TWI845901B - Rolling dies - Google Patents

Abstract

[Topic] The present invention provides a threading die which is most suitable for the flow of rolled materials during rolling processing, prevents the tooth tops of the products from forming incomplete shapes, and does not require the removal of protrusions after rolling processing. [Solution] A threading die used when rolling a spiral tooth shape (21) on the outer peripheral surface of a rolled material (20) comprises a guide cone portion (1), a finishing portion (2) and a clearance portion (3) from the starting end side in the rolling direction to the terminal end side in the rolling direction. The guide cone portion (1), the finishing portion (2) and the clearance portion (3) are respectively provided with processing teeth that abut against the rolled material (20). The processing tooth (4) of the guide cone portion (1) has a mountain-shaped front end portion (7) convex toward the front end at the tooth top. The mountain-shaped front end portion (7) is relative to the tooth thickness center line (C _r ) of the processing tooth (4). ) is configured so that the wall thickness on the starting end side in the rolling direction becomes thicker than the wall thickness on the terminal end side in the rolling direction.

Description

Thread Die

The present invention relates to a threading die.

In the past, in the manufacturing of threads, lead screws, and worms, rolling processing was widely used, in which a threaded die with a rolling die was formed to clamp a roughly cylindrical material to be rolled, and plastic deformation was performed while applying pressure. This rolling process has the advantages of excellent mass production and is most suitable for mass production; the hardness of the product to be processed can be increased by about 20%~30% through work hardening; the surface roughness of the product to be rolled is good through the calendering effect of the threaded die and the material to be rolled.

In addition, in this rolling process, when a long-sized rolled material is continuously processed, a through-feed rolling processing device (through-feed rolling processing device) of a circular plate tooth as shown in Japanese patent documents 1 to 5 is used. This through-feed rolling processing device is a pair of circular plate teeth with spiral rolling tooth dies arranged side by side on the outer surface, rotating in the same direction relative to the rotating shaft, and tilting in opposite directions at predetermined angles relative to the axial direction of the rolled material. A pair of circular plate teeth are arranged on the rotating shaft, thereby utilizing the "step phenomenon" of the axial movement of the rolled material to continuously process the long-sized rolled material.

Furthermore, the circular plate die used in the through-feed rolling processing device generally has a guide taper portion, a finishing portion, and a clearance portion having different inclination angles with respect to the rolling direction in sequence from the rolling direction starting end side of the cylindrical bottom surface corresponding to one end. Specifically, the guide taper portion is formed so that the rotation trajectory of the tooth top line of the processing tooth is different from the rolling direction. The starting end of the rolling direction is an expanding tapered shape that expands toward the terminal end of the rolling direction. The finishing part is formed into a cylindrical shape that makes the diameter of the rotation track of the top line of the processing tooth become the same as the diameter of the terminal position of the guide cone part. The clearance part is formed into a reduced tapered shape that makes the rotation track of the top line of the processing tooth shrink toward the terminal end of the rolling direction.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 2004-66272

[Patent Document 2] Japanese Patent Publication No. 2001-300675

[Patent Document 3] Japan Publication No. 46-22426

[Patent Document 4] Japanese Patent Publication No. 2009-95883

[Patent Document 5] Japanese Utility Model Publication No. 5-88733

However, in the past, the shape of the processed teeth in this round die was a trapezoidal shape with a flat tooth top formed in the finishing part and the residual gap part, and the guide cone part was a tooth with a left-right symmetrical mountain-shaped (equilateral triangle) part formed at the tooth top.

However, when the processing teeth of the guide cone are formed into the above-mentioned shape, the through-feed rolling process is performed, as shown in FIG. 22, while the tooth surface of the threading die 30 is abutted against the rolled material 40, and the rolled material 40 is rotated, so that the rolled material 40 flows from the tooth top of the threading die 30 toward the tooth bottom to transfer the shape of the processing teeth 31 and plastically deform (rolling). There is a friction force that causes the rolled material 40 to flow toward the bottom of the die teeth. The rolled material 40 processed by the processing teeth 31 of the guide cone of the threaded die 30 is compared with the contact portion of the processing teeth 31 and the tooth flank 33 on the rolling direction starting side (the tooth flank on the tooth surface toward the rolling direction starting side). The contact portion with the tooth flank 32 on the rolling direction terminal side has a large bulge. In addition, the rolling direction indicated by the arrow in Figure 22 is the direction in which the rolled material 40 moves during the rolling process (the axial direction of the rolled material 40).

In the case where the above bulge occurs, as shown in FIG. 23, a protrusion 42 is formed at the front end of the tooth shape 41 of the rolled material 40, making the tooth shape 41 incomplete. When using a product having the above tooth shape 41, there will be problems such as interference with the relative parts, resulting in loud movement noise (vibration), or wear on the relative parts, resulting in an impact on the service life.

To this end, in the past, the protrusion 42 was removed by grinding after rolling. Although this solved the above problem, the addition of the protrusion 42 removal process would cause new problems such as reduced output or increased costs.

The present invention is developed in view of the above-mentioned current situation, and aims to provide a threading die that is most suitable for the flow of rolled material during rolling processing, prevents the tooth top of the product from forming an incomplete shape, and does not require the removal of the protrusion 42 after rolling processing.

See the attached diagrams for an illustration of the gist of the invention.

