formed is fixed as a double nut by the first nut and the second nut of a female screw having a coarse tooth. The conventional lock bolt B01 is fastened and fixed as a double nut using a second nut of a female screw having fine teeth and a first nut of a female screw having coarse teeth. The bolt B11 in which the double-screw structure 11 is formed is a first screw nut (tightening nut) 54 using a female screw with a thick tooth and a second screw nut using a female screw having a plurality of new screws. The cap (nut for preventing loosening) 53 is fastened and fixed as a double nut.

As shown in FIG. 22, even if the bolt B11 in which the double-screw structure 11 is formed is excited, almost no drop in the axial force occurs, and the locking effect is maintained. In contrast, the normal coarse bolt B0 has a significantly reduced axial force immediately after the vibration, and the locking effect cannot be maintained. In the conventional lock bolt B01, a slight decrease in the axial force was observed immediately after the excitation, but the effect of the subsequent lock was maintained. Next, after the bolt B0 with coarse teeth before the excitation and the bolt B11 of the double screw structure 11 are tightened with the same axial force, an excitation test is performed under the above conditions to further confirm the locking effect.

The results are shown in FIG. 23. Even if the bolt B11 in which the double-screw structure 11 is formed is excited, almost no drop in the axial force occurs, and the locking effect is maintained. On the other hand, after the coarse bolt B0 is excited, the axial force immediately decreases. That is, the double screw structure 11 can be confirmed to have a locking effect. In the above-mentioned tightening test, the double screw structure 11 as a modification of the first embodiment will be described as a representative example. However, it is confirmed that the double screw structure of another embodiment can obtain the same result. Test results.

In the double-screw structure 1, the configuration of the thread and the screw groove is equivalent to a coarse-threaded screw, and it has a rigid shape compared with a conventional double-screw including a fine-threaded screw, and the strength is maintained. When tightening, the first screw nut tightened to the first screw is tightened into a normal coarse-threaded screw, and therefore has a particularly increased strength compared to a thin-threaded screw. When a load is applied to the structure fastened by the double-screw structure 1, even if an axial force is generated in the double-screw structure 1, it is held by the first screw nut tightened to the first screw. Its axial force. In addition, in the double-screw structure 1, in addition to the frictional force caused by the tightening force between the first screw nut and the second screw nut, in the lead of the first screw and the second screw, There is a difference that two nuts cannot be rotated at the same time, which can produce a locking effect. As a result, the double-screw structure 1 can increase the axial force (torque) as compared with the conventional anti-loosening double-screw structure including a fine screw.

In addition, if it is a double-screw bolt including a coarse tooth screw and a fine tooth screw as in the prior art, it is impossible to fill the screw groove of the fine tooth screw in the plating process, especially the thicker film plating process. For double screws containing fine screws. For example, if a thin screw is plated with a thick film such as a molten tin plating having high corrosion resistance, the plating will collect on the fine thread and fill the screw groove. However, since the double-screw structure 1 does not use a fine-pitch screw, it does not cause the screw groove to be buried, so this type of plating can be used. As a result, the bolts and screw shafts including the double screw structure 1 can be plated to increase the value and function. In addition to the existing mechanical and electrical fields, they can also be used in the construction and civil fields where corrosion resistance is required. .

[Embodiment 4] The double screw structure according to the embodiments described in Figs. 5 and 6, 10 and 11, 15 and 16 shows each angular position (screw angle) and area. The relationship graph shows that the area ratio (%) is small at a certain angular position. Therefore, when the "double-screw structure tensile test" test is performed on each of the double-screw structures using the test device of FIG. 17, shear failure occurs from a portion having a small area ratio (%). Even if there is a part with a small area ratio (%), there is no problem in the strength in mechanical design. However, if the allowable shear failure stress in the design is exceeded, shear failure will occur first from the portion with a small area ratio (%). FIG. 26 is a partial cross-sectional view of a double screw structure in which a fastening nut is screwed into a specific angular position. FIG.

