JP2000110817A - Internal thread member and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cause no defect in thread fastening of external and internal thread members. SOLUTION: An internal thread part 2 is formed on an inner periphery of a hole formed on the center of a nut 1 as an internal thread member, other than an upper portion. A screwing guide projection 4 is formed in the hole, on the leading front side in screwing direction between the internal thread part 2 and an external thread 8 of an external thread member (bolt) 7. The external thread 8 of the bolt 7 is screwed with the guide projection 4, prior to the internal thread 2, and then screwed with the internal thread 2. The screwing guide projection 4 has substantially complete screw threads, causing no defect in assembling. The internal thread 2, formed thereafter and aligned in a position of screwing, similarly causing no defect in screwing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a female screw member such as a nut, and more particularly, to a female screw member having a function of preventing a defective assembly when screwed with a male screw member.

[0002]

2. Description of the Related Art Conventionally, when a male screw member is fastened to a female screw member, a screw thread of the male screw member is caught (bited) at a tip of the screw thread of the female screw member, and a screwing failure (poor assembly) occurs. there were. As shown in FIG. 7, when the female screw portion 104 of the female screw member (nut) 100 is formed by rolling, the screw thread 101 of the female screw portion 104 is screwed in the threading direction end 102 so that the inner peripheral surface of the nut 100 An incomplete screw thread that rises obliquely from the screw thread, and when the rolling tap forms the screw thread by raising the meat, the build-up amount is insufficient, and as shown in FIG. This is because there is a recess (for example, like a double-start thread) in the hole.
That is, since the first screw thread 101 is an incomplete screw thread and its tip 103 is underfilled, the male screw portion (bolt) 1
The ten screw threads 111 may be bitten by the tip 103 of the incomplete screw thread, resulting in a so-called biting state, which may cause a poor screwing.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a female screw member having an incomplete screw thread, and even if the tip of the screw thread is lacking, it is possible to prevent a poor screwing in tightening the male screw member. An object of the present invention is to provide a female screw member that does not cause a rise.

[0004]

In order to solve the above problems, a female screw member according to the present invention has a hole formed with a female screw portion to be screwed with a male screw portion of a male screw member. In the hole, the initial screwing of the male screw portion to the female screw portion is guided so as to be located on the leading end side in the screwing direction of the female screw portion and the male screw portion to be screwed, and the axial direction of the screwing start Is formed, and the screw guide protrusion has a lead screw thread equal to the lead angle of the female screw portion so as to be located on an extension of the spiral of the female screw portion. The leading end of the portion engages with the threaded guide projection, and is uniquely screwed into the female screw portion after the axial position is uniquely determined. Incidentally, the female screw member targeted by the present invention is typically a nut screwed into a male screw member such as a bolt, but in addition, a weld nut fixed to a predetermined member or directly formed on the member. The present invention can be applied to a female screw hole or the like. In that case, the member in which the female screw hole is formed can be grasped as a female screw member.

According to the above female screw member, the screw guide projection forms an independent projection without being continuous with the screw thread of the female screw portion, and is arranged on the leading end side in the screwing direction. It has a short thread located on the extension of the helix of the female thread. Therefore, the male screw portion is first screwed into the screw guide protrusion, and then screwed into the female screw portion. The screw guide projection is used to adjust the screw position (the axial position is uniquely determined). Therefore, it is possible to prevent the occurrence of poor screwing such as the engagement of the male screw portion with the female screw portion. In this case, for example, the threaded end of the thread of the female thread is a normal incomplete thread that gradually rises from the inner peripheral surface of the hole of the female thread member, and the tip of the thread is relatively long. Even if the outer thread member is underfilled, poor screwing of the male screw member does not occur.

It is desirable that an insertion guide hole for guiding the insertion of the male screw member into the female screw member be provided on the leading end side of the female screw portion, and the screw guide protrusion be formed on the inner peripheral surface of the insertion guide hole. If provided in combination with the insertion introduction hole, the center axis of the male screw member is aligned at the time of insertion of the male screw member, and the screwing failure prevention function is more effectively exhibited.

[0007] The screw guide protrusion is long in the circumferential direction so as not to be damaged at the time of screwing, and short enough to prevent an incomplete screw thread from being engaged with the screw guide protrusion. May be. Furthermore, as long as it has a thread with the same lead angle as the lead angle of the spiral of the female screw portion, it is also possible to provide one or more at the pitch of an integral multiple of the spiral pitch of the female screw portion from the leading end of the spiral of the female screw portion. it can.

The above-described female screw member can be manufactured by the following method. That is, in the method for manufacturing a female screw member of the present invention, a protrusion forming step of forming a protrusion for forming a screw guide protrusion using a molding die on a base material forming the female screw member, A thread forming step of simultaneously threading the female screw portion and the protrusion using a tap for forming a female screw portion on the formed base material.

