JPH03229006A - Internal enforcing element of pipe fitting and method of manufacturing the same - Google Patents

Abstract

PURPOSE: To enlarge the contact surface of a joint part, to improve the mechanical strength and to obtain good appearance without cracks in the periphery by providing a tube internal end part with an axial slotted cylindrical section integrally formed with a concave end wall. CONSTITUTION: A reinforcement element 10 is formed by side walls 12a, b and an end wall 14 integraly formed therewith to have the same form as that of the inner surface of an open end of a tube member 12, and the end wall 14 is formed in the same shape as that of the outer surface of a tube member 4. Accordingly, the contact surface can be enlarged to obtain high mechanical strength, the appearance can made favorable without cracks, and working can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a tube reinforcing element between a hollow tube member and another member, and to a method for manufacturing such a tube element. The present invention has particular application to reinforcing the joint of two hollow tube members, such as those constituting a bicycle tube frame, and the following description will therefore also be made in connection with that application, although it goes without saying that the present invention It can be similarly applied to many other uses.

PRIOR ART The conventional common technique for splicing together two hollow tubular members, such as when assembling a bicycle frame, uses an external lug with a sleeve and a peripheral flange, with the sleeve attached to one side. The first tube member is fitted onto the outer surface of the other tube member, and the flange is bonded to the outer surface of the other tube member. The connection of this external lug is done by welding or brazing. Pipe fittings of such a configuration have a relatively high mechanical strength, but are visible from the outside and therefore have a poor appearance. Furthermore, the manufacturing cost is also high.

German Patent No. 94.366@ describes a method for joining two tube sections of a bicycle frame. The reinforcing member is made by investment casting, which is expensive to manufacture.

British Patent No. 421.687 relates to the bicycle G-Dog. This is a standard conventional fully symmetrical drawing cup with a flat bottom, with or without a tab made by cutting a slot into the side wall of its lug.

OBJECT OF THE INVENTION The object of the present invention is to provide a front reinforcing element between one hollow tubular member and another tubular member, and also such a reinforcing element, returning from those prior art. The object of the present invention is to provide a manufacturing method. Another object of the invention is to provide a reinforcing element and a method for its manufacture, which is particularly applicable to the assembly of bicycle frames.

Another object of the present invention is to provide a reinforcing element manufactured by single-stage double-act forming of a blank blank.

(Means for solving the problem 1) According to the invention, a front reinforcing element made from a punched blank is installed between one hollow tube member and another tube member with the open end 81S to the right. A tubular element is provided with an axially slotted cylindrical section extending from a concavely curved end wall.Such a construction facilitates the fabrication of the reinforcing element by a single-stage double-acting deep drawing-like process. make it easier.

It also increases the length of the edges of the internal reinforcing elements or lugs that are joined to the two pipe members, and thus increases the fillet of the braze applied to those edges, further increasing the mechanical strength of the pipe fitting. Make it expensive.

According to features in preferred embodiments of the invention described below, the further tubular member has a curved outer surface, and the end wall of the internal reinforcing element of the invention complements the curved outer surface of the other member. It has a curved outer surface. This internal lug is joined to the tubular member and other members by brazing.

According to another feature of embodiments of the invention, the tubular member is joined at an oblique angle to another hollow tubular member, for example in the case of a bicycle frame. In this case, the open end of the hollow tube member is cut from the beginning with a bias corresponding to the inclination angle, and a side wall is then formed integrally with the end wall of the reinforcing element with the same inclination angle. .

The front reinforcing element made of -UI with the above characteristics can obtain very high mechanical strength since the contact area of the element for joining the two pipe members together is large. . Furthermore, because the elements are placed internally and hidden from view, the cracks have a clean appearance.

According to another object of the present invention, there is provided a method of fabricating a front reinforcing element by forcing an IJ punched flat blank through a drawing die to form it into the desired shape.

In one embodiment, the reinforcing element is simultaneously joined by brazing to the hollow tubular member and the hollow member after it has been inserted into the open end of the hollow tubular member. In a second embodiment, after the reinforcing element has been inserted into the hollow tube, the side walls of the element are first brazed to the hollow tube.

Then that hollow tube i! g3n is abutted against the other part and the end wall of the reinforcing element is brazed to the other part.

