JP3869567B2 - Hose fittings and brake hoses - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hose fitting used for an industrial hose and a brake hose for an automobile using the same.
[0002]
[Prior art]
Hose fittings taking into consideration detachability, leakage prevention, reliability and the like are used at the attachment end of the industrial hose. As a method for producing such a hose fitting, there are a method of making by full cutting and a method of making by plastic working, particularly precision cold forging. However, the former is inferior in economic efficiency and is not suitable for mass-produced products. On the other hand, the latter case is excellent in terms of quality, performance, and economy, and is expected to spread in the future, and the inventors have already made some proposals. In Japanese Patent Application No. 10-33135 previously proposed by the inventors, a male seal portion is provided on the head on one end side in the axial direction to connect the other flare tube or the like. Also, such hose fittings are usually plated on the surface for corrosion resistance. There is galvanization as a kind of plating.
[0003]
[Problems to be solved by the invention]
However, on the other hand, it is conceivable that a female seal portion is provided on the head and the plating is tin / zinc alloy plating. In particular, tin / zinc alloy plating is superior in corrosion resistance to salt damage than zinc plating. When the inventors actually made this and tested it, the following problems occurred.
[0004]
That is, when the plating type was changed from galvanizing to tin / zinc alloy plating, it was found that the head breaking torque dropped to about half. In the case of zinc plating, the breaking torque, which was 500 kgf · cm, falls to 260 to 270 kgf · cm just by changing to tin / zinc alloy plating.
[0005]
In such a hose fitting, the base of the head is constricted and has a minimum diameter. A female screw hole is provided in the head, and a female seal part is provided at the bottom of the female screw hole. When connecting a mating pipe member, such as a metal flare tube, to the hose fitting, insert the flare tube into the female screw hole, screw the flare nut into the female screw hole and tighten it, and then attach the tip of the flare tube to the female seal part. It will be in close contact. If the tightening torque at this time is too large, the head will be destroyed from the constriction at the base of the head, which is the most fragile.
[0006]
Generally, the tightening torque of a flare nut is about 150 kgf · cm. Therefore, in anticipation of safety, we want the head breaking torque to be doubled to about 300kgf · cm. However, in the case of tin-zinc alloy plating, it is about 260 to 270 kgf · cm, and the required value cannot be satisfied.
[0007]
On the other hand, this is also a problem caused by changing the type of plating. However, when the flare nut was tightened, the flare tube was excessively rotated. The flare nut is initially turned by hand and then rotated with a torque wrench until the torque reaches 150 kgf · cm. At the time of tightening with the torque wrench, the flare tube rotates about the same angle by contact friction between the flare nut and the flare tube. In many cases, the flare tube is fixed to the fixed side of the vehicle body or the like, and if the flare tube rotates too much, the flare tube is excessively twisted and the worst break occurs. For this reason, when the flare nut is rotated with a torque wrench, the flare nut rotation angle should be kept below 150 °.
[0008]
Note that the rotation angle of the flare tube during co-rotation is only about 0 to 10 ° smaller than the rotation angle of the flare nut. The above problem does not occur in the case of the male seal part, but is a problem peculiar to the female seal part.
[0009]
[Means for Solving the Problems]
The present invention is a hose fitting in which a head on one end side in the axial direction to which a mating pipe member is connected is integrally formed by plastic working, and a tin / zinc alloy plating is applied to the head surface. Are provided with a female screw hole, a female seal portion formed at the bottom of the female screw hole and gradually reduced in diameter from the terminal end of the female screw toward the center in the axial direction, and a constricted portion formed at the base of the head. , the hardness of the neck portion and Hv160 or more, and female threads formed in the female screw hole is characterized by having a groove in the thread tip.
[0010]
Here, the female screw hole has a female screw having a nominal diameter of M10 × 1, this female screw has a groove having a V-shaped cross section at the tip of the thread, and the effective diameter of the female screw is smaller than the reference effective diameter. It is preferably +147 μm or less.
[0011]
Alternatively, the female screw hole has a female screw having a nominal diameter of M10 × 1, the female screw has a U-shaped groove at the tip of the screw thread, and the effective diameter of the female screw is +108 μm with respect to the reference effective diameter. It is preferable that:
[0012]
Further, the present invention is obtained by the grooves of the thread tip of the female screw and the V-shaped section.
