JPH06104259B2 - Manufacturing method of thread forming body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a thread forming body having a thread such as a trapezoidal screw and a square screw.

[Prior art]

As a feed screw shaft material of a feed mechanism of a machining device such as a lathe or various lifting devices, a thread forming body having a trapezoidal screw or a square screw is widely used. The feed screw shaft material has various lengths from short to long, but the length is generally 2 to 5 m. Further, the shape of the thread is considerably larger in pitch, groove depth, etc. than that of the thread forming body in which the triangular screw is formed.

When such a trapezoidal screw or a square screw is formed, the groove depth of the thread is different from that of the triangular screw which has a relatively small groove depth with respect to the shaft diameter and can be cold-rolled. However, the cold rolling is practically impossible because it is large and the processing amount is large.

Therefore, the trapezoidal screw or the square screw is generally formed by cutting.

[Problems to be solved by the invention]

When the trapezoidal screw thread or the square screw is formed by cutting, there is a problem that the processing time becomes long and the processing cost increases because the cutting amount is large and the processing speed is limited. Further, when the trapezoidal screw or the screw forming body on which the square screw is formed is long, when processing the trapezoidal screw or the square screw, the work material is bent by the pressing force of the cutting tool, There is a problem that accuracy decreases,
Further, there is a problem in that it is necessary to sufficiently reduce the processing speed because cutting heat is easily generated. Further, in order to suppress the occurrence of the bending that becomes a problem when processing the trapezoidal screw or the square screw of the long thread formation body, the hardness of the work material is increased (for example, when the work material is carbon steel, The workpiece is subjected to quenching and tempering treatment to increase its hardness),
Since the cutting resistance increases as the hardness increases, there is a problem that the processing cost further increases.

The present invention has been made in view of such circumstances, and a method for manufacturing a thread forming body for forming a screw thread such as a trapezoidal screw or a square screw by plastic working instead of cutting having various problems as described above. The purpose is to improve the manufacturing efficiency and reduce the manufacturing cost.

[Means for solving problems]

In the method for manufacturing a thread forming body according to the present invention, three or four rolling rolls each having a plurality of annular grooves for roughly forming a thread formed in the circumferential direction of the outer peripheral surface are arranged around the pass line. By using a tilt rolling mill and feeding the metal material between the rolling rolls in a hot manner, the metal material is tilt-rolled, and a screw thread is roughly formed on the outer peripheral surface of the metal material to form the first thread. Obtaining a forming body, then removing the metal oxide on the surface of the first thread forming body to obtain a second thread forming body, and then rolling with a disk portion for finishing the threads. By using an inclined rolling machine in which three or four rolls are arranged around the pass line and feeding the second thread forming body between the rolling rolls in a cold state, the second thread forming body is formed. It is characterized by performing inclined rolling to finish the threads on the outer peripheral surface thereof.

[Action]

In the case of such a method of the present invention, since the metal material is hot-rolled in an inclined manner to roughly form the threads, the trapezoidal screw, the square thread and the like, which had to be cut by the conventional cutting process, are plastically formed. It can be realized by processing. Moreover, the roughly formed threads can be subjected to cold tilt rolling capable of highly precise finishing by removing the metal oxide on the surface thereof. Therefore, the thread is subjected to cold tilt rolling to form a thread with high dimensional accuracy, and the surface roughness of the thread is equal to or higher than the surface roughness of the machined one.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings showing an embodiment in the case where the number of rolls is three.

FIG. 2 is a front view (a groove of a rolling roll is omitted) showing an essential part of an apparatus used for carrying out the method of the present invention, particularly for carrying out the hot tilt rolling step, and FIG. 3 is shown in FIG. FIG. 4 is a side view showing, in an enlarged manner, a rolled portion having a cross section taken along line III-III.
Indicates a solid metal material having a circular cross section, and the metal material 4 is transferred in the axial direction and is provided at the rolling position of the pass line. The first thread forming body 41 is formed by obliquely rolling 1, 2 and 3 and roughening the threads on the outer peripheral surface thereof.

The rolling rolls 1, 2 and 3 have the same face angle α (see FIG. 3), and their axes are inclined so that the shaft ends on the same side are directed to the same side in the circumferential direction (this axis The angle β of the line with respect to the pass line is inclined, and the shaft end on the same side is inclined so that it approaches or separates toward the pass line (the angle γ of this axis with respect to the pass line is referred to as the crossing angle). Good, the crossing angle γ in the direction in which the roll axis deviates on the exit side with respect to the pass line is defined as positive).