Further, the method for manufacturing a female screw member having an insertion introduction hole includes a step of forming an insertion introduction hole in a base material forming the female screw member, and a step of forming a female screw using a tap in the base material. A screw thread forming step of forming a screw thread of the portion, the inserting and introducing hole forming step is performed by a forming die having a notch, and the notch forms a protrusion for forming a screw guide projection together with the introducing hole. It is characterized by forming.

In the above method, for example, a projection and an insertion introduction hole are simultaneously formed by the above-described mold, and thereafter, a hole is formed, and then a screw guide projection and a female screw portion are simultaneously threaded using a tap. Can be. The hole may be formed before the protrusion is formed.

[0011]

Embodiments of the present invention will be described below with reference to embodiments shown in the drawings. A nut 1 as a female screw member according to an embodiment of the present invention shown in FIG.
The female screw portion 2 is threaded on the inner peripheral surface other than. Further, as shown in FIG. 3, a screw for guiding the screwing of the male screw member (bolt) 7 to the leading end side in the screwing direction with the male screw portion 8 as shown in FIG. Mating guide projection 4
Are formed. In this embodiment, as shown in FIG. 2, the screw guide 4 has a screw thread 43 formed one pitch ahead of the spiral of the female screw part 2, and the height of the screw thread is The height of the thread 5 of the part 2 is almost 80%.

The circumferential length of the screw guide 4 is
An angle which is viewed from the center axis of the hole 34 to both circumferential edges of the screwing guide projection 4 is formed at 30 ° (that is, 30 °)
It has an arc shape with a central angle of 30 °). This angle is preferably formed in the range of, for example, 15 to 50 °. If the angle is less than 15 °, the build-up of the thread may be reduced when the thread is formed by rolling, and depending on the material, the strength may be reduced. May cause problems. If the angle is larger than 50 °, there is a possibility that an incomplete screw thread which meshes with the male screw portion 8 of the bolt 7 is formed at a position preceding the screw guide protrusion 4. The angle is desirably formed in the range of 20 to 45 °. In addition, the circumferential end surfaces 11 and 12 of the screw guide protrusion 4 are raised almost perpendicularly from the inner circumferential surface of the hole 34 in this case.

The bolt 7 is screwed into the nut 1 from the bearing surface 13 side, and the bolt 7 is advanced in the direction of arrow A (FIG. 3) to tighten the two. At this time, the male screw portion 8 of the bolt 7 is screwed to the screw guide protrusion 4 prior to the female screw portion 2, and then screwed to the female screw portion 2. In the male screw portion 8, the screw guide protrusion 4 has a shape close to a complete screw thread or a predetermined height. In the female screw portion 2 formed later, the screw engagement is performed by the screw engagement guide projections 4, so that the female screw portion 2 is similarly screwed without causing an assembly failure.

Circumferential end surfaces 11, 1 of the screwing guide projections 4
2 both stand almost perpendicularly from the inner peripheral surface of the hole 34 in the case of the present embodiment, but it is sufficient that at least one end face 11 in the traveling direction has that shape,
Is not particularly limited.

Hereinafter, a method of manufacturing the nut 1 of the above embodiment will be described with reference to FIG. First, as shown in FIGS. 4A and 4B, a base material 40 forming a female screw member is fixed with a die 50 and a pin 51, and a punch (forming die) 30 having a notch 31 is placed from the seat surface 13 side. Press in axially,
The insertion introduction hole 34 and the projection 33 are formed. Here, the amount of protrusion of the protrusion 33 in the axial direction is one pitch of the thread 5 of the female screw portion 2. The shape of the protrusion 33 may be somewhat trapezoidal. That is, the notch 31 may have a trapezoidal shape with a wide skirt. Next, as shown in FIG.
And the punch 52 are used to punch out the hole 35. The above is the insertion introduction hole forming step. Reference numeral 55 denotes the scrap.
The punch 30 is provided with a notch 31. In this insertion introduction hole forming step, the projection 3 is formed simultaneously with the insertion introduction hole 34.
3 is formed. In this case, the base material 40 is formed from a columnar material in advance by a driving step
Is formed as an intermediate product in a general process of manufacturing a nut by forging.

