Rolling die

Abstract

Provided is a rolling die that, in the rolling of a hollow member, neither makes the rolling die large, nor requires the use of a special structure core rod at the time of rolling, and that can suppress elongation deformation of a rolled raw material in the circumferential and axial directions as much as possible, and that can obtain a product having a desired tooth profile. A rolling die that, from the start end side of a bite portion (2) to a position in the rolling direction of the bite portion (2), is provided with a plurality of strip grooves (6) that are inclined at a prescribed inclination angle (α) with respect to the rolling direction in plan view, on each of the processing teeth (5), and that form a plurality of divided processing teeth (5a) through the strip grooves (6), each of the divided processing teeth (5a) being arranged in the rolling direction with a phase difference in the width direction of the die main body (1).

Description

Technical Field

[0001] This invention relates to rolling dies. Background Technology

[0002] Currently, rolling is widely used in the manufacturing of metal splines, saw teeth, gears, screws, lead screws, worm gears, etc. This rolling process uses a rolling die with rolled teeth (processed teeth) to clamp the roughly cylindrical raw material to be rolled, and while applying pressure, the outer peripheral surface of the raw material to be rolled undergoes plastic deformation to form the desired tooth shape.

[0003] Compared with cutting, rolling has the following advantages: excellent mass production capability and is most suitable for mass production; the surface hardness and strength of the rolled product are increased through work hardening; and the surface roughness of the rolled product is improved through the polishing effect of the machining teeth of the rolling die and the rolled raw material.

[0004] Furthermore, splines and sawtooth are also widely used in automotive components such as drive shafts and steering shafts. With the increasing demand for lightweight automobiles in recent years, the requirements for the aforementioned spline and other products (rolled products) have also increased, not only for solid products, but also for hollow products with holes having a circular cross-section along the central axis of a roughly cylindrical shape.

[0005] However, if the raw material being rolled is a hollow part and the outer circumferential surface of the hollow part is rolled, the raw material being rolled will elongate and deform in the circumferential and axial directions, making it impossible to obtain a product with the desired tooth profile. Furthermore, under excessive rolling load, the raw material being rolled may sometimes break.

[0006] In order to prevent the rolled raw material (hollow part) from elongating and deforming in the circumferential and axial directions as much as possible, a rolling process is also adopted in which a rod-shaped mandrel (sometimes called a mandrel, spindle, etc.) is inserted into a hole along the central axis of a roughly cylindrical shape. However, if only a mandrel is used, there is a problem that it is difficult to obtain a product with the desired tooth shape.

[0007] Furthermore, in a typical rolling die or rolling die with a bite-in portion, a finishing portion, and a retraction portion, the bite-in portion is formed such that as rolling processing at the bite-in portion proceeds (to the end of the rolling direction), the amount of pressing (processing amount) of the processing teeth into the rolled material increases. For example, in a rolling die, the processing teeth of the bite-in portion are configured such that the tooth tip line (an imaginary line connecting the tooth tip of the processing teeth) is formed to be inclined closer to the rolled material from the beginning of the rolling direction toward the end of the rolling direction.

[0008] Although attempts were made to prevent the rolled material (hollow part) from elongating in the circumferential and axial directions by gradually applying rolling load to the raw material by reducing the inclination of the tooth tip line of the biting part, the problem of not being able to obtain a product with the desired tooth profile was not solved. Moreover, the length of the biting part needs to be increased, which leads to the problem of having to increase the size of the rolling die.

[0009] Therefore, in manufacturing hollow products like the above, the following manufacturing method is generally adopted: rolling a solid part of a roughly cylindrical shape to form a desired tooth shape such as splines, and then machining a hole with a circular cross section along the central axis of the roughly cylindrical shape to produce a hollow product. However, this method adds a hole machining step, which increases the manufacturing cost.

[0010] Therefore, a rolling process for hollow parts, as shown in Patent Documents 1 and 2, has been proposed.

[0011] Patent Document 1: Japanese Patent Application Publication No. 2014-054644

[0012] Patent Document 2: Japanese Patent Application Publication No. 2002-143970

[0013] Patent Document 1 disclosed the following method for rolling a hollow part: a group of hard balls consisting of multiple hard balls is placed in the through hole of a hollow part having a through hole communicating with the openings at both ends; a jig is inserted from the openings at both ends; the hard ball group is pressurized by the two jigs while the hollow part is positioned; the outer peripheral surface of the hollow part is rolled by pressing the toothed processing surface of the rolling die against the outer peripheral surface of the hollow part; after rolling, the hard ball group is taken out from the through hole, thereby manufacturing a hollow rolled product.

[0014] However, this method uses a set of hard balls composed of multiple hard balls instead of a rod-shaped mandrel with a circular cross-section (so-called a round bar). It requires a process of housing the set of hard balls into the through hole of the hollow part, a process of positioning the hollow part while pressurizing the set of hard balls, and a process of removing the set of hard balls from the through hole after rolling. Therefore, it has the problem of time consumption and cannot take advantage of the excellent mass production performance and suitability for mass production of rolling.

[0015] Furthermore, Patent Document 2 disclosed a method for manufacturing a hollow gear as follows: an inner diameter mandrel with concave and convex portions on its outer circumferential surface is inserted into the central shaft hole of a cylindrical workpiece. While rotating the workpiece and the inner diameter mandrel together, the tooth-shaped processing surface of a rolling die is pressed against the outer circumferential surface of the workpiece, thereby forming a tooth shape on the outer circumferential surface. The concave portions and convex portions of the aforementioned concave and convex portions extend axially parallel to each other and are continuously arranged in the circumferential direction. Since the rolling is performed while pressing the convex portions provided on the outer circumferential surface of the inner diameter mandrel against the inner circumferential surface of the workpiece, the material flow in the circumferential direction of the inner circumferential surface of the workpiece can be restricted by the convex portions, and the circumferential expansion of the workpiece in the circumferential direction can be suppressed.

[0016] However, this method involves rolling while pressing the protrusions on the outer circumferential surface of the inner diameter mandrel (mandrel) against the inner circumferential surface of the workpiece. Therefore, not only does the inner circumferential surface of the workpiece sometimes deform and fail to meet the dimensional standard of the inner diameter of the workpiece, but it also takes time to remove the workpiece from the inner diameter mandrel (mandrel), and sometimes it is even impossible to disassemble it. Summary of the Invention

[0017] The present invention was made in view of the current situation, and its purpose is to provide a rolling die that, in the rolling process of hollow parts, neither makes the rolling die large-scale nor requires the use of a mandrel with a special structure during the rolling process, and can suppress the elongation deformation of the rolled raw material in the circumferential and axial directions as much as possible, so as to obtain a product with a desired tooth shape.

[0018] The main points of the invention will be described with reference to the accompanying drawings.

[0019] A rolling die, extending from the beginning of the rolling direction of the die body (1) toward the end of the rolling direction, has a biting part (2), a finishing part (3), and a retraction part (4) respectively provided with processing teeth (5), wherein the outer peripheral surface of the raw material (W) being rolled is plastically deformed by the processing teeth (5) to roll out the desired tooth shape, characterized in that, from the beginning of the biting part (2) to a predetermined position in the rolling direction of the biting part (2), a plurality of grooves (6) are provided on each of the processing teeth (5), which are inclined at a predetermined angle (α) relative to the rolling direction when viewed from above, and a plurality of segmented processing teeth (5a) are formed by the grooves (6), and each of the segmented processing teeth (5a) is arranged in the rolling direction with a phase difference in the width direction of the die body (1).

[0020] Furthermore, in the rolling die described in technical solution 1, the characteristic is that the splitting processing tooth (5a) is arranged in such a way that it can process the entire area of ​​the rolling width of the raw material (W) in the splitting processing tooth area (7) in which the splitting processing tooth (5a) is arranged, such that it has a phase difference.

