JP5311901B2 - Screw rolling dies - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screw form rolling die capable of rolling a rolled bolt having a high-quality screw structure, preventing wobbling vibration in rolling and deterioration in service life and having improved durability. <P>SOLUTION: The screw form rolling die 31 is provided with a coarse screw thread portion A having a developed coarse thread, and a protrusion corresponding to the fine screw thread periodically formed on the valley portion of the coarse screw thread in accordance with phase shift between a fine screw thread portion B having a developed fine thread and the mount portion of the coarse screw thread, wherein the protrusion is formed such that a small valley portion 40 side of the two valley portion formed on both sides of the mount portions of the coarse screw thread of the screw form rolling die and the mount portion of the fine screw thread is a flat or cylindrical plane 39 having a height aligned to the top portion of the fine screw thread. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a screw rolling die used for manufacturing a bolt having a loosening prevention function. More specifically, in a thread rolling die that rolls a double threaded rolling bolt, high-quality rolling bolts can be easily rolled, causing chatter vibration during rolling, shortening of service life, etc. The present invention relates to a thread rolling die that can prevent and improve durability.

  In recent years, various bolts having a function of preventing loosening, manufacturing methods thereof, dies used therein, and the like have been researched and developed, and various results thereof have been disclosed. For example, a coarse thread portion having a standard pitch P defined by a standard related to a screw formed from the tip end portion of the bolt shaft portion to a predetermined position, and at least the total length of the coarse screw portion of the bolt shaft portion or the tip portion. A bolt configuration including a fine screw portion having a pitch p (p = P / n, where n is an integer of 2 or more) smaller than a standard pitch formed to overlap the coarse screw portion up to a predetermined position of the fine screw portion is disclosed. (For example, refer to Patent Document 1).

  In this bolt, after the coarse nut is screwed into the coarse screw portion of the bolt, the fine nut is overlapped on the coarse nut and screwed onto the coarse nut, and the bolt and both nuts are fastened. It can be done. At this time, since the pitch between the fine nut and the coarse nut is different, if both rotate together in the same direction, a repulsive force acts on the contact surface between the two nuts, and the coarse nut rotates in the loose direction. Can be prevented.

  Further, the inventors of the present invention also provide a thread portion of a coarse thread in which at least one of the thread rolling dies has developed a coarse thread, and a spiral winding in the same direction as the coarse thread in a valley portion of the coarse thread. A fine screw having a pitch smaller than that of the coarse screw (where the pitch ratio between the coarse screw and the fine screw is a to b, where a and b are the smallest integer ratio), A protrusion corresponding to a fine thread that appears periodically for each b winding of the coarse thread according to the phase shift from the coarse thread when deployed so as to be higher than the valley bottom of the coarse thread (For example, refer patent document 2).

Furthermore, the manufacturing method of the screw rolling die regarding this is also disclosed (for example, refer patent document 3).
Japanese Patent No. 3770320 Japanese Patent No. 3546211 Japanese Patent No. 3534117

  In general, a thread rolling die is manufactured by subjecting a thread rolling die material to a cutting process, a grinding process, an electric discharge process, a milling process, and the like to form a thread portion. With this screw rolling die, a bolt is manufactured while being pressed against a round bar-shaped bolt material and rolled. A method of manufacturing a large number of bolts in a short time using this thread rolling die is common. Therefore, the shape on the screw rolling die side is formed in a shape according to the screw of the nut. The bolt having a loosening prevention function has, for example, a double screw bolt structure in which a coarse screw and a fine screw are provided as described above.

  When rolling with this screw rolling die, the round bar-shaped bolt material is gradually pressed, and the outer peripheral surface of the round bar-shaped bolt material is gradually deformed to obtain a desired screw shape. The screw rolling die side constitutes a nut-shaped screw portion corresponding to the screw portion of the bolt as described above. Therefore, in the case of a double screw bolt of a coarse screw and a fine screw, the screw shape of the screw rolling die has both a coarse screw shape and a fine screw shape.

  The depth of the periodically changing groove of the thread rolling die is such that the position of the bottom of the coarse thread and the position of the bottom of the fine thread of the fine thread developed to form the protrusions best overlap each other. It is the deepest and the shallowest in the part where the positions of the two are shifted most. For this reason, when rolling a double screw bolt with a conventional screw rolling die, the cross-sectional areas of the groove portions, which are cross sections at the respective angular positions, are different, resulting in a difference in the material filling rate in the groove portions at the respective cross sections. That is, the grooves are filled in order from the part having the smallest cross-sectional area, and the part having the larger cross-sectional area of the groove is filled last. In particular, at the end of processing, since the filling rate of the material into the groove is high, there is no place for surplus material to escape.

  As a result, when rolling, there is a risk of chatter vibration, noise, and the like. In addition, depending on the degree of chatter vibration, there is a possibility that a precision failure may be caused, the tool life may be significantly shortened, and the manufacturing apparatus may be adversely affected.

  Ideally, the rolling by the screw rolling die is such that the screw portion is pressed evenly and the bolt material is deformed so that a partially biased load is not applied to the screw rolling die. In other words, with respect to the screw rolling die, it is ideal that the contact portion of the bolt material is in an evenly built-up state and deformed at any rotational angle position of the rolled portion.

  When the threaded portion of the thread rolling die is matched to the shape of a normal nut, the thread rolling die has a fine thread valley with respect to the coarse thread, resulting in a small convex part with a small cross-sectional area. The shallow valley portion is also formed on the screw rolling die side. That is, in the final stage where the rolling of the screw gradually approaches the fine screw portion from the coarse screw portion, the small convex portion of this rolling screw die, which is a part of the peak portion of the fine screw thread, is When rolling, the bolt material is bitten, and then the valley portion is built up to form a screw portion of the bolt.

  The build-up molding by this valley part gradually progresses from a wide part to a narrow part, and when it reaches the fine screw part, the build-up part is formed in the valley part formed on both sides of this small convex part at the same time as the bite. Is divided and rolling proceeds. As the rolling progresses, the pressing force increases, and finally, the valley portion is filled with the built-up portion, and the bolt shape is adjusted by pushing in by over rolling. When the bolt is rolled, there is a time difference between the final shape portion that is first rolled and the target shape portion that is finally rolled and the target shape portion. For this reason, a portion where the plastic flow is increased, that is, a portion that is over-rolled is generated.