The type of the first nut (fastening nut) 110 in this example is a metric coarse tooth nut. The example shown in FIG. 26 shows a cross section of the double screw structure 100 at a certain angle (a cross section of 90 ° of the “3 times lead 2 screws” shown in FIG. 5) on the double screw structure 100 and the first 1 cross section of the nut 110. When the first nut 110 is tightened, a load in the axial direction W is applied to the double screw structure 100 by a reaction force from a fastened body (not shown). When tightened at the angular position until shear failure occurs, shear failure first occurs at the position of the line segment (section shape) 103 of the hill-shaped thread 101. The line segment 103 is parallel to the center line 109 of the double screw structure 100. The line segment 103 is shorter than the line segment 104 of the thread 102 of a coarse-tooth screw of a usual size (cross-sectional area). Therefore, when the load in the axial direction W from the first nut 110 (the tightening nut) is applied equally to each thread, shear failure occurs first from the portion of the line segment 103 of the hill-shaped thread 101.

Even if the length of the first nut 110 in the axial direction is extended, shear failure occurs locally from the portion of the line segment 103 of the hill-shaped thread 101. Therefore, in order to avoid the shear failure of the hill-shaped thread 101, the double screw structure 100 of the fourth embodiment is formed by filling the space (gully) of the two hill-shaped threads 101 arranged in the axial direction with a base metal. Part (gray part in the figure) 105. As a result, the line segment 103 of the hill-shaped thread 101 is extended integrally with the next hill 101, and becomes substantially the same length as the line segment 104 of the thread 102 as a normal metric coarse tooth. Therefore, even if a load in the axial direction W is applied to the double-screw structure 100 on the hill-shaped thread 101, shear failure does not occur from the portion of the line segment 103 first.

FIG. 27 is a view showing a cross-sectional shape when a lock nut is screwed into a double-screw structure (4 times lead 2 screws). That is, the anti-loosening nut 120 is a nut which is screwed into two screws having a lead of 4 times as the double screw structure 10, and is another nut of a metric coarse tooth nut. As illustrated in FIG. 26, two mountain-like threads 101 in the shape of a mountain are buried by the filling portion 105. The second nut (nut for anti-loosening) 120 is provided with the filling portion 105 so that it cannot be engaged with two hill-shaped threads 101 having a mountain shape. Therefore, a straight portion (section) 121 is provided, that is, A spiral hole is provided. At the angular position (60 ° shown in FIG. 10) of the double screw structure 10 of this example, the double screw structure 10 and the second nut (nut for preventing loosening) 120 and two hills in the shape of a mountain The thread 101 is not substantially engaged.

However, since the tightening force is shared by the first nut 110 shown in FIG. 26, there is no problem. The function of the second nut 120 is not a tightening force, but a nut that exerts the locking function of the first nut 110, so that the second nut 120 does not shear and break. When it is determined that the strength of the shear fracture stress of the first nut 110 and the second nut 120 is insufficient in design, the thickness of the nut may be increased. FIG. 28 is a modified example of ｢3 times lead 2 screws｣, ｢3 times lead 2 screws 将, and｢ 3 times lead 1 screw applying this embodiment 4 to embodiment 1 shown in FIG. 5 The cross-sectional shape of the double screw structure 10, the double screw structure 11, and the double screw structure 12 at various angular positions of ｣. FIG. 28 is a view showing a cross-sectional shape when the filling portion 105 is filled with the base metal for the valleys of the two hill-shaped threads 101 having the mountain shape described above. Similarly, FIG. 29 is a double screw structure at each angular position of the ｢4 times lead 2 screws 实施 and the 32 times lead 1 screw 的 of the third embodiment shown in FIGS. 10 and 15. The cross-sectional shape of the body 20.