Then, a portion where the distance between the outer peripheral surface of the rolling rolls 1, 2, 3 and the pass line is smaller than the radius of the outer periphery of the metal material 4 passing therethrough, that is, the outer periphery of the rolling portion has a thread on the metal material 4. In order to rough-form, a plurality of annular grooves having a trapezoidal cross section, which are wider on the opening side, are cut in the circumferential direction at appropriate intervals in the axial direction, for example, 5 to 7 threads. The positions, intervals, widths, and depths of the grooves are different among the rolls, as partially shown in FIG. 3, and the intervals of the rolling rolls are also different in the axial direction.

Then, the positions and intervals of the grooves are determined according to the heights and intervals of the threads to be formed, and the α, β, γ, etc. of the inclined rolling rolls related thereto are determined. The position of the groove differs between rolling rolls, and for each rolling roll, the interval gradually widens from the material entry side to the material exit side according to the amount of stretching. The mountain is guided to the groove of the next roll and is sequentially formed. The width and depth of the groove are almost the same between the rolling rolls, and each rolling roll is changed as needed (for example, the change is small on the material input side and large on the material output side). ing.

The inclination angle of each groove with respect to the center line of the roll axis in the depth direction is such that, when the thread to be formed is perpendicular to the screw axis, the standing direction of the groove is the crossing angle γ in the material exit side direction. The same angle is formed.

FIG. 4 is a front view (a groove of a rolling roll is omitted) showing an essential part of an apparatus used for carrying out the method of the present invention, particularly for carrying out the cold tilt rolling step, and FIG. 5 is FIG. FIG. 42 is a cross-sectional view taken along line V-V of FIG. 4, in which reference numeral 42 denotes a second thread forming body obtained by the above-described device from which the metal oxide on the surface of the first thread forming body 41 is removed. The thread forming body 42 is transferred in the axial length direction, is obliquely rolled by the cone type rolling rolls 11, 21, 31 of a set of three cross type inclined rolling machines provided at the rolling position of the pass line, and its outer periphery is The threads on the surface are finished.

The cross-type inclined rolling mill provided with the rolling rolls 11, 21, and 31,
A rolling mill having the same rolling rolls 1, 2 and 3 as the rolling mill is used. Further, the rolling rolls 11, 21, 31 are rolling rolls having two kinds of disc portions, that is, a disc portion A for forming a groove portion and a disc portion B for forming a top portion, which are provided at different portions. The groove portion between the adjacent screw threads of the second thread forming body 42 is finished (sizing), and the top portion of the screw thread is finished by the top forming disk portion B. When three rolling rolls 11, 21, and 31 are used as in this embodiment, the phases of the adjacent rolls are shifted by 120 ° so that the finish machining can be effectively performed on each of the disk portions A and B. There is.

When carrying out the method of the present invention using such an apparatus, first,
A metal material 4 having a circular cross section as shown in FIG. 1 (a) is heated at a predetermined temperature (for example, in the case of medium carbon steel, 10
Heat to 00 ℃).

Next, the metal material 4 heated to a predetermined temperature is shown in FIG.
As shown in Fig. 6, the material is fed between the rolling rolls 1, 2 and 3 and is subjected to inclined rolling by the rolling rolls 1, 2 and 3 to form threads on its outer peripheral surface as shown in Fig. 6 (a), (b), As shown in (C) and (D), the first thread forming body 41 is formed by rough molding. The sixth
The arrows in the figure indicate the direction of the load applied to the metal material 4. That is, when the rolling of the metal material 4 is started, the metal material 4 is sequentially bitten into the rolling rolls 1, 2 and 3 and then rolled at three places in the circumferential direction by them to rotate around the axis. While proceeding. Therefore, the subsequent rolling is performed in a spiral manner, and the rolled metal material 4 advances to the roll exit side where the interval between the pass line and the rolls 1, 2, 3 is narrow. And three rolls 1,2,
By the sequential rolling of 3, the inside of the rolled portion is stretched in the axial direction, whereby the thread pitch is widened. If the roll is set so that the groove that contributes to the next rolling comes to the thread portion where the interval is widened, the screw thread such as a trapezoidal screw with a high height and a long pitch can be provided without dipping the thread. The pile can be molded.