  As described above, since the load fluctuation due to plastic flow is intense, the weak part of the screw rolling die is particularly damaged, and there is a possibility that the screw rolling die may be damaged in this screw rolling. Further, when the thread rolling die is damaged, it is necessary to replace it with a new thread rolling die. In other words, the work efficiency and productivity associated with the screw rolling die replacement are reduced, and the cost of the bolt manufacturing cost is increased.

  The present invention has been made to solve the above-described problems of the prior art, and achieves the following object.

  An object of the present invention is to provide a screw rolling die capable of improving the equalization of the filling amount filled in the groove at each angular position when performing rolling.

  Another object of the present invention is to provide a screw rolling die that can equalize the load accompanying rolling and improve the rigidity and durability of the screw rolling die.

The present invention takes the following means in order to achieve the object.
The screw rolling die of the present invention 1 is
It is periodically formed in the valley portion of the coarse screw according to the phase shift between the thread portion of the coarse screw in which the coarse screw is developed, and the fine screw thread in which the fine screw is developed and the mountain portion of the coarse screw. A thread rolling die having a protrusion corresponding to the fine thread thread, wherein the protrusion is formed in a valley portion of a coarse thread thread of the thread rolling die, and the thread thread of the fine thread thread. of the two valleys are formed at both sides of the parts, the one is snack unit, at a site other is formed in Otani portion, the snack portion within a predetermined range in the longitudinal direction of the valley, the specifics The protrusion is a flat or cylindrical surface that matches the height of the top of the screw thread.

The screw rolling die of the present invention 2 is the present invention 1,
The thread rolling die is round die, wherein the projection is a cylindrical surface of said predetermined range, centered on the rotational centerline of said thread rolling dies to match the height of the crest of the fine thread It is characterized by being a projection.

The screw rolling die of the present invention 3 is the present invention 1,
The thread rolling die is flat die, said protrusions, wherein the within a predetermined range, a projection and the plane to match the height of the crest of the fine thread.

The screw rolling die of the present invention 4 is the present invention 2 or 3,
The protrusion and the coarse thread thread are joined so as to form a continuous surface.

The screw rolling die of the present invention 5 according to the present invention 2 or 3,
The protrusion is formed so that a small valley portion side of a valley portion formed on both sides of the mountain portion of the fine screw thread becomes a flat portion in accordance with the height of the mountain peak portion of the fine screw thread. It is characterized by.

The thread rolling die of the present invention 6 is the present invention 5,
A boundary portion between the flat portion and the coarse screw thread has an arc shape in cross section.

The screw rolling die of the present invention 7 is
It is formed periodically in the valley portion of the coarse screw in accordance with the phase shift between the coarse screw thread in which the coarse screw is developed, and the fine screw thread in which the fine screw is developed and the coarse screw mountain. A thread rolling die having a projection corresponding to the fine thread thread, wherein the first rolling tool has a shape in which a peak portion corresponding to the coarse thread thread is flattened on the thread rolling die material. , By feeding to a position below the maximum height of the protrusion corresponding to the fine thread thread, and removing a part of the thread rolling die material, a thread portion of the coarse thread thread on the thread rolling die is formed. A second thread removal tool having a fine thread shape is applied to the thread rolling die material after the thinning, and the fine thread from the trough portion of the coarse thread thread on the thread rolling die. Move according to the shape of the protrusion corresponding to the mountain and remove the screw rolling die material By the valley portions of the fine thread of the thread rolling dies, and among the valleys formed on the crest both sides of the fine thread, the one is snack unit, at a site other is formed on Otani portion In addition, a protrusion is formed which flattens the small valley portion in accordance with the height of the top of the fine screw thread.

The screw rolling die of the present invention 8 is the present invention 7,
The protrusions of the fine screw threads are formed in a tip shape having a radius larger than the tip shape of the second metal removal tool on the screw rolling die material partially thinned by the first metal removal tool. After forming the fine screw thread valley portion within a predetermined angle range by the third metal removal tool, the fine screw thread valley portion within the remaining angle range by the second metal removal tool, and The protrusion is formed.

The screw rolling die of the present invention 9 is the present invention 7 or 8,
The processing by the second removal tool and the third removal tool is performed in a direction around the axis of the thread rolling die, a direction parallel to the axis, and a position in a direction orthogonal to the axis. It is a cutting process in which the speed is synchronously controlled and the thread rolling die material is thinned.

  As described above, the thread rolling die of the present invention can improve the equalization of the filling amount filled in the groove at each angular position when performing the rolling process. As a result, chatter vibration, noise, and the like are not generated when rolling. In addition, the chatter vibration causes a precision failure, significantly shortens the tool life, and does not adversely affect the manufacturing apparatus.

  Further, the thread rolling die of the present invention can produce a thread rolling die with improved rigidity and durability in a balanced state so as to equalize the load associated with the rolling. When the fine thread is provided in the coarse thread, the cross-sectional shape of the protrusion is made to be an arc and / or a straight line so as not to form the valley in the thread rolling die and to uniformize the plastic processing amount. . By adopting such a configuration, the screw portion of the screw rolling die is a screw rolling die having high rigidity and improved durability. As a result, troubles such as damage to the screw part can be prevented during rolling, the life of the thread rolling die can be extended, and the time during which the rolling process can be performed without replacing the thread rolling die is increased. The work efficiency can be improved.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a thread rolling die of the present invention will be described in detail with reference to the drawings. FIG. 1 is a conceptual diagram showing a basic configuration of a manufacturing device for a rolling screw having a double screw structure (hereinafter referred to as a double screw bolt) according to the present invention, which is manufactured by a screw rolling die which is a round die. Manufacturing equipment. FIG. 2 is an external view of the thread rolling die (round die) shown in FIG. As shown in these drawings, the double screw bolt manufacturing apparatus has a predetermined pair of screw rolling dies 1 and a round bar-shaped bolt material (hereinafter referred to as “workpiece”) 3 arranged to face each other at a predetermined interval. It is comprised with the workpiece | work support part (workrest) 2 supported at a position.