[Modification of Embodiment 4] In a modification of the embodiment 4, the contour line 106 of the outer peripheral surface of the filling portion 105 is a straight line parallel to the center line 109 of the double screw structure 100 in a cross-sectional view. However, the filling method of the filling section 105 is not limited to the method described above. FIG. 30 (a) is a view showing that the double screw structure 100 is filled with the filling portion 130 to a position of the effective diameter 131 of the first screw (S1) constituting the double screw structure 100. That is, it is an example in which the space between the two hill-shaped threads 101 is filled up to the effective diameter 131 of the first screw (S1), that is, the outer peripheral surface. The diameter of the outer diameter (a part of the cylindrical surface) 132 of the filling portion 130 is the same as the effective diameter 131. FIG. 30B is an example in which the double screw structure 100 is filled with the filling portion 130 to an outer diameter (a part of the cylindrical surface) 134 smaller than the effective diameter 131. The effective diameter refers to the diameter of a virtual cylinder whose width of the screw groove is equal to the width of the thread.

FIG. 31 (a) is an example in which the double screw structure 100 is filled so that the outer diameter 135 of the filling portion 130 becomes a slope. That is, the shape line of the outer diameter shown in the cross section of the filling part 130 is an oblique line, and forms an acute angle with the center line 109. FIG. 31 (b) is a diagram in which the double screw structure 100 is filled with the filling portion 130 so that the outer diameter 136 becomes a V-shaped V-slope. That is, the shape line of the outer diameter shown in the cross section of the said filling part 130 becomes a V-shaped line whose center is the most concave part. FIG. 31 (c) is a diagram in which the double screw structure 100 is filled with the filling portion 130 so that the outer diameter 137 becomes a convex portion. The shape line of the outer diameter shown in the cross section of the filling portion 130 is a convex line with the center being the most convex portion. Furthermore, when the double screw structure 100 is subjected to rolling processing, when the contour lines of these outer diameters are convex arcs or ellipses, plastic deformation becomes easy, and the rolling workability is excellent. . Therefore, the life of the rolls which roll these double screw structures is also long.

[Other Embodiments] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Needless to say, changes can be made without departing from the purpose and spirit of the present invention. For example, a double screw structure including a combination of two screws (the first screw and S1) and two screws with four times the lead (second screw (S2)), and two screws with three times of the lead (second Double screw structure with 1 screw (S1)) and 4 screws (2 screws (S2)). In other words, as long as the double screw structure is formed at each angular position in the circumferential direction of the axis of the screw shaft portion, a thread of a reference mountain shape or a shape close to the reference mountain shape may be formed continuously or at predetermined intervals.

Moreover, in the said embodiment, although the lead of the 1st screw (S1) and the 2nd screw (S2) was demonstrated as the lead which is an integral multiple of a coarse tooth screw, it may not be an integral multiple. For example, the second screw may be a screw whose lead is a multiple of 3.1 times that of a coarse screw. Moreover, the screw of which the lead of the 1st screw is a multiple of 1.1 times as large as a coarse screw may be sufficient. In other words, the double screw structure may be formed with a reference mountain shape or a shape close to the reference mountain shape continuously or at predetermined intervals at each angular position in the circumferential direction of the axis of the screw shaft portion.

In addition, in the above-mentioned embodiment, the double screw structure is described as being formed by a rolling process using a circular rolling die and a flat die, but may be selected from cutting processing and injection. It is formed by one of forming processing, 3D printing (3D printing) processing, metal injection molding (MIM) processing, and lost-wax casting. However, the formation of the thread by the rolling process does not cut off the metal flow line inside the metal structure by the rolling process. Therefore, it is rough to see that the fiber structure continuously flows along the screw surface. The structure is characterized by high tensile strength and fatigue strength as a screw.