[0021] Furthermore, in the rolling die described in technical solution 1, the groove (6) is provided from the beginning position of the biting part 2 to a position of 60% to 95% of the length (L2) of the biting part (2).

[0022] Furthermore, in the rolling die described in technical solution 2, the groove (6) is provided from the beginning position of the biting part 2 to a position of 60% to 95% of the length (L2) of the biting part (2).

[0023] Furthermore, in the rolling die described in technical solution 1, the groove (6) is positioned at a distance from the beginning of the bite portion 2 to a position at 60% to 95% of the length (L2) of the bite portion (2).

[0024] Furthermore, in the rolling die described in technical solution 2, the groove (6) is positioned at a distance from the beginning of the bite portion 2 to a position at 60% to 95% of the length (L2) of the bite portion (2).

[0025] Furthermore, in the rolling die described in technical solution 1, the rolling die is characterized in that the tooth width (W1) of the split processing tooth (5a) is 3.3 mm or less, and the grooves (6) are provided at equal intervals in the tooth line direction of the split processing tooth (5a).

[0026] Furthermore, in the rolling die described in technical solution 2, the rolling die is characterized in that the tooth width (W1) of the split processing tooth (5a) is 3.3 mm or less, and the grooves (6) are provided at equal intervals in the tooth line direction of the split processing tooth (5a).

[0027] Furthermore, in the rolling die described in technical solution 3, the rolling die is characterized in that the tooth width (W1) of the split processing tooth (5a) is 3.3 mm or less, and the grooves (6) are provided at equal intervals in the tooth line direction of the split processing tooth (5a).

[0028] Furthermore, in the rolling die described in technical solution 4, the rolling die is characterized in that the tooth width (W1) of the splitting processing tooth (5a) is 3.3 mm or less, and the grooves (6) are provided at equal intervals in the tooth line direction of the splitting processing tooth (5a).

[0029] Furthermore, in the rolling die described in technical solution 5, the rolling die is characterized in that the tooth width (W1) of the splitting processing tooth (5a) is 3.3 mm or less, and the grooves (6) are provided at equal intervals in the tooth line direction of the splitting processing tooth (5a).

[0030] Furthermore, in the rolling die described in technical solution 6, the rolling die is characterized in that the tooth width (W1) of the splitting processing tooth (5a) is 3.3 mm or less, and the grooves (6) are provided at equal intervals in the tooth line direction of the splitting processing tooth (5a).

[0031] Furthermore, in any one of the rolling dies described in technical solutions 1 to 12, the tilt angle (α) is characterized in that it is 0.35° to 7.10°.

[0032] Furthermore, in any one of the rolling dies described in technical solutions 1 to 12, the characteristic is that, when viewed from above, the groove (6) is arranged in a straight line.

[0033] Furthermore, in the rolling die described in technical solution 13, the characteristic is that, when viewed from above, the groove (6) is arranged in a straight line.

[0034] Furthermore, in any one of the rolling dies described in technical solutions 1 to 12, a tapering portion (7b) is provided within a predetermined range on the rolling direction end side of the region (7) where the cutting teeth (5a) are provided. The tapering portion (7b) is configured such that as it moves toward the rolling direction end, the groove depth (D) of the groove (6) gradually becomes shallower and the groove width (W2) of the groove (6) gradually becomes narrower.

[0035] Furthermore, in the rolling die described in technical solution 13, a tapering portion (7b) is provided within a predetermined range on the rolling direction end side of the region (7) where the cutting teeth (5a) are provided. The tapering portion (7b) is configured such that as it moves toward the rolling direction end, the groove depth (D) of the groove (6) gradually becomes shallower and the groove width (W2) of the groove (6) gradually becomes narrower.

[0036] Furthermore, in the rolling die described in technical solution 14, a tapering portion (7b) is provided within a predetermined range on the rolling direction end side of the region (7) where the cutting teeth (5a) are provided. The tapering portion (7b) is configured such that as it moves toward the rolling direction end, the groove depth (D) of the groove (6) gradually becomes shallower and the groove width (W2) of the groove (6) gradually becomes narrower.

[0037] Furthermore, in the rolling die described in technical solution 15, a tapering portion (7b) is provided within a predetermined range on the rolling direction end side of the region (7) where the cutting teeth (5a) are provided. The tapering portion (7b) is configured such that as it moves toward the rolling direction end, the groove depth (D) of the groove (6) gradually becomes shallower and the groove width (W2) of the groove (6) gradually becomes narrower.

[0038] As described above, the present invention is configured to produce a rolling die that, in the rolling of hollow parts, neither increases the size of the rolling die nor requires the use of a specially structured mandrel during rolling, thereby suppressing the elongation deformation of the rolled raw material in the circumferential and axial directions as much as possible, and producing a product with the desired tooth profile. Attached Figure Description

[0039] Figure 1 These are the top view and the front view illustrating this embodiment.

[0040] Figure 2 This is a top view illustrating the segmented processing tooth area of ​​the biting section in this embodiment.

[0041] Figure 3 This is an illustrative side view showing the groove and the splitting teeth of this embodiment.

[0042] Figure 4 These are explanatory front and side views showing the biting part of this embodiment.

[0043] Figure 5 This is a top view illustrating the tapering portion of the bite section in this embodiment.

[0044] Figure 6 This is an explanatory diagram showing the processing teeth (splitting processing teeth) of the first groove for processing the rolled raw material in this embodiment.

[0045] Figure 7 This is a graph showing the measurement results of the overpin diameter in Experiment 1.

[0046] Figure 8 This is a graph showing the measurement results of the tooth root circle diameter in Experiment 1.

[0047] Figure 9 This is a graph showing the measurement results of the cumulative pitch error in Experiment 1.

[0048] Figure 10 This is a graph showing the measurement results of the tooth groove runout in Experiment 1.

[0049] Figure 11These are illustrative side views (a) and illustrative top views (b) showing another example of this embodiment (a shallower type of groove) of the groove and the cutting teeth.

[0050] Figure 12 This is a schematic diagram illustrating the rolling process using the rolling die of this embodiment.

[0051] Figure 13 This is a schematic diagram (a) and a top view (b) of the main parts of a rolling process using another example of this embodiment (applied to the case of rolling a missing circle die).

[0052] Figure 14 This is an explanatory diagram showing the processing state of the first groove of the rolled raw material when using this embodiment.

[0053] Figure 15 This is an explanatory diagram showing the processing state of the first groove of the rolled raw material when using this embodiment.

[0054] Figure 16 This is an explanatory diagram showing the processing state of the first groove of the rolled raw material in the case of using an existing example.

[0055] Figure 17 This is a graph showing the measurement results of the span distance in Experiment 3.

[0056] Figure 18 This is a graph showing the measurement results of the tooth root circle diameter in Experiment 3.

[0057] Figure 19 This is a graph showing the measurement results of the tooth profile error in Experiment 3.

[0058] Figure 20 This is a graph showing the measurement results of the tooth line error in Experiment 3.

[0059] Figure 21 This is a graph showing the measurement results of the cumulative pitch error in Experiment 3.

[0060] Figure 22 This is a graph showing the measurement results of the tooth groove runout in Experiment 3.

[0061] Figure 23 This is an explanatory top view showing another example of this embodiment (a type in which the cutting tooth area and the biting part are separated by a predetermined distance).

[0062] Label Explanation

[0063] 1: Mold body; 2: Biting part; 3: Finishing part; 4: Retreat part; 5: Machining tooth; 5a: Separating machining tooth; 6: Groove; 7: Separating machining tooth area; 7b: Gradient part; D: Groove depth; L2: Length of biting part; W: Rolled raw material; W1: Tooth width of separating machining tooth; W2: Groove width; α: Inclination angle of groove. Detailed Implementation

[0064] The function of the present invention is illustrated with reference to the accompanying drawings, and preferred embodiments of the present invention are briefly described.