[0013]
Further, the present invention is obtained by the grooves of the thread tip of the female screw and the U-shaped cross section.
[0014]
In addition, the brake hose according to the present invention includes any one of the above hose fittings at least at one end.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0016]
First, the configuration of the hose fitting 1 according to the present invention will be described with reference to FIG. This hose fitting 1 has a head portion 4 on one end side (left side) in the axial direction, a socket portion 2 on the other end side (right side), and a nipple portion 3 positioned radially inward thereof. It has a brim part 12 in the part. The socket portion 2 is a large-diameter tubular member, and the nipple portion 3 is a small-diameter tubular member. As will be described later, as shown in FIG. 3, a flexible hose 22 (rubber hose or the like) is inserted between the socket portion 2 and the nipple portion 3, and the socket portion 2 is caulked from outside in the radial direction. Thus, the brake hose 23 according to the present invention is completed. The socket part 2 and the nipple part 3 are coaxially arranged, and the shaft hole 7 formed in the nipple part 3 penetrates the flange part 12 and communicates with the female screw hole 5 in the head part 4.
[0017]
The head 4 has a female screw hole 5 formed coaxially therewith, a female seal part 10 formed at the bottom of the female screw hole 5, and a constricted part 6 formed at the base of the head 4. It consists of The female screw hole 5 is opened at the end face position of the head 4 and has a female screw 13 on the inner peripheral portion. The female seal portion 10 is a concave tapered surface that is gradually reduced in diameter from the terminal end of the female screw 13 toward the center in the axial direction. The previous shaft hole 7 is opened at the shaft center portion of the female seal portion 10, but the opening is slightly enlarged with respect to the reference diameter of the shaft hole 7. The expanded diameter portion is indicated by 8. The constricted portion 6 is formed by forming a groove 11 continuous in the circumferential direction on the outer periphery of the base of the head 4. The cross-sectional shape of the groove 11 is U-shaped. This constricted portion 6 is the smallest diameter portion of the head 4 and is the most fragile portion. The constricted portion 6 is located radially outward of the female seal portion 10.
[0018]
The flange portion 12 has a diameter larger than that of the head portion 4 and the socket portion 2, and the head portion 4 side of the outer peripheral portion thereof is reduced in a stepped shape, and at least one of the large diameter portion or the small diameter portion has two surfaces for preventing rotation. The shape or hexagonal shape such as a nut is used.
[0019]
As shown in FIG. 2, the head 4 is a portion to which a mating pipe member, here, a metal flare tube 14 is connected. The flare tube 14 is integrally formed with a flare-shaped expanded sheet portion 15 at the distal end, and the distal end surface of the sheet portion 15 is a convex tapered surface that fits the female seal portion 10. Therefore, sealing is achieved by bringing the front end surface of the seat portion 15 into close contact with the female seal portion 10. The close contact is achieved by tightening the flare nut 16 in the female screw hole 5. The flare nut 16 is formed in a cylindrical shape, and is fitted to the outer peripheral side of the flare tube 14 so as to be rotatable with a predetermined gap. As shown in FIG. 6, the taper angle θ _{1 of the} front end surface of the seat portion 15 is substantially the same as the taper angle θ ₂ of the female seal portion 10. Therefore, at the time of close contact, the outer peripheral edge portion of the front end surface of the sheet portion 15 hits the female seal portion 10, and the sheet portion 15 is appropriately deformed to obtain a good sealing property.
[0020]
The initial tightening of the flare nut 16 is performed manually. This tightening is performed until the flare nut 16 sandwiches the sheet portion 15 of the flare tube 14 between the female seal portion 10 and cannot be turned by hand. The subsequent tightening is performed with a torque wrench (not shown). Thus, when the flare nut 16 is tightened with a predetermined torque, the seat portion 15 of the flare tube 14 comes into close contact with the female seal portion 10 sufficiently. An engaging portion 17 formed in a hexagonal nut shape or the like is provided at the rear end portion of the flare nut 16 in order to engage the tool.
[0021]
The entire hose fitting 1 is integrally formed by plastic working, particularly precision cold forging, and further, tin / zinc alloy plating is applied to the entire surface. In particular, when tin / zinc alloy plating was used instead of the conventional zinc plating, the above-described problems occurred. The yellow chromate treatment may be performed after the tin / zinc alloy plating. Since it is an integrally molded product by plastic working, there are advantages such as no brazing part and no risk of liquid leakage, easy management because the number of parts is one, and high yield of materials because no chips are generated.