The first thread forming body 41 thus obtained is subjected to pickling treatment as shown in FIG. 1 (c) to remove the metal oxide on the surface to form the second thread forming body 42.

Further, as shown in FIG. 1 (d), the second thread forming body 42 is cold-fed between the rolling rolls 11, 21, 31 and is subjected to tilt rolling by the rolling rolls 11, 21, 31. Then, the outer peripheral surface of the thread is finished. That is, the rolling rolls 11, 21,
The groove portion between the adjacent screw threads is finished in the groove portion forming disk portion A of 31, and the top portion of the screw thread is finished in the groove portion forming disk portion B of the rolling rolls 11, 21, 31.

Although three rolling rolls are arranged around the pass line in the above embodiment, four rolling rolls may be arranged. However, it should be avoided to dispose two or more rolling rolls. The reason for limiting the number of rolling rolls to three or four is that when two rolling rolls are used, internal cracks are generated from inclusions, porosity, etc. due to the action of the rotary forging effect peculiar to inclined rolling. Easy to do,
This is because the occurrence of the internal cracks can be suppressed by using three or more rolling rolls. Further, when the number of rolling rolls is 5 or more, the structure of the rolling mill becomes complicated, and the roll diameter or roll shaft diameter cannot be increased relative to the material diameter due to the contact (kissing) limit between adjacent rolls. This is because the strength and rigidity of the machine are reduced, the reduction amount cannot be increased, and the dimensional accuracy is reduced.

Further, in the above-described embodiment, the pickling treatment is used to remove the metal oxide on the surface of the first thread forming body 41, but the metal oxide can be removed by shot processing. . The reason for removing the metal oxide on the surface of the first thread forming body 41 before the cold finishing process is that when the cold finishing process is performed without removing the metal oxide, the metal oxide is not This is because the metal oxide does not have ductility like that of the base metal, does not expand together with the metal base material during rolling, peels off during rolling, becomes caught on the metal surface (new surface), and flaws occur.

Further, in the above-described embodiment, the groove forming disk portion A and the top forming disk portion B are different from each other as the rolling rolls 11, 21, 31 used for performing the cold tilt rolling of the second thread forming body 42. The rolling rolls 11, 21 and 31 are provided for the parts, but as shown in FIG.
It is also possible to provide a disc portion C which also serves as the above. However, when there is a large variation in the height of the threads formed by the rough forming by the rolling rolls 1, 2 and 3, the disc portion C is When the finishing process is performed by using the rolling rolls 11, 21, and 31 provided, as shown in FIG. 8, a biting portion 42a is generated at a corner portion of the thread of the second thread forming body 42, which is not preferable. Rolls with 1
1,21,31 cannot be used. In this case, the rolling rolls 11, 21, 31 provided with the both disk portions A, B in different parts are used.

When finishing the threads of the second thread forming body 42 by using the rolling rolls 11, 21, and 31, the dimensional accuracy of the threads is high, and the surface roughness of the threads is the surface roughness of the machined product. Or more, and mechanical processing (for example, polishing finishing) as a post-process becomes unnecessary. Further, the bending of the second thread forming body 42 can be corrected by such finishing.

When forming a thread by the method of the present invention as described above, the pitch is 0.20 to 1.0 times the screw outer diameter and the screw depth is 0.10 to 0.25 times the screw outer diameter regardless of the screw outer diameter. Can be formed. This is because conventional cold-rolled triangular threads and other threads have a pitch of 0.03-0.
It is 20 times and the thread depth is formed only in the range of 0.01 to 0.10 times the outer diameter of the screw, and as the outer diameter increases, the ratio of the thread pitch and the thread depth to the outer diameter becomes smaller. On the other hand, it has been shown that the method of the present invention can form a remarkably wide range of threads.

(Numerical example)

Under the conditions listed below, outer diameter: 55.0 mmφ, valley diameter: 39.0 mm
φ, pitch 14.0 mm, thread angle: 30 °, thread depth: 8 mm
A metric trapezoidal screw (JIS B0216-1980) was prototyped.