A threading die is used when rolling a spiral tooth shape 21 on the outer peripheral surface of a rolled material 20, and is characterized in that: from the starting end side of the rolling direction to the terminal side of the rolling direction, a guide taper portion 1, a finishing portion 2 and a clearance portion 3 are provided, respectively, with processing teeth abutting against the rolled material 20, and the processing tooth 4 of the guide taper portion 1 has a mountain-shaped front end portion 7 convex to the front end at the tooth top, and the mountain-shaped front end portion 7 is relative to the tooth thickness center line C of the processing tooth 4. _r is configured so that the wall thickness on the starting end side in the rolling direction becomes greater than the wall thickness on the terminal side in the rolling direction.

Furthermore, the threading die described in claim 1 is characterized in that the top portion 7a located at the front end of the mountain-shaped front end portion 7 is biased toward the starting end side in the rolling direction relative to the tooth thickness center line _Cr .

In addition, in the threading die described in claim 2, the mountain-shaped front end portion 7 is a threading die characterized in that the right-angle cross-sectional shape of the teeth is triangular.

In addition, in the threading die described in claim 2, there is a description related to the threading die having a characteristic that the degree of deviation of the above-mentioned top portion 7a relative to the above-mentioned tooth thickness center line _Cr obtained by the following formula (1) is 12% or more.

Bias degree (%) = D/(W-(W _dL -W _rL ))×100 (1)

Here, D is the deviation amount of the top portion 7a of the processing tooth 4 relative to the tooth thickness center line _Cr in the right-angle section of the processing tooth 4 of the guide cone portion 1, W is the tooth top thickness of the front end of the processing tooth 5 of the finishing portion 2, _WdL is the tooth thickness at a distance L from the tooth bottom of the terminal side of the rolling direction of the processing tooth 5 adjacent to the finishing portion 2 toward the tooth top, and _WrL is the tooth thickness at a distance L from the tooth bottom of the terminal side of the rolling direction of the processing tooth 4 adjacent to the guide cone portion 1.

In addition, in the threading die described in claim 3, there is a description related to the threading die having a characteristic that the degree of deviation of the above-mentioned top portion 7a relative to the above-mentioned tooth thickness center line _Cr obtained by the following formula (1) is 12% or more.

Bias degree (%) = D/(W-(W _dL -W _rL ))×100 (1)

Here, D is the deviation amount of the top portion 7a of the processing tooth 4 relative to the tooth thickness center line _Cr in the right-angle section of the processing tooth 4 of the guide cone portion 1, W is the tooth top thickness of the front end of the processing tooth 5 of the finishing portion 2, _WdL is the tooth thickness at a distance L from the tooth bottom of the terminal side of the rolling direction of the processing tooth 5 adjacent to the finishing portion 2 toward the tooth top, and _WrL is the tooth thickness at a distance L from the tooth bottom of the terminal side of the rolling direction of the processing tooth 4 adjacent to the guide cone portion 1.

In addition, among the threading dies listed in claim 4, the records related to the threading dies characterized by the above-mentioned bias level being greater than 24% and less than 44%.

In addition, among the threading dies listed in claim 5, the records related to the threading dies characterized by the above-mentioned bias level being greater than 24% and less than 44%.

Furthermore, in the threading die described in any one of claims 1 to 7, the processing teeth 5 provided in the above-mentioned finishing portion 2 and the processing teeth 6 provided in the above-mentioned clearance portion 3 are respectively formed into flat surfaces at the front ends, and the processing teeth 5 provided in the above-mentioned finishing portion 2 are provided in a predetermined range on the side of the above-mentioned guide cone portion 1, and the threading die is characterized in that the width of the above-mentioned flat surface becomes narrower as it approaches the side of the above-mentioned guide cone portion 1.

In the threading die described in any one of claims 1 to 7, the threading die is configured as a circular plate die that rotates around the die rotation axis O, the guide cone portion 1 is a rotation trajectory of the tooth top line T1 of the processing tooth 4 of the guide cone portion 1 is formed into an expanded tapered shape that expands from the starting end side of the rolling direction toward the terminal end side of the rolling direction, and the finishing portion 2 is a rotation trajectory of the tooth top line T1 of the processing tooth 4 of the guide cone portion 1 The diameter of the rotation trajectory of the tooth top line T2 of the processing tooth 5 of the finishing part 2 is formed into a cylindrical shape with the same diameter as the diameter of the terminal position of the above-mentioned guide cone part 1, and the above-mentioned clearance part 3 is a description related to the thread die characterized by forming the rotation trajectory of the tooth top line T3 of the processing tooth 6 of this clearance part 3 into a tapered tapered shape with a reduced diameter toward the terminal side in the above-mentioned rolling direction.

In the threading die described in claim 8, the threading die is constituted as a circular plate die rotating around the die rotation axis O, the guide cone portion 1 is a rotation trajectory of the tooth top line T1 of the processing tooth 4 of the guide cone portion 1 is formed into an expanded tapered shape that expands from the starting end side of the rolling direction toward the terminal end side of the rolling direction, and the finishing portion 2 is a finishing portion 2 of the finishing portion 2. The diameter of the rotation trajectory of the tooth top line T2 of the processing tooth 5 of the part 2 is formed into a cylindrical shape with the same diameter as the diameter of the terminal position of the above-mentioned guide cone part 1, and the above-mentioned clearance part 3 is a description related to the thread die characterized by forming the rotation trajectory of the tooth top line T3 of the processing tooth 6 of this clearance part 3 into a tapered tapered shape with a reduced diameter toward the terminal side in the above-mentioned rolling direction.

