WO2003014584A1 - Inverse saw-tooth internal thread - Google Patents

Abstract

The angle of inclination (β) of a clearance flank of a saw-tooth internal thread is made the angle of inclination (β) of an inverse pressure flank (20A) receiving a load, and the angle of inclination (θ) of the pressure flank is made the angle of inclination (θ) of an inverse clearance flank (2B).

Description

 Description Inverted female screw Technical field

 The present invention relates to a reverse saw tooth screw used for an accumulator or the like. Technology background

 A saw-toothed female screw is provided at the tip of the container body of the accumulator, and an external thread of the lid is screwed to the female screw.

 The saw-toothed female screw is shaped like a combination of a square screw and a triangular screw, and one side of each female thread is provided with a pleated flank for receiving the load of the male screw, and the other side is provided with , Clearance flank is provided. The angle of inclination of the flank flank is formed to be smaller than that of the clearance flank.For example, the angle of skew of the flank flank is formed at 7 °, and that of the clearance flank is formed at 45 °. Have been.

 When the pressure in the accumulator rises, the lid is pushed up, and the male screw presses against the screw flank of the female screw to push up the screw flank. The push-up force acting on the pleated flank generates a force that is dispersed and spreads the container body outward, a so-called expanding force.

The diameter expansion becomes smaller when the inclination angle of the pleated flanks is small. For example, when the inclination angle is 7 °, the diameter expansion diameter is about 1/5 as compared with the case where the inclination angle is 30 °. For this reason, the distal end portion of the container main body hardly expands, so that the load of the external thread applied to the internal thread cannot be released to the next internal thread and is damaged. In particular, the first to third largest female threads on the proximal end Since a load is applied and a particularly large tensile stress is generated at the root of the female thread, it often breaks from this point.

The present invention has been made in view of the above circumstances, and has as its object to prevent breakage of a female screw. Disclosure of the invention

 An inverted saw-toothed screw according to the present invention includes a standard saw-toothed screw having a clearance flank and a pleated flank. The pleated flank is an inverted clearance flank.

 The inverted saw tooth screw according to the present invention is an inverted pleated flank which receives a load from the inverted clearance flank by reversing the shape of the flank flank and the shape of the clearance flank of the saw toothed female screw. Is formed.

 A reverse saw tooth screw according to the present invention is characterized in that the inclination angle of the clearance flank of the saw tooth screw is set to the inclination angle of the inverted pleated flank receiving a load, and the clearance flank is shifted to the inverted flank. It is formed on an inverted clear flank smaller than the angle of the Tusha flank. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a longitudinal sectional view showing a first embodiment of the present invention, and is an enlarged view of a main part of FIG. 3, and FIG. 2 shows a state where a reverse saw-toothed screw of FIG. 1 is under load. FIG. 3 is an enlarged sectional view of a main part of FIG. 4, and FIG. 4 is a longitudinal sectional view showing an accumulator. FIG. 5 is an enlarged longitudinal sectional view showing a second embodiment of the present invention, FIG. 6 is an enlarged longitudinal sectional view showing a third embodiment of the present invention, and FIG. 7 is a fourth embodiment of the present invention. It is a longitudinal section enlarged view. BEST MODE FOR CARRYING OUT THE INVENTION

 A first embodiment of the present invention will be described with reference to FIGS.

 The accumulator ACC has a bladder 2 built in a container body 1. The bladder 2 is a pleated bladder, which has a folding habit so as to be folded into a predetermined shape. The flange 3 of the bladder 2 is locked to the upper part 1 a of the container body 1 and is fixed by the lid 5. The lid 5 is provided with a supply / exhaust port 6 communicating with the inside of the bladder 2 and a male screw 21 screwed into the female screw 20 of the container body 1. The internal thread 20 is an inverted saw-toothed female thread, and has two internal threads F1 to F12, but the internal thread F1 has a proximal end 20 D side of the internal thread 20. , And the female thread F12 is located on the tip 2 OW side.

 This reverse saw female screw is a saw tooth female screw, for example, a saw tooth female screw with a pleated flank inclination angle of 15 ° and a clearance flank inclination angle of 45 °, a female screw thread F The shape (tilt angle) of the clearance flank and the shape (tilt angle) of the clearance flank of 1 to F12 are opposite to each other. The inclination angle of the pleated flank is formed at the inclination angle の of the inverted clearance flank 20 B.

 In other words, the inclination angle of the inverted flank flank 20 A] 3 is the inclination angle of the clearance flank 45 °, and the inclination angle 逆 of the inverted clearance flank 、 is the inclination angle 1 of the pleated flank. 5 °.