(I) Material (a) Outer diameter: 60 mmφ (b) Material: S45C (ii) Hot rolling roll (b) Material: SCM440 (b) Gorge diameter: 200 mmφ (maximum part) (c) Entrance face angle α: 11.5 ° (iii) Cold rolling roll (b) Disc material: SKD coated with TiC (b) Disc diameter: 200 mmφ (maximum) (iv) Hot tilt rolling conditions (b) Roll crossing angle γ: 0 ° ( (B) Roll inclination angle β: 5 ° (c) Roll speed: 100 rpm (d) Heating temperature: 1050 ° C (v) Pickling treatment condition (a) Pickling treatment liquid: Sulfuric acid (vi) Cold tilt rolling condition ( B) Roll crossing angle γ: 0 ° (b) Roll inclination angle β: 6.5 ° (c) Roll speed: 100 rpm (d) Lubrication method: Machine oil lubrication (e) Rolling amount: 0.5 mm (maximum) Dimensional accuracy is ± 0.1m in outer diameter after hot-rolled rolling
m and pitch were ± 0.4%, but after finishing processing by cold tilt rolling, the dimensional accuracy was ± 0.03 mm in outer diameter and ± 0.03 mm in pitch.
It was 0.2%. For surface roughness, JIS B0031 symbol after pickling treatment (Ra: 25 μm or less), but JIS B0031 symbol after finishing by cold tilt rolling (Ra: 6 μm or less), which is as smooth as the finished surface to be ground. Regarding the surface hardness, H _B : 185, which was equivalent to that of the S45C normalized structure material after hot tilt rolling, became H _B : 208 after finish working by cold tilt rolling.

〔effect〕

As described above in detail, according to the method of the present invention, the trapezoidal screw, the screw thread of the screw forming body such as the square screw is roughly formed by hot working, so that the trapezoidal screw that cannot be processed by the conventional cold rolling, A thread having a high height and a long pitch, such as a thread of a thread forming body such as a square screw, is formed by plastic working. Further, since the thread is finished by cold tilt rolling, the surface quality, dimensional accuracy, etc. are equivalent to or better than those of the machined product. As a result, a cutting process is not required to manufacture a thread forming body such as a trapezoidal screw or a square screw, and the manufacturing efficiency can be improved and the manufacturing cost can be reduced. In addition, while the thread formed by cutting as in the past cuts the tissue fiber,
The threads formed by the method of the present invention have the advantage that the tissue fibers are continuous and the strength is improved.

[Brief description of drawings]

FIGS. 1 (a), (b), (c), and (d) are schematic explanatory views showing an implementation state of the method of the present invention, and FIG. 2 shows a main part of an apparatus used for implementing the method of the present invention. A front view, FIG. 3 is a side view showing an enlarged cross section taken along the line III-III of FIG. 2, FIG. 4 is a front view showing an essential part of an apparatus used for carrying out the method of the present invention, and FIG. FIG. 4 is an enlarged side view showing a cross section taken along the line VV of FIG. 4, and FIGS. 6 (a), (b), (c), and (d) show a state in which a screw thread is roughly formed by hot tilt rolling. FIG. 7 is a side view showing another embodiment of a rolling roll for cold finishing, and FIG. 8 is a state in which the threads are finished by the rolling roll shown in FIG. It is a schematic explanatory view showing an example. 1,2,3 …… Rolling roll for rough forming 4 …… Metal material, 11,21,31 …… Rolling roll for finish forming, 41 …… First thread forming body, 42 …… Second thread Formed body, A,
B, C ... Disk part

Claims (1)

[Claims] 1. A tilt rolling machine in which three or four rolling rolls each having a plurality of annular grooves for roughly forming a screw thread in the circumferential direction of the outer peripheral surface are arranged around a pass line are used for rolling. By sending the metal material between the rolls while hot,
The metal material is subjected to tilt rolling, a screw thread is roughly formed on the outer peripheral surface of the metal material to obtain a first thread forming body, and then the metal oxide on the surface of the first thread forming body is removed. To obtain a second thread forming body, and then, using an inclined rolling machine in which three or four rolling rolls each having a disk portion for finishing a screw thread are arranged around the pass line, and between the rolling rolls. The second thread forming body is cold-fed to the second thread forming body so that the second thread forming body is inclined and rolled to finish the threads of the outer peripheral surface thereof. A method for manufacturing a strip forming body.