The present invention, by virtue of the above-mentioned structure, can optimize the flow of the rolled material during rolling processing and prevent the tooth tops of the product from forming incomplete shapes as much as possible.

Therefore, the present invention eliminates the need to remove protrusions (ridges) after rolling, thereby reducing the number of man-hours and achieving the effects of improved mass production and reduced costs.

1: Guide cone

2: Finishing Department

3: Remaining space

4: Processing teeth (of the guide cone)

5: Processing teeth (of the finishing part)

6: Processing teeth (of the clearance part)

7: Mountain-shaped front end

7a: Top

20,40: Rolled material

21: Teeth

C _r : (of the machined teeth of the guide cone) tooth thickness center line

O: Mold shaft

T1: (of the processed teeth of the guide cone) tooth top line

T2: Tooth top line (of the finishing tooth)

T3: Tooth top line (of the processed teeth in the clearance area)

[Figure 1] is a front view illustrating this embodiment.

[Figure 2] is an enlarged explanatory cross-sectional view showing the guide cone portion and the finishing portion of this embodiment.

[Figure 3] is an explanatory diagram showing the processing teeth of the guide cone portion of this embodiment.

[Figure 4] is a diagram showing symbols related to the processing teeth of the guide cone part and the finishing part of this embodiment.

[Figure 5] is an explanatory diagram showing the flow state of the rolled material in the guide cone section when using this embodiment.

[Figure 6] is an explanatory diagram showing the rolled material after the rolling process using this embodiment.

[Figure 7] is an explanatory diagram showing the processing teeth of the guide cone portion of Experimental Example 1 of this embodiment.

[Figure 8] is an explanatory diagram showing the processing teeth of the guide cone portion of Experimental Example 2 of this embodiment.

[Figure 9] is an explanatory diagram showing the processed teeth of the guide cone portion of Experimental Example 3 of this embodiment.

[Figure 10] is an explanatory diagram showing the processing teeth of the guide cone portion of Experimental Example 4 of this embodiment.

[Figure 11] is an explanatory diagram showing the processing teeth of the guide cone portion of Experimental Example 5 of this embodiment.

[Figure 12] is an explanatory diagram showing the processed teeth of the guide cone portion of Experimental Example 6 of this embodiment.

[Figure 13] is an explanatory diagram showing the processed teeth of the guide cone portion of Experimental Example 7 of this embodiment.

[Figure 14] is an explanatory diagram showing the processed teeth of the guide cone portion of Experimental Example 8 of this embodiment.

[Figure 15] is an explanatory diagram showing the processed teeth of the guide cone portion of Experimental Example 9 of this embodiment.

[Figure 16] is an explanatory diagram showing the processed teeth of the guide cone portion of Experimental Example 10 of this embodiment.

[Figure 17] is an explanatory diagram showing the processed teeth of the guide cone portion of Experimental Example 11 of this embodiment.

[Figure 18] is an explanatory diagram showing the machining teeth of the guide cone portion of a comparative example.

[Figure 19] is a table summarizing the evaluation results of this experiment.

[Fig. 20] is a table summarizing the details of the S ₂ /S ₁ area ratio in this experiment.

[Figure 21] is a diagram showing the criteria for the evaluation of magnification in this experiment.

[Figure 22] is an explanatory diagram showing the flow state of the rolled material in the guide cone section when using the known example (comparative example).

[Figure 23] is an explanatory diagram showing the rolled material after rolling using the known example (comparative example).

Proper considerations

The implementation form of the present invention is briefly explained based on the diagram and the function of the present invention.

The present invention provides a processing tooth 4 of the guide cone portion 1 with a mountain-shaped front end portion 7 convex toward the front end at the tooth top. The mountain-shaped front end portion 7 is _configured to make the wall thickness on the starting end side in the rolling direction thicker than the wall thickness on the terminal side in the rolling direction relative to the tooth thickness center line Cr of the processing tooth 4. Therefore, during the rolling process, the amount of pressing (bite) of the rolled material from the tooth thickness center line _Cr of the processing tooth 4 of the guide cone portion 1 toward the starting end side in the rolling direction becomes greater than the amount of pressing of the rolled material from the tooth thickness center line _Cr toward the terminal side in the rolling direction.

Thus, in the present invention, when the rolled material 20 and the processing tooth 31 having a known left-right symmetrical mountain-shaped (equilateral triangle) portion are rolled, the flow amount toward the tooth belly 9 of the processing tooth 4 of the guide cone portion 1 in the rolling direction starting end side increases (the flow deviation toward the tooth belly 8 of the processing tooth 4 of the guide cone portion 1 in the rolling direction terminal side decreases), so that the flow of the rolled material 20 toward the rolling direction starting end side and the rolling direction terminal side of the processing tooth 4 of the guide cone portion 1 becomes roughly equal, preventing the tooth top of the product from forming an incomplete shape (protrusion 42 is formed according to the bulge).

Therefore, the present invention eliminates the need to remove the protrusion 42 (ridge) after rolling, thereby reducing the number of man-hours and achieving the effects of improved mass production and reduced costs.

Furthermore, in the present invention, the mountain-shaped front end portion 7 of the tooth top of the processing tooth 4 of the guide cone portion 1 means that the tooth bottom adjacent to the terminal side of the processing tooth 4 in the rolling direction of the guide cone portion 1 is formed into a convex mountain shape toward the front end side (tooth top side) from a position spaced a predetermined distance in the tooth top direction (for example, the oblique line diagram shown in FIG. 3).

