JP2010133528A - Lock screw - Google Patents

Abstract

A male screw and a female screw can be firmly screwed together by mechanical screwing under any conditions, and a stable and strong anti-loosening function can be effectively exhibited even at a small screwing site, and also easy to manufacture. To provide a screw.
With A providing the screw crest 5 at equal intervals to form a reduced form the summit parts of the male screw 1 than the pressure flank angle theta ₁ play side flank angle theta ₂ to the non-circular shape, the pressure side of the external thread 1 This is a loosening prevention screw in which an inclined protrusion 7 is formed between the inclined surface 6 with the flank angle θ ₁ and the valley diameter d ₁ . In this loosening prevention screw, when the male screw 1 is screwed into the female screw 2, the crest 5 of the male screw ₁ is bitten into the root diameter D _{1 of the} female screw 2 with the inclined protrusion 7 as a fulcrum.
[Selection] Figure 3

Description

  The present invention relates to a loosening prevention screw that prevents loosening at the time of screwing or after tightening, and particularly relates to a screw suitable for preventing loosening of a machine screw.

  Conventionally, in a screw such as a small screw, since a dimensional tolerance is provided between the male screw and the female screw, the male screw may be loosened due to this dimensional tolerance. In order to prevent this loosening, a loosening prevention function is provided on the head seat surface side of the male screw to prevent loosening by pressing against the contact surface on the female screw side when the male screw is completely tightened. Further, in addition to this, the thread portion of the male screw may be provided with a loosening prevention function. In this case, the loosening prevention effect is more effective than when the loosening prevention function is provided only on the head seat surface.

  And when providing the loosening prevention function in the thread part of a male screw, generally coating agents, such as resin, are given to the outer peripheral side of a male screw as an object for loosening prevention. The coating agent is usually applied by post-processing to a male thread portion formed by machining. Also, for example, after tightening the male screw, if the head seat surface of the male screw is separated from the work to be tightened, an adhesive is applied as a coating agent to the outer periphery of the head by post-processing to prevent loosening. Sometimes it is planned.

  On the other hand, as a measure for preventing screw loosening, the thread portion of the male screw may be provided in a special shape by machining (see, for example, Patent Document 1). The male screw in this document has the same crest width as the valley width of the female screw, eliminates the gap between the female screw, and provides two slopes bent on the slope in the back of the tightening direction. It is intended to prevent the screw from loosening by overlapping with the slope and forming a gap between the other slope and the female screw.

By the way, for example, when assembling small electric appliances such as mobile phones, personal computers, video visual equipment, car audio, etc., small screws are used, and these electric appliances tend to be smaller and thinner in recent years. Smaller machine screws are used. At that time, in order to improve the quality of electric appliances, a small screw having a stronger fastening force is essential, and a strong loosening prevention performance is also required for the small screw. For example, when a thin plate material is used as a workpiece of an electrical product, a strong fastening force is required even when a small screw of M2 or less is tightened on the thin plate material.
Furthermore, when tightening thin workpieces, the male screw may be screwed together with a single screw thread, and at this time, it will be loosened only by screwing the screw thread without using the locking mechanism on the head seating surface. Sometimes stop. Even in this case, the function of preventing loosening must be surely performed.

Japanese Patent No. 3977496

  However, when trying to prevent screws from being loosened with a coating agent such as resin or adhesive, if the male screw is used repeatedly several times, the coating agent will peel off and looseness will occur after tightening, making it impossible to exert the function of preventing loosening. there were. For this reason, when the coating agent is used, it is difficult to stabilize the tightened state, and it may be necessary to readjust the male screw after fixing. Further, if the coating agent is peeled off during use or at the time of retightening, the peeled particles may be scattered to adversely affect other parts.

Furthermore, if the tightening location becomes hot and vibration is applied to this tightening location, the screw or tightening location may be damaged when the tightening force becomes excessive, so it is necessary to perform the tightening operation with high accuracy. there were. As mentioned above, when male and female screws are screwed together, the tightening accuracy must be high, resistant to vibration and temperature changes, and must be compatible with any tightening location. These cannot be fully satisfied with male screws.
In addition, since the coating agent is applied after the thread is provided by machining, the number of work steps is increased and the cost is increased.

  On the other hand, in the male screw of Patent Document 1, the slope on the summit side is overlapped with the slope of the female screw in a state where the crest side is the same width as the female screw and the gap is eliminated, and a gap is provided between the female screw on the other slope. It is intended to prevent loosening in the state. As described above, this screwed structure is designed to prevent loosening only on the mountain peak side of the male screw, and is not sufficient as a locking function because it is fixed by the slope on the rear side of the mountain peak, and there is a risk of loosening after tightening. Sex still remains. For this reason, in the same document, in order to prevent loosening, the anti-sagging agent is buried between the male screw and the female screw, and as a result, the man-hour by post-processing increases.