[0065] In this invention, from the starting end of the biting part 2 to a predetermined position in the rolling direction of the biting part 2, a plurality of grooves 6 are provided on each processing tooth 5, which are inclined at a predetermined angle α relative to the rolling direction when viewed from above. The processing tooth 5 is divided by the grooves 6 to form a plurality of segmented processing teeth 5a. Each of the segmented processing teeth 5a is arranged in the rolling direction with a phase difference in the width direction of the die body 1 (adjacent segmented processing teeth 5a in the rolling direction are not in a state along the rolling direction but in a state staggered in the tooth direction). Therefore, in the segmented processing tooth area 7 of the biting part 2, the raw material W to be rolled is processed intermittently, and the processing load is concentrated on the tooth tip of the segmented processing tooth 5a with a pressing area smaller than that of the processing tooth 5. Even when the raw material W to be rolled is thin-walled and hollow, the elongation deformation of the raw material W in the circumferential and axial directions can be suppressed as much as possible.

[0066] That is, in the existing rolling dies, such as Figure 16 As shown, the top of the machining tooth 25, which extends along the tooth line direction of the die body 21, is pressed into the tooth groove of the rolled material W. Therefore, when the rolled material W is a thin-walled hollow part, it cannot effectively perform the function of raising the wall in the tooth groove of a die used for machining solid parts. As a result, it will be flattened radially without the use of a mandrel, and even with the use of a mandrel, it will deform in the axial and circumferential directions of the rolled material W, making it impossible to plastically process it to the specified tooth shape. In the present invention, for example, as... Figure 14 , Figure 15 As shown, the cutting teeth 5a, relative to the pressed position of the rolled raw material W, move intermittently along the tooth line direction as the rolling process progresses. Furthermore, the area pressed into the rolled raw material W decreases, and the processing load is concentrated at the tooth tip of each cutting tooth 5a. This improves the wall bulging of the rolled raw material W, forming a desired shape. Therefore, even when the rolled raw material W is a thin-walled hollow part, circumferential and axial elongation deformation can be suppressed.

[0067]

Example

[0068] Specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0069] This embodiment relates to a rolling die. The rolling die has a biting part 2, a finishing part 3, and a retraction part 4, which are respectively provided with processing teeth 5, extending from the starting end side of the rolling direction of the die body 1 to the ending end side of the rolling direction. The processing teeth 5 are used to cause plastic deformation of the outer peripheral surface of the raw material W to be rolled, thereby rolling out the desired tooth shape. Specifically, in this embodiment, the rolling die of the present invention is applied to a rolling die for rolling splines, saw teeth, gears, etc.

[0070] The following is a detailed description of the structural components of this embodiment.

[0071] In this embodiment, as Figure 1 As shown, when viewed from above, the mold body 1 is rectangular in shape, the bottom surface 8 is flat as a reference surface, and multiple processing teeth 5, which form a tooth shape for the rolled raw material W, are provided on the upper surface opposite to the bottom surface 8. Figure 1 The description of the main view shows the tooth tip line of the machined tooth 5 as a solid line (an imaginary line connecting the tooth tip of the machined tooth 5). Figure 1 (The image below).

[0072] Furthermore, in this embodiment, the die body 1, with the aim of preventing the rolled raw material W from slipping (preventing the rolled raw material W from shifting its position relative to the processing teeth 5), performs shot peening within a specified range from the beginning of the rolling direction on the upper surface of the die where the processing teeth 5 are provided, toward the end of the rolling direction (in this embodiment, shot peening is performed within approximately 2 / 3 of the length (total length) of the bite portion 2 shown by reference numeral L2 in the figure (the range shown by reference numeral SB in the figure)). Additionally, reference numeral L1 in the figure represents the sum of the rolling direction ranges (lengths) of the bite portion 2, the finishing portion 3, and the retraction portion 4.

[0073] Furthermore, this embodiment uses a conventional rolling die for processing splines (splines with teeth formed parallel to the axial direction of the raw material W being rolled). In the die body 1, from the front view, the processing teeth 5 of the biting part 2, the finishing part 3, and the retraction part 4 are each formed in a mountain shape (approximately trapezoidal shape). These are straight processing teeth that extend linearly in the width direction of the die body 1, specifically in a direction perpendicular to the rolling direction, and are arranged side by side at predetermined intervals in the rolling direction. Moreover, by setting the extension direction of the processing teeth 5 to an angle relative to the direction perpendicular to the rolling direction, this method can be applied to rolling dies used for processing helical splines, helical gears, etc.

[0074] Specifically, regarding the processing teeth 5 of the biting part 2, the tooth height gradually increases from the beginning side of the rolling direction to the end side of the rolling direction, and is configured to gradually press into the outer periphery of the raw material W being rolled, causing it to bulge and form a tooth shape. Furthermore, the processing teeth 5 of the finishing part 3 are set to a constant tooth height (approximately the same tooth height as the processing teeth 5 at the end of the biting part 2), and are configured to finish the tooth shape formed by the biting part 2 to the product size. Moreover, the processing teeth 5 of the yielding part 4 are provided on an inclined surface that slopes downward toward the end side of the rolling direction, and are configured such that the position of the top surface gradually decreases toward the end side of the rolling direction.

[0075] And, as Figure 1 As shown, in this embodiment, the biting portion 2 is configured as a segmented processing tooth region 7 with a plurality of segmented processing teeth 5a from the starting position to a position specified in the rolling direction. These plurality of segmented processing teeth 5a are obtained by segmenting each processing tooth 5 in the width direction of the die body 1 by a plurality of grooves 6. In addition, the reference numeral X in the figure indicates the rolling direction range (length) of the segmented processing tooth region 7.

[0076] In the segmented machining area 7, such as Figure 2 As shown, the cutting teeth 5a are arranged in a straight line in the width direction of the die body 1, and are arranged in a way that has a phase difference in the width direction of the die body 1 in the rolling direction. Specifically, the cutting teeth 5a in the cutting tooth region 7 are arranged in a way that has a phase difference that enables them to process the entire rolling width region or approximately the entire rolling width region of the rolled raw material W in the cutting tooth region 7.

[0077] Here, the rolling width refers to the axial range of the raw material W being rolled to form a tooth shape through rolling processing.

[0078] Furthermore, in this embodiment, the segmentation processing tooth area 7 is provided from the beginning position of the biting part 2 to a position of 60% to 95% of the length L2 of the biting part 2.

[0079] By setting the segmentation processing tooth region 7 from the beginning of the bite portion 2, in other words, the segmentation processing tooth 5a can set the range of the segmentation processing tooth region 7 to be wider within the bite portion 2 of a specified length. As a result, more rolling processing based on the segmentation processing tooth 5a can be performed, and the effect of the present invention, namely, the effect of suppressing the elongation deformation of the rolled raw material W in the circumferential and axial directions, can be better realized.

[0080] Furthermore, the section 7 for the splitting machining teeth may not start from the beginning of the biting section 2, but may adopt a structure that... Figure 23The structure starts at a position that is appropriately spaced from the beginning of the biting part 2, as shown. In this case, the position where the cutting tooth area 7 is set (the starting position of the cutting tooth area 7, in other words, the starting position of the groove 6) is preferably a position that is spaced apart by a distance of 0.5 to 2 revolutions from the rolling material W.

[0081] Furthermore, the reason for setting the range of the cutting teeth 5a to 60% to 95% of the length L2 of the biting portion 2 is that if the cutting teeth 5a are only set to less than half the length of the biting portion 2, the desired effect cannot be achieved. Moreover, if they are set throughout the entire length of the biting portion 2, in other words, if they are set at the boundary with the finishing portion 3, the tooth lines formed on the rolled raw material W may not be neat even after rolling using the cutting teeth 5 of the finishing portion 3, leaving scratches (grooving marks caused by the grooves 6) on the rolled tooth surface. Therefore, the upper limit of the range of the cutting teeth 5a can be set slightly forward of the boundary with the finishing portion 3 (towards the beginning of the rolling direction), and more preferably at 95% of the length L2 of the biting portion 2.

