JP2013204671A - Pipe joint bolt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipe joint bolt that can be easily tightened and prevents loosening.SOLUTION: A pipe joint bolt 1 includes a longitudinal groove 5 for a flow passage in the axial direction on the outer periphery of a shaft portion 2 including a threaded portion 4. The edge angle β of a second edge portion Q of the longitudinal groove 5 located in the anti-tightening direction of the bolt is set to be larger than the edge angle α of a first edge portion P of the longitudinal groove 5 located in the tightening direction of the bolt 1. Thereby, during tightening, hanging of the second edge portion Q to a screw hole is little, and tightening can be performed with a relatively small torque. In a tightened state, loosening can be suppressed by hanging of the first edge portion P.

Description

The present invention relates to a pipe joint bolt used for an oil cooler pipe or the like of an automobile transmission.

Conventionally, pipe joint bolts as shown in FIG. 5 have been used for cooler piping that sends oil in a transmission to an oil cooler or returns oil cooled by the oil cooler to the transmission. In FIG. 5, 20 is a pipe joint bolt, 30 is a case such as a transmission, 31 is a cooler pipe, 32 is a pipe joint, and 33 is a gasket.

The shaft portion of the pipe joint bolt 20 is provided with an axial vertical hole 21 that opens to the lower end and a horizontal hole 22 that communicates with the vertical hole 21 in the orthogonal direction. The front end of the vertical hole 21 communicates with the inside of the case 30, and the horizontal hole 22 communicates with the inside of the pipe joint 32. Therefore, by fastening the pipe joint bolt 20 to the case 30 via the pipe joint 32, the pipe joint 32 connected to the tip of the cooler pipe 31 and the inside of the case 30 are connected to the vertical hole 21 of the pipe joint bolt 20 and It communicates through the lateral hole 22.

However, since the pipe joint bolt 20 having the above-described structure needs to be drilled from two directions in order to form an oil flow path, there is a problem that the manufacturing cost is increased. Further, by machining inside the bolt, the screw strength is lowered, and it is difficult to apply to a portion where a high torque is applied (a portion requiring sealability).

Patent Document 1 discloses a pipe joint bolt in which a longitudinal groove in the axial direction is formed on a surface portion where a screw of a shaft portion is formed. FIG. 6 shows an attachment structure of a pipe joint bolt with a longitudinal groove shown in Patent Document 1, and FIG. 7 shows a sectional shape thereof. Reference numeral 40 denotes a bolt, 41 denotes a shaft portion thereof, 42 denotes a screw portion, and 43 denotes a longitudinal groove. For other parts, the same parts as those in FIG. In this example, two vertical grooves 43 having a V-shaped cross section are formed at 180 degrees symmetrical positions of the shaft portion 41, and the inside of the pipe joint 32 and the screw hole 34 of the case 30 are connected via the vertical grooves 43. Communicate.

Since the vertical groove 43 of the pipe joint bolt 40 can be formed by non-cutting processing such as cold forging and header processing, the manufacturing cost can be reduced as compared with the pipe joint bolt 20 shown in FIG. Moreover, since only the vertical groove 43 is formed on the outer periphery of the shaft portion 41, there is an advantage that a decrease in mechanical strength can be suppressed compared to the pipe joint bolt 20.

However, when the vertical groove 43 as described above is formed, the following problem may occur. That is, when the bolt 40 is tightened in the direction of the arrow in FIG. 7, the edge 43 a opposite to the tightening direction side of the vertical groove 43 is caught on the inner surface of the screw hole 34 of the case 30. Torque is required. On the other hand, when a force is applied in the loosening direction with the bolt 40 fastened, the edge portion 43b on the tightening direction side of the vertical groove 43 is engaged with the inner surface of the screw hole 34. Since it is after the inner surface of the hole 34 is scraped off, the loosening suppression effect is low. As a result, there is a possibility that the axial force in the fastening state is not sufficiently generated, the pressure-bonding force of the gasket 33 is lowered, and the sealing performance is lowered. This problem occurs even if the cross-sectional shape of the vertical groove 43 is a shape other than the V shape (for example, a U shape).

JP-A-9-49515

Accordingly, an object of the present invention is to provide a pipe joint bolt that is easy to tighten and is not easily loosened.

In order to achieve the above object, the present invention is a pipe joint bolt in which a longitudinal groove for a flow passage is provided in the axial direction on the outer periphery of a shaft portion provided with a screw portion, and is positioned on the tightening direction side of the bolt. Compared to the edge angle α of the first edge portion P of the vertical groove, the edge angle β of the second edge portion Q of the vertical groove located on the side opposite to the bolt tightening direction is set to be larger. A pipe joint bolt is provided.