 The inverted pleated flank 20 A and the inverted clearance flank 32 B are continuous through the thread valley bottom 20 C. The radius rl of this valley bottom 20 C is formed to 0.4 mm. ing. The radius rl of the thread root is appropriately selected as necessary, but is preferably in the range of 1/10 to 1/3 of the thread pitch.

A through hole 10 is provided in the bottom 1 b of the container body 1, and a supply / discharge cylinder 13 is attached to the through hole 10 via an O-ring. Flange 1 of this supply / discharge cylinder 1 3 4 is pressed into contact with the receiving portion 11 of the through hole 10. A port valve 16 with a cushion cup 15 is slidably supported on the supply / discharge cylinder 13. The supply / discharge cylinder 13 is fixed to the container body 1 by a nut 17. Next, the operation of the present embodiment will be described.

 Connect the accumulator Acc to the hydraulic circuit (not shown) via the supply / discharge cylinder 13. When the hydraulic pressure of the hydraulic circuit changes and the pressure inside the container body 1 increases, the lid 5 is pressed in the direction of arrow A5, and as shown in FIG. Press the M1 female screw 20 against the inverted pleated flank 2 OA.

 At this time, the load applied to the female thread F 1 is dispersed and generates a pressing force in the direction of arrow A 20, that is, an expanding force. It is elastically deformed and spreads outward while sliding on the side of one male thread M 1. The inclination angle jS of the inverted pleated flank 20 A is 45 °, which is three times the pleated flank inclination angle 15 ° of the conventional example, so that the amount of circumferential displacement is greatly increased. Then, the load that cannot be covered by the female thread F 1 is released and is applied to the next thread F 2, and the load that cannot be fully loaded by the female thread F 2 is released and Thread F3. By repeating this process, the total load on the male screw is transmitted to the female threads F1 to F12. A second embodiment of the present invention will be described with reference to FIG.

The difference between this embodiment and the first embodiment (FIGS. 1 to 4) is that the radius of the female root 20 C of the inverted saw-toothed female screw is 0.21 mm. A third embodiment of the present invention will be described with reference to FIG.

The difference between this embodiment and the first embodiment (FIGS. 1 to 4) is that the reverse plunger female screw has an inverted pleat flank 2 OA inclination angle] 3 of 50 ° and an inverted clearance. Hula The inclination angle of the link 20B] 3 is 10 ° and the radius r1 of the female thread root is 0.21mm. A fourth embodiment of the present invention will be described with reference to FIG.

The difference between this embodiment and the first embodiment (FIGS. 1 to 4) is that the inverted saw-toothed female screw is a stepped tapered female screw. The female screw has a stepped portion 20X and a tapered portion 20Y. The female threads F 1 to F 3 of the stepped portion 20 X are cut at the peaks, and the line connecting the peaks is a straight line L parallel to the center line 10 C of the accumulator. The female threads F3 to F12 of the tapered portion 20Y are peak-cut, and the line connecting the peaks is a center line 10C from the base end 20D side toward the tip end 2OW side. Becomes a taper line T inclined in a direction approaching.

 The embodiment of the present invention is not limited to the above, and may be, for example, as follows.

 In the standard arrangement state, for example, the tip is placed on the upper side and the base end is placed on the lower side, the flank with the smaller inclination angle (the surface receiving the load) is set as the lower surface of the female thread, and the one with the larger inclination angle With the flank on its upper surface, the saw-toothed screw in the reverse arrangement, for example, with the top and bottom of the saw-toothed screw turned upside down, with the tip down and the base up In this case, the flank with the larger inclination angle becomes the inverted pressure flank that receives the load, and the flank with the smaller inclination angle becomes the inverted clearance flank. In this way, by turning the saw-tooth female screw in the reverse state, the reverse saw-tooth female screw may be used.

 Further, the inclination angle of the inverted pleated flank] 3 may be appropriately selected within the range of 30 ° to 60 ° instead of being equal to the inclination angle of the clearance of the saw-tooth female screw.

Further, instead of making the inclination angle 0 of the inverted clearance equal to the inclination angle of the pre-stress flank of the saw-tooth female screw, it may be set to a different inclination angle. No. The inclination angle Θ is formed to be smaller than the inclination angle / 3 of the inverted pleated flank, and the angle Θ is appropriately selected within a range of 0 ° to 15 °. When the inclination angle of the pret-shaft flank] 3 is 45 °, 0 ° is adopted as the reverse clearance inclination angle Θ. Experimental example:

Next, for the internal thread, 60 ° triangular internal thread, and saw-tooth internal thread of the above embodiment, the total load applied to the external thread was set to 33 26 20N, and the tensile load was calculated by the finite element method. When the maximum tensile stress (N · mm ² ) of the female thread valleys of the peaks F 1 to F 12 was examined, the results shown in Table 1 below were obtained.

