JP2012115862A - Form rolling die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a form rolling die having very excellent practicability which can prevent damage on a tooth flank of a member to be form-rolled by suppressing interference between the member to be form-rolled and a form rolling tooth profile of the die in a relief part as much as possible.SOLUTION: The form rolling die form-rolls a desired tooth profile by causing an outer circumferential surface of the member to be form-rolled to plastically deform by abutting a form rolling tooth profile on the outer circumferential surface of the member to be form-rolled. The form rolling tooth profile is constituted by a leading part A, a finishing part B, and the relief part C, and a gradual decrease part of the tooth thickness in which a tooth thickness T of tooth parts of the form rolling tooth profile in the prescribed height position gradually decreases from a form rolling direction start end side to a form rolling direction terminal end side is provided on the relief part C, and the gradual decreasing part of the tooth thickness is constituted so that the gradual decreasing degree of the tooth thickness T on the form rolling direction terminal end side in the relief part C is larger than the gradual decreasing degree of the tooth thickness T on the form rolling direction start end side.

Description

  The present invention relates to a rolling die.

  Conventionally, worms and screw teeth (threads) are plastically processed by applying pressure while sandwiching and rotating a substantially cylindrical rolled member (workpiece) with a rolling tooth mold formed on a rolling die. A rolling flat die (with a chamfered portion, a finish portion, and a relief portion formed) and other rolling dies have been proposed (see, for example, Patent Document 1).

  In the rolling process, it is common to gradually release the load applied to the member to be rolled at the time of machining at the biting part and finishing part of the rolling die at the escape part. For example, the shape of the relief portion is inclined so that the rolling process proceeds (as the rolling direction end side), the rolling tooth die (blade edge) is inclined so as to be separated from the member to be rolled, that is, by gently releasing the load. Opening little by little, the phenomenon (spring back) that the rolled member tries to return to the state before processing is gradually caused. Usually, the rolling tooth mold (tooth tip) of the relief portion is formed in a one-step inclined manner. It is known that the shape of the relief portion having such a shape can prevent shape defects such as the outer shape of the rolled member being substantially elliptical.

  By the way, a worm, a screw, or the like that is plastically processed by a rolling die is likely to be scratched on the tooth surface of the rolled member depending on the tooth profile specification.

  When using a rolled product with a flawed tooth surface, the operating noise (vibration noise) due to interference with the mating part increases, the runout increases, and the life due to wear of the mating part may be affected. Many problems arise.

JP 10-1113740 A

  As a result of various studies by the inventors, the present invention has found that the tooth surface of the rolled member has been damaged at the relief portion of the rolling die, and has been made to solve this problem. A rolling die with excellent practicality that can prevent the tooth surface of the rolled member from being scratched as much as possible by preventing interference between the rolled member and the die rolling tooth mold of the die. It is to provide.

  The gist of the present invention will be described with reference to the accompanying drawings.

  A rolling die for rolling a desired tooth shape by plastically deforming the outer peripheral surface by bringing a rolling tooth die into contact with the outer peripheral surface of the rolled member, wherein the rolling tooth die is a biting portion A, A finish portion B and a relief portion C are formed. In the relief portion C, the tooth thickness T of each tooth portion 1 of the rolling tooth mold at a predetermined height position extends from the rolling direction start end side to the rolling direction end side. The tooth thickness gradually decreasing portion is provided so that the degree of gradual decrease in the tooth thickness T on the end side in the rolling direction in the relief portion C is such that the tooth thickness T on the rolling direction start end side is gradually decreased. The present invention relates to a rolling die characterized by being configured to have a degree greater than the degree.

  The rolling die according to claim 1, wherein the rolling tooth bottom 2 of the rolling portion C in the relief portion C is configured to incline downward toward the end in the rolling direction. This is related to die making.

  3. The rolling die according to claim 2, wherein the tip position of the rolling tooth die at the rolling direction end position of the relief portion C is the rolling tooth die at the finishing direction end position of the finishing portion B. It is related to the rolling die characterized by being configured to be 0.08 to 0.3 times lower than the tooth height L in the finished portion B of the rolled tooth mold with respect to the tooth tip position. is there.

  4. The rolling die according to claim 2, wherein a bottom position of the rolling tooth mold at a rolling direction end position of the relief portion C is a rolling direction end of the finish portion B. 5. It is comprised so that it may become 0.1 times-0.4 times lower than the tooth height L in the finishing part B of the said rolling-tooth type with respect to the root position of the said rolling-tooth type in a position. It relates to rolling dies.

  Further, in the rolling die according to claim 4, a first tooth thickness gradually decreasing portion is provided on the rolling direction start end side of the escape portion C, and a second tooth thickness is provided on the rolling direction end side of the relief portion C. A gradually decreasing portion is provided, and the bottom position of the rolling tooth mold in the rolling direction end position of the first tooth thickness gradually decreasing portion is the bottom of the rolling tooth mold in the rolling direction end position of the finishing portion B. The rolling height is configured to be 0.05 to 0.2 times lower than the tooth height L in the finished portion B of the rolling tooth mold, and the rolling at the end position in the rolling direction of the second tooth thickness gradually decreasing portion. The tooth bottom position of the tooth forming mold is 0 of the tooth height L in the finished portion B of the rolling tooth mold with respect to the tooth bottom position of the rolling tooth mold in the rolling direction end position of the first tooth thickness gradually decreasing portion. The present invention relates to a rolling die characterized by being configured to be 0.05 times to 0.2 times lower.