  Further, in any of the above cases, when a thin workpiece of a small electrical product is tightened, it is likely to be loosened more easily than normal tightening because it is tightened with few screw threads.

  The present invention was developed in order to solve the conventional problems, and the object of the present invention is that the male screw and the female screw can be firmly screwed together by mechanical screwing under any conditions, It is an object of the present invention to provide a loosening prevention screw that can effectively exhibit a stable and strong loosening prevention function even with a small number of screwed parts, and is easy to manufacture.

  In order to achieve the above object, according to the first aspect of the present invention, the crest portion of the male screw having the pressure side flank angle smaller than the play side flank angle is formed in a non-circular shape, and the crests are provided at equal intervals. An inclined protrusion is formed between the inclined surface of the pressure side flank angle of the male screw and the valley diameter, and when the male screw is screwed into the female screw, the screw thread crest of the male screw is set to the valley diameter of the female screw with the inclined protrusion as a fulcrum. It is a loosening prevention screw.

  The invention according to claim 2 is a loosening prevention screw having a non-circular thread crest having three triangular vertices.

  The invention according to claim 3 is a loosening prevention screw in which a space region is formed between the pressure-side flank angle of the male screw and the flank angle of the female screw facing the male screw.

  The invention according to claim 4 is a loosening prevention screw in which the play side flank angle of the male screw is 30 °, the pressure side flank angle is 25 °, and the inclination angle of the inclined protrusion is 38 °.

  The invention according to claim 5 is a loosening prevention screw formed by rolling a male screw.

  According to the first aspect of the present invention, the male screw and the female screw can be mechanically engaged with each other under any conditions such as a high temperature state or when vibrations are applied. Even when the number of joints is small, it is a loosening prevention screw that can effectively exhibit a stable loosening prevention function to prevent backlash and is easy to manufacture. Furthermore, even when the head seat surface of the male screw is separated from the contact surface of the female screw, it is possible to reliably prevent the occurrence of looseness.

  According to the second aspect of the present invention, the male screw can be screwed in while maintaining an appropriate sliding resistance while preventing the seizure phenomenon from occurring, and it is possible to reliably prevent the occurrence of backlash after the male screw and the female screw are screwed together. It becomes possible to prevent the occurrence of looseness. For this reason, it is possible to automate the tightening operation with an electric screwdriver or the like.

  According to the invention which concerns on Claim 3, when an inclination protrusion tries to deform | transform, this inclination protrusion can be escaped to a space area, and the high loosening prevention effect can be exhibited, preventing a sliding resistance increasing.

  According to the invention of claim 4, the screw can be screwed while minimizing the load torque when tightening the male screw to prevent an increase in sliding resistance, and can be repeatedly used while preventing damage to the screwed portion. It is possible to demonstrate the function of preventing loosening while maintaining

  According to the invention of claim 5, male screws can be easily manufactured by a general rolling machine without using a special production machine or manufacturing method, and mass production can be achieved while suppressing an increase in work man-hours by a simple work process. Is possible.

Below, one embodiment of the loosening prevention screw in the present invention is described in detail based on a drawing.
In FIG. 1, the loosening prevention screw has a male screw 1 and a female screw 2 into which the male screw 1 is screwed. Further, the male screw 1 is provided with a head 4 for tightening.
As shown in FIGS. 2 and 3, the male screw 1 is formed with a pressure side flank angle θ ₁ and a play side flank angle θ ₂ . The pressure side flank angle θ ₁ is formed smaller than the play side flank angle θ _{2. In} this embodiment, the pressure side flank angle θ ₁ is formed at 25 ° and the play side flank angle θ ₂ is formed at 30 °. .

  Further, the crest portion of the male screw 1 is formed in a non-circular shape, and the screw crests 5 are provided at equal intervals by this non-circular shape. In the present embodiment, the non-circular thread crest 5 is the apex of three triangular points.

Between the inclined surface 6 of the male screw 1 at the pressure side flank angle θ ₁ and the valley diameter d ₁ , an inclined protrusion 7 is integrally formed of steel of the same member, and the inclination angle θ ₃ of the inclined protrusion 7 is In this embodiment, the angle is set to 38 °. As a result, the inclination angle θ ₃ is larger than the play-side flank angle θ ₂ .