The present invention is based on the finding that making the cross-sectional shape of the longitudinal groove asymmetrical is effective in obtaining a pipe joint bolt that is easy to tighten and does not loosen. When the bolt is fastened, the second edge portion Q on the side opposite to the tightening direction of the longitudinal groove advances to the back while being in contact with the inner surface of the screw hole such as the case. Since the edge angle β of the second edge portion Q is larger than the edge angle α of the first edge portion P (always an obtuse angle), there is little catching on the inner surface of the screw hole, it can be tightened smoothly, and tightening torque is reduced. it can. On the other hand, when the bolt tries to turn in the loosening direction in the tightened state, the first edge portion P on the tightening direction side of the vertical groove comes into contact with the inner surface of the screw hole of the case or the like. Since the edge angle α of the first edge portion P is smaller than the edge angle β of the second edge portion Q, the first edge portion P is likely to be caught on the inner surface of the screw hole. Therefore, it is difficult to loosen in the fastened state, and good sealing performance can be maintained.

In the present invention, the edge angle is an angle formed by a tangent at the edge portion and a side surface of the longitudinal groove. Depending on the processing method, both side edges of the vertical groove are not necessarily edge-shaped, and sag (R surface) may occur, but the intersection of the extension line of the side surface and the outer circumference of the screw portion is assumed to be the edge portion. In this case, the angle formed between the tangent at the edge and the side surface is referred to as an edge angle.

The number of vertical grooves may be one or a plurality of two or more, and the cross-sectional shape of the vertical grooves is arbitrary, and is not limited to a V-shape. The number of longitudinal grooves and the cross-sectional shape may be selected in consideration of the flow path area and mechanical strength.

As described above, according to the present invention, as compared with the edge angle α of the first edge portion P of the vertical groove positioned on the bolt tightening direction side, the vertical groove of the vertical groove positioned on the bolt anti-tightening direction side is compared. Since the edge angle β of the two edge portion Q is set to be large, it is possible to realize a pipe joint bolt that is easy to tighten and does not loosen easily. Since the bolt of the present invention only forms a longitudinal groove on the outer periphery of the shaft portion provided with the threaded portion, it can be manufactured at a lower cost than a bolt with a hole, has high mechanical strength, and has good sealing properties. A simple pipe joint bolt can be realized.

It is a front view of the 1st example of the pipe joint bolt concerning the present invention. It is an AA line expanded sectional view of FIG. It is sectional drawing of the connection structure of the cooler piping using the pipe joint bolt shown in FIG. It is an expanded sectional view of 2nd Example of the pipe joint bolt which concerns on this invention. It is sectional drawing of an example of the connection structure of the cooler piping using the conventional pipe joint bolt. It is sectional drawing of the connection structure of the cooler piping using the pipe joint bolt shown by patent document 1. FIG. FIG. 7 is an enlarged sectional view taken along line B-B in FIG. 6.

(First embodiment)
FIG. 1 shows an example of a pipe joint bolt according to the present invention. In FIG. 1, 1 is a pipe joint bolt (union bolt) made of, for example, an iron-based metal, and has a hexagonal head portion 2 and a shaft portion 3. A threaded portion 4 is formed on the outer periphery of the shaft portion 3 from the lower end to a predetermined height, and a longitudinal groove 5 for a flow path extending in the axial direction in substantially the same area as the threaded portion 4 (shown by hatching in FIG. 1). Is formed. The lower end of the vertical groove 5 extends to the lower end of the shaft portion 3, and the depth of the vertical groove 5 is deeper than the depth of the screw portion 4. Note that the upper end of the vertical groove 5 does not have to be the same height as the upper end of the threaded portion 4, and may be a position higher than the upper end of the threaded portion 4 as long as it communicates with the internal space of the pipe joint 13 described later. However, it may be in a low position. In this embodiment, two longitudinal grooves 5 are formed at symmetrical positions of 180 °, but may be one or three or more in the circumferential direction. The longitudinal grooves 5 can be formed by non-cutting such as cold forging or header processing, but may be formed by cutting. A convex seat surface 6 is integrally formed on the lower surface side of the head 2.

FIG. 2 shows a cross-sectional shape of the pipe joint bolt 1. The cross-sectional shape of the vertical groove 5 is substantially V-shaped and asymmetrical. The arrow direction in FIG. 2 is the tightening direction. The depth of the vertical groove 5 is deeper than the depth of the screw portion 4 (difference between the peak portion and the valley portion), and the channel area can be gained by the cross-sectional area of the vertical groove 5. A first edge portion P and a second edge portion Q are formed on both side edges of the vertical groove 5, that is, on the tightening direction side and the counter-tightening direction side of the bolt 1. As shown in the following equation, the edge angle β of the second edge portion Q is set larger than the edge angle α of the first edge portion P.
α <β
In this embodiment, α≈90 ° and β≈130 ° are set, but the angle is not limited to these. For example, α = 90 ° ± 10 ° and β = 130 ° ± 10 ° may be used. In the case of a reverse screw, the magnitude relationship between α and β is reversed.

As shown in FIG. 2, the edge angles 痾 and 竈 are angles formed by tangent lines at the edge portions P and Q and the side surfaces 5 a and 5 b of the vertical groove 5 (an angle on the outer side surface of the vertical groove 1). For example, when the vertical groove 5 is processed first and then the threaded portion 4 is processed by rolling, the side edges P and Q of the vertical groove 5 are not necessarily edge-shaped, and sagging (R surface) may occur. However, even in this case, the intersection of the extension lines of the side surfaces 5a and 5b of the longitudinal groove 5 and the outer circumference of the screw portion 4 is referred to as an edge portion.