[0082] Furthermore, the groove 6 forming the segmented machining tooth 5a (the groove 6 that segments the machining tooth 5) is formed by grinding using an abrasive tool. Figure 3 The groove shown is a tapered groove whose width increases from the bottom side upwards. Furthermore, the formation of the groove 6 is not limited to the above-described processing; for example, it can also be formed by laser processing.

[0083] Furthermore, regarding the groove width W2 of the groove 6, if the groove width W2 is too narrow relative to the tooth width W1 of the cutting tooth 5a (described later), it becomes similar to the shape of existing products (products without groove 6 and without cutting teeth 5a). Therefore, it is impossible to obtain sufficient deformation suppression effect on the thin-walled rolled raw material W. Moreover, if the groove width W2 is too wide relative to the tooth width W1, an unprocessed portion will appear, resulting in an excessive processing load at the finishing portion 3, causing deformation of the rolled raw material W. Therefore, the groove width W2 of the groove 6 needs to be set according to the tooth width W1 of the cutting tooth 5a.

[0084] In view of this point, the groove width W2 of the groove 6 can be appropriately set within the range without impairing the effect of this embodiment, but it is preferably the same as or narrower than the tooth width W1 of the cutting tooth 5a. Specifically, it is preferred to set the ratio of the tooth width W1 of the cutting tooth 5a to the groove width W2 of the groove 6 to be 0.9 to 1.8.

[0085] Furthermore, the specification where the ratio of the tooth width W1 of the splitting tooth 5a to the groove width W2 of the slot 6 is 0.9 (the specification of Experimental Example 2 described later) is a specification where the groove width W2 is slightly wider than the tooth width W1. In this case, a small amount of unprocessed portion is left in the splitting tooth area 7 of the biting portion 2, but since the rolling width is processed over approximately the entire area, the processing load in the finishing portion 3 will not become too large. Therefore, it is included in the preferred range as described above, and is included in "the groove width is equal to the tooth width W1 of the splitting tooth 5a".

[0086] Furthermore, in this embodiment, as Figure 3 As shown, the groove width W2 of the groove 6 refers to the groove width of the upper edge of the groove 6 (the part with the largest groove width) in the width direction of the mold body 1. Furthermore, in this embodiment, as... Figure 3 As shown, the tooth width W1 of the splitting machining tooth 5a refers to the tooth width of the top surface of the splitting machining tooth 5a in the width direction of the mold body 1.

[0087] Furthermore, in this embodiment, the groove 6 is provided along the inclination of the machining teeth 5 of the bite portion 2 (the inclination of the tooth tip line of the machining teeth 5) from the beginning side of the rolling direction toward the rear side of the rolling direction, and the groove depth D of the groove 6 based on the tooth tip of the machining teeth 5 is set to a constant depth. In addition, the groove depth D of the groove 6 can be appropriately set within the range that does not impair the effect of this embodiment, or it may not be set to a constant depth based on the tooth tip of the machining teeth 5.

[0088] Furthermore, in this embodiment, the groove depth D of the groove 6 is set to a depth greater than or equal to the tooth height of the machined tooth 5, thus completely separating the machined tooth 5. However, any depth sufficient to achieve the desired effect of this embodiment is acceptable, or it can be as follows: Figure 11 The depth D of the groove 6 is set to be shallower than the tooth height of the machining tooth 5, as shown. For example, the groove depth D of the groove 6 can be set according to the machinability of the raw material W being rolled. If the raw material W being rolled is a material that is easy to bulge during rolling (a material with high ductility), the groove depth D of the groove 6 can be set to be deeper (for example, set to be greater than the tooth height of the machining tooth 5). If the material is not easy to bulge (a material with high work hardening), in order to prevent defects during rolling due to the low strength of the cutting machining tooth 5a, the groove depth D of the groove 6 can be set to be shallower (shallower than the tooth height of the machining tooth 5, for example, set to 50% of the tooth height of the machining tooth 5).

[0089] Furthermore, in this embodiment, the grooves 6 are provided at equal intervals in the tooth line direction of the cutting teeth 5a so that the tooth width W1 of the cutting teeth 5a is 3.3 mm or less (if the tooth width W1 of the cutting teeth 5a is set to a value larger than the above value (becoming a width value), the effect of suppressing the deformation of the thin-walled rolled raw material W cannot be fully obtained).

[0090] In addition, as described above, this embodiment is a conventional rolling die for processing splines (splines whose tooth profile is parallel to the axial direction of the raw material W being rolled), so the tooth line direction is consistent with the width direction of the die body 1.

[0091] A narrower tooth width W1 of the cutting tooth 5a is more effective in suppressing deformation of the rolled raw material W, but on the other hand, it is more prone to defects, resulting in a shorter tool life. Therefore, the setting of the tooth width W1 of the cutting tooth 5a needs to consider the balance between suppressing deformation of the rolled raw material W and tool life.

[0092] Specifically, the tooth tip width in the rolling direction of the first tooth of the die is set as a threshold. If the tooth width W1 is narrower than this threshold, defects are very likely to occur. Therefore, the tooth width W1 is preferably set to be greater than or equal to the tooth tip width in the rolling direction of the first tooth of the die.

[0093] In view of this point, the grooves 6 in this embodiment are arranged side by side at equal intervals along the tooth line direction of the segmented processing teeth 5a such that the tooth width W1 of the segmented processing teeth 5a in the complete shape (the state divided by two grooves 6) is 0.5 mm or more and 3.3 mm or less.

[0094] Furthermore, in this embodiment, the groove 6 is inclined relative to the rolling direction toward the width direction of the die body 1, in other words, toward the tooth line direction of the processed tooth 5. Specifically, when viewed from above (along the tooth height direction), it is inclined at a predetermined angle α relative to the rolling direction, and, as... Figure 2 As shown, when viewed from above, each of the strip grooves 6 is arranged in a straight line (straight and continuous) in the rolling direction. By arranging the strip grooves 6 in this way, it is easy to arrange the cutting teeth 5a in the rolling direction with a phase difference in the width direction of the die body 1.

[0095] Furthermore, the groove 6 is not limited to being arranged in a straight line when viewed from above, as in this embodiment; it can also be arranged as follows: Figure 11 As shown in another example of this embodiment (b), when viewed from above, it is arranged in a straight line (straight and discontinuous).

[0096] Specifically, when viewed from above, the groove 6 of this embodiment is inclined at an angle (inclination angle α) of 0.35° to 7.10° relative to the rolling direction. In this embodiment, the amount by which the cutting teeth 5a are pressed deepest into the rolled raw material in the tooth height direction (maximum processing amount) is set to within 0.14 mm, and the groove 6 is set according to the above angle. Thus, in the cutting tooth area 7, the entire rolling width area or approximately the entire rolling width area of ​​the rolled raw material W is processed during the period when the rolled raw material W rotates 0.5 to 2 times, and no unprocessed part is formed. (If the inclination angle α becomes larger, the axial load is applied to the rolled raw material W during rolling, and the possibility of the rolled raw material W bending becomes higher. Therefore, it is preferable to set the inclination angle α to not exceed the above range.)

[0097] The reason why the maximum machining amount of the splitting machining tooth 5a must be set to within 0.14 mm is that, according to the results of various experiments including Experimental Examples 1 to 3 (in this embodiment, the maximum machining amount of the splitting machining tooth 5a is 0.14 mm), when the maximum machining amount exceeds 0.14 mm, the machining load on the rolled raw material becomes too large, and the rolled raw material W will undergo elongation deformation in the circumferential direction and axial direction.