[Application Example 1] FIG. 24 (a) and FIG. 24 (b) are examples in which the double screw structure is used for a fastener with a lock nut, FIG. 24 (a) is a partial cross-sectional view, and FIG. 24 ( b) is a sectional view showing the engagement between the nut and the double screw structure. The fastener 80 with a lock nut is an example of clamping the fastened member 86. On the screw portion 81 serving as the shaft portion of the hexagon bolt, there are formed the ｢coarse tooth screws｣ and ｢3 times lead screws 所示 shown in Figs. 2 (a) and 2 (b) (see Fig. 2 (a)). And Figure 2 (b)). A first nut 82 is screwed into the ｢coarse tooth screw｣. The thread (helix h ₁ ) of the first nut 82 is a normalized thread. In this example, a conical surface 83 is formed integrally with the first nut 82 at one end of the first nut 82. A second nut 84 is screwed into two screws ｢(helix h ₃ ) with a lead of 3 times. Since the second nut 84 is screwed into ｢3 times the lead 2 screws｣, it is longer than the lead of the first nut 82 (in accordance with the pitch P), and therefore, the amount of advancement per turn is large.

A tapered hole 85 is formed in one end portion of the second nut 84. When the first nut 82 is screwed in, the conical surface 83 is in contact with the conical hole 85 of the second nut 84, and the frictional force is used to firmly clamp the conical surface. In addition, since the first nut 82 is rotated and screwed in, the rotational driving can be performed at the same time. Therefore, it is not necessary to screw in the second nut 84 as a lock nut. The reason is that, since the lead P is longer than the lead of the second nut 84 and longer than the pitch P of the first nut [because the pitch P of the first nut is longer than the lead of the second nut 84], only the first nut is screwed in The cap 82 is sufficient, and the second nut 84 is rotated and clamped. Application Example 2 FIG. 25 is a front view showing an example in which a double screw structure is used for the lead cam mechanism 90. In the above-mentioned embodiment, the description is made by using a metric coarse tooth screw as a screw, and an example in which a double screw structure in which the two kinds of threads and screw grooves with different pitches and different leads are formed as the lead cam 91 is used. . The first cam follower 92 is engaged with the ｢coarse tooth screw｣ (helix h ₁ ). A second nut 84 is screwed into two screws ｢(helix h ₃ ) with a lead of 3 times. The second cam follower 94 is engaged with a plurality of screw grooves. When the lead cam 91 is rotationally driven by the servo motor 93, the first cam follower 92 and the second cam follower 94 have different amounts of advancement per revolution, so they are used to rotate the lead motion. Convert the movement into the desired linear motion. The required amount of movement is achieved by the number of revolutions of the servo motor 93, the pitch of the ｢coarse screw｣, and the size of the lead of 倍 3 times the lead of 2 screws ｣. Therefore, the so-called double screw structure in the present invention is a guide cam.

In the above-mentioned embodiment, the thread is described using a metric coarse tooth screw, but the same thread may have a triangular cross-sectional shape and a standardized Whitworth screw, a unified standard screw, a fine screw, and the like. Therefore, in the double screw structure of the present invention, the screw ｣having a standard pitch (P) formed on the outer periphery of the cylindrical shaft is not limited to the metric coarse tooth screw, but can be said to be the reference A screw having a screw groove having substantially the same shape as that of the screw is formed on the thread. [Industrial availability]

The double screw structure of the present invention can be used for a screw fastening body that needs to have a loosening prevention function, and a mechanical, electrical, architectural, civil, aviation, space, Automotive, railway, shipbuilding and other industries.