  6. The rolling die according to claim 5, wherein the rolling tooth bottom 2 of the rolling tooth mold as the first tooth thickness gradually decreasing portion is inclined substantially linearly at a predetermined first inclination angle. 4 and a second inclined portion 5 in which the rolled tooth bottom 2 as the second tooth thickness gradually decreasing portion is inclined downward with a degree greater than the inclination of the first inclined portion 4. The present invention relates to a rolling die characterized by

  The rolling die according to any one of claims 5 and 6, wherein the bottom 2 of the rolling tooth mold as the first tooth thickness gradually decreasing portion is substantially linear at a predetermined first inclination angle. The first inclined portion 4 that inclines downward and the rolled tooth bottom 2 as the second tooth thickness gradually decreasing portion inclines substantially linearly at a second inclination angle that is larger than the first inclination angle. The present invention relates to a rolling die characterized in that a second inclined portion 5 is provided.

  The rolling die according to any one of claims 3 to 7, wherein the inclination angle of the tip 3 of the rolling tooth mold of the escape portion C is the rolling tooth mold of the first inclined portion 4. The rolling die is characterized in that it is set to the same angle as the first inclination angle of the tooth bottom 2 or larger than the first inclination angle.

  Further, in the rolling die according to any one of claims 1 to 8, a substantially planar or curved chamfered portion 7 is provided on the tooth tip 3 of the rolling tooth mold of the relief portion C. The present invention relates to a rolling die characterized by this.

  Further, in the rolling die according to claim 9, the chamfered portion 7 is chamfered with a width of 0.05 mm or more in a tooth thickness direction of a cross section perpendicular to the rolling direction at a rolling direction end position of the relief portion C, and The chamfered portion 7 has a shorter length of at least 3 mm or a quarter length of the outer peripheral length of the rolled member in the rolling direction from the rolling direction end position of the escape portion C. The present invention relates to a rolling die characterized by being provided in the above range.

  Further, in the rolling die according to any one of claims 1 to 10, the rolling die is used for forming a worm, and the pressure angle α of the tooth portion 1 of the rolling tooth mold is described. Is related to a rolling die characterized by being set to 3 ° to 25 °.

  Since the present invention is configured as described above, interference between the rolled member and the rolling tooth mold of the die at the relief portion is suppressed as much as possible to prevent the tooth surface of the rolled member from being damaged. It can be a rolling die with excellent practicality.

It is a schematic explanatory perspective view of a flat die. It is a structure outline explanatory side view of a present Example. It is an expansion outline explanatory side view of the principal part of a present Example. It is an expansion outline explanatory side view of the principal part of a prior art example. It is a rough explanatory cross-sectional view of the rolling direction termination position of the finishing part of a present Example. It is a schematic explanatory perspective view of a 1st inclination part among the escape parts of a present Example. It is a schematic explanatory perspective view of the escape part (a 1st inclination part and a 2nd inclination part) of a present Example. 12 is a schematic explanatory perspective view of another example 1. FIG. 10 is an enlarged schematic explanatory side view of another example 2. FIG. 10 is an enlarged schematic explanatory side view of another example 3. FIG. It is a schematic explanatory perspective view of the rolling direction terminal position part of the 2nd inclination part of another example 4. It is a schematic explanatory drawing of the example of a flat die for reciprocating rolling, and reciprocating rolling. 10 is a side view schematically illustrating the configuration of another example 5. FIG. It is a table | surface which shows the experimental condition and experimental result of an experiment example. It is a photograph which shows the example (a) with which the tooth surface was damaged, and the example (b) with which the tooth surface was not damaged.

  An embodiment of the present invention which is considered to be suitable will be briefly described with reference to the drawings showing the operation of the present invention.

  A rolling member is sandwiched between a pair of rolling dies to perform a rolling process. Here, after releasing the chamfered portion A and the finishing portion B, when releasing the load applied to the rolled member in the escape portion C, the load is gradually released in the tooth thickness gradually decreasing portion on the rolling direction start end side ( The outer shape of the rolled member is not substantially elliptical), and the load is released at a stretch in the tooth thickness gradually decreasing portion at the end of the rolling direction, and the rolled member is inserted into the gap generated in the tooth thickness direction of the rolled tooth mold. The spring back can be released (the tooth thickness gradually decreases at the end of the rolling direction at the end of the rolling direction, and the tooth thickness gradually decreases at the end of the rolling direction. The gap between the building members is increased). Therefore, it becomes possible to suppress the interference between the rolled member and the rolling tooth mold as much as possible.

  Specific embodiments of the present invention will be described with reference to the drawings.

  The present embodiment is a rolling die for rolling a desired tooth profile by plastically deforming the outer peripheral surface by bringing a rolling tooth mold into contact with the outer peripheral surface of the member to be rolled. As shown in FIGS. 1 and 2, specifically, the biting part A, the finishing part B, and the escape part C are formed in order from the rolling direction starting end side. The relief portion C is formed at a predetermined height position (a predetermined position in a tooth height region from the tooth tip to the tooth bottom when the die bottom surface 6 is used as a reference surface, for example, a straight line D in FIG. 7). A tooth thickness gradually decreasing portion is provided in which the tooth thickness T of each tooth portion 1 of the rolling tooth mold gradually decreases from the rolling direction start end side to the rolling direction end side, and this tooth thickness gradually decreasing portion is the escape portion C. The degree of gradual decrease in the tooth thickness T on the end side in the rolling direction is greater than the degree of gradual decrease in the tooth thickness T on the start side in the rolling direction. Those that are configured so that. The gradually decreasing degree of the tooth thickness T mentioned here is expressed as a reduction amount of the tooth thickness T in a predetermined length in the rolling direction.