[0098] For example, in the case of a spline machining die with a module of 0.3, a spline tooth count of 66, and a bite-in machining amount of 0.055 mm / turn, if the groove 6 is set such that the entire rolling width area or approximately the entire rolling width area is machined during the rolling of the raw material W in 2 turns, the maximum machining amount of the split machining tooth 5a (machining amount of the second turn) is 0.1375 mm, which is within 0.14 mm, thus achieving the effect of the present invention. In contrast, with a spline machining die having a module of 1.0, 27 spline teeth, and a bite-in machining allowance of 0.14 mm / turn, if the groove 6 is set to machine the entire or approximately the entire rolling width during two rotations of the rolled material W, the maximum machining allowance of the cutting tooth 5a (machining allowance in the second rotation) is 0.35 mm, exceeding 0.14 mm. Therefore, the rolled material W undergoes elongation deformation in both the circumferential and axial directions, resulting in unsatisfactory results. In this case, to ensure the maximum machining allowance does not exceed 0.14 mm, the groove 6 must be set to machine the entire or approximately the entire rolling width every 0.5 rotations.

[0099] Specifically, in the tooth tip circle diameter In the case of a spline with a module of 0.3 and a number of teeth of 66, the total length L of the die body 1 is 410 mm, and the length L2 of the biting part 2 is 289 mm. When the tooth pitch P of the groove 6 is set to 0.782 mm, and the raw material W is rotated 2 revolutions to process the entire or approximately the entire rolling width, the tilt angle α is 0.35° (minimum). When the tooth pitch P of the groove 6 is set to 6.967 mm, and the raw material W is rotated 1 revolution to process the entire or approximately the entire rolling width, the tilt angle α is 5.88° (maximum).

[0100] Furthermore, in the tooth tip circle diameter With a spline of 17.4, a module of 0.47, and 36 teeth, the total length L of the die body 1 is 410 mm, and the L2 of the biting part 2 is 304 mm. When the tooth pitch P of the groove 6 is set to 1.347 mm, and the raw material W is rotated 2 revolutions to process the entire or approximately the entire rolling width, the tilt angle α is 0.73° (minimum). When the tooth pitch P of the groove 6 is 6.967 mm, and the raw material W is rotated 1 revolution to process the entire or approximately the entire rolling width, the tilt angle α is 7.10° (maximum).

[0101] Furthermore, in the tooth tip circle diameter With a module of 1.0 and a number of teeth of 27.5, the tilt angle α is 1.79° to 4.13° (refer to Experimental Examples 1 to 4 described later).

[0102] Furthermore, in this embodiment, a tapering section 7b is provided on the rolling direction end side of the segmented processing tooth region 7.

[0103] Specifically, the reduction section 7b is provided within the range of 6 to 12 processing teeth 5 including the end of the cutting processing tooth region 7. The groove 6 of each processing tooth 5 provided in the reduction section 7b is set to be shallower and narrower than the groove 6 of the cutting processing tooth region 7a on the beginning side of the rolling direction of the reduction section 7b. Moreover, the groove 6 of the processing tooth 5 that is closer to the end of the reduction section 7b is set to be shallower and narrower.

[0104] Furthermore, the groove depth of the groove 6 in the tapering section 7b can be curved and shallower from the boundary between the machining tooth region 7a and the tapering section 7b at the beginning side toward the end of the tapering section 7b. For example, it can also be along a tapering angle g set as follows (refer to...). Figure 4 The slope gradually becomes shallower in a straight line.

[0105] The reduction angle g = arctan(the groove depth D of the groove 6 at the boundary between the starting side split machining area 7a and the reduction section 7b / the length of the reduction section 7b in the rolling direction)

[0106] By providing the tapering section 7b, the shape change of the processing teeth 5 caused by the presence or absence of the groove 6 at the end side of the split processing tooth area 7a on the starting side and the biting section 2 on the end side of the split processing tooth area 7 in the rolling direction can be stabilized, thereby suppressing the rapid change of processing load and suppressing the elongation deformation of the rolled raw material.

[0107] Furthermore, regarding the biting part 2 in this embodiment, as... Figure 1 As shown, the inclination of the tooth tip line is set to be constant, that is, the processing amount of the biting part 2 (the processing amount of the rolled raw material W per revolution) is set to be constant. However, the biting part 2 can also be configured such that a defined range at the beginning of the biting part 2 is defined as the first biting segment, and the remaining biting part 2 is defined as the second biting segment. The inclination of the tooth tip line in the first biting segment is increased, and the inclination of the tooth tip line in the second biting segment is decreased. The processing amount is greater in the first biting segment and less in the second biting segment.

[0108] Furthermore, as described above, this embodiment applies the rolling die of the present invention to... Figure 12 The rolling die shown is an example of a flat rolling die, but the rolling die of the present invention can also be applied to... Figure 13 The rolling die shown is a circular die.

[0109] The rotation direction of the rolling die is the rolling direction. Regarding the rolling teeth formed on its outer circumference, starting from the beginning of the rolling direction, a biting portion 2, a finishing portion 3, and a retraction portion 4 are sequentially arranged, each with different distances from the rotation axis of the rolling die to the tooth tip of the machining tooth 5. Furthermore, in the case of the rolling die, the groove 6 is spirally arranged around the rotation axis of the rolling die with a lead angle α, which corresponds to the tilt angle α in a flat rolling die (see reference). Figure 13 (b)

[0110] By spirally arranging the groove 6 around the rotation axis of the rolling die, the groove 6 is configured to be inclined at a predetermined angle α relative to the rolling direction when viewed from above at the bite portion 2 of the rolling die where the groove 6 is formed, and when viewed from above, it becomes a straight line (a slightly curved, approximately straight line) in the rolling direction. In other words, as... Figure 13As shown in (b), the groove 6 is configured such that, in the unfolded state where the outer peripheral surface of the rolling die is unfolded into a plane, it is inclined at a predetermined angle α relative to the rolling direction, similar to a rolling flat die, and becomes a straight line in the rolling direction when viewed from above. Therefore, in a rolling die, by arranging the groove 6 in a spiral shape around the rotation axis of the rolling die, the same effect as that described below in the case of a rolling flat die is achieved. Furthermore, since the rolling die is approximately cylindrical, the groove 6 located at the left-right end (rolling direction) of the visual confirmation range appears slightly curved when viewed from above, but in this embodiment, this slightly curved appearance also includes "being a straight line when viewed from above".

[0111] As described above, in the biting section 2, the cutting teeth area 7 is processed intermittently while the cutting teeth 5a are moved relative to the pressing position of the rolled material W along the width direction of the die body 1. Moreover, compared with the case where the cutting teeth 5 are used to press the rolled material W, the area pressed into the rolled material W is smaller, and the processing load is concentrated on the tooth tip of each cutting tooth 5a. As a result, the cutting teeth 5 can easily bite into the rolled material W, and even when the rolled material W is a hollow part with a thin wall, circumferential and axial elongation deformation can be suppressed.

[0112] In the rolling process of splines for hollow parts, the larger the ratio of the spline tooth height to the wall thickness of the rolled raw material W, the easier it is for the circumferential and axial elongation deformation to increase, and the more difficult it is to form the desired tooth shape. Furthermore, the larger the ratio of the inner diameter (diameter of the hollow part of the rolled raw material W) to the outer diameter (diameter of the rolled raw material W), that is, the thinner the wall thickness of the rolled raw material W, the easier it is for the circumferential and axial elongation deformation to increase, and the more difficult it is to form the desired tooth shape.