[Implementation example]

The specific embodiments of the present invention are described according to the diagrams.

The present embodiment is about a thread die used when rolling a tooth shape 21 on the outer peripheral surface of a rolled material 20. Specifically, the circular die used when rolling a spiral tooth shape 21 on the outer peripheral surface of a long rod-shaped rolled material 20 by through-feed rolling (through-rolling) is shown in FIG. 1 and is composed of: a guide cone portion 1 with an expanded diameter and an inclined cone shape that expands from the starting end side of the rolling direction toward the terminal end side of the rolling direction, formed by the rotation trajectory of the tooth top line T1 of the processing tooth 4; and a continuous guide cone portion 1 with a continuous guide cone portion 1 and a guide cone portion 1 having an expanded diameter and an inclined cone shape that expands from the starting end side of the rolling direction toward the terminal end side of the rolling direction. In this guide cone part 1, the diameter of the rotation trajectory of the tooth top line T2 of the processing tooth 5 forms a cylindrical finishing part 2 with the same diameter as the diameter of the terminal position of the above-mentioned guide cone part 1; and the rotation trajectory of the tooth top line T3 of the processing tooth 6 connected to this finishing part 2 forms a reduced diameter tapered clearance part 3 with a reduced diameter toward the terminal side in the above-mentioned rolling direction. On the outer peripheral surfaces of each of the guide cone part 1, the finishing part 2 and the clearance part 3, continuous spiral processing teeth (thread tooth mold) are provided.

Here, the tooth top line T1 is a hypothetical line connecting the tooth tops of the processing tooth 4 of the guide cone part 1, the tooth top line T2 is a hypothetical line connecting the tooth tops of the processing tooth 5 of the finishing part 2, and the tooth top line T3 is a hypothetical line connecting the tooth tops of the processing tooth 6 of the clearance part 3. Figure 1 shows the tooth top lines T1, T2, and T3 with solid lines and shows the outline of the circular die.

Specifically, this spiral processing tooth is formed around the mold axis O.

In addition, among the processing teeth, the processing teeth 5 provided in the finishing portion 2 and the processing teeth 6 provided in the clearance portion 3 are shown in the enlarged view in FIG1 , and the front end (tooth top) is formed as a flat surface, and the tooth thickness forms a roughly bilaterally symmetrical tooth right-angled cross-section trapezoid that becomes thinner toward the front end side.

In addition, as shown in FIG. 2, the width of the front end flat surface of the processing tooth 5 in the predetermined range on the side of the guide cone portion 1 becomes narrower as it approaches the side of the guide cone portion 1, and the front end flat surface is formed near the guide cone portion 1. With such a shape, the rapid shape change of the processing tooth 4 of the guide cone portion 1 and the processing tooth 5 of the finishing portion 2 is gradually alleviated, and the occurrence of processing problems caused by this shape (scratches or peeling of the bottom of the tooth of the rolled product, etc.) is prevented, which is very suitable for obtaining a rolled product with a high-quality tooth shape.

Furthermore, the predetermined range on the guide cone portion 1 side is less than 70% of the width of the finishing portion 2 (the distance in the direction of the mold axis O from the boundary between the guide cone portion 1 and the finishing portion 2 to the boundary from the finishing portion 2 to the clearance portion 3). When the processing teeth 5 with a narrow width of the front end flat surface are formed at more than 70% of the width of the finishing portion 2, the processing of the processing teeth 5 formed on the front end flat surface of the clearance portion 3 side in the finishing portion 2 without being narrowed becomes insufficient, and there is a risk that the rolled material 20 cannot be finished into the predetermined shape.

Furthermore, the processing tooth 4 of the guide cone portion 1 is configured such that the wall thickness on the starting end side in the rolling direction is greater than the wall thickness on the ending end side in the rolling direction with respect to the tooth thickness center line _Cr of the processing tooth 4.

Here, the above wall thickness can be replaced by cross-sectional area for comparison as shown below.

Specifically, as shown in FIG. 3 , the machined tooth 4 of the guide cone portion 1 has a mountain-shaped front end portion 7 at the tooth top that is convex toward the front end. That is, the machined tooth 4 of the guide cone portion 1 of the present embodiment is formed in a mountain shape (mountain-shaped front end portion 7) with the tooth top convex toward the front end, and this mountain-shaped front end portion 7 is configured relative to the tooth thickness center line _Cr of the machined tooth 4 so that the wall thickness on the starting end side in the rolling direction is thicker than the wall thickness on the terminal end side in the rolling direction.

More specifically, in the right-angled section of the tooth, the top portion 7a of the mountain-shaped front end portion 7 is biased toward the starting end side in the rolling direction relative to the tooth thickness center line _Cr , and forms a roughly triangular convex shape with a larger side cross-sectional area _S2 (the lower left oblique portion in Figure 3) at the starting end in the rolling direction from the tooth thickness center line _Cr relative to the rolling direction terminal end side cross-sectional area _S1 (the lower right oblique portion in Figure 3). In other words, the hypotenuse of the rolling direction terminal end side is longer than the hypotenuse of the rolling direction starting end side, and the shape of a roughly triangular convex shape with a gentle inclination angle.