1, 10, 11, 12, 20, 30, 100‧‧‧ double screw structure

2‧‧‧Double Screw

2h‧‧‧ height of nut 53b

3‧‧‧ screw shaft

50, 55, 60, 81‧‧‧ bolts

50a‧‧‧Head

51‧‧‧Fixed side fixture components

52‧‧‧Moving side fixture

53, 62, 84, 120‧‧‧ 2nd nut

53a, 53b, 58‧‧‧ nut

54, 61, 82, 110‧‧‧ 1st nut

56‧‧‧ spacer

65‧‧‧Sensor

70‧‧‧Locking Tester

71‧‧‧ Fulcrum

72‧‧‧The first component

73‧‧‧ Heavy Hammer

74‧‧‧excitation point

75‧‧‧The second component

80‧‧‧ Fastener with lock nut

83‧‧‧ conical surface

85‧‧‧ conical hole

86‧‧‧ Fastened member

90‧‧‧lead cam mechanism

91‧‧‧lead cam

92‧‧‧1st cam follower

93‧‧‧Servo motor

94‧‧‧ 2nd cam follower

101‧‧‧ Hill-shaped thread

102‧‧‧ Usual Metric Coarse Thread

103‧‧‧ Hill-shaped thread 101

104‧‧‧ Normal metric coarse thread 102 line segment

105, 130‧‧‧ Filling Department

106‧‧‧ contour

109‧‧‧center line

121‧‧‧Straight line

131‧‧‧ effective diameter

132, 134, 135, 136, 137‧‧‧

B01‧‧‧Locking bolt

B0, B11, B12‧‧‧bolts

B11-1, B11-2‧‧‧bolt body

de‧‧‧ part (the part which is the outer peripheral surface of the screw shaft part and is flat in cross section)

D‧‧‧Double screw rolling mold

F‧‧‧ direction

F2‧‧‧Exciting force

g ₀ ‧‧‧Screw slot for 1st screw (coarse screw)

g ₁ , g ₂ , g ₁₁ , g ₁₂ , g ₂₁ ‧‧‧ 2nd screw (3x lead 2nd screw) screw slot

g ₃₁ , g ₃₂ ‧‧‧ 2nd screw (2nd screw with 4 times lead)

g ₄₁ ‧‧‧Screw slot for 2nd screw (2x 2 lead screw)