  Specifically, the present embodiment is a flat die X as shown in FIG. 1, and is rotated between the opposed surfaces of a pair of flat dies X arranged to face the rolled member at a predetermined interval. A worm or screw tooth shape (thread) is formed by applying pressure while sandwiching and rotating the forming member.

  Specifically, in the flat die X, the bottom surface 6 where the rolling tooth mold is not provided is set as a die reference surface, and a plurality of teeth 1 are rolled at predetermined intervals on the upper surface opposite to the bottom surface 6. It has rolling tooth molds that are arranged in a skewed manner with respect to the direction, and the rolling tooth molds of this flat die X have different biting angles with respect to the rolling direction in order from the rolling direction starting end side. The part A, the finishing part B, and the relief part C are provided continuously. In addition, the rolling tooth mold is formed by grinding a die base material that has been previously machined to a predetermined size.

  Finishing part B is along the surface parallel to the bottom surface 6 (die reference surface) in the rolling direction, and the biting part A is along the surface inclined toward the bottom surface side toward the rolling direction start end side, The escape portion C extends along a surface that inclines toward the bottom as it goes toward the rolling direction end side.

  Therefore, when the pair of flat dies X arranged opposite to each other move relative to each other in the opposite direction, the distance between the biting portion A, the finishing portion B, and the escape portion C is different (specifically, the most in the finishing portion B). The rolled member sandwiched between the pair of flat dies X is pressed while being rotated, and a tooth profile (thread) of a worm or screw is formed.

  In the present embodiment, the shape of the tooth portion 1 has a substantially trapezoidal shape in a sectional view or a substantially triangular shape in a sectional view, and the thickness (tooth thickness T) decreases toward the tooth tip side. The shape has a substantially trapezoidal shape in cross-sectional view or a substantially triangular shape in cross-sectional view, the width of which becomes smaller toward the tooth bottom side. Further, the corner of the tooth bottom 2 has a substantially circular arc shape (substantially rounded shape) in sectional view that protrudes toward the tooth portion 1 side.

  Each part will be specifically described.

  In the present embodiment, a first tooth thickness gradual decreasing portion in which the tooth thickness T is gradually decreased by a predetermined gradual decrease degree is provided on the rolling direction start end side of the relief portion C, and the first tooth thickness gradual decreasing portion is provided on the rolling direction end side. A second tooth thickness gradually decreasing portion is provided in which the tooth thickness T gradually decreases with a degree greater than the gradually decreasing degree of the first tooth thickness gradually decreasing portion.

  Specifically, as illustrated in FIGS. 2 and 3, the rolling tooth type tooth bottom 2 as the first tooth thickness gradually decreasing portion is inclined downwardly in a substantially straight line at a predetermined first inclination angle β 1. The inclined portion 4 and the second inclined portion 5 in which the rolled tooth bottom 2 as the second tooth thickness gradually decreasing portion is inclined downward with a degree greater than the inclination of the first inclined portion 4 are connected. More specifically, the tooth thickness gradually decreasing portion of the present embodiment is the second inclined portion 5 that is inclined downward substantially linearly at the second inclined angle β2 that is larger than the first inclined portion 4 and the first inclined angle β1. Are connected in series. The degree of inclination referred to here is expressed as a drop amount of the tooth thickness 2 at a predetermined length in the rolling direction, and the tooth thickness gradually decreasing portion (inclined portion) that descends substantially linearly is as described above. May be represented by an inclination angle (β1, β2, etc.).

  As shown in FIG. 8, the tooth thickness gradually decreasing portion reduces the tooth thickness itself of the tooth portion 1 without inclining the tooth bottom (by moving the grinding wheel in the tooth thickness direction or the like from the middle of the relief portion). As shown in FIG. 9, the tooth bottom may be formed in a curved shape that is convex in the direction of the tip of the die, instead of being linearly inclined. Further, as shown in FIG. 10, a third inclined portion 8 or the like may be provided between the first inclined portion 4 and the second inclined portion 5, and the shape may be escaped not only in two steps but also in three or more steps. In FIG. 10, the first inclined portion 4 and the third inclined portion 8 constitute a first tooth thickness gradually decreasing portion on the rolling direction start end side, and the second inclined portion 5 is a second tooth thickness gradually decreasing on the rolling direction end side. It is the aspect which comprises a part.