To further explain in detail, the processed tooth 4 of the guide cone portion 1 of this embodiment is formed into a roughly trapezoidal shape in a right-angled section view, the same as the finely processed portion 2 or the residual gap portion 3, at the bottom side of the tooth (the side at the base end of the processed tooth), and the top side of the tooth (the side at the front end of the processed tooth), specifically, the mountain-shaped front end portion 7, is formed into a roughly triangle in a right-angled section view (the top portion 7a is a roughly triangle that is biased toward the starting end side of the rolling direction relative to the tooth thickness center line _Cr ), and the tooth height h is set to the same height as the finely processed portion 2 or the residual gap portion 3. Here, the tooth height h of the processing tooth 4 of the guide cone portion 1 and the processing tooth 5 of the finishing portion 2 is the distance in the radial direction of the mold from the tooth bottom adjacent to the end side of each processing tooth in the rolling direction to the tooth top, and the tooth height h of the processing tooth 6 of the clearance portion 3 is the distance in the radial direction of the mold from the tooth bottom adjacent to the starting side of the processing tooth 6 in the rolling direction to the tooth top.

Furthermore, in the processing tooth 4 of the guide cone portion 1, when the rolling direction terminal side tooth flank 8 is formed in the range of the same shape as the rolling direction terminal side tooth flank 10 (see FIG. 4) of the processing tooth 5 of the finishing portion 2, the inclination angle of the inclined surface from the top portion 7a to the rolling direction terminal side tooth flank 8 becomes smaller, and in the guide cone portion 1, the side tooth flank 8 of the rolling direction starting end is suppressed. The flow rate of the rolled material 20 on the side of the belly 9 is increased, so the range of the same shape as the end side tooth belly 10 (see Figure 4) of the processing tooth 5 of the finishing part 2 in the rolling direction is preferably less than 50% from the tooth bottom to the tooth height h. In this embodiment, the part from the tooth bottom to less than 42% of the tooth height h is formed into a shape roughly the same as the processing tooth 5 of the finishing part 2.

Furthermore, the processed tooth 4 of the guide cone portion 1 is configured such that the top portion 7a of the tooth in the substantially triangular right-angled cross-section of the mountain-shaped front end portion 7 has a deviation of 12% or more relative to the tooth thickness center line _Cr obtained by the following formula (1), preferably 24% or more and 44% or less.

Bias degree (%) = D/(W-(W _dL -W _rL ))×100 (1)

Here, referring to FIG. 4 , D is the deviation of the top portion 7a relative to the tooth thickness center line _Cr in the right-angle section of the processed tooth 4 of the guide cone portion 1 (indicated by a solid line in FIG. 4 ), W is the tooth top thickness of the front end of the processed tooth 5 of the finishing portion 2 (indicated by a dotted line in FIG. 4 ), W _dL is the tooth thickness at a distance L from the tooth bottom of the terminal side of the rolling direction of the processed tooth 5 adjacent to the finishing portion 2 toward the tooth top, and W _rL is the tooth thickness at a distance L from the tooth bottom of the terminal side of the rolling direction of the processed tooth 4 adjacent to the guide cone portion 1 toward the tooth top.

The distance L is a distance from the tooth bottom on the rolling direction terminal side of the processing tooth 4 of the guide cone portion 1 where the mountain-shaped front end portion 7 is not formed and the tooth shape is maintained in a substantially trapezoidal shape (an arbitrary portion maintaining the engagement angle _α1 of the tooth flank 8 on the rolling direction terminal side and the engagement angle _α2 of the tooth flank 9 on the rolling direction starting side). Here, the engagement angles _α1 and _α2 are angles formed by (parallel to) the tooth thickness center line _Cr and each tooth flank.

In addition, _Cd is the tooth thickness center line shown by the tooth right-angled section of the machined tooth 5 of the finished portion 2.

Moreover, in this embodiment, although the engagement angle _α1 of the tooth flank 8 on the terminal side in the rolling direction and the engagement angle _α2 of the tooth flank 9 on the starting side in the rolling direction are the same angle, they may also be different angles.

In addition, for the tooth top thickness W of the processed tooth 5 of the finishing portion 2, when the flat surface of the front end (tooth top) is connected to the tooth flank 11 on the starting end side of the rolling direction or the tooth flank 10 on the terminal side of the rolling direction by a curved surface or a chamfered surface, the flat surface and the extension lines of the two tooth flanks are extrapolated, and the distance between the intersection points of each extension line is set as the tooth top thickness W.

In addition, when the top 7a of the processing tooth 4 of the guide cone 1 is in a pointed shape, chips are easily generated and the mold life is shortened. Therefore, it is better to have an R shape as shown in Figure 3, or a chamfered shape with a surface that slopes downward from the top 7a toward the starting end side of the rolling direction.

The effects of the present embodiment constructed as above are described below.