  Further, in the screw rolling die (round die) 1 shown in FIG. 2, a transfer pattern 4 which is a spiral unevenness for forming a double screw bolt is formed on the outer periphery of a cylindrical die. This transfer pattern 4 has a spiral shape in accordance with a nut shape screwed into a double screw bolt. Basic techniques and configurations related to the screw rolling die 1 are described in detail in Patent Documents 2 and 3, but in order to facilitate understanding of the present embodiment, a double screw bolt as a premise thereof is used. The structure of the screw rolling die 1 manufactured by the rolling process will be described.

  FIG. 3 is a development view of the outer periphery of the screw rolling die 1, and the transfer pattern 4 is schematically developed in a plane. The parts at different angular positions of the outer peripheral double screw configuration are shown by 6 divisions A to F along the transfer pattern 4 around the double screw bolt, and cross-sectional views corresponding to the respective parts A to F are shown in FIG. (A) to (F). Accordingly, (A), (B), (C), (D), (E), and (F) in FIG. 4 are respectively taken along the AA cross-sectional view, BB cross-sectional view, and C- This corresponds to a C sectional view, a DD sectional view, an EE sectional view, and an FF sectional view.

  As shown in FIG. 3, a screw shape of the transfer pattern 4 of the screw rolling die 1 corresponding to the double screw bolt to be manufactured is formed on the outer periphery of the screw rolling die 1. Corresponds to 16 rounds of a double screw bolt. Therefore, on the outer periphery of the screw rolling die 1, the angle position of 22.5 degrees is equivalent to one turn of the double screw bolt, and the transfer pattern 4 corresponding to the one is formed. Each part of FIG. 3 is divided into six parts and provided at intervals of angles of 3.75 °.

  As shown in FIG. 4, the transfer pattern 4 of the thread rolling die 1 is a part of a coarse screw thread (hereinafter referred to as a standard screw thread) that is a reference screw thread developed on the outer peripheral surface (surface) of a cylindrical die. , 5 and the additional protrusions 6 formed periodically (constant pitch) in the valleys 5a of the coarse screw threads. The protrusion 6 has a helical winding in the same direction as the original coarse screw thread of the developed coarse screw thread portion, and a fine screw thread in which a fine screw having a smaller pitch than the coarse screw is developed (imaginary line 6a in FIG. 4). And a periodic shape corresponding to the phase shift 7 between the coarse screw threads. The coarse thread portion is preferably formed with a coarse thread having a standard pitch P defined by a standard for screws.

  Here, if the pitch ratio between the coarse screw and the fine screw is a: b (where a and b are the minimum integer ratio, and 2: 1 in the illustrated example of FIG. 4), the protrusion 6 is When the fine screw is developed, it becomes a part of the fine screw thread that appears periodically every b turns (one turn in the illustrated example) of the coarse screw thread according to the phase shift from the coarse screw thread. . As shown in FIG. 4, the fine screw thread indicated by an imaginary line 6 a has a coarse screw thread portion in which a portion protruding from the coarse screw thread is an additional protrusion 6 due to a phase shift 7 from the coarse screw thread. Appears in the valley 5a.

  That is, the protrusion 6 is not the fine screw thread itself, but is additionally protruded from the coarse screw thread 5 so as to correspond to the imaginary line 6a of the fine screw thread by the amount shifted according to the phase shift 7. It is a protrusion. The cross section of the coarse screw thread 5 is a portion excluding a part of the fine screw thread (the surface of the protrusion 6) appearing on the surface of the screw rolling die 1.

[Manufacturing method 1 of thread rolling die]
The manufacturing method 1 of the screw rolling die 1 will be described. FIG. 5 is a flowchart showing an outline of the manufacturing process of the screw rolling die 1. FIG. 6A is a plan view showing the first cutting tool 20 used for manufacturing the thread rolling die 1, FIG. 6B is a plan view showing the second cutting tool 25, and FIG. 6C. FIG. 9 is a plan view showing a third cutting tool 125.

  FIG. 7 is an explanatory diagram for explaining a process of machining the coarse thread formed on the screw rolling die 1 in the present embodiment. FIG. 8 is an explanatory diagram for explaining a process of processing the protrusion. First, a cutting tool (thickening tool) for cutting (thickening) a thread of the thread rolling die 1 will be described. As shown in FIG. 6 (a), the first cutting tool 20 has its tip end portion (the peak portion of the coarse screw thread shape 21) 22 flattened, and both corners of the tip end are rounded R1. This is a bit with a trapezoidal shape. In FIG. 6A, an imaginary line 23 is a line indicating the shape of a cutting tool used when forming a coarse screw thread on a normal screw rolling die. As indicated by the imaginary line 23, the first cutting tool 20 in the present embodiment corresponds to a tool in which the tip of a bit having a normal coarse thread shape is cut into a required shape (flat). Is.

  The second cutting tool 25 shown in FIG. 6B is a cutting tool having a shape corresponding to a fine screw thread, and a rounded end R2 is formed at the distal end portion 27. That is, the tip portion (the peak portion of the fine screw thread shape 26) 27 of the second cutting tool 25 is preferably formed in an arc or a curve (plan view) in plan view. A rounded edge R2 is formed at the tip. The third cutting tool 125 shown in FIG. 6C is a cutting tool in which a roundness R3 larger than the roundness R2 of the second cutting tool 25 is formed at the tip portion (the peak portion of the fine screw thread shape 126) 127.

  As shown in FIG. 5, when the screw rolling die 1 is manufactured, first, a thread rolling die material 30 (see FIG. 7) as a raw material is turned (step S11), followed by a coarse thread thread machining step. (Step S12) and a protrusion (corresponding to a fine thread) processing step (Step S13) are performed.