[0022]
As the material of the hose fitting 1, a carbon steel wire for cold heading (for example, SWCH6A) or an equivalent thereof is selected. In addition, aluminum or its alloy, copper or its alloy, etc. can be selected as another material. A solid coil material is used as the starting material for forging, and this is finished in stages with a multi-stage part former. Specifically, the first forging process → cleaning / annealing → second forging process → cutting → plating → inspection is performed.
[0023]
As for each dimension value of the hose fitting 1, the outer diameter D of the constricted portion 6 is φ12.3 mm, the width H of the groove 11 is 2.2 mm, the nominal diameter of the female screw 13 is M10 × 1.0 (standard effective diameter 9.350 according to JIS B 0207) mm). The female screw 13 is processed by a tap, but here, one of two types of taps is adopted. The thread shape differs depending on which one is used, and when one is used, a minute groove 19 having a V-shaped cross section is formed along the tip of the thread 18 as shown in FIG. This female screw 13 is referred to as a V-groove female screw. When the other is used, as shown in FIG. 5, a minute groove 20 having a U-shaped cross section is formed along the tip of the screw thread 18. This female screw 13 is referred to as a U-groove female screw.
[0024]
Further, as described above, the tightening torque of the flare nut 16 is about 150 kgf · cm, and the required breaking torque of the neck 4 and the constricted portion 6 is 300 kgf · cm or more. The required angle for final tightening of the flare nut 16 with a torque wrench is 150 ° or less.
[0025]
Now, when the cause of the above-mentioned problem was examined, it was found that the fact that the friction coefficient was reduced due to the change of plating greatly influenced. As estimated from various literatures, it is considered that the dynamic friction coefficient of tin is 0.05 and the dynamic friction coefficient of zinc is about 0.15. The tin-zinc alloy used for plating contains 70% tin and 30% zinc, so the coefficient of dynamic friction is estimated to be about 0.08, about half that of zinc. In particular, on the surface of the female screw hole 5 and the female seal portion 10 inside the metal fitting, a measurement result that the ratio of tin is increased has been obtained, and it is considered that the dynamic friction coefficient decreases to about 0.08 or less.
[0026]
On the other hand, as shown in FIG. 6, in the final tightening stage, the seat portion 15 and the female seal portion 10 of the flare tube 14, the seat portion 15 and the flare nut 16, the thread 21 of the flare nut 16, and the thread of the female screw 13. Friction contact occurs between 18 respectively. A part of the tightening torque applied to the flare nut 16 is used to resist these frictions. However, when the friction is reduced, the torque absorbed here is reduced correspondingly, which is borne by the constricted portion 6, and As a result, it is considered that the constricted portion 6 breaks with a small torque.
[0027]
Therefore, in order to solve this, the hardness of the constricted portion 6 is optimized. FIG. 7 shows the relationship between the hardness (Hv) of the constricted portion 6 and the breaking torque (kgf · cm). As can be seen, it is sufficient that the constriction 6 has a hardness of Hv160 or more in order to satisfy the required torque of 300 kgf · cm or more. For this reason, for such a hose fitting 1, the hardness of the constricted portion 6 is set to Hv160 or more. The conventional hardness was about Hv140.
[0028]
As a method for increasing the hardness of the constricted portion 6, the principle of work hardening is basically used. That is, the processed part of the metal becomes hard, and this is remarkable in the case of cold forging. In the present plan, emphasis is placed on improving the hardness around the constricted portion 6, and the periphery of the constricted portion 6 is processed in the second forging process among the above-described processes. In this case, delicate dimensional management is required, and the unreasonable machining affects the mold life, so the process design is carefully conducted.
[0029]
Next, the co-rotation problem of the flare tube 14 was dealt with by optimizing the accuracy of the female screw 13. FIG. 8 shows the relationship between the accuracy (+ μm) with respect to the reference effective diameter of the female screw 13 and the rotation angle (°) of the flare nut 16. As can be seen, in order to keep the rotation angle of the flare nut 16 (approximately equal to the co-rotation angle of the flare tube 14) below the required angle of 150 ° or less, the V groove female screw is +147 μm or less, and the U groove female screw is +108 μm. What is necessary is as follows. Therefore, it was decided to do so for the hose fitting 1. As a result, the co-rotation angle is suppressed to a required angle or less, and the assembly property to the vehicle body or the like is improved.