[0113] Specifically, in the applicant's experience to date, assuming a spline with a module of 0.3 to 1.1, the ability to process the rolled raw material W as a hollow component well without a mandrel (without elongation deformation) is limited to situations where the ratio of the spline tooth height to the wall thickness of the rolled raw material W is 17% or less and the ratio of the inner diameter (diameter of the hollow portion of the rolled raw material W) to the outer diameter (diameter of the rolled raw material W) is 47% or less. Furthermore, even with a mandrel, the ability to process the rolled raw material W without a mandrel is limited to situations where the ratio of the spline tooth height to the wall thickness of the rolled raw material W is 20% or less and the ratio of the inner diameter (diameter of the hollow portion of the rolled raw material W) to the outer diameter (diameter of the rolled raw material W) is 47% or less. When the ratio of the spline tooth height to the wall thickness of the rolled material W is 55% or less, processing can be performed well. However, by using this embodiment, even when the conditions are met that the ratio of the spline tooth height to the wall thickness of the rolled material W is 20% or less and the ratio of the inner diameter (diameter of the hollow portion of the rolled material W) to the outer diameter (diameter of the rolled material W) is 55% or less, processing can be performed well without using a mandrel. Furthermore, by using a mandrel, even when the conditions are met that the ratio of the spline tooth height to the wall thickness of the rolled material W is 30% or less and the ratio of the inner diameter (diameter of the hollow portion of the rolled material W) to the outer diameter (diameter of the rolled material W) is 70% or less, processing can be performed well.

[0114] The following is an experiment (evaluation experiment) that confirms the effectiveness of the above embodiment.

[0115] <Experiment 1>

[0116] Using a total of six rolling dies, including existing general rolling dies as shown in Tables 1 and 2 (hereinafter referred to as "existing example 1" and "existing example 2") and rolling dies of Experimental Examples 1 to 4 with different structures such as the tooth width of the split processing tooth 5a in this embodiment, spline rolling of the raw material W, which is a hollow part, was performed using a general mandrel, and the presence or absence of circumferential and axial elongation deformation of the raw material W was evaluated.

[0117] Additionally, regarding the reference numerals listed in Table 1, L: length of the die body 1, L2: length of the biting portion 2, X: rolling direction range (length) of the cutting tooth area 7, X / L2: ratio of the range X (length of the rolling direction range of the cutting tooth area 7) of the cutting tooth area 7 to the length L2 (biting portion length L2) of the biting portion 2 (refer to...). Figure 1 ).

[0118] Furthermore, regarding the reference numerals recorded in Table 2, W1: tooth width of the splitting tooth 5a, W2: groove width of the slot 6, P: tooth pitch of the slot 6, α: inclination angle of the slot 6, β: groove angle of the slot 6, D: groove depth of the slot 6, W3: tooth tip width in the rolling direction of the first tooth of the splitting tooth region 7 in the biting part 2, W1 / W3: tooth width ratio of the splitting tooth 5a, DP: spline tooth pitch of the die (tooth pitch of the spline processing teeth in the rolling direction), W1 / W2: ratio of the tooth width of the splitting tooth 5a to the groove width of the slot 6 (refer to...). Figure 2 , Figure 3 ).

[0119] Table 1

[0120]

[0121] Table 2

[0122]

[0123] Specifically, for hollow raw materials W with varying wall thicknesses (wall thickness 4mm to 8mm), spline rolling was performed using mandrels under the following conditions. The span of the mandrel, root circle diameter, tooth profile error, tooth line error, cumulative tooth pitch error, and tooth groove runout were measured. Based on the measurement results, the presence or absence of circumferential and axial elongation deformation of the rolled raw material W was evaluated.

[0124] <Processing conditions, etc.>

[0125] Spline specifications: Tooth tip circle diameter It is 27.5 × Z, 27 × m, 1.0 × PA, and 37.5°.

[0126] Tooth height: 1.2mm

[0127] Where Z is the number of teeth in the spline, m is the module, and PA is the symbol representing the pressure angle.

[0128] • Material of the raw material being rolled: Carbon steel (S45C)

[0129] • Raw material diameter: 26.46mm

[0130] • Processing volume:

[0131] Existing Example 1 and Experimental Examples 1-3: 0.14 mm / cycle,

[0132] Existing Example 2 and Experimental Example 4: 0.09 mm / turn

[0133] • The tooth height h of the first tooth in the biting part 2:

[0134] Existing Example 1 and Experimental Examples 1-3: 0.6964 mm,

[0135] Existing Example 2 and Experimental Example 4: 0.6464 mm

[0136] • Material of the rolling die: Die steel (SKD11)

[0137] • The distance the raw material travels in the rolling direction per revolution: 83.1 mm

[0138] (= The tooth pitch DP of the machined teeth of the spline in the rolling direction is 3.0777mm × Z is 27)

[0139] • Processing conditions: At the center of the rolling width, the target is the standard median span distance.

[0140] <The mandrel used>

[0141] Material: Carbon steel (quenched)

[0142] • Mandrel dimensions and inner diameter: Refer to Table 3 below

[0143] Table 3

[0144]

[0145] Furthermore, regarding Experimental Examples 1-4, further explanation is provided. Regarding the number of grooves in the rolled raw material W, the first tooth of the die is used as a reference (first groove). In Experimental Examples 1-3, when the biting length L2 of the die is designed to be 449 mm and the number of teeth in the biting part 2 is set to 146, as follows... Figure 6 As shown, in the lower die, the first, 28th, 55th, 82nd, 109th, and 136th teeth (processing teeth 5) are used to process the first groove of the rolled raw material W. In the upper die, by rotating the rolled raw material W half a turn, the same groove as the groove processed by the first tooth of the lower die is processed. Therefore, the 14th, 41st, 68th, 95th, and 122nd teeth (processing teeth 5) are used to process the first groove of the rolled raw material W. In Experimental Example 4, when the bite length L2 of the die is designed to be 754 mm and the number of teeth in the bite part 2 is designed to be 245, as... Figure 6As shown, in the lower die, the processing teeth 5 of the 1st, 28th, 55th, 82nd, 109th, 136th, 163rd, 190th, 217th, and 244th teeth become teeth that process the first groove of the rolled raw material W. In the upper die, by rotating the rolled raw material W half a turn, the same groove as the groove processed by the 1st tooth of the lower die is processed. Therefore, the processing teeth 5 of the 14th, 41st, 68th, 95th, 122nd, 149th, 176th, 203rd, and 230th teeth become teeth that process the first groove of the rolled raw material W. Based on this, in Experiments 1 to 4, the phase of the groove 6 (the offset in the width direction of the die body 1) was set such that the rolled raw material W would be processed over the entire rolling width area or approximately the entire rolling width area every half rotation (0.5 rotations).

[0146] Table 4 shows the standards for each measurement item. Table 5 shows the evaluation results. In the evaluation results, a "○" indicates that all evaluation items (split pitch, root circle diameter, tooth profile error, tooth line error, cumulative pitch error, and tooth space runout) fall within the standards shown in Table 4; a "×" indicates that even if one evaluation item falls outside the standard. A "-" indicates that no evaluation was conducted.

[0147] Table 4

[0148] Spacing between bars [mm] 29.793～29.853 Tooth root circle diameter [mm] 24.90～25.10 Tooth profile error [μm] Under 15 Tooth line error [μm] Below 20 Cumulative pitch error [μm] Below 41 Tooth groove runout [μm] Under 32

[0149] Table 5

[0150] Spline tooth height / wall thickness [%) 15 17 20 24 30 Inner diameter / raw material diameter [%] 40 47 55 62 70 Example 1 ○ ○ ○ × × Example 2 - - - - × Experimental Example 1 ○ ○ ○ ○ × Experimental Example 2 ○ ○ ○ ○ × Experimental Example 3 ○ ○ ○ ○ × Experiment Example 4 ○ ○ ○ ○ ○

[0151] As shown in Table 5, in Existing Example 1, it was confirmed that a good processing shape that suppresses circumferential and axial elongation deformation could be obtained for rolled raw materials W with wall thicknesses of 8 mm, 7 mm, and 6 mm. However, in the case of rolled raw materials W with a wall thickness of 5 mm or less, circumferential and axial elongation deformation occurred. In contrast, in Experimental Examples 1 to 4 (this embodiment), it was confirmed that a good processing shape that suppresses circumferential and axial elongation deformation could also be obtained for rolled raw materials W with a wall thickness of 5 mm in all dies. Furthermore, in Existing Example 2, in which the bite length L2 was set to be longer than that in Existing Example 1 and Experimental Examples 1 to 3, it was confirmed that circumferential and axial elongation deformation also occurred for rolled raw materials W with a wall thickness of 4 mm. In Experimental Example 4 (this embodiment), in which the bite length L2 was set to the same length as that in Existing Example 2, a good processing shape that suppresses circumferential and axial elongation deformation could also be obtained for rolled raw materials W with a wall thickness of 4 mm.