  In the coarse screw thread machining step of step S12, the first cutting tool 20 is used. As shown in FIG. 7, in the coarse screw thread machining step, the screw rolling die material 30 held by the chuck at the front end of the main shaft (not shown) and fixed to the main shaft side is moved at a predetermined rotation speed (rotation number). While rotating, the first cutting tool 20 is applied to the thread rolling die material 30 in the X-axis direction (direction perpendicular to the main axis) in FIG. The first cutting tool 20 is moved in the Z-axis direction (a direction parallel to the main axis) in FIG. 7 at a pitch of coarse threads. That is, the thread rolling die material 30 is turned by the first cutting tool 20. At this time, the direction around the axis of the main axis and the Z-axis direction are controlled in synchronization. That is, the first cutting tool 20 is synchronously controlled so as to move by one pitch of the coarse screw thread in the Z-axis direction with respect to one rotation of the main shaft. A part of the thread rolling die material 30 is cut by the processing by the first cutting tool 20. Thereby, the coarse screw thread part 5 is formed in the screw rolling die material 30.

  In the projection processing step in step S13, the second cutting tool 25 is used. As shown in FIGS. 8A to 8H, in the protrusion processing step, the screw rolling die material 30 is rotated at a predetermined rotational speed (number of rotations) and after being cut in the coarse thread processing step. The second cutting tool 25 is moved to the screw rolling die material 30 in the X-axis direction (direction orthogonal to the main axis) and the Z-axis direction (direction parallel to the main axis). From the valley part 5a of a part of the above, the valley part of the fine screw thread and the projection 6 are processed. That is, a screw thread of a screw rolling die having a desired shape can be manufactured by simultaneously controlling the three axes of the direction around the main axis, the X-axis direction, and the Z-axis direction in synchronization. In other words, the thread rolling die material 30 is subjected to compound turning with the second cutting tool 25.

By performing such control, the threaded thread valleys and the protrusions 6 are formed in the thread rolling die material 30. This cutting process is illustrated in FIG.
FIGS. 8A to 8H show the machining state of the second cutting tool 25 and the screw rolling die material 30 every 45 ° in the direction around the main axis (the machining of the valleys and protrusions of the fine screw thread). It is the figure which showed the relationship with (state) as sectional drawing. In FIG. 8, the fine screw thread is illustrated by a two-dot chain line. Also, for convenience of explanation, FIG. 8 is illustrated in such a manner that the state of (a) is 0 °, (b) is 45 °, (C) is 90 °, and (h) is 315 °. Yes.

  Such machining by the first cutting tool 20 and the second cutting tool 25 may be performed by a machine tool called an NC (numerical control) lathe, an NC compound lathe, a turning center, or the like. That is, using the control function of an NC device, CNC (computer numerical control) device, etc., the direction around the spindle axis, the X-axis direction (direction perpendicular to the spindle axis), and the Z-axis direction (direction parallel to the spindle axis) 3 Machining can be performed by controlling the axes simultaneously. Further, the NC program used for the machining may be easily programmed by using a function called automatic programming or the like.

  Thereafter, (1) quenching and (2) tempering heat treatment steps (step S14) are performed (see FIG. 5). Thereby, the screw rolling die 1 having the cross-sectional shape shown in FIG. 4 is obtained.

  In the example shown in the cross-sectional views of FIGS. 4A to 4F, the valley bottom 5b of the reference thread valley 5a and the valley bottom of the fine screw thread imaginary line 6a corresponding to the protrusion 6 are used. Although the position with 6b is made to correspond, it is not restricted to this.

  When the thread rolling die 1 (31) is manufactured by the manufacturing method 1 as described above, in the screw rolling die manufactured by the conventional method, a region in the vicinity of 90 ° to 270 ° (for example, a region in the vicinity of 90 ° of the portion). , The shallower groove of the fine screw thread appearing in the region near the region 270 ° can be removed. That is, the screw rolling die 1 can relieve stress concentration generated in the portion during rolling.

[Manufacturing method 2 of thread rolling die]
Since this manufacturing method 2 is different from the manufacturing method 1 described above only in the protrusion processing step S13, the description will focus on that step. That is, the cutting with the third cutting tool 125 is performed between the cutting of the coarse thread with the first cutting tool 20 and the cutting with the second cutting tool 25, and the fine screw in a predetermined angle range. Part of the processing of mountain valleys.

  As shown in FIGS. 9A to 9H, in the protrusion processing step according to the manufacturing method 2, the screw rolling die material 30 is rotated at a predetermined rotational speed (number of rotations), and in the coarse thread processing step. The third rolling tool 125 and the second cutting tool 25 are applied to the thread rolling die material 30 after being cut, in the X-axis direction (direction perpendicular to the main axis line) and the Z-axis direction (direction parallel to the main axis line). Then, the trough portion 5a of the fine screw thread portion and the projection 6 are processed from the trough portion 5a which is a part of the coarse screw thread portion 5. That is, a screw thread of a screw rolling die having a desired shape can be manufactured by simultaneously controlling the three axes of the direction around the main axis, the X-axis direction, and the Z-axis direction in synchronization. In other words, the thread rolling die material 30 is subjected to a complex turning process using the second cutting tool 25 and the third cutting tool 125. As a result, fine thread valleys and protrusions 6 are formed on the thread rolling die material 30.

9A to 9H show the processing states of the second cutting tool 25, the third cutting tool 125, and the screw rolling die material 30 every 45 ° in the direction around the main axis (the fine screw threads). It is the figure which showed the relationship between a trough part and the processing state of a processus | protrusion etc. as sectional drawing. In FIG. 9, the fine screw thread is shown by a two-dot chain line. For convenience of explanation, the state of FIG. 9A is 0 °, and (b) is 45 °, (c) is 90 °, and (h) is 315 °.
The groove contour corresponding to the valley portion of the fine screw thread is first processed according to the fine groove contour by the third cutting tool 125 having a rounded edge R3 (≧ R2). In this case, the region from the region 0 ° to the region 90 ° and the region 270 ° to the region 360 ° has a constant groove depth, and the region from the region 90 ° to the region 270 ° is gradually shallower in accordance with the fine groove contour. Process to be.

