JPH0459194B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an improvement of a hawk crown in a bicycle front fork.

<Prior Art> As shown in FIG. 3, a typical bicycle used today has an upper head lug 101 and a lower head lug 103 fixed to a head pipe 102 by brazing, and a bottom ball head cap 10.
8 is press-fitted into the lower end of the head pipe 102.
And Hawk Stem 104 is Hawk Crown 1
05 and is fixed by brazing. On the upper surface of the hawk crown 105, a protrusion 107 for press-fitting the crown ball race 106 is press-fitted into the inner surface of the crown hole race 106 and fixed. Then, this protrusion 107 is attached to the Hawk stem 1
04 and the hawk crown 106 will be deformed by brazing, so after brazing, the crown ball race 106 is machined to be press-fitted, and a press-fitting surface that is perfectly circular in plan view is formed. Press-fitting is performed.

<Problems to be Solved by the Invention> Nowadays, bicycle frames are being made lighter, and the inventor of the present invention has developed a bicycle frame that consists of hawk crowns and various lug parts made of light metal such as aluminum alloy.
Furthermore, pipes such as head pipes are made of carbon,
The aim is to develop an extremely light frame that is constructed from various types of fiber-reinforced plastics (FRP) such as boron and Kepler, and each joint is bonded with adhesive instead of welding or brazing.

However, when the material of the hawk crown is an aluminum alloy with the same structure as the conventional structure, the protrusion 107 for press-fitting the crown ball race in the hawk crown 105 is limited by the inner diameter of the crown ball race 106, and the protrusion 107 is limited by the inner diameter of the crown ball race 106. 10
It is not possible to increase the inner thickness of 7. To give a specific example, the outer diameter of the Hawk stem 104: 25.4 mm, the inner diameter of the crown ball race 106: 27.0 mm, and the protrusion.
Inner diameter of 107: 25.4mm, outer diameter of protrusion 107: 27.0mm
Therefore, the thickness of the protrusion 107 becomes 0.8 mm. However, with a wall thickness of 0.8 mm, sufficient strength cannot be obtained when the hawk crown is made of steel or aluminum alloy. As a result, this protrusion 107 is connected to the crown ball race 10.
6, there is a risk that the protrusion 107 may be destroyed or damaged starting from its base.

Also, Hawk Stem 104 and Hawk Crown 10
5 is to be fixed with an adhesive, it is considered desirable to extend the protrusion 107 upward to increase the bonding area. However, extending the conventional thin protrusions only increases the possibility of breakage and does not improve the strength, so this idea cannot be applied to actual frames.

On the other hand, Japanese Patent Publication No. 60-13877 and Japanese Patent Application Laid-open No. 49-56338 propose a front hawk in which the hawk crown and the hawk stem are integrally formed. However, in order to integrally form the hawk crown and the hawk stem, it is unavoidable to increase the size of the mold manufacturing equipment.

<Means for Solving the Problems> Therefore, the present invention solves the above problems with the following configuration in a bicycle hawk crown in which the hawk crown 51 and the hawk stem 50 are formed separately. .

A crown ball race portion 52 is integrally formed on the upper surface of the hawk crown 51 of the present invention, and a steel ring body 54 for forming a race surface that receives the ball retainer 42 is placed on the upper surface of the crown ball race portion 52. This crown ball race part 52
The upper end of the extension part 55 is integrally extended upward.
The extension portion 55 reaches above the ball retainer 42 in the bottom ball cap portion 17. Hawk Crown 51 is made of light alloy such as aluminum alloy, and Hawk Crown 51 is made of light alloy such as aluminum alloy.
1 and the inner circumferential surface of the extension part 55 are bonded to the outer circumferential surface of the lower end of the Hawk stem 50 with an adhesive.