[0030]
Since the reference effective diameter of the female screw 13 is 9.350 mm, the female screw 13 here has an effective diameter of 9.497 mm or less for the V-groove female screw and 9.458 mm or less for the U-groove female screw. In general, the accuracy or tightening degree of the female screw is determined with a positive value with respect to the reference effective diameter. The smaller this positive value, the higher the accuracy and the tighter the tightening. Conventionally, in the case of galvanization, it was as large as +134 μm with a U groove female screw.
[0031]
Referring to FIG. 6, increasing the accuracy of the female screw 13 means that the screw thread 18 of the female screw 13 is moved radially inward to approach the screw thread 21 of the flare nut 16. It means reducing the radial clearance. Therefore, the contact area between the threads 18 and 21 is increased by this amount, the frictional resistance is increased, and the tightening property of the flare nut 16 is deteriorated. In other words, the torque is absorbed accordingly, and the specified value 150 kgf · cm is quickly reached with a small tightening angle of the flare nut 16. Therefore, it is considered that the co-rotation angle of the flare tube 14 is also reduced and the required angle of 150 ° or less can be satisfied by the above-mentioned female screw accuracy.
[0032]
The hose fitting 1 can be applied to any industrial hose, but can also be applied to, for example, an automobile brake hose as described below. As shown in FIG. 3, the brake hose 23 has the above-described hose fittings 1 attached to both ends of a flexible hose 22 (rubber hose or the like). As described above, as described above, the hose 22 is inserted between the socket part 2 and the nipple part 3 and the socket part 2 is caulked from outside in the radial direction. As a result, the hose 22 is brought into close contact with the nipple portion 3 to achieve sealing. The flare tube 14 is connected to the hose fittings 1 at both ends, and brake oil is circulated in the flare tube 14, the hose 22, and the shaft hole 7.
[0033]
As described above, various other embodiments of the present invention can be considered. For example, the present invention can be applied to a separate hose fitting if the constriction is integrally formed by plastic working, and the plating is tin / zinc alloy plating except for the head. Applicable to non-hose fittings. The counterpart tube member is not limited to the above-described flare tube, and the shape of the constricted portion is not limited to the above-described one. The brake hose may be provided with the hose fitting of the present invention at least at one end.
[0034]
【The invention's effect】
In short, according to the present invention, even when tin / zinc alloy plating is applied, a sufficient head breaking torque can be obtained, and the co-rotation angle of the pipe member can be suppressed within the required angle. Is done.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view of a hose fitting according to the present invention.
FIG. 2 is a longitudinal side view showing a connection state between a hose fitting and a flare tube.
FIG. 3 is a longitudinal side view of a brake hose to which a hose fitting according to the present invention is applied.
FIG. 4 is an enlarged vertical side view of a female screw, showing a V-groove female screw.
FIG. 5 is an enlarged vertical side view of the female screw, showing a U-groove female screw.
FIG. 6 is an enlarged longitudinal sectional side view showing a connection state between a hose fitting and a flare tube.
FIG. 7 is a graph showing the relationship between the hardness of the constricted portion and the breaking torque.
FIG. 8 is a graph showing the relationship between the accuracy of the female screw and the rotation angle of the flare nut.
[Explanation of symbols]
1 Hose fitting 4 Head 23 Brake hose 22 Hose

Claims (4)

A head part on one end side in the axial direction to which the opposite pipe member is connected is integrally formed by plastic working, and a hose fitting in which tin-zinc alloy plating is applied to the surface of the head part. A hole, a female seal portion formed at the bottom of the female screw hole and gradually reduced in diameter from the terminal end of the female screw toward the axially central side, and a constricted portion formed at the base of the head, and the constricted portion The hose fitting has a hardness of Hv160 or more, and the female screw formed in the female screw hole has a groove at the tip of the screw thread . The hose fitting according to claim 1, wherein the groove at the tip of the thread of the female screw is a groove having a V-shaped cross section. The hose fitting according to claim 1, wherein the groove at the tip of the thread of the female screw is a groove having a U-shaped cross section. A brake hose comprising the hose fitting according to any one of claims 1 to 4 at least at one end.

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