  As shown in FIG. 1, the head 4 is formed with a cross hole 10 that engages the tip of a driver (not shown). Further, a head seat surface 11 having an arbitrary aspect is formed on the bottom surface side of the head 4. When the male screw 1 is tightened to the female screw 2 to the end and the head seat surface 11 comes into contact with the contact surface 12 formed in the vicinity of the female screw 2, a predetermined gap is formed between the head seat surface 11 and the contact surface 12. The frictional force acts to prevent loosening of the male screw 1 when the screwing is completed.

  The male screw 1 is formed by rolling using a general rolling machine, for example. In this case, a mold for forming the male screw 1 can be provided in a mold (not shown), and the screw thread top 5 may be formed to have a large diameter slightly deviating from the JIS standard or ISO standard.

On the other hand, the female screw 2 is formed with respect to the workpiece 13 in accordance with a general standard such as JIS standard or ISO standard. That is, in FIG. 3, the female screw 2 is formed with a thread angle of 60 ° where the flank angles θ ₄ and θ ₅ are 30 ° and 30 °, respectively, and is formed in a substantially circular shape. Further, the inner diameter side tip portion 14 of the female screw 2 is provided with an inner diameter dimension capable of being pressed against the inclined protrusion 7.

When the male screw 1 is screwed into the female screw 2, the inner diameter side distal end portion 14 and the inclined protrusion 7 are pressed against each other, and the male screw 1 is pressed in the screwing direction with respect to the female screw 2 with the inclined protrusion 7 serving as a fulcrum. As a result, the thread crest 5 of the male screw 1 bites into the root diameter D _{1 of the} female screw 2. At this time, a space S is formed between the pressure-side flank angle θ _{1 of} the male screw 1 and the flank angle θ ₅ of the female screw 2 facing the male screw 1.

Next, the operation and action of the loosening prevention screw of the present invention in the above embodiment will be described.
FIG. 2 shows a state at the start of tightening of the male screw 1 of the loosening prevention screw of the present invention. In the figure, when the male screw 1 is tightened with respect to the female screw 2, the three thread crests 5 are screwed together while moving to the valley diameter D ₁ side while contacting the female screw 2. At this time, the pressure-side flank angle θ ₁ (= 25 °) is smaller than the play-side flank angle θ ₂ (= 30 °), so that the pressure-side flank angle θ ₁ side is prevented from contacting the female screw 2. The external thread 1 is screwed in such a state that only the thread crest 5 side is in contact with the valley diameter D _{1 of the} internal thread 2.

Next, when the tightening is advanced, the state shown in FIG. 3 is reached, and the play-side flank angle θ ₂ is 30 °, and the inclination angle θ ₃ of the inclined protrusion 7 is 38 °. an inclined protrusion 7 and is pressed against the screw crest 5 bite into the root diameter D ₁ of the female thread 2 of the inclined projection 7 as the fulcrum. At this time, since the thread crest 5 of the male screw 1 is the apex of three triangular points, there are three contact points between the male screw 1 and the female screw ₂ on the play-side flank angle θ ₂ side, A strong force generated by the pressure contact of the inclined protrusion 7 over the entire circumference is transmitted to the pressure contact positions of the three screw threads 5 and the female screw 2. Thus, since the inner diameter side distal end portion 14 and the inclined projection portion 7 are not in pressure contact over the entire circumference, the screwing direction of the male screw 1 and the female screw 2 in a state where the sliding resistance during tightening is suppressed. The gap is filled, thereby preventing the loosening.

  Moreover, since the male screw 1 is screwed into the female screw 2 while being rotated, the positions of the three press contact points change with the screwing. Strong power is not applied.

As a result of this pressure contact, the steel constituting the inclined protrusion 7 is a space S formed between the pressure-side flank angle θ ₁ of the male screw ₁ and the flank angle θ ₅ of the female screw 2 facing in FIG. As a result of being elastically deformed so as to be guided by the lead angle of the flank angle θ _5, the inclined protrusion 7 is pressed between the pressure side flank angle θ ₁ and the flank angle θ ₅ , thereby Due to the frictional force, the male screw 1 and the female screw 2 are firmly prevented from loosening. In this case, if the dimensional tolerance of the minor diameter D ₁ of the female thread 2 is formed to tilt radially inward, the inner diameter side distal end portion 14 and the pressing force is stopped force loosening becomes stronger the inclined projection 7 Further improvement.

  Moreover, when the inclined protrusion 7 escapes into the space region S, the inclined protrusion 7 is deformed so as to fill the dimensional difference between the male screw 1 and the female screw 2 and the contact area between the male screw 1 and the female screw 2 increases. Therefore, even when the dimensional tolerance is large, a large friction coefficient between the male screw 1 and the female screw 2 can be ensured, and a strong loosening prevention effect can be maintained even when vibration or the like is applied.