h‧‧‧ height of nut 53a

h ₁ , h ₂ , h ₃ , h ₄ , hn‧‧‧ spiral

L ₁ , L ₂ , L ₃ , L ₄ , Ln‧‧‧Lead

M‧‧‧Screw material

Q1‧‧‧ the outline of the first screw

Outline of Q3-1, Q3-1 ', Q3-2, Q4-2, Q2-1‧‧‧ 2nd screw

r‧‧‧first thread

r _s , r _s ', r _s1 ‧‧‧ 2nd thread

r _s2 ‧‧‧3rd thread

W‧‧‧axis load

θ‧‧‧ direction

1 (a) and 1 (b) are views showing a double screw structure of the present invention, FIG. 1 (a) is a side view, and FIG. 1 (b) is a front view. FIGS. 2 (a) and 2 (b) are cross-sectional views for illustrating the structure of a double screw portion of a double screw structure 10 according to Embodiment 1 of the present invention, which is cut by a plane passing through a screw shaft, and FIG. 2 ( a) is an explanatory view partially showing the cross-sectional shape of the double screw portion at ｢0 ° angle position｣, and FIG. 2 (b) is an explanatory view partially showing the cross-sectional shape of the double screw portion at ｢90 ° angle position｣. 3 (a) and 3 (b) are diagrams for explaining the configuration of the double screw portion of the double screw structure 11 as a modification of the double screw structure 10 of the first embodiment, which is cut by a plane passing through the screw shaft. 3 (a) is an explanatory view partially showing a cross-sectional shape of a double screw portion at ｢0 ° angle position｣, and FIG. 3 (b) is a partial view showing a double screw portion at ｢90 ° angle position｣ An illustration of a cross-sectional shape. 4 (a) and 4 (b) are diagrams for explaining the structure of the double screw portion of the double screw structure 12 which is another form of the double screw structure of the first embodiment, and are cut by a plane passing through the screw shaft. 4 (a) is an explanatory view partially showing a cross-sectional shape of a double screw portion at ｢0 ° angle position 角度, and FIG. 4 (b) is a partial view showing a double screw portion at｢ 90 ° angle position ｣ An illustration of a cross-sectional shape. FIG. 5 is a partial view of the angular position of the double screw structure 10, the double screw structure 11, the double screw structure 12, and the double screw structure including the coarse screw and three well-known screws, according to the first embodiment. A list of cross-sectional views of the cross-sectional shape of the double screw portion at each position, cut by a plane passing through the screw shaft. FIG. 6 is a graph showing the relationship between the angular position and the area ratio for the double screw structure shown in FIG. 5. FIG. 7 is an explanatory diagram for explaining a filling condition at each of the angular positions when the screw material is subjected to rolling processing using a rolling die in the double screw structure 11 according to the first embodiment. FIG. 8 is a graph showing the relationship between the amount of plugging of the rolling die and the filling rate of the space portion in the double screw structure 11 of the first embodiment. FIGS. 9 (a) and 9 (b) are partial cross-sectional views for explaining the configuration of the double screw portion of the double screw structure 20 according to the second embodiment of the present invention. An explanatory view showing a cross-sectional shape of a double screw portion of ｢0 ° angular position｣ and ｢90 ° angular position｣. FIG. 10 is a cross-sectional view partially showing the cross-sectional shape of the double screw portion at each of the angular positions for the double-screw structure 20 of the second embodiment and the double-screw structure including the coarse screw and the four known screws. Illustration. FIG. 11 is a graph showing the relationship between the angular position and the area ratio of the double screw structure 20 shown in FIG. 10. FIG. 12 is an explanatory diagram for explaining a filling condition at each of the angular positions when the screw material is subjected to rolling processing using a rolling die in the double screw structure 20 according to the second embodiment. FIG. 13 is a graph showing the relationship between the amount of plugging of a rolling die and the filling rate of the space portion in the double screw structure 20 according to the second embodiment. 14 (a) and 14 (b) are cross-sectional views illustrating the structure of the double screw portion of the double screw structure 30 according to the third embodiment of the present invention, which is cut by a plane passing through the screw shaft, and is partially shown. An explanatory view showing a cross-sectional shape of a double screw portion of ｢0 ° angular position｣ and ｢90 ° angular position｣. FIG. 15 is a cross-sectional view partially showing the cross-sectional shape of the double screw portion at each of the angular positions for the double-screw structure 30 and the double-screw structure including the coarse screw and two well-known screws in the third embodiment. Illustration. FIG. 16 is a graph showing the relationship between the angular position and the area ratio of the double screw structure 30 shown in FIG. 15. FIG. 17 is a schematic diagram showing an outline of a test device for measuring a tensile strength of a screw including a double screw structure of the present invention. FIG. 18 is a diagram showing a tensile test result of a double-screw structure 11 that is a normal coarse screw and a modification of the first embodiment (see FIGS. 3 (a) and 3 (b)). FIG. 19 is a schematic diagram showing an outline of a test device for performing a ｣screw cutting torque comparison test｣ of a screw including a double screw structure of the present invention. 20 is a view showing a conventional coarse screw, a conventional lock bolt including a fine screw and a coarse screw, and a modified example of the first embodiment (see FIG. 3 (a) and FIG. 3 (b)), that is, a double screw structure Histogram of test results of screw cutting torque of 11. 21 (a) and 21 (b) are diagrams showing an outline of a test device for confirming the locking effect of a screw, and FIG. 21 (a) is a front view schematically showing a main part of the device. 21 (b) is a sectional view taken along the line AA in FIG. 21 (a). FIG. 22 shows a double-screw structure 11 that is a conventional coarse screw, a conventional lock bolt including a fine screw, and a coarse screw, and a modification of the first embodiment (see FIGS. 3 (a) and 3 (b)). A graph of comparative test results of the locking effect. FIG. 23 is a diagram showing the results of a comparative test of the locking effect of a double screw structure, which is a normal coarse screw and a modification of the first embodiment (see FIGS. 3 (a) and 3 (b)). 24 (a) and 24 (b) are examples of using the double screw structure for a fastener with a lock nut. FIG. 24 (a) is a partial cross-sectional view, and FIG. 24 (b) shows a screw A cross-sectional view of the engagement of the cap with the double screw structure. FIG. 25 is a conceptual diagram showing an example of using a double screw structure for a lead cam mechanism. FIG. 26 is a cross-sectional view of a specific screw position where a fastening nut is screwed into a double screw structure (4 times lead 2 screws), and a space in which a thread represented by two hills is filled with base metal ( Gully) example. FIG. 27 is a view showing a state in which a lock nut is screwed into the double screw structure of FIG. 26, and is a cross-sectional view of a specific angular position thereof. FIG. 28 shows a modified example of ｢3 times lead 2 screws｣, ｢3 times lead 2 screws 将, and｢ 3 times lead 1 screw ｣applied to the first embodiment in the fourth embodiment The cross-sectional shape of the double screw structure at various angular positions. FIG. 29 is a cross-section of a double screw structure at each angular position of ｢4 times lead 2 screws 实施 and｢ 2 times lead 1 screw 的 of the second embodiment shown in FIGS. 10 and 15. shape. 30 (a) and 30 (b) are modification examples of the filling portion of the fourth embodiment, and FIG. 30 (a) shows a space (gully) of a thread represented by two hills filled with a base metal to an effective diameter. Fig. 30 (b) is an example in which the space (gully) is filled to a diameter smaller than the effective diameter. Figs. 31 (a) to 31 (c) are modified examples of the filling portion of the fourth embodiment. Fig. 31 (a) is a landfill using a base metal with an inclined cross-sectional shape (relative to the centerline). Fig. 31 (b) is an example of a V-shaped landfill, and Fig. 31 (c) is an example of a convex-shaped landfill.