  Further, in the conventional general flat die X ′ as shown in FIG. 4, the finish B ′ is parallel to the tooth tip 3 ′ and the tooth bottom 2 ′, and the rolling direction of the finish B ′. The length is a length corresponding to 1.5 rotations of the rolled member, and the inclined portion (tooth thickness gradually decreasing portion) in the tooth tip 3 ′ and the tooth bottom 2 ′ of the relief portion C ′ is only one stage, and this relief portion C ′. The length in the rolling direction is set to a length corresponding to two rotations of the rolled member. In this regard, in this embodiment, as shown in FIG. 3, the length in the rolling direction (section G) of the finished portion B (the portion where the tooth tip 3 and the tooth bottom 2 are parallel) is similarly the member to be rolled. Although the length is 1.5 rotations, the root 2 is configured as follows for the escape portion C. That is, the section H of the first inclined portion 4 is longer than the section I of the second inclined portion 5 in order to release the load applied to the rolled member little by little, and is set to be longer than the length corresponding to two rotations of the rolled member. The section I of the second inclined portion 5 is set within a length corresponding to two rotations of the rolled member in order to release the load at once. Specifically, the section H of the first inclined portion 4 is a length corresponding to three rotations of the rolled member, and the section I of the second inclined portion 5 is a length corresponding to one rotation of the rolled member. If the section H is less than the length corresponding to two rotations of the rolled member, the load applied to the rolled member remains almost unreleased, and the remaining load is released at once in the second inclined portion 5. The rolled member may become an ellipse, and the length corresponding to 2 to 4 rotations of the rolled member is considered to be appropriate. Further, if the section I is made longer than the length of two rotations of the rolled member, the incomplete screw (tooth profile) portion may become longer due to the influence of the step. It is better to have a length of 1.5 rotations.

  In addition, the inclination angle γ of the tooth tip 3 of the rolling tooth mold of the relief portion C is the same as the first inclination angle β1 of the tooth root 2 of the rolling tooth mold of the first inclination portion 4 or the first inclination. The angle is set larger than β1. The inventors have obtained the knowledge that when the inclination angle γ of the tooth tip 3 is less than the same angle as the first inclination angle β1, the runout of the rolled member becomes large. . In the present embodiment, the inclination angle γ of the tooth tip 3 and the first inclination angle β1 of the tooth bottom 2 are set to the same angle.

  In addition, the rolling tooth type tip 3 of the relief portion C has the same number of steps as the bottom 2 and the inclination angle γ of each tip 3 is set to the first inclination angle in the first inclined portion 4 region. It may be set to the same angle as β1 and set to the same angle as the second inclination angle β2 in the second inclined portion 5 region.

  Further, the gradual decrease degree of the tooth thickness T (setting of the first inclination angle β1 and the second inclination angle β2) is set as follows based on the experimental results described later as shown in FIG. It is considered preferable. 5 is a schematic cross-sectional view of the end position in the rolling direction of the finishing portion B. FIG. 6 is a perspective view of the schematic position of the end portion in the rolling direction of the first inclined portion 4 in the escape portion C. FIG. 7 is a schematic explanatory perspective view of the escape portion C (the first inclined portion 4 and the second inclined portion 5). In FIG. 7, the relief portion C is a predetermined height position (a predetermined position in a tooth height region from the tooth tip to the tooth bottom when the die bottom surface 6 is used as a reference surface, straight line D). The tooth thickness gradually decreasing portion is formed so that the tooth thickness T of the tooth portion 1 gradually decreases toward the end in the rolling direction.

  The tooth tip position of the rolling tooth mold at the end position in the rolling direction of the escape portion C is compared with the tooth tip position of the rolling tooth mold at the end position in the rolling direction of the finish section B. The length is set to be 0.08 times to 0.3 times lower than the length from the lowest part of the tooth bottom 2 to the tooth tip 3 in the finishing portion B, which is a section where the tooth tip 3 and the tooth bottom 2 are parallel.

  That is, the inclination angle γ of the tooth tip 3 is set so that the tooth tip drop amount M at the rolling direction end position of the relief portion C from the rolling direction end position of the finish portion B is 0.08L to 0.3L. . This is because if it is less than 0.08L, the tooth surface is likely to be damaged, and if it exceeds 0.3L, the outer shape of the valley of the rolled member tends to be elliptical.

  In addition, the rolling tooth mold finishing portion of the rolling tooth mold at the rolling direction end position of the relief portion C is opposite to the rolling tooth mold bottom position of the finishing portion B at the rolling direction terminal position. It is set to be 0.1 to 0.4 times lower than the tooth height L in B.

  That is, the amount of tooth bottom drop at the rolling direction end position of the relief portion C from the rolling direction end position of the finish portion B, that is, the total tooth bottom drop amount N at the relief portion C is 0.1L to 0.4L. Set as follows. When the total drop amount N of the tooth bottom is less than 0.1 L, the tooth surface and the outer peripheral portion (mountain portion) of the rolled member are likely to be damaged, or the outer shape of the rolled member is likely to be elliptical. This is because the load applied to the rolled member cannot be reduced little by little when it exceeds 4L, and the load is released at a stretch, so that the outer shape of the rolled member tends to be elliptical.

  In the present embodiment, specifically, the root position of the rolling tooth mold at the end position in the rolling direction of the first inclined portion 4 is the bottom of the rolling tooth mold at the end position in the rolling direction of the finished portion B. It is set to be 0.05 to 0.2 times lower than the tooth height L in the finished part B of the rolling tooth mold with respect to the position, and the rolling tooth mold of the second inclined part 5 at the end position in the rolling direction is set. The tooth bottom position is 0.05 times to 0.2 times the tooth height L in the finished part B of the rolling tooth mold with respect to the tooth bottom position of the rolling tooth mold at the rolling direction end position of the first inclined portion 4. Set to lower.