In this embodiment, the processing tooth 4 of the guide cone portion 1 has a mountain-shaped front end portion 7 with a convex shape toward the front end of the tooth top. This mountain-shaped front end portion 7 is configured relative to the tooth thickness center line _Cr of the processing tooth 4 so that the wall thickness on the starting end side in the rolling direction is thicker than the wall thickness on the terminal side in the rolling direction. Specifically, the mountain-shaped front end portion 7 is formed into a triangular shape in a right-angled cross-sectional view of the tooth, and is configured so that the degree of deviation of the tooth thickness center line C _r relative to the top 7a of the mountain-shaped front end portion 7 is 12% or more, preferably 24% or more and 44% or less, and the wall thickness of the wall thickness of the processing tooth 4 relative to the tooth thickness center line C _r is made to be thicker than the wall thickness of the terminal side in the rolling direction. Therefore, during the rolling process, the amount of pressing (bite amount) of the rolled material 20 from the tooth thickness center line C _r of the processing tooth 4 of the guide cone portion 1 toward the starting end side of the rolling direction is greater than that from the tooth thickness center line C r. The amount of the rolled material 20 pressed toward the end side of the rolling direction becomes greater, _and the rolled material 20 and the processing teeth formed into a right-angled section of the base plate shape with a known left-right symmetrical mountain shape (equilateral triangle) are compared. The amount of flow toward the tooth belly 9 of the processing tooth 4 of the guide cone part 1 in the rolling direction of the starting end side becomes greater (the rolling amount toward the processing tooth 4 of the guide cone part 1 is greater). 5 ), so that the flow of the rolled material 20 on the starting side of the rolling direction and the terminal side of the machining tooth 4 of the guide cone portion 1 becomes roughly equal, thereby preventing the tooth top of the product (guide screw) from forming an incomplete shape (forming a protrusion 42 based on the bulge), and performing the rolling formation of the tooth shape 21 of the appropriate shape as shown in FIG. 6 .

In addition, in this embodiment, the top portion 7a of the processing tooth 4 of the guide cone portion 1 is formed into an R shape, so it is not easy to generate chips, thereby extending the life of the mold.

Therefore, using this embodiment, there is no need to remove the protrusion 42 (ridge) after rolling, which can reduce the number of man-hours and improve mass production and reduce costs.

Next, the experimental results (performance evaluation results) that verify the effectiveness of this embodiment are explained.

This experiment uses a through-feed rolling circular die for a lead screw with a right spiral direction (right spiral). Specifically, circular dies with different shapes of deviations _D relative to the tooth thickness center line Cr of the top 7a of the mountain-shaped front end 7 as shown in Figures 7 (Experimental Example 1) to 17 (Experimental Example 11) and circular dies with a known shape (deviation D=0) as shown in Figure 18 (Comparative Example) are used to form a lead screw with a tooth shape 21 on the rolled material 20 by through-feed rolling, and the bulging state of the tooth shape 21 of the rolled material 20 is confirmed, and the mold life of each circular die is confirmed.

The specifications of the lead screws in Experimental Examples 1, 2, and 9 are 8mm in outer diameter, 1.96mm in pitch, and 5 in number of threads; in Experimental Examples 3, 4, and 10, they are 8mm in outer diameter, 2.5mm in pitch, and 6 in number of threads; in Experimental Examples 5 to 8, 11 and the comparative example, they are 9mm in outer diameter, 2.55mm in pitch, and 4 in number of threads.

Furthermore, the tooth profile specifications of the lead screws are all that the shoulder of the tooth top of the tooth profile 21 is rounded, that is, the first tooth flank 23 (see FIG. 21) that contacts the tooth flank on the end side of the machining tooth 5 of the finishing portion 2 of the through-feed rolling circular plate die in the rolling process and the second tooth flank 24 (see FIG. 21) that contacts the tooth flank on the start side of the machining tooth 5 of the finishing portion 2 of the through-feed rolling circular plate die in the rolling process and the tooth top surface have the specifications of the arc portion 22 that is convex outward.

In addition, in the finishing portion 2 of the circular die, the width of the area formed by narrowing the width of the flat surface of the front end of the processing tooth 5 is 61.0% for Experimental Examples 1, 2, and 9, 68.7% for Experimental Examples 3, 4, and 10, and 51.2% for Experimental Examples 5 to 8 and 11 relative to the width of the finishing portion 2.

<Uplift Assessment>

The evaluation of the bulge of the tooth shape 21 of the rolled material 20 is performed by correlating the degree of deviation of the top portion 7a in the tooth right-angled cross-sectional shape of the mountain-shaped front end portion 7 of the processing tooth 4 of the guide cone portion 1 and the area ratio of the side cross-sectional area _S2 at the starting end in the rolling direction / the side cross-sectional area S1 at the ending end in the rolling direction in the tooth right-angled cross-sectional shape of the mountain-shaped front end portion ₇ .

The degree of bias of each experimental case is calculated using the following formula (1).

Bias degree (%) = D/(W-(W _dL -W _rL ))×100 (1)

Here, D is the deviation of the top 7a of the machined tooth 4 relative to the tooth thickness center line _Cr in the right-angle section of the machined tooth 4 of the guide cone portion 1, W is the tooth thickness of the front end of the machined tooth 5 of the finishing portion 2, _WdL is the tooth thickness at a distance L from the tooth bottom of the terminal side of the rolling direction of the machined tooth 5 adjacent to the finishing portion 2 toward the tooth top, and _WrL is the tooth thickness at a distance L from the tooth bottom of the terminal side of the rolling direction of the machined tooth 4 adjacent to the guide cone portion 1 (see Figure 4).

Furthermore, the maximum value of the bias obtained by the above formula (1) is 50%.

Furthermore, the area ratio of the side cross-sectional area _S2 at the starting end in the rolling direction / the side cross-sectional area _S1 at the terminal end in the rolling direction is as shown in FIG3. The tooth shape area is the same as the processed tooth 5 of the finishing portion 2 on the tooth bottom side of the mountain-shaped front end portion 7, that is, the tooth shape area S2 at the terminal end in the rolling direction on the front end side (tooth top side) of the straight line is obtained and calculated from the points a and b formed on the boundaries of the two inclined surfaces constituting the mountain-shaped front end portion ₇ and the tooth flank 8 on the terminal end side in the rolling direction or the tooth flank 9 on the starting end side in the rolling direction. ₁ and the side section area S ₂ at the starting end in the rolling direction (see Figure 20).