FIG. 3 shows an example in which the above-described pipe joint bolt 1 is applied to a connection part of an oil cooler pipe of an automobile transmission. In FIG. 3, 10 is a case such as a transmission, 12 is a cooler pipe, 13 is a pipe joint, and 14 is a gasket. The pipe joint bolt 1 is fastened to the screw hole 11 of the case 10 via a gasket 14 and a pipe joint 13. The seating surface 6 is crimped to the gasket 14 by the tightening force of the pipe joint bolt 1, and a part of the gasket 14 is crushed to exhibit sealing performance. In the fastened state, since the upper end of the vertical groove 5 is open to the inside of the pipe joint 13 and the lower end communicates with the screw hole 11 of the case 10, the vertical groove 5 is connected to the inside of the case 10 and the cooler pipe 12. Can be communicated with each other.

When the pipe joint bolt 1 is fastened to the case 10, the edge portion on the side opposite to the tightening direction of the vertical groove 5, that is, the second edge portion Q is screwed while rubbing against the inner surface of the screw hole 11. In general, the case 10 is formed of a material softer than the pipe joint bolt 1 (for example, aluminum). Therefore, if the second edge portion Q of the vertical groove 5 is sharp, the second edge portion Q covers the inner surface of the screw hole 11. It will be screwed while shaving. However, in the present invention, the edge angle の of the second edge portion Q is larger than the edge angle の of the first edge portion P (竈 is always an obtuse angle). There is little catch and it can be tightened with a relatively small tightening torque. On the other hand, when a torque in the loosening direction (the direction opposite to the tightening direction in FIG. 2) acts on the bolt 1 in the tightened state, the first edge portion P on the tightening direction side is in sliding contact with the inner surface of the screw hole 11. . At this time, the first edge portion P, which is sharper than the second edge portion Q, is caught on the inner surface of the screw hole 11, and the loosening of the bolt 1 can be suppressed.

As a method for manufacturing the pipe joint bolt 1, various methods are conceivable. As a preferred method, first, the longitudinal groove 5 in the axial direction is formed in the shaft portion 3 (the thread portion is not processed) of the pipe joint bolt 1. The longitudinal groove 5 may be formed by cutting, but is preferably formed by non-cutting such as cold forging or header processing. Next, the screw part 4 is rolled from both sides of the shaft part 3 in which the vertical groove 5 is formed using a flat die or the like. When the threaded portion 4 is rolled, the threaded portion 4 is rolled such that the depth of the threaded portion 4 is shallower than the depth of the longitudinal groove 5. In this way, the pipe joint bolt 1 with a longitudinal groove can be manufactured. In this method, since the longitudinal groove 5 can be formed by non-cutting, it can be manufactured at a lower cost than a bolt (see FIG. 5) in which an oil passage is formed. As another method, the threaded portion 4 may be first rolled on the shaft portion 3 of the pipe joint bolt 1 and then the longitudinal groove 5 may be cut.

In the present invention, since the vertical groove 5 for forming a flow path is formed on the outer peripheral surface of the shaft portion 3 of the pipe joint bolt 1, the mechanical strength is larger than that of a bolt (see FIG. 5) having an oil hole formed therein. , Can increase the axial force. As a result, the present invention can also be applied to parts that require high sealing performance.

(Second embodiment)
FIG. 4 shows a second embodiment of the pipe joint bolt according to the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. In this embodiment, an unequal trapezoidal vertical groove 5 is formed on the outer periphery of the shaft portion 3 of the bolt 1. Compared to the angle α (first edge angle) formed between the side surface 5a on the tightening direction side of the vertical groove 5 and the tangent line, the angle β (second edge angle) formed between the side surface 5b on the anti-clamping direction side and the tangent line. Is set larger. The bottom 5c of the vertical groove 5 is a flat bottom, and the cross-sectional area (flow channel area) is secured while the depth of the vertical groove 5 is shallow.

The cross-sectional shape of the longitudinal groove according to the present invention is not limited to the shape shown in FIGS. Compared with the edge angle α of the first edge portion P of the longitudinal groove located on the tightening direction side, the edge angle β of the second edge portion Q of the longitudinal groove located on the anti-tightening direction side is an asymmetrical shape. If is set to be large, it is arbitrary.

DESCRIPTION OF SYMBOLS 1 Pipe joint bolt 3 Shaft part 4 Thread part 5 Vertical groove 5a Side surface 5b on the tightening direction side Side surface 10 on the anti-tightening direction side Case
11 Screw hole 12 Cooler piping 13 Fitting 14 Gasket P First edge portion Q Second edge portion

Claims (1)

In the pipe joint bolt in which the longitudinal groove for the flow path is provided in the axial direction on the outer periphery of the shaft portion provided with the screw portion,
Compared with the edge angle α of the first edge portion P of the vertical groove located on the bolt tightening direction side, the edge angle of the second edge portion Q of the vertical groove located on the bolt anti-tightening direction side A pipe joint bolt, wherein β is set large.

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