  That is, the first inclination is such that the amount of tooth bottom drop N1 in the rolling direction end position of the first inclined part 4 of the escape portion C from the rolling direction end position of the finishing part B is 0.05L to 0.2L. The angle β1 is set, and the tooth bottom drop amount N2 at the rolling direction end position of the second inclined portion 5 from the rolling direction end position of the first inclined portion 4 of the escape portion C is 0.05L to 0.2L. Thus, the second inclination angle β2 is set. When the tooth bottom drop amount N1 is less than 0.05L, the tooth surface and the outer peripheral portion (mountain portion) of the rolled member are likely to be damaged, or the outer shape of the workpiece is likely to be elliptical. This is because the load applied to the member to be rolled cannot be reduced little by little and the load is released at a stretch, so that the outer shape of the member to be rolled tends to be elliptical. If the tooth bottom drop amount N2 is less than 0.05L, this means that the difference between the first inclined portion 4 and the second inclined portion 5 is too small. When the effect cannot be obtained (the tooth surface is likely to be damaged), and the rolling process is completed before the spring back is completely removed, and the rolled member is separated from the end portion of the die escape portion. As a result, the load is released at a stretch and springs back, so that the tooth surface and the outer peripheral portion of the rolled member are damaged. Further, if it exceeds 0.2L, this means that the second inclination angle β2 becomes large, and the first inclined part 4 and the second inclined part 5 are connected with a sudden angle difference, This is because the workpiece is easily damaged.

  In consideration of the above points, in Experimental Example 1 which is the present embodiment, the tooth height L is 1.925 mm, the drop amount M of the tooth tip 3 at the relief portion C is 0.4 mm (0.208 L), and the tooth tip 3 Is set to 0.35 °. Further, the tooth thickness gradually decreasing portion is configured as follows, and the total drop amount N of the tooth bottom is set to 0.6 mm (0.312 L). Specifically, the first inclined portion 4 of the root is set with a first inclination angle β1 of 0.35 ° (γ = β1), and the section H is set to a length corresponding to three rotations of the rolled member. The drop amount N1 of the tooth bottom is set to 0.3 mm (0.156 L). Further, a second inclined portion 5 of the tooth base is provided continuously with the first inclined portion 4 of the tooth bottom, and the second inclined portion 5 of the tooth bottom sets the second inclination angle β2 to 1.04 °. In the section I, the length N1 of the bottom of the rolled member is set to 0.3 mm (0.156 L).

  Further, as shown in another experimental example of FIG. 14, the tooth tip position and the root position of the rolling tooth mold at the end position in the rolling direction of the finish portion B, and the end position in the rolling direction of the first inclined portion 4. If the root position of the rolling tooth mold and the root position of the rolling tooth mold at the end position in the rolling direction of the second inclined portion 5 are within the appropriate ranges shown above, the tooth surface will be damaged. The effect can be exhibited not only in the prevention effect but also in other points such as the outer shape of the rolled member becomes an ellipse.

  In addition, when considering a flaw on the tooth surface, a chamfered portion 7 is provided on the tooth tip 3 of the rolling tooth mold of the relief portion C, as in another example 4 shown in FIG. It is possible to prevent scratches. Although this chamfering may be provided over the entire region of the tooth tip 3 of the relief portion C, it is not always necessary to provide the chamfering over the entire region. More preferably, the chamfered portion 7 is chamfered with a width of 0.05 mm or more in the tooth thickness direction of the cross section perpendicular to the rolling direction (hereinafter referred to as a chamfered width) at the end position of the relief portion C in the rolling direction. The chamfered portion 7 has a length of at least 3 mm or a quarter length of the outer peripheral length of the member to be rolled (one quarter rotation of the workpiece) in the rolling direction from the rolling direction end position of the relief portion C. It is preferable to provide it within a range that is equal to or longer than the shorter one of the two). Even if the chamfered shape is substantially planar, it has a sufficient effect of preventing scratches, but it is more effective if it is formed in a curved shape that protrudes outward from the tooth portion 1. In this embodiment, as shown in FIG. 11, it is a substantially planar shape that is substantially triangular in appearance, and the chamfer width is 0.08 mm at the rolling direction end position of the relief portion C, and the work is rotated by one rotation in the rolling direction. A chamfered portion 7 having a length of 1 mm is provided (this experimental example 2 shown in FIG. 14 has a configuration in which only the chamfered portion 7 is provided with the same specifications as the experimental example 1).

  Further, in this embodiment, the shape of the tooth portion 1 in the rolling die has a substantially trapezoidal shape in a sectional view in which the thickness (tooth thickness T) decreases toward the tooth tip side, while the tooth gap The shape of this is a shape that has a substantially trapezoidal shape in a sectional view, the width of which becomes smaller toward the tooth bottom side. A worm is formed by this rolling tooth mold, and the rolling tooth mold shown in FIG. It is considered to be particularly effective when the pressure angle α of the tooth portion 1 is 3 ° to 25 °. When the angle is smaller than 3 °, the tooth shape is not a trapezoidal shape but a substantially rectangular shape. Even if the tooth bottom is sharply inclined at the second inclined portion 5 to escape, the gap in the tooth thickness direction hardly occurs. When forming the second inclined portion 5 of the present embodiment, the grinding wheel is pressed deeper (in the direction of the bottom surface of the die) than when the first inclined portion 4 is formed, so as to form a deeper tooth gap. Since the tooth thickness is reduced, the smaller the pressure angle α is, the more the tooth shape of the die becomes rectangular. The gap in the tooth thickness direction can hardly be secured, and the effect of the present invention cannot be obtained. If the angle exceeds 25 °, the clearance in the tooth thickness direction can be kept large without increasing the depth to which the grinding wheel is pressed. Therefore, the relief part is the relief part of the rolling die even in the normal specification (one-stage relief). This is because it is difficult for the tooth surface of the workpiece, which is the subject of this time, to be damaged on the end surface.