  Next, the fine grooves in the region from the part 90 ° to the part 270 ° are processed by the second cutting tool 25 having a rounded edge R2 (≦ R3) according to the fine groove contour. Further, processing is performed so as to remove the shallower grooves in the region near the part 90 °, the region near the part 270 °, and the like. In this manner, the fine thread thread valleys and the protrusions 6 are formed on the thread rolling die material 30 by the second cutting tool 25 and the third cutting tool 125.

When the thread rolling die 1 (31A) is manufactured by the manufacturing method 2 as described above, in the screw rolling die manufactured by the conventional method, the region near 90 ° to 270 ° (for example, the region near 90 °) , The shallower groove of the fine screw thread appearing in the region near the region 270 ° can be removed. That is, the screw rolling die 1 can relieve stress concentration generated in the portion during rolling.
Furthermore, the difference in the cross-sectional area of the groove portion at each angular position of the screw rolling die 1 can be reduced more than the screw rolling die manufactured by the conventional manufacturing method.

[Manufacture of double screw bolts]
A method of manufacturing a double screw bolt using the above-described double screw bolt manufacturing apparatus will be described. As shown in FIG. 1, a work 3, which is a round bar-shaped bolt material, is disposed on a work support portion 2, and the work 3 is pressed between a pair of screw rolling dies 1, thereby a pair of screw rolling dies 1. Are rotated in the same direction. As a result, the double screw bolt in which the coarse screw thread and a part of the fine screw thread are simultaneously rolled in one step on the outer peripheral surface of the work 3 and the coarse screw part and a part of the fine screw part are formed. can get.

  On the outer peripheral surface of the obtained double screw bolt, a screw shape having a reverse pattern of the transfer pattern 4 of the screw rolling die 1 shown in FIG. 4 is formed. This double screw bolt is in a state in which a coarse screw thread is formed and a fine screw thread is formed in the same manner as a double screw bolt formed by a conventional processing method. Therefore, a coarse screw nut and a fine screw nut can be screwed into the rolled double screw bolt.

  Incidentally, the double screw bolt is a screw that can screw the coarse thread crest of the coarse screw nut into the valley of the coarse screw thread of the double screw bolt. The thread portion of the fine screw of the fine screw nut can be screwed into the valley portion of the fine screw thread formed at the peak portion of the fine screw thread. For this reason, it is general that the radial position of the peak of the coarse screw thread and the radial position of the peak of the fine thread thread always coincide with each other.

  The protrusions of the thread rolling die 1 for manufacturing such a double screw bolt expand the fine screw so that the position of the valley bottom when the fine screw is expanded coincides with the position of the valley bottom of the coarse screw thread. , Consisting of a part of fine thread that appears periodically for every b turns of the coarse thread according to the phase shift with the coarse thread. Since the structure and manufacture of the screw rolling die having such a protrusion are described in Patent Documents 2 and 3, detailed description thereof is omitted.

  Next, a characteristic part is demonstrated in the structure of the screw rolling die | dye of this Embodiment. 10 and 11 are screw rolling dies 31 and 31A manufactured by the manufacturing methods 1 and 2, and are cross-sectional views of the screw rolling dies 31 and 31A corresponding to FIG. A section corresponding to a double screw bolt is divided into eight sections, and a transfer pattern 32 up to a 180 ° range at different angles is shown at angular positions of 0 °, 45 °, 90 °, 135 °, and 180 °. FIG.

  FIG. 10 is a cross-sectional view when the R-shape 33 at the corner between the coarse thread and the flat portion (in the cross-sectional shape) is small, and FIG. 11 is a cross-sectional view when the R-shape 33 is large. FIG. 12 is a development view of the surface screw portion of the screw rolling dies 31 and 31A according to FIGS. 10 and 11, and corresponds to FIG. 3 described above. This development view shows a predetermined range of the thread rolling die. 10 and 11 are cross-sectional views of the screw rolling die of each angle position of 0 ° to 180 ° of the double screw bolt, but FIG. 12 shows a range exceeding 360 ° which is one round of the double screw bolt. Is shown.

  Further, as can be understood from the developed view of FIG. 12, at the respective angular positions of 225 °, 270 °, and 315 ° of the thread rolling die, the portion 225 ° is a different shape pattern in the case of the portion 135 °. Yes, the part 270 ° is an arbitrarily shaped pattern in the case of the part 90 °, and the part 315 ° is an arbitrarily shaped pattern in the case of the part 45 °. 12, reference numeral 34 denotes a portion 34 corresponding to a trough portion in the cross-sectional views of FIGS. 10 and 11 formed on the screw rolling die 31, and reference numeral 35 denotes FIG. 10 formed on the screw rolling die 31. , 11 shows a portion corresponding to the flat portion 39 in the sectional view. In addition, the imaginary line 36 of FIG. 12 shows the cross-sectional shape of the trough part of the site | part 34 virtually for each angle for convenience of understanding.

  FIG. 18 is a development view of a surface screw portion of a conventional screw rolling die. FIG. 18 is shown for comparison with FIG. 12, but conventionally, troughs are formed on both sides of the crest of the fine screw thread. The part 34a in FIG. 18 corresponds to the part 34 in FIG. 12, and the imaginary line 36a in FIG. 18 corresponds to the imaginary line 36 in FIG. In FIG. 18, for example, at an angle position of a part of 135 °, an Otani portion 37 and an Otani portion 38 are formed. The protrusion between the large valley portion 37 and the small valley portion 38 has a configuration in which a flat portion (cylindrical surface) is not provided on the upper portion.

  This is the same as that shown in the transfer pattern 4 of FIG. On the other hand, in the case of the present embodiment, as shown in FIGS. 10 to 12, among the valley portions formed on both sides of the mountain portion of the fine screw thread A (6 a), the small screw thread 40 is disposed on the small valley portion 40 side. It is flattened according to the height of the top of the peak of A. For example, in the case of the angle position of the part 135 ° shown in FIGS. 10 and 11, if the part of the boundary with the coarse thread B (5) of the pattern shown in the figure is conventional, the small valley part 40 indicated by a two-dot chain line As shown in the figure, a flat portion 39 is formed where the shape should be (corresponding to the small valley portion 38 in FIG. 18).