Further features and advantages of the invention will become apparent from the description of the exemplary embodiments that follows, with reference to the accompanying drawings.

Embodiment The reinforcing element shown in the drawings is particularly useful for joining together two tubular members 2 and 4, which constitute, for example, a bicycle frame. As shown in FIG. 3, the open end of the tube member 2 is joined to the outer surface of the tube member 4 at an inclined angle.

According to the present invention, the tube member 2 is joined to the tube portion i14 using another member. This separate member will hereinafter be referred to as a reinforcing element and will be designated generally by the number 10 to distinguish it from the external lugs commonly used when assembling bicycle frames and other similar structures.

In a pipe joint made using the reinforced type *io, the element is installed inside the open end of the pipe member 2. The reinforcing element 10 includes a side wall 12 having the same shape as the inner surface of the open end of the tube member 2 and joined thereto, and a fii wall 1 formed integrally with this side wall 12 and extending in a direction transverse to the side wall 12.
4. The end wall 14 is made substantially flush with the open end of the tubular member 2 and is joined to the outer surface of the tubular member 4.

The structure of the reinforcing element 10 and one method of manufacturing it (by a deep drawing-like process) are shown in particular in FIGS. 1 and 2. FIG. If the reinforced mold Jk 10 is manufactured by a deep drawing-like process, first a flat blank 10' having the required shape as shown in FIG. 1 is stamped out of a flat sheet metal. The flat blank 10' is then passed through a single-acting double-acting drawing tool die to undergo a process similar to forming drawing.
It is shaped as shown in FIG.

The flat blank shown in FIG. 1 has a central formation 14' which, in the constricted configuration of the element shown in FIG.
form. The blank 10' is a suitably angled concave curve with four slotted cylindrical sections as shown in FIG.

The blank 10' further includes a central hole 18 passing through the formation 14' and tabs 12a', 12b'1.
An arbitrary hole 20 penetrating each of 2c' and 12d'
Equipped with The hole 18 is therefore centered in the end wall 14 of the constricted internal element 1o as shown in FIG.
will exist in The central hole 18 is preferably non-circular, for example square in shape, since it can be used for positioning in a drawing tool when the element is formed by drawing.

The optional holes 20 in tabs 12a-12b are circular as shown, but may also be non-circular. These holes distribute stress during assembly.

During the drawing process, tabs 12a'-12d' are folded out of the plane of central formation 14' to form a four slotted cylindrical section.

After the reinforcing element 10 of FIG. 2 has been fabricated as described above, this element extends in the transverse direction with its end wall 14 substantially coplanar with the open end wall of the tubular member 2. In this way, it is inserted into the open end of the tube member 2. The tubular member 2 with its internal lugs 10 is then abutted firmly against the outer surface of the tubular member 4, and the entire assembly is brazed by a conventional brazing process.

Alternatively, the brazing may be carried out in two stages, in which the M-cord 10 is first brazed to the tubular member 2 in a first stage and then to the outer surface of the tubular member 4 in a second stage.

[Effect of the invention 1] As understood from the above description, the joint shown here has a very high mechanical strength due to the large contact surface of the reinforcing element 10 that joins the two pipe members 2 and 4. It can provide strength. Also, since the reinforcing element 10 is hidden from view, the pipe fitting exhibits a clean, tear-free appearance.

Furthermore, the provision of relief by four angled slots is a significant advantage. This facilitates drawing the blank into the form of a one-piece lug, as shown in FIG. 2, by a single-stroke multi-stage drawing process.

Although the reinforcing element 10 described here has been produced by a deep drawing-like process, it goes without saying that it can also be produced by a bond process, such as an investment casting process or a conventional multi-step deep drawing process. . The reinforcing element of the present invention can also be used in other applications than joining two tubular members to create a bicycle frame.

Other variations and applications of the invention will be apparent to those skilled in the art. For example, the reinforcing element can have more or less than four tabs.