  As described above, in this embodiment, the biting part A, the finishing part B, and the relief part C are illustrated in FIGS. A configuration applicable to reciprocating rolling as shown in FIG. Specifically, in the rolling direction, the finish direction (B, b) along the surface parallel to the bottom surface 6 (the die reference surface), the rolling direction outward side (the rolling direction start side or the rolling direction) It is good also as a structure which forms a biting part by making into a relief part of the same specification along the surface which inclines to a bottom face side, so that it goes to the manufacturing direction termination side. By adopting such a configuration, it becomes possible to perform rolling processing during reciprocating movement instead of rolling processing only during one-way movement of the die, and the rolling processing efficiency is improved. In particular, the reciprocating rolling is very effective when using a rolled member made of a material that hardly causes a step during rolling. When performing reciprocating rolling, the member to be rolled is rotatably supported at a predetermined position, and rotates according to the direction of movement of the die during the rolling process. For example, the rolled member W is supplied to a predetermined position, and the rolled member W is rotatably supported by a center member (not shown), and a pair of dies Y indicated by solid lines are opposite to each other in the directions of black arrows. Move to, and roll processing. At this time, the rolled member W rotates in the direction of the black arrow shown in the vicinity of the rolled member W. The position of the die Y after the rolling process is represented by the die Y indicated by a two-dot chain line. Next, the member to be rolled W is replaced with the material before the rolling process, and the pair of dies Y indicated by the two-dot chain line moves in the opposite direction, that is, in the direction of the white arrow, to perform the rolling process. At this time, the rolled member W rotates in the direction of the white arrow shown in the vicinity of the rolled member W. The position of the die Y after the rolling process is not shown.

  In the figure, A, B, and C are when the rolling process is performed by the die Y indicated by a solid line (when the direction of movement of the die and the direction of rotation of the rolled member W are represented by the direction of the black arrow. ) Shows a biting part A, a finishing part B, and a relief part C. The section of the first tooth thickness gradually decreasing part (first inclined part) in the relief part C at this time is H, and the second tooth thickness gradually decreasing part (second The section of (inclined part) is shown as I. In addition, a, b, and c are formed by rolling with a die Y indicated by a two-dot chain line (the direction of movement of the die and the direction of rotation of the rolled member W are represented by directions of white arrows. A chamfered portion a, a finished portion b, and a relief portion c, and a section of the first tooth thickness gradually decreasing portion (first inclined portion) in the relief portion c at this time is represented by h and a second tooth thickness gradually decreasing portion ( A section of (second inclined portion) is indicated by i.

  In addition, along the surface which inclines to the bottom side, as it goes to the rolling direction outward side (rolling direction start end side or rolling direction end side) between B and A in the figure or between B and C. A portion corresponding to the intermediate finish portion may be provided.

  The present embodiment is an example in which the present invention is applied to the flat die X, but it is applied to a so-called cut-out die Q having a shape in which a part of a substantially cylindrical outer periphery is notched as shown in FIG. The same applies to the fifth example. The description of the case of the flat die X described above can also be applied to the missing circular die Q. The rotation direction of the round die D is the rolling direction, and the rolling tooth mold of the die has a distance r (hereinafter referred to as a radius r) from the rotation axis O to the tooth tip in order from the rolling direction start end side. However, the biting part A, the finishing part B, and the relief part C, which are different from each other, are continuously provided. In addition, the rolling tooth mold is formed by grinding a die base material that has been previously machined to a predetermined size.

  Finished portion B is along the circumferential surface having a constant radius r in the rolling direction, and biting portion A is along the circumferential surface where radius r decreases toward the starting end side in the rolling direction. Is along the circumferential surface where the radius r decreases toward the end in the rolling direction.

  Accordingly, the pair of cutout dies Q arranged opposite to each other rotate synchronously, so that the intervals at the chamfered portion A, the finished portion B, and the escape portion C are different (specifically, the most spaced at the finished portion B). The rolled member sandwiched between the pair of cutout dies Q is applied with pressure while being rotated, and a worm or screw tooth profile (thread) is formed.

  Note that in the case of the above-mentioned circular die, the bottom surface (die reference surface) that serves as a reference for the inclination of the bottom of the flat die X may be read as the rotation axis O of the circular die. That is, the predetermined height position in the relief portion C may be interpreted as a predetermined position in the tooth height region from the tooth tip to the tooth bottom when the rotation axis O is used as a reference, and the tooth thickness is thin at the height position. It has become.