  As shown in FIGS. 10 and 11, the flat portion 39 does not form a valley portion on the small valley portion 40 side as described above at an angular position of 135 ° to 225 °, ie, the upper portion on the protrusion side, that is, The top of the fine screw thread is flat. As shown in FIG. 12, this flat shape has a configuration in which a flat portion (in a sectional view) is provided over one round of the double screw bolt. In the case of a round die, the flat portion (flat shape) is a cylindrical surface in which the small valley portion side within a predetermined range is matched with the summit portion of the fine screw thread.

  In the cross-sectional views of FIGS. 10 and 11, all the valley 40 side of the angular positions of 0 °, 45 °, 90 °, and 135 ° other than the angular position of the portion 180 ° has a flat shape. In the case of an angular position of 180 °, the size of both valleys is the same, and valleys are arranged on both sides. In addition, the range of the angular position from the part 135 ° to 225 ° across the angular position of the part 180 ° is such that the small valley side is gently inclined, the angular position near the part 135 ° or the part 135 °, and the part 225 It is inclined so as to be flat at an angular position in the vicinity of ° or part 225 °. The reason for flattening is to increase the rigidity of the protruding portions of the thread rolling dies 31 and 31A, and to prevent excessive rolling of these portions. This flattening configuration is the same for other screw threads.

  Conventionally, since the fine screw thread A is formed in the thread rolling die in a theoretical shape between the coarse screw thread B and the coarse screw thread B, notched small steps and small protrusions have been generated. Although this is a theoretically accurate shape, an unbalanced force is applied to the small steps and small protrusions of the thread rolling die as the material is deformed on the workpiece 3 side during rolling. This means that this part causes troubles such as deformation, damage, and loss. Making the upper part of the projection flat eliminates the above-mentioned problems and increases the rigidity. Next, a rolling method in the case of rolling a double screw bolt using the screw rolling dies 31, 31A according to the present embodiment will be described.

  13 and 14 are cross-sectional views at the angular positions of 0 °, 90 °, and 180 ° in FIGS. 10 to 12, and examples of the material flow state in the rolling process are as follows: i, b, c, d, h, It is the figure divided into 7 steps of F and G. The flow change state of the material (work 3) when the pair of screw rolling dies 31 or the pair of screw rolling dies 31A is rotated in the same direction and the distance between them is reduced is schematically shown. Show. 13 shows a state in which the workpiece 3 is rolled by the screw rolling die 31, and FIG. 14 shows a state in which the workpiece 3 is rolled by the screw rolling die 31 </ b> A.

  As shown in FIGS. 13A to 13C and FIGS. 14A to 14C, as the thread rolling dies 31 and 31A are gradually pushed into the work 3, the work 3 is first a coarse thread B of the thread rolling dies 31 and 31A. The valley portion of the coarse screw thread B is filled while plastically deforming along the surface. At this time, the difference in the cross-sectional area of the groove portion at each angular position of the screw rolling dies 31 and 31A can be made smaller than that of the screw rolling dies manufactured by the conventional manufacturing method.

  In this way, by reducing the difference in the cross-sectional area of the groove at each angular position, it is possible to minimize the occurrence of chatter vibration, noise and the like when performing the rolling process. Therefore, it is possible to suppress the occurrence of poor accuracy of the double screw bolt due to the chatter vibration, the reduction of the tool life of the screw rolling die, and the adverse effect on the manufacturing apparatus.

Furthermore, as shown in FIG. 13 to FIG. 14 and FIG. 14 to FIG. 14, the thread rolling dies 31 and 31 A are gradually pushed into the work 3 to fill the valleys of the fine thread A and the coarse thread B. Go. At this time, the trough is filled while deforming along the surface (cylindrical surface) of the flat portion 39.
Note that the screw rolling die 31A can further reduce the difference in the cross-sectional area of the groove at each angular position as compared with the screw rolling die 31 as shown in FIGS.

  Conventionally, when the part is 90 °, as shown in FIG. 19, the screw rolling die 105 is gradually pushed into the work 107, and when the large trough 106B and the small trough 106A on both sides of the crest 106 are filled, Pressures F1 and F2 are generated. Since the pressing forces F1 and F2 are unbalanced pressing forces, there is a possibility that the fine thread crest 106 of the thread rolling die (corresponding to the crest 43 in FIGS. 10 and 11) may be deformed or lost. . However, in the case of the portion of 90 ° according to the present embodiment, the valley portion 44 is configured only on one side of the peak portion 43 and the valley portion 45 is not configured. Therefore, a force that deforms or breaks the peak portion 43 of the screw rolling dies 31 and 31A is prevented from being generated.

In the case of the part 180 ° of the present embodiment, as shown in FIGS. 10 and 11, two valley portions 44 and 45 are formed on both sides of the peak portion 43 of the convex fine screw thread A. The work 3 is plastically deformed and pushed into the two valley portions 44 and 45.
This indentation hits the final end of the plastic deformation and enters an over-rolled state, and a strong indentation force is generated. If the thread rolling form to the two troughs 44 and 45 is unbalanced, as described above, the crests of the thread rolling dies 31 and 31A, that is, the crests 43 of the fine thread crests are weak parts, and abnormal In many cases, a large amount of force is applied and deformation damage occurs. This causes the generation of defective products, and there are many problems such that the screw rolling dies 31 and 31A must be replaced due to damage or the like.

  The feature of the present invention solves this problem. That is, as shown in the example of the angular positions of the portions 90 ° and 135 in FIGS. 10 to 12, among the valley portions 44 and 45 formed on both sides of the mountain portion 43 of the fine screw thread A, the small valley portion (Otani Part) The side corresponding to 45 (40) was made into a projection that became substantially flat (cylindrical) in accordance with the peak height of the peak part 43 of the fine thread A. FIG. 10 shows a case where the corner portion between the flat portion and the peak portion of the coarse thread B is made into a relatively small R shape 33, and FIG. 11 shows the corner portion formed into a large R shape 33. is there.