[0152] Furthermore, Table 6 and Figures 7-10 This is a detailed result of spline rolling of the raw material W with a wall thickness of 5 mm, as described in Existing Example 1 and Experimental Examples 1-4.

[0153] Table 6

[0154]

[0155] As shown in Table 6, in the existing example 1, due to circumferential and axial elongation deformation, the three items of span pitch, cumulative tooth pitch error, and tooth groove runout are outside the standard. In contrast, in this embodiment (experimental examples 1-4), none of the items are outside the standard, and a good machining shape with suppressed circumferential and axial elongation deformation can be obtained.

[0156] Furthermore, based on the mold specifications of Experimental Example 1, the groove depth D of the slot 6 was changed to a shallower depth, set at 0.10 mm, and spline rolling processing and evaluation were carried out under the same conditions as the above experiment. Similar to the case where the groove depth D of the slot 6 was 0.95 mm (Experimental Example 1), none of the evaluation items were outside the standard, and a good processing shape with suppressed circumferential and axial elongation deformation was obtained.

[0157] In the spline rolling process of Experimental Example 1, in the splitting tooth area 7 of the bite section 2, for every 0.5 revolutions of the rolled raw material W, the splitting tooth 5a contacts different positions in the rolling width direction (axial direction of the rolled raw material W) for the same tooth groove on the rolled raw material W. This is because the machining amount is 0.14 mm / revolution, so if the groove depth D is set to a depth of 0.07 mm (0.14 mm × 0.5) or more, the groove 6 will not contact the rolled raw material W during the rolling process.

[0158] <Experiment 2>

[0159] In Experiment 2, using the existing Examples 1 and 1-4 from Experiment 1, spline rolling was performed on hollow raw materials W with different wall thicknesses (wall thickness of 6 mm to 8 mm) without the use of mandrels, under the same conditions as in Experiment 1. The span of the mandrel, root circle diameter, tooth profile error, tooth line error, cumulative tooth pitch error, and tooth groove runout were measured. Based on the measurement results, the presence or absence of circumferential and axial elongation deformation of the rolled raw material W was evaluated.

[0160] The evaluation results are shown in Table 7. In addition, as in Experiment 1, in the evaluation results, if all evaluation items, namely the span distance, root circle diameter, tooth profile error, tooth line error, cumulative tooth pitch error, and tooth space runout, are within the standards shown in Table 4, “○” is marked; if even one evaluation item is outside the standard, “×” is marked.

[0161] Table 7

[0162] Spline tooth height / wall thickness [%) 15 17 20 Inner diameter / raw material diameter [%] 40 47 55 Example 1 ○ ○ × Experimental Example 1 ○ ○ ○ Experimental Example 2 ○ ○ ○ Experimental Example 3 ○ ○ ○ Experiment Example 4 ○ ○ ○

[0163] As shown in Table 7, the following results were confirmed: In Existing Example 1, if the wall thickness is not 7 mm or more, it is not possible to obtain a good processing shape that suppresses circumferential and axial elongation deformation. However, in Experimental Examples 1 to 4 (this embodiment), for the rolled raw material W with a wall thickness of 6 mm, even without the use of a mandrel, it is possible to obtain a good processing shape that suppresses circumferential and axial elongation deformation.

[0164] Experiment 3

[0165] In Experiment 3, rolling was performed under different processing conditions than in Experiment 1, including spline specifications and the material of the rolled raw material. The presence or absence of circumferential and axial elongation deformation of the rolled raw material W was evaluated.

[0166] Specifically, using the rolling dies of Examples 5-8, which differ in specifications from those of Examples 1-4 as shown in Tables 8 and 9, spline rolling was performed on the hollow raw material W without the use of a mandrel. The span between mandrels, root circle diameter, tooth profile error, tooth line error, cumulative tooth pitch error, and tooth groove runout were measured. Based on these measurements, the presence or absence of circumferential and axial elongation deformation of the raw material W was evaluated (Examples 7 and 8 evaluated the presence or absence of circumferential and axial elongation deformation of the raw material W when the tooth width W1 of the split processing tooth 5a was set to the minimum width (Example 7) and the maximum width (Example 8)). Furthermore, the descriptions of the reference numerals in Tables 8 and 9 are the same as in Experiment 1, and therefore omitted.

[0167] Table 8

[0168]

[0169] Table 9

[0170]

[0171] <Processing conditions, etc.>

[0172] Spline specifications: Tooth tip circle diameter It is 17.4 × Z, 36 × m, 0.47 × PA, and 45°.

[0173] Tooth height: 0.512mm

[0174] Where Z is the number of teeth in the spline, m is the module, and PA is the symbol representing the pressure angle.

[0175] • Material of the raw material being rolled: Carbon steel (S43C)

[0176] • Raw material diameter: 16.91mm

[0177] • Processing volume:

[0178] Experimental Examples 5, 7, and 8: 0.05 mm / turn.

[0179] Experimental Example 6: 0.031 mm / turn

[0180] • The tooth height h of the first tooth in the bite section 2 is 0.289 mm.

[0181] • Material of the rolling die: Die steel (SKD11)

[0182] • The distance the raw material travels in the rolling direction per revolution: 53.0 mm

[0183] • Processing conditions: At the center of the rolling width, the target is the standard median span distance.

[0184] • No mandrel is used (the two ends of the rolled raw material W are held in the very center).

[0185] In addition, in Experiment 3, the presence or absence of circumferential and axial elongation deformation was evaluated in two types of rolled raw materials W (wall thickness of 4.2 mm and 3.5 mm) used as hollow parts with different wall thicknesses.

[0186] Table 10 shows the standards for each measurement item. Table 11 shows the evaluation results. Figures 17-22 The results of each measurement item in Experiments 5 and 6 are shown. In addition, in the evaluation results, if all evaluation items, namely the span distance, root circle diameter, tooth profile error, tooth line error, cumulative tooth pitch error, and tooth space runout, are within the standards shown in Table 10, “○” is marked; if even one evaluation item is outside the standard, “×” is marked.

[0187] Table 10

[0188] Spacing between bars [mm] 18.52～18.60 Tooth root circle diameter [mm] 16.35～16.40 Tooth profile error [μm] Under 15 Tooth line error [μm] Below 20 Cumulative pitch error [μm] Below 60 Tooth groove runout [μm] Below 35

[0189] Table 11

[0190] Spline tooth height / wall thickness [%) 12 15 Inner diameter / raw material diameter [%] 50 59 Experimental Example 5 ○ ○ Experimental Example 6 ○ ○ Experimental Example 7 ○ ○ Experimental Example 8 ○ ○

[0191] As shown in Table 11, it was confirmed that in all experimental examples 5 to 8, a good processing shape was obtained for any wall thickness, which suppressed circumferential and axial elongation deformation.

[0192] And, as Figures 17-22As shown, Experiment 6 generally achieved better results compared to Experiment 5. This is because the deformation suppression effect was improved by halving the tooth pitch P of the groove 6 and narrowing the tooth width W1 of the split machining tooth 5a to half.