<Function> In the present invention, since the hawk crown 51 and the crown ball race portion 52 are integrally formed, there is no need to fix the two by press fitting as in the conventional case, and the hawk crown is not press-fitted during press-fitting. There will be no damage to the protrusions. Furthermore, the outer diameter of the protrusion of the hawk crown 51 is no longer limited to the inner diameter of the crown hole race.

<Example> An example of the present invention will be described below based on the drawings.
FIG. 1 is a cutaway side view showing the front portion of a bicycle frame according to one embodiment, and FIG. 2 is an exploded front view from the lower head lug to the hawk crown.

The head pipe 1, upper pipe 2, and lower pipe 3 of the illustrated frame are made of fiber-reinforced plastic, and the head upper lug 10 and the lower head lug 15 are made of fiber-reinforced plastic.
is made of a light metal such as an aluminum alloy, and the pipes 1, 2, 3 and the lugs 10, 15 are bonded and joined using an epoxy adhesive or the like.

The Hawk stem 50 is made of steel and includes a head pipe 1, an upper head lug 10, and a lower head lug 15.
The lower end thereof is fixed to the hawk crown 51.

This hawk crown 51 is made of aluminum alloy, and has a crown ball race portion 5 on its upper surface.
2 are integrally formed. That is, conventionally, the hawk crown 105 and the crown ball race 106
However, in the present invention, the hawk crown 51 and the crown ball race portion 52 are integrally formed, the conventional protrusion 107 for press fitting is eliminated, and the hawk crown 51 and the crown ball race portion 52 are formed integrally. crown 105
This eliminates the need for press fitting between the crown ball race 106 and the crown ball race 106. And crown ball race part 5
The upper surface 53 of 2 is a tapered surface, and a steel ring body 54 for forming a race surface is simply placed on the tapered surface.

On the other hand, the lower head lug 15 side has the same structure as the conventional one, that is, the lower head lug 103 and the bottom ball head cap 108 are formed separately, and the bottom ball head cap 108 is connected to the head pipe 102.
However, in this embodiment, a flared bottom ball head cap part 17 is integrally formed at the lower end of the lower head lug 15, and its lower surface 18 is a tapered surface, and the race surface Just place the steel ring body 35 for forming.

Then, between the crown ball race portion 52 and the bottom ball head cap portion 17,
It encloses a ball retainer 42 in which steel balls are slidably connected in a ring shape.

Next, Hawk Stem 50 and Hawk Crown 5
To explain the fixed structure with 1, Hawk stem 50
The lower end is inserted into the stem insertion hole of the hawk crown 51 and bonded and fixed with an adhesive. More specifically, an extension portion 55 is integrally extended upward from the upper end of the crown ball race portion 52 of the hawk crown 51. The extension 55 extends above the ball retainer 42 in the bottom ball head cap 17, as shown in FIG. Then, the inner circumferential surfaces of the hawk crown 51 and the extension portion 55 are bonded to the outer circumferential surface of the lower end of the hawk stem 50 using an adhesive. This increases the adhesion area between the two and enables firm fixation. still,
In order to securely fix the two, screws may be processed on the corresponding inner and outer circumferential surfaces so that the two fixing means of adhesive bonding and screwing can be applied at the same time. To give an example of specific numerical values of the diameters of each part in the above embodiment, if the outer diameter of the Hawk stem 50 is 25.4 mm as in the conventional case, the inner diameter of the crown ball race part 52 is 25.4 mm, and the inner diameter of the crown ball race part 52 is 25.4 mm. The outer diameter is 33.0mm at the thickest part a.
becomes. Furthermore, the outer diameter of the narrowest extension portion 55 is
Even if the extension part 55 is extended to be inserted into the head lower lug 15 and further into the head pipe 1, the inner diameter of the lug 15 or pipe 1:
Its dimensions can be freely changed within a range smaller than 30.0mm. Therefore, if the outer diameter of the extension part 55 of the crown ball race part is 29.4 mm, its wall thickness is 2.0 mm.
mm, and sufficient strength can be obtained even when made of light metal such as aluminum alloy.