Further, since the inclination angle θ ₃ of the inclined protrusion 7 is 38 ° and the pressure side flank angle θ ₁ is 25 °, it is possible to prevent a sudden contact pressure from being applied to the inclined protrusion 7 at the start of tightening of the male screw 1. Thus, a sudden increase in load torque can be prevented. Thereby, it can tighten easily, suppressing a tightening torque.

  Since the above-described loosening prevention function between the male screw 1 and the female screw 2 is exerted on each screw thread in which the male screw 1 and the female screw 2 are screwed together, the male screw 1 and the female screw 2 are screwed into a plurality of screw threads. Thus, the loosening prevention function can be improved.

As described above, the loosening prevention screw according to the present invention has a non-circular shape of the top portion of the male screw 1 in which the pressure side flank angle θ ₁ is smaller than the play side flank angle θ _2, and the screw tops 5 are equally spaced. And an inclined protrusion 7 is formed between the inclined surface 6 of the male screw 1 at the pressure side flank angle θ ₁ and the valley diameter d _1, and the inclined protrusion 7 is inserted when the male screw 1 is screwed into the female screw 2. Since the thread crest 5 of the male screw ₁ is bitten into the root diameter D1 of the female screw 2 with the fulcrum 7 as a fulcrum, it is possible to prevent backlash and gaps caused by repeated use as in the case of using a coating agent. Further, there is no adverse effect on other parts due to the generation of particles or the like. Further, even when vibration is applied in a high temperature state, the screwed portion is not damaged, and a predetermined loosening prevention effect can be exhibited only by tightening the male screw 1 and the female screw 2. Therefore, it is necessary to perform the tightening operation with high accuracy. Nor.

  At this time, since the inclined protrusion 7 and the screw thread top 5 are provided at symmetrical positions before and after one screw thread in the screwing direction, the lever is used to tighten with a high pressure contact force while preventing wobbling. be able to. Therefore, the function of preventing loosening from the state in which the head seat surface 11 and the contact surface 12 of the female screw 2 are separated from the state in which the male screw 1 is engaged with the female screw 2 to the completion of the screwing is ensured. The Further, since it is possible to prevent loosening by screwing the male screw 1 and the female screw 2 without post-processing, the male screw 1 and the female screw 2 can be easily formed with a small number of work steps.

Furthermore, even when the workpiece 13 is thin, it is possible to prevent loosening with a few screwed portions. For example, even in the case of a small screw in which the screwing of the male screw 1 and the female screw 2 is performed with a single thread, it is surely prevented from loosening. Function is demonstrated.
In addition, as described above, the function of preventing loosening is exhibited even when the head seat surface 11 is separated from the contact surface 12, so that the lower end side of the male screw 1 does not protrude from the lower surface 13a of the workpiece 13. Even when the male screw 1 is tightened halfway, the same loosening prevention effect as when fully tightened is exhibited.

It is the front view which showed the loosening prevention screw in this invention. It is the partially expanded schematic diagram which showed the principal part of the loosening prevention screw of this invention. FIG. 3 is a partially enlarged schematic view showing a state after tightening in FIG. 2. It is a right view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Male screw 2 Female screw 5 Screw crest 6 Inclined surface 7 Inclined protrusion θ ₁ Pressure side flank angle θ ₂ Play side flank angle θ ₃ Inclination angle θ ₄ , θ ₅ Frank angle d ₁ Male thread trough diameter D ₁ Female thread trough diameter S Space area

Claims (5)

  The crest portion of the male screw whose pressure side flank angle is made smaller than the play side flank angle is formed in a non-circular shape to provide screw crests at equal intervals, and between the inclined surface of the male screw pressure side flank angle and the root diameter A slack prevention screw characterized in that when the inclined protrusion is formed on the male screw and the male screw is screwed into the female screw, the top of the male screw is bitten into the root diameter of the female screw with the inclined protrusion as a fulcrum.   The loosening prevention screw according to claim 1, wherein the non-circular thread ridges are triangular vertices.   The loosening prevention screw according to claim 1 or 2, wherein a space region is formed between a pressure side flank angle of the male screw and a flank angle of the female screw facing the male screw.   4. The loosening prevention screw according to claim 1, wherein said male screw has a play-side flank angle of 30 °, a pressure-side flank angle of 25 °, and an inclination angle of said inclined protrusion is 38 °.   The loosening prevention screw according to any one of claims 1 to 4, wherein the male screw is formed by rolling.

Images