[0193] <Experiment 4>

[0194] In Experiment 4, for splines with different specifications (tooth tip circle diameter) compared to Experiment 3... The diameter of the raw material W to be rolled was set to 20.42 mm (material: carbon steel (S45C)). The raw material W, which is a hollow part, was rolled without the use of a mandrel. The presence or absence of circumferential and axial elongation deformation of the raw material W was evaluated.

[0195] Specifically, the span distance, root circle diameter, and gauge evaluation were measured under the conditions of setting the tooth width W1 of the splitting machining tooth 5a to the minimum width (Experimental Example 9) and the maximum width (Experimental Example 10), as shown in Table 12. Based on these measurement results, the presence or absence of circumferential and axial elongation deformation of the rolled raw material W was evaluated. Furthermore, the setting conditions of each die body 1 in Experimental Examples 9 and 10 are shown in Table 13. The explanations of the labels in Tables 12 and 13 are the same as in Experiment 1, and therefore omitted.

[0196] Table 12

[0197]

[0198] Table 13

[0199]

[0200] Table 14 shows the standards for each measurement item. Table 15 shows the evaluation results. In the evaluation results, a "○" indicates that all evaluation items fall within the standards, while a "×" indicates that even one evaluation item falls outside the standards.

[0201] Table 14

[0202] Spacing between bars [mm] 21.307～21.507 Tooth root circle diameter [mm] 19.754～20.080 Gauge Evaluation Pass, Fail

[0203] Table 15

[0204] Spline tooth height / wall thickness [%) 8 10 Inner diameter / raw material diameter [%] 41 51 Experimental Example 9 ○ ○ Experimental Example 10 ○ ○

[0205] As shown in Table 15, in Experiment 9 where the tooth width W1 of the splitting tooth 5a was set to the minimum width of 0.503 mm and in Experiment 10 where the tooth width W1 was set to the maximum width of 3.3 mm, all evaluation items obtained results within the standard for any wall thickness.

[0206] <Experiment 5>

[0207] In Experiment 5, using dies with different positions of the split processing tooth area 7, the raw material W, which is a hollow part, was rolled without the use of a mandrel, and the presence or absence of circumferential and axial elongation deformation of the raw material W was evaluated.

[0208] Specifically, the span, root circle diameter, tooth profile error, tooth line error, cumulative tooth pitch error, and tooth groove runout were measured in the following cases: when the splitting processing tooth area 7 is set from the beginning of the bite section 2 as shown in Table 16 (Experimental Example 11), and when the splitting processing tooth area 7 is set from a position that is a distance equal to two rotations of the rolled material W away from the beginning of the bite section 2 (Experimental Example 12). Based on the measurement results, the presence or absence of circumferential and axial elongation deformation of the rolled material W was evaluated.

[0209] Additionally, in Experiment 5, for spline specifications with a tooth tip circle diameter... The spline is 18×Z = 22×m = 0.8×PA = 40°, and the diameter of the raw material W to be rolled is set to 16.89 mm (material: carbon steel (S45C)). Furthermore, the setting conditions of the die body 1 for each of Experiments 11 and 12 are shown in Table 17. The explanations of the labels in Tables 16 and 17 are the same as in Experiment 1, and therefore omitted.

[0210] Table 16

[0211]

[0212] Table 17

[0213]

[0214] The evaluation results are shown in Table 18. Additionally, in the evaluation results, a "○" indicates that all evaluation items fall within the standard, while a "×" indicates that even one evaluation item falls outside the standard.

[0215] Table 18

[0216] Spline tooth height / wall thickness [%) 20 25 Inner diameter / raw material diameter [%] 40 52 Experimental Example 11 ○ ○ Experimental Example 12 ○ ○

[0217] As shown in Table 18, even when the cutting tooth area 7 is set at a position that is a distance equal to the amount of two rotations of the rolled raw material W from the beginning of the biting part 2, all evaluation items are within the standard for each wall thickness.

[0218] Furthermore, regarding this embodiment, in Experiments 1 to 5 above, when the rolled raw material W is a hollow part, the excellent effect of the present invention was confirmed. When the rolled raw material W is a solid part for rolling, the elongation deformation of the rolled raw material W in the circumferential and axial directions can be suppressed as much as possible, and an excellent product with the desired tooth shape can be obtained.

[0219] Furthermore, the present invention is not limited to this embodiment, and the specific structure of each constituent element can be appropriately designed.

Claims

1. A rolling die, comprising a biting portion, a finishing portion, and a retraction portion respectively provided with machining teeth from the beginning end side of the rolling direction of the die body toward the end side of the rolling direction, wherein the machining teeth are used to plastically deform the outer peripheral surface of the raw material being rolled, thereby rolling out a desired tooth shape, characterized in that, From the starting end of the biting portion to a predetermined position in the rolling direction of the biting portion, a plurality of grooves are provided on each of the processing teeth, which are inclined at a predetermined angle relative to the rolling direction when viewed from above. A plurality of segmented processing teeth are formed by these grooves. Each of the segmented processing teeth is arranged in the rolling direction with a phase difference in the width direction of the die body. Furthermore, a tapering portion is provided within a predetermined range on the rolling direction end side of the segmented processing tooth area where the segmented processing teeth are provided. The tapering portion is configured such that the groove depth gradually becomes shallower and the groove width gradually becomes narrower as it moves toward the end of the rolling direction.

2. The rolling die according to claim 1, characterized in that, The cutting teeth are arranged in such a way that they have a phase difference that enables them to process the entire area of ​​the rolling width of the rolled raw material in the cutting tooth region where the cutting teeth are arranged.

3. The rolling die according to claim 1, characterized in that, The groove is positioned from the beginning of the bite portion to a position at 60% to 95% of the length of the bite portion.

4. The rolling die according to claim 2, characterized in that, The groove is positioned from the beginning of the bite portion to a position at 60% to 95% of the length of the bite portion.

5. The rolling die according to claim 1, characterized in that, The groove is positioned from a predetermined distance from the beginning of the bite portion to a position at 60% to 95% of the length of the bite portion.

6. The rolling die according to claim 2, characterized in that, The groove is positioned from a predetermined distance from the beginning of the bite portion to a position at 60% to 95% of the length of the bite portion.

7. The rolling die according to claim 1, characterized in that, The rolling die is configured such that the tooth width of the splitting processing teeth is less than 3.3 mm, and the grooves are equally spaced along the tooth line direction of the splitting processing teeth.

8. The rolling die according to claim 2, characterized in that, The rolling die is configured such that the tooth width of the splitting processing teeth is less than 3.3 mm, and the grooves are equally spaced along the tooth line direction of the splitting processing teeth.

9. The rolling die according to claim 3, characterized in that, The rolling die is configured such that the tooth width of the splitting processing teeth is less than 3.3 mm, and the grooves are equally spaced along the tooth line direction of the splitting processing teeth.

10. The rolling die according to claim 4, characterized in that, The rolling die is configured such that the tooth width of the splitting processing teeth is less than 3.3 mm, and the grooves are equally spaced along the tooth line direction of the splitting processing teeth.

11. The rolling die according to claim 5, characterized in that, The rolling die is configured such that the tooth width of the splitting processing teeth is less than 3.3 mm, and the grooves are equally spaced along the tooth line direction of the splitting processing teeth.

12. The rolling die according to claim 6, characterized in that, The rolling die is configured such that the tooth width of the splitting processing teeth is less than 3.3 mm, and the grooves are equally spaced along the tooth line direction of the splitting processing teeth.

13. The rolling die according to any one of claims 1 to 12, characterized in that, The tilt angle is 0.35° to 7.10°.

14. The rolling die according to any one of claims 1 to 12, characterized in that, When viewed from above, the groove is arranged in a straight line.

15. The rolling die according to claim 13, characterized in that, When viewed from above, the groove is arranged in a straight line.

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