  By making this portion flat (cylindrical) and / or arcuate, the final rolled portion concentrates on one trough and undergoes material deformation. Accordingly, since the over-rolled state is formed only in one valley, it is possible to prevent the occurrence of unbalanced pushing force due to over-rolling by the two valleys as in the prior art. Furthermore, the pressing pressure of the screw rolling dies 31 and 31A depending on the rotational angle position during rolling, that is, the reaction force from the material to the screw rolling dies 31 and 31A during plastic working can be made constant. That is, by changing the shapes of the R shape 33 and the flat portion 39, the reaction force to the screw rolling dies 31 and 31A can be made constant.

  In other words, the plastic flow amount of the material can be made constant. As a result, thread rolling can be performed smoothly, and the thread rolling die is damaged as in the prior art, and it is no longer necessary to frequently replace the damaged thread rolling die.

  The machining by the second cutting tool 25 and the third cutting tool 125 has a complicated shape as compared with the conventional one. For example, by using an NC (numerical control) machine tool or a CNC (computer numerical control) machine tool. Since processing can be easily performed, there is no difficulty in processing. FIG. 11 shows an enlarged R shape of the rising portion of the flat portion. By increasing the R of the R shape, the plastic flow of the material accompanying the rolling smoothly passes through the R shape portion without resistance, and a large rolling load is avoided.

[Screw rolling dies (flat dies)]
The screw rolling die for manufacturing the double screw bolt may be a so-called flat die.
FIG. 17 is a schematic view schematically showing an apparatus for manufacturing a rolling bolt having a double screw structure, and shows a manufacturing apparatus manufactured by a screw rolling die that is a flat die.
As shown in FIG. 17, the double screw bolt can be manufactured with screw rolling dies 101 and 101 which are flat dies. A double screw bolt is manufactured by rolling the workpiece 103 with the screw rolling dies 101, 101. The transfer pattern 104 of the thread rolling die 101 has the same shape as that shown in the developed view of FIG. 12 and is formed on the plane of the thread rolling die 101.

The cross-sectional shape corresponding to each angular position of the double screw bolt is also the same as the shape shown in FIGS. By moving the upper and lower screw rolling dies 101, 101 in parallel with the arrow direction, for example, a double screw bolt can be manufactured.
In the case of a flat die, the flat portion (flat shape) is a flat surface in which the small valley portion side within a predetermined range is matched with the summit portion of the fine screw thread.

  15 and 16 show a double screw bolt 50 manufactured with the screw rolling die 31 and a fine screw nut 47 and a coarse screw nut 48 on the double screw bolt 50A manufactured with the screw rolling die 31A. It is the figure which showed the state screwed. FIG. 15A shows the state of the part corresponding to the angular position of the part 0 ° in the screw rolling die 31 (manufacturing method 1), and FIG. 15B shows the state of the part corresponding to the angular position of the part 90 °. ) Shows the state of the part corresponding to the angular position of the part 180 °. FIG. 16A shows the state of the part corresponding to the angular position of the part 0 ° in the screw rolling die 31A (manufacturing method 2), FIG. 16B shows the state of the part corresponding to the angular position of the part 90 °, (c ) Shows the state of the part corresponding to the angular position of the part 180 °.

  In the double screw bolt 50, a peak portion of a coarse nut 48 in which a female screw that is a coarse screw is formed is screwed into a valley portion of the coarse screw thread 53. A fine nut 47 formed with a female screw which is a fine screw is screwed into the fine screw thread 52 of the fine screw. Since the fine nuts 47 and the coarse nuts 48 have different pitches, when they rotate together in the same direction, a repulsive force acts on the contact surface between the fine nuts 47 and the coarse nuts 48, and It is possible to prevent the eye nut 48 from rotating in the loosening direction. The small mountain part 52S is a flat part.

  In the double screw bolt 50A, the peak portion of the coarse nut 48 in which the female screw as the coarse screw is formed is screwed into the valley portion of the coarse screw thread 53a. A fine nut 47 having a female screw as a fine screw is screwed into the fine screw thread 52a of the fine screw. Since the fine nuts 47 and the coarse nuts 48 have different pitches, when they rotate together in the same direction, a repulsive force acts on the contact surface between the fine nuts 47 and the coarse nuts 48, and It is possible to prevent the eye nut 48 from rotating in the loosening direction. The small mountain part 52S is a flat part. The double screw bolt 50A is configured such that the corner portion 51b between the flank of the coarse screw thread 53a and the flat portion 51a is formed in a large R shape, and other parts are the same as the double screw bolt 50. is there.

The loosening prevention function can be exhibited by the screwed and fixed state as shown in FIGS.
The state of the corresponding part of the other angular position not shown in the figure also changes the shape of the bolt due to the flat projection, and there is a difference in the screwing relationship with the nut. There is no problem.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the content demonstrated by this embodiment. Needless to say, changes can be made without departing from the scope and spirit of the present invention. For example, a thread rolling die may be manufactured by performing a grinding process after the heat treatment process. Further, the thread rolling die that is a round die or a flat die may be processed by other processing methods such as grinding, milling, and electric discharge. In other words, a grinding wheel, milling tool, electric discharge machining electrode, or the like may be used as a metal removal tool. When the removal tool is a rotating tool such as a grinding wheel or a milling tool, the axis of the rotating tool may be inclined with respect to the axis of the screw rolling die by a predetermined angle corresponding to the pitch of the screw.