  Specifically, in another example 5, the amount M of the tooth tip drop is r1 (distance from the rotation axis O to the tooth tip 3 at the start position of the relief portion C in the rolling direction) −r2 (the distance of the relief portion C from the rotation axis O). The distance to the tooth tip 3 at the end position in the rolling direction). Further, the amount of tooth bottom drop from the rolling direction end position of the finishing portion B to the rolling direction end position of the first inclined portion 4 (in the flat die X, the escape portion C from the rolling direction end position of the finishing portion B). The tooth bottom drop amount N1 at the rolling direction end position of the first inclined portion 4 is r3 (the distance from the rotation axis O to the tooth bottom 2 at the rolling direction start end position of the first inclined portion 4 of the escape portion C). ) -R4 (distance from the rotation axis O to the root 2 at the end position in the rolling direction of the first inclined portion 4 of the escape portion C). Further, the amount of tooth bottom drop from the rolling direction end position of the first inclined portion 4 to the rolling direction end position of the second inclined portion 5 (the rolling direction of the first inclined portion 4 of the relief portion C in the flat die X). The tooth bottom drop amount N2 at the rolling direction end position of the second inclined portion 5 from the end position is r4 (the tooth bottom at the rolling direction end position of the first inclined portion 4 of the escape portion C from the rotation axis O). 2) −r5 (distance from the rotation axis O to the root 2 at the end position in the rolling direction of the second inclined portion 5 of the escape portion C). Further, the amount of tooth bottom drop at the end in the rolling direction of the escape portion C from the end of the finish portion B in the rolling direction, that is, the total amount N of the bottom loss at the escape portion C is the sum of N1 and N2. Or r3 (distance from the rotation axis O to the root 2 at the rolling direction start end position of the first inclined portion 4 of the escape portion C) -r5 (second inclined portion of the escape portion C from the rotation axis O). The distance to the tooth bottom 2 at the end position in the rolling direction 5). In the figure, θ1 is the range of the relief portion C, θ2 is the range of the first inclined portion 4 (corresponding to the section H in the flat die X), and θ3 is the range of the second inclined portion 5 (section I in the flat die X). Equivalent).

  Therefore, the tip drop amount M (= r1-r2) is set to 0.08L to 0.3L (L is the tooth height in the finished portion B of the rolled tooth mold) in the range of the clearance portion C (the range of θ1). .Theta.2 is set so that the range of the first inclined portion 4 corresponding to the section H in the flat die X is equal to or longer than the length of 2 rotations of the rolled member, more preferably 2 to 4 rotations. Then, the bottom drop amount N1 (= r3-r4) in this range is set to 0.05 L to 0.2 L (L is the tooth height in the finished portion B of the rolled tooth mold), and the section in the flat die X Θ3 is set so that the range of the second inclined portion 5 corresponding to I is equal to or less than the length of 2 rotations of the rolled member, more preferably 0.125 to 1.5 rotations, The amount of tooth bottom drop N2 (= r4-r5) in this range is 0.05L to 0.2L (L is the finish of the rolling tooth mold) By setting the tooth height) in Part B, it is possible to prevent the scratches caused on the tooth surface of the workpiece as with flat dies.

  Since the present embodiment is configured as described above, the tooth thickness gradually decreasing portion on the rolling direction start end side when releasing the load applied to the rolled member in the escape portion C after machining in the biting portion A and finishing portion B. The load is released little by little (so that the outer shape of the rolled member does not become approximately elliptical), and the load is released at a stretch in the tooth thickness gradually decreasing portion at the end of the rolling direction, and the tooth thickness direction of the rolled tooth type The amount of spring back of the rolled member can be released in the gap generated in (the tooth thickness gradually decreasing portion on the rolling direction end side has a smaller tooth thickness, and the tooth thickness gradually decreasing portion on the rolling direction end side) In this case, the gap between the rolling tooth mold and the member to be rolled increases. Therefore, it becomes possible to suppress the interference between the rolled member and the rolling tooth mold as much as possible.

  Therefore, this embodiment can prevent the tooth surface of the rolled member from being damaged by suppressing the interference between the rolled member and the rolling tooth mold of the die as much as possible in the escape portion. .

  An experimental example supporting the effect of the present embodiment will be described.

  That is, it was confirmed whether or not the tooth surface was damaged or other problems were caused by variously changing the pressure angle, the tip drop amount, and the bottom drop amount. FIG. 14 shows experimental conditions and experimental results.

  All of the experimental examples are formed with worms, the experimental example 1 has the configuration of the present example, the experimental example 2 has the configuration of the above-described another example 4, and the experimental example 5 has the configuration of the above-described another example 5. . Note that Experimental Example 5 is a round die, and the other experimental examples are flat dies.

  In Experimental Examples 4 and 6, it was confirmed that the tooth surface of the rolled member (work) was damaged as shown in FIG. In Experimental Examples 3, 8, and 10, it was confirmed that the outer shape of the workpiece and the outer shape of the valley portion of the workpiece were elliptical, although no scratch was generated on the tooth surface of the workpiece. From these experimental results, it was confirmed that problems other than the scratches on the tooth surface occurred when the configuration of the relief portion, such as the amount of tip drop or the amount of tooth bottom drop, was outside the appropriate range.

  In Experimental Examples 1, 2, 5, 7, and 9, the tooth surface is not damaged as illustrated in FIG. 15B, and the outer shape of the workpiece and the outer shape of the valley portion of the workpiece are elliptical. Thus, it was confirmed that a good rolled product could be obtained.

  From the above, it is preferable to set the tip drop amount M at the rolling direction end position of the escape portion C from the rolling direction end position of the finishing part B to 0.08L to 0.3L. The bottom drop amount N1 at the rolling direction end position of the first inclined portion 4 of the relief portion C from the direction end position is 0.05L to 0.2L, and the rolling direction end position of the first inclined portion 4 of the relief portion C It is considered that the bottom drop amount N2 at the rolling direction end position of the second inclined portion 5 is preferably set to 0.05L to 0.2L.