Claims (11)

A double screw structure is formed with two kinds of screws on a screw shaft. The double screw structure is characterized in that it includes: a first screw (S1) formed on the screw shaft (3), and a cross section of a thread is formed; A screw having a triangular shape with a pitch (P); and a second screw (S2), which is a screw formed continuously on the thread and having a triangular cross-section, has the same twisting direction as the thread, and is One or more screws are reduced from a plurality of screws having a lead (Ln) of a predetermined multiple (n) of the pitch (P) of the threads. The double screw structure according to item 1 of the patent application scope, wherein the predetermined multiple (n) is an integer multiple of the pitch (P). According to the double screw structure described in the first or second scope of the patent application, wherein in the second screw (S2), the lead (Ln) is twice the pitch (P) of the thread, The number of the plurality of screws is two, and one of the screws is formed. The double screw structure according to item 1 or item 2 of the patent application scope, wherein in the second screw (S2), the lead (Ln) is 3 times the pitch (P) of the thread, The number of the plurality of screws is three, and one or two of the screws are formed. The double screw structure according to item 1 or item 2 of the patent application scope, wherein in the second screw (S2), the lead (Ln) is 4 times the pitch (P) of the thread, The number of the plurality of screws is four, and two of the screws are formed. The double screw structure according to item 1 or 2 of the scope of patent application, wherein a cross section of the first screw (S1) and the second screw (S2) at a center line including the double screw structure In the middle, the valleys of the hill-shaped threads appearing at specific angular positions are filled with the base metal. The double screw structure according to item 6 of the patent application scope, wherein an outer diameter of the groove is an effective diameter of the first screw (S1). The dual screw structure according to item 1 or item 2 of the scope of the patent application, wherein the first screw (S1) and the second screw (S2) are a coarse fiber structure of a raw material continuously along the thread Flowing rolled screws. The double screw structure according to item 1 or item 2 of the patent application scope, wherein the first screw (S1) is a metric coarse tooth screw. The dual screw structure according to item 1 or 2 of the scope of patent application, wherein the dual screw structure is a part of a fastener (80) for tightening and fixing parts and components, including the screw The shaft (3) serves as a bolt (81), a first nut (82) screwed into the first screw (S1), and a cross-sectional shape of the thread screwed into the second screw (S2). 2nd nut (94). The double screw structure according to item 1 or 2 of the scope of patent application, wherein the double screw structure is a part of a lead cam device (90) and includes the screw shaft (3) as a lead cam ( 91) a first cam follower (94) engaged with the first screw (S1), and a second cam follower (92) engaged with the second screw (S2).