FIG. 1 is a schematic view schematically showing an apparatus for manufacturing a rolling bolt having a double screw configuration, which is a manufacturing apparatus manufactured by a screw rolling die that is a round die. FIG. 2 is an external view showing the screw rolling die of FIG. FIG. 3 is a plan development view of a part of the transfer pattern on the outer periphery of the screw rolling die of FIG. 4 is a cross-sectional view of each part shown in FIG. 3, and (A), (B), (C), (D), (E), and (F) are cross-sectional views taken along line AA in FIG. , BB sectional view, CC sectional view, DD sectional view, EE sectional view, FF sectional view. FIG. 5 is a flowchart showing the manufacturing process of the thread rolling die. FIG. 6 is a partial plan view showing a cutting tool for manufacturing a thread rolling die, FIG. 6 (a) shows a first cutting tool, and FIG. 6 (b) shows a second cutting tool. FIG. 6 (c) shows a third cutting tool. FIG. 7 is an explanatory diagram for explaining a processing state in which a coarse thread of a thread rolling die is processed. FIG. 8 is an explanatory diagram for explaining a processing state in which the protruding portion (fine thread) of the screw rolling die is processed in the manufacturing method 1. FIG. 9 is an explanatory diagram for explaining a processing state in which the protruding portion (fine screw thread) of the screw rolling die is processed in the manufacturing method 2. FIG. 10 is a cross-sectional view of a screw rolling die having a small R shape at the upper part of the protrusion, and is a view showing each angular part in stages. FIG. 11 is a cross-sectional view of a thread rolling die having a large R shape at the top of the protrusion, and is a view showing each angular part in stages. FIG. 12 is a development view of a thread rolling die corresponding to FIGS. 10 and 11. FIG. 13 shows the filling state of the groove at the angular positions of 0 °, 90 ° and 180 ° in FIGS. 10 to 12 in each stage of the thread rolling die processed by the manufacturing method 1. FIG. FIG. 14 shows the filling state of the grooves at the angular positions of 0 °, 90 °, and 180 ° in FIGS. 10 to 12 at each stage of the thread rolling die processed by the manufacturing method 2. FIG. FIG. 15 is a cross-sectional view showing a state in which a fine screw nut and a coarse screw nut are screwed into a screw rolling bolt manufactured by a screw rolling die processed by the manufacturing method 1. FIG. 16 is a cross-sectional view showing a state in which a fine screw nut and a coarse screw nut are screwed into a screw rolling bolt manufactured by a screw rolling die processed by the manufacturing method 2. FIG. 17 is a schematic view schematically showing an apparatus for manufacturing a rolling bolt having a double screw structure, which is a manufacturing apparatus manufactured by a screw rolling die that is a flat die. FIG. 18 is a development view of a conventional screw rolling die. FIG. 19 is a partial cross-sectional view showing a state where a thread rolling bolt is rolled with a conventional thread rolling die.

Explanation of symbols

1, 31, 31A ... Thread rolling dies (round dies)
2 ... Bolt support 3, 103 ... Bolt material (workpiece)
4, 32 ... Transfer pattern 5 ... Coarse screw thread portion 5a ... Valley portion 5b ... Valley bottom 6 ... Projection (fine screw thread)
6a ... Fine screw thread imaginary line 6b ... Valley bottom 20 ... First cutting tool 25 ... Second cutting tool 125 ... Third cutting tool 30 ... Screw rolling die material 39 ... Flat portion 101 ... Screw rolling die ( Flat dice)
A ... Fine screw thread B ... Coarse screw thread

Claims (9)

It is periodically formed in the valley portion of the coarse screw according to the phase shift between the thread portion of the coarse screw in which the coarse screw is developed, and the fine screw thread in which the fine screw is developed and the mountain portion of the coarse screw. A thread rolling die provided with a projection corresponding to the fine thread thread,
The protrusion is formed in a valley portion of the coarse thread of the thread rolling die, and one of the two valleys formed on both sides of the thread portion of the fine thread is in the small valley, and the other at the site but formed Otani portion, the snack portion within a predetermined range in the longitudinal direction of the valley, is in that projections on the plane or cylindrical surface adapted to the height of the crest of the fine thread Screw rolling dies characterized by that. In the screw rolling die according to claim 1,
The screw rolling die is a round die,
The projection is a screw, wherein the within a predetermined range, a projection which the cylindrical surface centered on the rotational centerline of said thread rolling dies to match the height of the crest of the fine thread Rolling dies. In the screw rolling die according to claim 1,
The screw rolling die is a flat die,
The projections, thread rolling dies wherein said within a predetermined range, which is the plane and the projection to fit the height of the crest of the fine thread. In the screw rolling die according to claim 2 or 3,
The thread rolling die, wherein the protrusion and the coarse thread are joined so as to form a continuous surface. In the screw rolling die according to claim 2 or 3,
The protrusion is formed so that a small valley portion side of a valley portion formed on both sides of the mountain portion of the fine screw thread becomes a flat portion in accordance with the height of the mountain peak portion of the fine screw thread. Screw rolling dies characterized by. In the screw rolling die according to claim 5,
The thread rolling die, wherein a boundary portion between the flat portion and the coarse screw thread has an arc shape in cross section. It is formed periodically in the valley portion of the coarse screw in accordance with the phase shift between the coarse screw thread in which the coarse screw is developed, and the fine screw thread in which the fine screw is developed and the coarse screw mountain. A thread rolling die having a protrusion corresponding to the fine thread,
The screw rolling die material is fed with a first removal tool having a shape with a flat top corresponding to the coarse thread to a position below the maximum height of the protrusion corresponding to the fine thread, By removing a portion of the thread rolling die material, a thread portion of a coarse thread on the thread rolling die is formed,
A second thread removal tool having a fine screw thread shape is applied to the thread rolling die material after the metal removal from the valley of the thread portion of the coarse thread thread on the screw rolling die to the fine thread thread. By moving according to the shape of the corresponding protrusion and removing the thread rolling die material, it is formed on the both sides of the fine screw thread valley portion and the fine thread thread mountain portion of the screw rolling die. Of the valleys, one of the valleys is formed in the valley and the other is formed in the valley. The protrusions are formed so that the valley is flattened according to the height of the top of the fine screw thread. Thread rolling dies. In the screw rolling die according to claim 7,
The protrusion of the fine screw thread is
Predetermined by a third removal tool formed in a tip shape having a radius larger than the tip shape of the second removal tool on the screw rolling die material partially removed by the first removal tool After forming the fine screw thread valleys within the angle range, the fine screw thread valleys and the protrusions within the remaining angle range are formed by the second metal removal tool. Screw rolling dies characterized by that. In the screw rolling die according to claim 7 or 8,
Processing by the second removal tool and the third removal tool is as follows:
It is a cutting process in which the position and speed of a direction around the axis of the thread rolling die, a direction parallel to the axis, and a direction perpendicular to the axis are controlled to remove the thread rolling die material. Screw rolling dies characterized by.

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