1 tooth part 2 tooth bottom 3 tooth tip 4 first inclined part 5 second inclined part 7 chamfered part A chamfered part B finishing part C relief part L tooth height T tooth thickness α pressure angle

In the rolling process, it is common to gradually release the load applied to the member to be rolled at the time of machining at the biting part and finishing part of the rolling die at the escape part. For example, the shape of the relief part is inclined so that the rolling tooth mold ( tooth tip ) is separated from the rolled member as the rolling process progresses (toward the rolling direction end side), that is, by gently releasing the load. Is gradually released to gradually cause a phenomenon (spring back) in which the rolled member attempts to return to the state before processing. Usually, the rolling tooth mold (tooth tip) of the relief portion is formed in a one-step inclined manner. It is known that the shape of the relief portion having such a shape can prevent shape defects such as the outer shape of the rolled member being substantially elliptical.

Claims (11)

  A rolling die for rolling a desired tooth shape by plastically deforming the outer peripheral surface by bringing a rolling tooth die into contact with the outer peripheral surface of a rolled member, wherein the rolling tooth die is a bite portion, finish The tooth thickness of each tooth portion of the rolling tooth mold at a predetermined height gradually decreases from the rolling direction start end side to the rolling direction end side in the escape portion. The tooth thickness gradually decreasing portion is configured such that the gradually decreasing degree of the tooth thickness on the end side in the rolling direction in the escape portion is larger than the gradually decreasing degree of the tooth thickness on the starting end side in the rolling direction. Rolling dies characterized by being made.   The rolling die according to claim 1, wherein a bottom of the rolling tooth mold at the relief portion is configured to incline downward toward the end in the rolling direction.   3. The rolling die according to claim 2, wherein the tip position of the rolling tooth mold at the rolling direction end position of the relief portion C is the tip of the rolling tooth mold at the rolling direction end position of the finishing section. A rolling die characterized in that it is configured to be 0.08 to 0.3 times lower than the tooth height in the finished portion of the rolled tooth mold with respect to the position.   4. The rolling die according to claim 2, wherein a bottom position of the rolling tooth mold in the rolling direction end position of the relief portion is the rolling position in the rolling direction end position of the finish portion. 5. A rolling die characterized by being configured to be 0.1 to 0.4 times lower than a tooth height in a finished portion of the rolled tooth mold with respect to a tooth bottom position of the tooth forming mold.   5. The rolling die according to claim 4, wherein a first tooth thickness gradually decreasing portion is provided at a rolling direction start end side of the relief portion, and a second tooth thickness gradually decreasing portion is provided at a rolling direction end side of the relief portion. The bottom position of the rolling tooth mold at the rolling direction end position of the first tooth thickness gradually decreasing portion is relative to the bottom position of the rolling tooth mold at the rolling direction end position of the finishing section. The tooth bottom position of the rolling tooth mold is configured to be 0.05 to 0.2 times lower than the tooth height in the finished part of the rolling tooth mold, and the rolling tooth end position of the second tooth thickness gradually decreasing portion. Is 0.05 times to 0.2 times lower than the tooth height of the finished portion of the rolling tooth mold with respect to the root position of the rolling tooth mold at the end position in the rolling direction of the first tooth thickness gradually decreasing portion. A rolling die characterized in that it is configured as follows.   The rolling die according to claim 5, wherein the first inclined portion in which the bottom of the rolling tooth mold as the first tooth thickness gradually decreasing portion is inclined substantially linearly at a predetermined first inclination angle; A rolling die characterized in that a second inclined portion is provided, the second inclined portion as the second tooth thickness gradually decreasing portion is provided so that the bottom of the rolling tooth mold is inclined downward to a degree larger than the inclination of the first inclined portion. .   The rolling die according to any one of claims 5 and 6, wherein a bottom of the rolling tooth mold as the first tooth thickness gradually decreasing portion is inclined downward substantially linearly at a predetermined first inclination angle. A first inclined portion, and a second inclined portion in which the rolled tooth bottom as the second tooth thickness gradually decreasing portion is inclined substantially linearly at a second inclination angle larger than the first inclination angle; A rolling die characterized in that is provided.   The rolling die according to any one of claims 3 to 7, wherein an inclination angle of a tip of the rolling tooth mold of the relief portion is the tooth bottom of the rolling tooth mold of the first inclined portion. A rolling die characterized by being set to the same angle as the first inclination angle or an angle larger than the first inclination angle.   The rolling die according to any one of claims 1 to 8, wherein a chamfered portion having a substantially planar shape or a curved surface is provided on a tooth tip of the rolling tooth mold of the relief portion. Rolling dies.   The rolling die according to claim 9, wherein the chamfered portion is chamfered with a width of 0.05 mm or more in a tooth thickness direction of a cross section perpendicular to the rolling direction at a rolling direction end position of the relief portion, and the chamfered portion. Is provided in the rolling direction from the rolling direction end position of the relief portion in a range of at least 3 mm or a length equal to or shorter than the shorter one of the lengths of the outer circumference of the rolled member. Rolling dies characterized by being made.   The rolling die according to any one of claims 1 to 10, wherein the rolling die is used to form a worm, and a pressure angle of a tooth portion of the rolling tooth mold is 3 ° to 11 °. A rolling die characterized by being set to 25 °.