 In this Table 1,

 F no female thread number,

A is an inverted clear flank inclination angle of 15 °, an inverted pleated flank inclination angle of 45 °, a female screw root with a radius of 0.4mm and a reverse saw-toothed female screw (first embodiment), B is an inverted shape clear lance flank angle of inclination 15 °, opposite the saw blade internally threaded (second embodiment) of radius 0.21mm tilt angle 45 ° female thread root of Gyakukatachi pre Tsu Shah Frank, C is the Gyakukatachiku ¹ lance Frank Inclination angle 10 °, Inclination angle 50 of inverted pleatshaflank. Reverse threaded female screw with a radius of 0.21 mm (3rd embodiment), D is the inclination angle of the inverted clearance flank 15 °, the inclination angle of the inverted pleated flank 45 °, the radius of the female thread root 0.4mm, stepped taper inverted saw-tooth female screw (fourth embodiment),

 E is a conventional serrated female screw with a clearance flank inclination angle of 7 °, a pleated flank inclination angle of 45 °, and a radius of 0.21 mm at the female thread root

F is a 60 ° triangular female thread. Table 1 female thread root of the maximum tensile stress (N 'mm ²⁾

 From Table 1, the following became clear.

 (1) The root tensile stress of the female threads F1 to F3 on the base end side is larger than that of the other female threads F4 to F12. (2) The female thread A, B, C, and D should have a lower root valley tensile stress than the other female threads E and F. (3) Among the inverted saw-toothed female threads A, B, C, and D, the tensile stress at the root of the female thread of A must be the smallest. ④The root stress of the female screw thread A of the inverted saw tooth screw A is about 1 / 2.8 of that of the saw tooth screw E, which is extremely small. Experimental example 2:

Next, each of the female threads F 〖to B (inverted internal female thread in the second embodiment), C (inverted internal female thread in the third embodiment) and F (normally metric internal thread) is used. peripheral direction displacement amount of F ₁₂ (mm) of was measured and found to be as shown in Table 2. Table 2 Circumferential displacement (mm)

この表 2から次のことが明らかとなった。

From Table 2, the following became clear.

 (1) The amount of displacement in the circular direction tends to increase as the female thread number increases. (2) The amount of displacement in the circular direction of the inverted saw-tooth female screws B and C is larger than that of the normal female screw F. (3) The amount of deviation in the circular direction is larger in the reverse saw tooth screw C than in the reverse saw tooth screw B, and the effect of the invention.

According to the present invention, since the inverted pleated flank receiving the load is formed at the inclination angle of the clearance flank of the saw toothed screw, the inclination angle of the load receiving surface is significantly larger than that of the saw toothed screw. Become larger. For this reason, the diameter expansion diameter is larger than in the conventional example, and the load borne by the female thread is reduced, so that the female thread can be prevented from being damaged. Industrial applicability

 The inverted saw-toothed screw according to the present invention is used not only for an internal pressure container such as an accumulator, but also for a female screw for power and the like with only one load on an inverted plenum flank.

Claims

The scope of the claims 1. The standard sawtooth female screw having a clearance flank and a pleated flank is placed in an inversely disposed state, and the clearance flank is made into a reverse pleated flank which receives a load; An inverted serrated female thread, characterized in that an inverted clear flank is used.  2. The inverted saw flank, characterized in that the shape of the flared flank and the shape of the clearance flank of the saw toothed female screw are inverted to form an inverted clearance flank and an inverted pleated flank receiving a load. Tooth screw.  3. The inclination angle of the clearance flank of the saw-tooth internal thread is set to the inclination angle of the inverted flank flank receiving the load, and the clearance flank is set to the inverted clearance flank smaller than the inclination angle of the inverted flank flank. A reverse saw-toothed female screw, characterized in that:  4. The reverse saw toothed screw according to claim 1, 2, or 3, wherein the inclination angle of the inverted pleated flank is 30 ° to 60 °.  5. The inverted pleated flank and the inverted clearance flank force are continuous through the female thread root, and the radius of the female thread root is within the range of 10 to 1/3 of the thread pitch. The inverted saw-toothed female screw according to claim 1, 2, or 3.  6. The reverse saw toothed screw according to claim 1, 2, or 3, wherein the inclination angle of the inverted clearance flank is 0 ° to 15 °.  7. The reverse saw toothed screw according to claim 1, 2, or 3, further comprising a step portion and a tapered portion.