Furthermore, when point a and point b form an arc, a straight line perpendicular to the tooth thickness center line _Cr is drawn from the position closest to the tooth bottom side of the starting point of the arc, and the rolling direction end side cross-sectional area _S1 and rolling direction start side side cross-sectional area _S2 of the front end side (tooth top) of the straight line are calculated.

FIG19 shows the results of the bulge evaluation of Experimental Examples 1 to 11 and the Comparative Example. In addition, the bulge evaluation is determined as shown in FIG21. The connection between the first tooth flank 23 and the second tooth flank 24 of the tooth shape 21 of the lead screw of the rolled material 20 has an arc portion 22 convex outward, and the tooth shape 21 with a flat surface on the tooth top is set as "A". Although some unfilled parts can be seen, it is assumed that the material reaches the rolled material. The front end of the tooth shape 21 of the lead screw of the material 20 has an arc portion 22 obtained at the connection portion between the first tooth flank 23 and the second tooth flank 24 and the tooth top, which is "B". If the second tooth flank 24 is not raised enough to obtain the arc portion 22, and there is no obvious protrusion 42 at the front end of the tooth top of the tooth shape 21 of the lead screw of the rolled material 20, it is "C". The shape of "C" is related to the generation of motion noise caused by interference with the other parts and the deterioration of the service life caused by wear of the other parts. Compared to this, the shape of "B" has a circular arc portion 22 and can smoothly contact with the relative components, so there is no problem caused by the shape of "C" and it is a good shape. "A" is an even better shape.

As shown in FIG19, regarding the bulge evaluation, only in the comparative example (bias degree 0%), a clear protrusion 42 is seen at the front end of the tooth top of the tooth shape 21 of the lead screw of the rolled material 20.

Furthermore, in Experimental Examples 1 to 11 where no protrusion 42 was observed, Experimental Example 5 with a bias of 12.6% and Experimental Example 1 with a bias of 23.2% were judged as B. In addition, all other than Experimental Examples 1 and 5 were judged as A. Based on this result, it can be confirmed that Experimental Examples 1 to 11 are in a good protrusion state.

Furthermore, the area ratio S ₂ /S ₁ of the side section area at the starting end in the rolling direction S ₂ /the side section area at the ending end in the rolling direction S ₁ is 1.30-1.79. This area ratio roughly corresponds to the above-mentioned bias degree. The area ratio of Experimental Example 5 with the smallest bias degree is the smallest.

<Mold life assessment>

The mold life evaluation is to check the presence or absence of chips on the machining teeth 4 of the guide cone 1 after rolling the workpiece 20 with a length of 2.5m 300 times, and determine the mold life based on the presence or absence of chips. In this experimental example, no chips are set as "A" and chips are set as "B".

As shown in Figure 19, in the die life evaluation, the generation of chips was confirmed in the three round dies of Experimental Examples 9, 10, and 11. In Experimental Examples 9 to 11, as shown in Figures 15 to 17, the top 7a of the machining tooth 4 of the guide cone 1 was formed into a pointed shape. That is, the top 7a was formed into an R shape, and no chips were generated.

<Comprehensive judgment>

FIG. 19 shows the comprehensive judgment result based on the above-mentioned bulge evaluation result and the mold life evaluation result. The comprehensive judgment is to perform three-stage judgments of "A", "B", and "C" in order from the good result. The embodiment in which both the bulge evaluation and the mold life evaluation are A is set as comprehensive judgment A, the embodiment in which either the bulge evaluation or the mold life evaluation is A and the other is B, and the embodiment in which both the bulge evaluation and the mold life evaluation are B is set as comprehensive judgment B, and the embodiment in which the bulge evaluation result is C is set as comprehensive judgment C. Comprehensive judgment A is the best state of bulge and the mold life is also good, so it is the best state. Comprehensive judgment B is that the lead screw tooth shape 21 is in a good bulge state until the die life is determined by the chip generation of the machining teeth of at least the guide cone part. In contrast, comprehensive judgment C is that there will be no bulge 42 based on the die life.

The evaluation results show that experimental examples 2~4, 6~8 are comprehensive judgment A, experimental examples 1, 5, 9~11 are comprehensive judgment B, and the comparative example is comprehensive judgment C.

As described above, in view of the results of the above-mentioned bulge evaluation and the results of the mold life evaluation and comprehensive judgment, the processing tooth 4 of the guide cone portion 1 is preferably such that the deviation degree of the top portion 7a in the right-angle cross-sectional shape of the tooth of the mountain-shaped front end portion 7 is 12% or more, preferably 24% or more and 44% or less (the area ratio of _S2 / _S1 is 1.56 or more), and the shape of the top portion 7a is preferably an R shape (R=about 0.1~0.3mm) or a chamfered shape.

As mentioned above, as an experiment to verify the effect of this embodiment, although a through-feed rolling die for making a lead screw with a right spiral direction (right spiral) is used, the present invention is not limited to a right spiral lead screw, and can also be used to make a through-feed rolling die for making a lead screw with a left spiral direction (left spiral).