Next, the structure above the lower head lug 15 may be the same as the conventional structure, but a preferred specific example will be described below.

The upper head lug 10 has an inner diameter of the head pipe 1.
The head cap portion 11 is integrally formed at the upper end of the cylindrical body. That is,
The head lug and the head cap, which were conventionally separate parts, are formed integrally, thereby eliminating the step of press-fitting the head cap into the upper end of the head pipe.

The upper surface of the head cap portion 11 is a tapered surface, and only a steel ring body 30 for forming a race surface is placed thereon. This ring body 3
A ball retainer 40 is arranged on top of the ball cage 0 and is wrapped between it and a screw ball race 41. Above the screw ball race 41, a lock washer 44 and a lock nut 45 are provided as in the conventional case.
will be arranged.

Incidentally, a protrusion 12 having a diameter equal to or smaller than the inner diameter of the head pipe 1 and larger than the outer diameter of the Hawk stem 50 is provided around the inner wall of the upper head lug 10. On the other hand, a projection 19 is provided around the inner wall of the cylindrical portion of the upper portion 16 of the lower head lug 15, similar to the upper head lug 10.

At both ends of the head pipe 1 there are head upper lugs 1.
0 and the lower head lug 15 until they come into contact with protrusions 12 and 19 provided on the inner wall, and are bonded with an epoxy adhesive (not shown).

In addition to the embodiments described above, the present invention can be implemented with modifications within the scope of the claims. For example, the upper head lug 10 and the lower head lug 15 may be implemented as one unit. Further, the shape of the ring body 54 for forming the race surface may be changed depending on the shape and structure of the ball retainer 42.

<Effects of the Invention> As described above, the present invention eliminates the conventional configuration in which the hawk crown and the crown ball race are separately fixed by press fitting, and the crown ball race portion 52 is integrally formed on the upper surface of the hawk crown 51. It is. Therefore, there is no need to form a press-fitting surface on the protrusion for press-fitting as in the past, and there is no need for a process of machining the protrusion for press-fitting or a press-fitting process. Therefore, it not only simplifies the assembly process, but also prevents damage during press-fitting.
The hawk crown was made of light alloy.

Moreover, unlike the case where a conventional press-fitting protrusion is provided, its outer diameter is not limited by the inner diameter of the crown ball race, so the upper end of the crown ball race portion 52 of the hawk crown 51 is The extension part 55 can be formed by extending the extension part 55, and its wall thickness can be made sufficiently thick. Further, since the extension portion 55 can be extended upward while maintaining a sufficient wall thickness,
The hawk stem and hawk crown 51 can be bonded together using an adhesive.

Therefore, the present invention has been able to provide a hawk crown suitable for a new frame manufacturing method in which aluminum alloy hawk crowns and lugs are joined to the hawk stem by adhesive.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side view of the front part of a bicycle frame according to an embodiment of the present invention, Fig. 2 is an exploded partially cutaway front view of the main part, and Fig. 3 is a partially cutaway side view of the conventional front part. It is. 50...Hawk Stem, 51...Hawk Crown, 52...Crown Ball Race Club, 54...
ring body.

Claims (1)

[Claims] 1. In a bicycle hawk crown in which a hawk crown 51 and a hawk stem 50 are formed separately, a crown ball race portion 52 is integrally formed on the upper surface of this hawk crown 51, and this crown ball race A ring body 54 for forming a race surface that receives the ball retainer 42 is placed on the upper surface of the crown ball race part 52.
An extension portion 55 whose upper end extends upward integrally.
The extension part 55 reaches above the ball retainer 42 in the bottom ball head cap part 17, the hawk crown 51 is made of a light alloy such as an aluminum alloy, and the hawk crown 51 and the extension part 5
The hawk crown for a bicycle is characterized in that the inner circumferential surface of the hawk stem 50 is bonded to the outer circumferential surface of the lower end of the hawk stem 50 with an adhesive.