[Brief explanation of drawings]

FIG. 1 is a plan view of the reinforcing element used in the pipe fittings of FIGS. 3 and 4 in its initial flat state, showing that it is provided with a fan-shaped relief; FIG. , FIG. 3 shows a state in which the reinforcing element of FIG. 1 is drawn and before being inserted into the open end of a pipe member; FIG. 3 shows a pipe joint constructed using the reinforcing element of the present invention; FIG. 4 is a top view of the pipe fitting of FIG. 3; 2.4... Pipe member, 10... Reinforcement element, 10'
...Blank, 12-mW, 12a-12d-tab, 14...end wall, 14'...formation, 8...hole.

Claims (16)

[Claims] (1) In an internal reinforcing element of a pipe fitting between two tubular members, the reinforcing element comprises an axially slotted cylindrical section integral with a concave curved end wall. 2. The pipe fitting internal reinforcement element of claim 1 formed by a single step double action drawing process from a stamped flat blank. (3) the blank has four section reliefs, the two reliefs being symmetrically arranged along its longitudinal axis;
3. A pipe fitting internal reinforcement element according to claim 2, wherein the other two are arranged along the transverse axis. 4. The internal reinforcement of claim 3, wherein said flat blank comprises four tabs, two of which are on a longitudinal axis of symmetry and the other two are on a transverse axis. element. 5. The internal reinforcing element of claim 1, wherein the element is joined to the hollow tube member by brazing. 6. The internal reinforcing element of claim 1, wherein the end wall has a central hole formed therein. 7. The pipe fitting internal reinforcement element of claim 6, wherein said flat stamped blank has a central, non-circular positioning and orientation tool hole formed therein. (8) The pipe fitting internal reinforcing element according to claim 2, wherein a stress dispersion hole is formed at the tip of the tab of the blank. (9) The pipe brazing joint reinforcing element according to claim 2, wherein a stress relief hole is formed at the base of the fan-shaped relief. (10) The blank is adapted to form reinforcing elements with different tube diameters and joint angles for constructing a bicycle frame. Pipe fitting internal reinforcement element. (11) A method of fabricating an internal reinforcing element of a joint, comprising: a) a central formation, the formation being provided with a central non-circular locating tool hole, and having four ears or tabs formed by sector reliefs thereof; punching a flat blank from a metal plate with the desired shape such that the tabs extend from the formation and have rounded tips with holes for distributing stresses during brazing assembly; b) Place the blank in a forming device and force it into a drawing die to apply a single-stroke double-acting process, the first act of which forms a concave curved surface and the second act of which produces a cylinder with relief slots; c) drawing the joint reinforcing element so produced from the drawing die. (12) In an internal reinforcing element of a joint that abuts and joins the end of the first tubular member to the outer surface of the second tubular member, the internal reinforcing element is a flat sheet metal having a plurality of lobes extending outward. The element is made from a blank and has a longitudinal axis and a drawn end wall having a generally radially extending cylindrical concave surface, and a drawn axial direction integral with the end wall. a slotted cylindrical sidewall section, the cylindrical sidewall being comprised of a plurality of sections made from the lobes. (13) The generally radially extending cylindrical concave curved surface has an axis perpendicular to the longitudinal axis, and the cylindrical side wall is connected to the generally radially extending cylindrical concave curved surface. At least two such sections (12d-12c and 12a-12) separated by intersecting slots (16b and 16d)
13. Internal reinforcing element according to claim 12, comprising b). 14. The internal reinforcement element of claim 12, wherein said cylindrical sidewall comprises four said sections made of said lobes. (15) The generally radially extending cylindrical concave curved surface is
having an axis that intersects the longitudinal axis at an angle inclined from 90° such that at one end of the generally radially extending cylindrical concave surface the side wall is at an obtuse angle from the end wall. and at the other end of the generally radially extending cylindrical concave curve, the side wall is inclined at an acute angle from the end wall, and the cylindrical side wall is made of at least three lobes.
13. Internal reinforcing element according to claim 12, comprising three sections (12c-12b and 12a and 12d). (16) a brazed butt joint between the end of the first tubular member and the outer surface of the second tubular member, wherein the braze joint has a plurality of outwardly extending lobes within the brazed joint; supported by an internal reinforcing element made from a flat sheet metal blank having a longitudinal axis and a formed-drawn generally radially extending cylindrical concave end wall; and a drawn axially slotted cylindrical side wall section integral with the end wall, the cylindrical side wall comprising:
A brazed butt joint comprised of a plurality of sections made from the lobes.