Furthermore, when rolling a lead screw with a left spiral direction (left spiral), the same rolling direction is a prerequisite. That is, in this embodiment, as shown in FIG. 5, the rolled material 20 is a prerequisite for moving from the right side to the left side. With respect to the setting for rolling a lead screw with a right spiral, a circular die with the spiral direction of the processing teeth in the opposite direction is used, the direction of inclination of the mold axis is set in the opposite direction and a pair of circular dies are arranged, and the rotation direction of the circular dies is set in the opposite direction.

Furthermore, the rolling mold related to this embodiment is not limited to a lead screw, but can also be a trapezoidal screw or a worm, etc., and can also be used in the rolling processing of a rolled material with a spiral tooth shape.

Furthermore, the present invention is not limited to this embodiment, and the specific structure of each component element can also be appropriately designed.

1: Guide cone

2: Finishing Department

3: Remaining space

4: Processing teeth (of the guide cone)

5: Processing teeth (of the finishing part)

6: Processing teeth (of the clearance part)

O: Mold shaft

T1: (of the processed teeth of the guide cone) tooth top line

T2: Tooth top line (of the finishing tooth)

T3: Tooth top line (of the processed teeth in the clearance area)

Claims (10)

A threading die is used when rolling a spiral tooth shape on the outer peripheral surface of a rolled material, and is characterized in that: it has a guide taper portion, a finishing portion, and a clearance portion from the starting end side of the rolling direction to the terminal side of the rolling direction, and the guide taper portion, the finishing portion, and the clearance portion are respectively provided with processing teeth that abut against the rolled material, and the processing teeth of the guide taper portion have a mountain-shaped front end portion that is convex toward the front end at the tooth top, and the mountain-shaped front end portion is formed relative to the tooth thickness center line of the processing teeth so that the wall thickness of the starting end side of the rolling direction is thicker than the wall thickness of the terminal side of the rolling direction. As described in claim 1, the top of the front end of the mountain-shaped front end is biased toward the starting end side of the rolling direction relative to the tooth thickness center line. As described in claim 2, the thread die, wherein the mountain-shaped front end portion is a triangular shape in a right-angle cross-sectional view of the teeth. A threading die as recited in claim 2, wherein the degree of deviation of the top relative to the center line of the tooth thickness obtained by the following formula (1) is 12% or more, and the degree of deviation (%) = D/(W-(W _dL -W _rL ))×100 (1) where D is the deviation of the top of the processing tooth relative to the center line of the tooth thickness in the right-angled cross-section of the processing tooth of the guide taper portion, W is the tooth top thickness at the front end of the processing tooth of the finishing portion, W _dL is the tooth thickness at a position spaced a distance L from the tooth bottom on the terminal side of the processing tooth adjacent to the finishing portion in the rolling direction toward the tooth top, and W _rL is the tooth thickness at a distance L from the tooth bottom toward the tooth top on the terminal side of the machined tooth adjacent to the guide cone in the rolling direction. A threading die as recited in claim 3, wherein the degree of deviation of the top relative to the center line of the tooth thickness obtained by the following formula (1) is 12% or more, and the degree of deviation (%) = D/(W-(W _dL -W _rL ))×100 (1) where D is the deviation of the top of the processing tooth relative to the center line of the tooth thickness in the right-angled cross-section of the processing tooth of the guide taper portion, W is the tooth top thickness at the front end of the processing tooth of the finishing portion, W _dL is the tooth thickness at a position spaced a distance L from the tooth bottom on the terminal side of the processing tooth adjacent to the finishing portion in the rolling direction toward the tooth top, and W _rL is the tooth thickness at a distance L from the tooth bottom toward the tooth top on the terminal side of the machined tooth adjacent to the guide cone in the rolling direction. For the threaded die described in claim 4, the above-mentioned degree of bias is between 24% and 44%. For the threaded die described in claim 5, the above-mentioned degree of bias is between 24% and 44%. A threading die as recited in any one of claims 1 to 7, wherein the machining teeth provided in the finishing portion and the machining teeth provided in the residual clearance portion are respectively formed with the front ends thereof as flat surfaces, and the machining teeth provided in the finishing portion are within a predetermined range on the side of the guide cone portion, so that the width of the flat surface becomes narrower as it approaches the side of the guide cone portion. A threaded die as recited in any one of claim items 1 to 7, wherein the threaded die is configured as a circular die that rotates around a die rotation axis, and the guide cone portion is configured such that the rotation trajectory of the tooth top line of the processed tooth of the guide cone portion is formed into an expanded tapered shape that expands from the starting end side in the rolling direction toward the terminal end side in the rolling direction, The finishing part is formed by forming the rotation track of the top line of the processing tooth of the finishing part into a cylindrical shape having the same diameter as the diameter of the terminal position of the guide cone part, and the clearance part is formed by forming the rotation track of the top line of the processing tooth of the clearance part into a tapered tapered shape with a reduced diameter toward the terminal side in the rolling direction. The threaded die as recited in claim 8, wherein the threaded die is configured as a circular plate die rotating around a die rotation axis, the guide cone portion is configured such that the rotation trajectory of the tooth top line of the processed tooth of the guide cone portion is formed into an expanded tapered shape that expands from the starting end side of the rolling direction toward the terminal end side of the rolling direction, and the precision The processing part is to form the rotation track of the top line of the processing tooth of the finishing part into a cylindrical shape with the same diameter as the diameter of the terminal position of the above-mentioned guide cone part, and the above-mentioned clearance part is to form the rotation track of the top line of the processing tooth of the clearance part into a tapered tapered shape with a reduced diameter toward the terminal side in the above-mentioned rolling direction.

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