Thereafter, the inner peripheral surface of the hole 35 is thread-cut by using a tap 32 having a flat end surface as shown in FIG. At this time, the projection 33 is also threaded at the same time as the inner peripheral surface of the hole 35, and the nut 1 having the screw guide projection 4 shown in FIG. 4E is completed. The rolling tap 32 is capable of being threaded (screwed) from its first mountain, and is guided by the insertion introduction hole 34 to perform rolling from a state in which the peripheral edge of the tip abuts on the tip of the projection 33. Upon starting, the screw thread is started to be cut from the protrusion 33, and is always formed in a substantially constant shape. In the case of the present embodiment, the insertion introduction hole 34 functions as a tap introduction hole, and thread processing is performed more stably. In addition, as shown in FIG. 4F, the tap 32 may have a tapered guide portion 37 at the distal end which fits into the hole 35 and guides the direction of the center axis of the tap. In the case of manufacture without the insertion introduction hole 34, the driving portion 36 in FIG. 4A becomes shallower. Further, the base material 40 in which the holes 35 are formed in advance may be used.

As described above, the screw guide projection 4 of the present invention is provided.
Does not require a special manufacturing process, the projection 33 and the insertion introduction hole 34 are simultaneously formed, and the projection 33 and the hole 3 are formed.
5 is simultaneously threaded, so that the efficiency is high and the shape of the mold is simple. In the present embodiment, the corners of the screwing guide projections 4 are shown as acute angles, but actually appear as slightly dull shapes.

Further, as shown in FIG. 5, the rising end face 11 does not necessarily have to be formed substantially at a right angle from the inner peripheral surface of the hole (insertion introduction hole) 34, and a certain angle .theta. Can be. Is desirably about 0 to 45 °, in which case the screwing guide function is effectively performed. In addition, more desirably, approximately 5 to 30
It is preferable to set the angle to about {} or 10 to 30 °.

Further, as shown in FIG. 6, the height h of the screwing guide projection 4 can be set to approximately 80% of the height H of the female thread 5 of the complete thread as in this embodiment. However,
The screw engagement guide projection 4 defines the relative axial position of the nut and the bolt at the start of the screw engagement, and it is only necessary to prevent biting between the ridges including incomplete screw threads of both, so that any further It may be at height or less. For example, the height h of the screw guide protrusion 4 is set to the height H of the female thread 5 of the complete thread.
On the other hand, about 0.6H or more and less than 1.0H, especially 0.1H.
7 to 0.9H or 0.8 to 0.9H,
It can be said that it is desirable to exhibit a smooth screwing guide function.

[Brief description of the drawings]

FIG. 1 is a perspective view of a nut as a female screw member according to an embodiment of the present invention.

FIG. 2 is a partial sectional view of the nut of FIG. 1;

FIG. 3 is a partially enlarged view showing a screwed state of a nut and a bolt in FIG. 1 in an enlarged manner.

FIG. 4 is an explanatory view showing a method of manufacturing the nut of FIG. 1;

FIG. 5 is an explanatory diagram showing a rising angle of an end surface of a screw guide protrusion.

FIG. 6 is an explanatory diagram showing the height of the screw guide protrusion in comparison with the height of the female screw thread.

FIG. 7 is a perspective view and a partially enlarged view showing a conventional female screw member (nut).

FIG. 8 is a partially enlarged sectional view showing a main part of FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nut (female screw member) 2 Female thread part 4 Screw guide protrusion 5 Thread of female thread part 7 Bolt (male thread member) 8 Male thread part 9 Thread of male thread part 30 Mold 31 Notch 32 Tap 33 Projection part 34 Insertion introduction hole 40 Base material

Claims (4)

[Claims] 1. A male screw member having a hole formed with a female screw portion to be screwed with a male screw portion, the hole having a leading end in a screwing direction of the male screw portion to be screwed with the female screw portion. A screw guide protrusion is formed to guide the initial screwing of the male screw portion to the female screw portion so as to be positioned on the side, and to define an axial position at which screwing is started. A thread having a lead angle equal to the lead angle of the female thread is provided so as to be located on an extension of the spiral of the female thread, and the leading end of the male thread engages with the screw guide protrusion, A female screw member which is screwed into the female screw portion after the axial position is uniquely determined. 2. An insertion guide hole for guiding insertion of the male screw member into the female screw member is formed on a leading end side of the female screw portion, and the screw guide protrusion is formed on an inner peripheral surface of the insertion guide hole. The female screw member according to claim 1, wherein the female screw member is formed. 3. The method for manufacturing a female screw member according to claim 1, wherein a protrusion for forming a screw guide protrusion using a molding die is formed on a base material on which the female screw member is formed. And a screw thread forming step of simultaneously threading the female screw portion and the protrusion using a tap for forming a female screw portion on the base material on which the protrusion is formed. Production method. 4. The method of manufacturing a female screw member according to claim 2, wherein: a step of forming the insertion hole in the base material forming the female screw member; and using a tap as the base material. A thread forming step of forming a screw thread of the female screw portion.The inserting and introducing hole forming step is performed by a forming die having a notch, and the notch forms a projection for forming a screw guide protrusion. A method for manufacturing a female screw member, wherein the method is formed together with the insertion introduction hole.