KR101877435B1 - Bellows assembly with added convolution and Method for making the same - Google Patents

Abstract

The present invention relates to a bellows assembly with an added convolution reduced in stress and increased in fatigue life by added convolution formation and a method for manufacturing the same. To this end, the present invention provides a bellows assembly with an added convolution including a bellows in which a plurality of main convolutions are repeated at a cycle and an added convolution corresponding to 1/4 pitch with respect to one pitch equivalent to the cycle of the main convolution is provided at both ends; and a pair of flanges coupled to both ends of the bellows.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a bellows assembly,

The present invention relates to a bellows assembly having a conformal convolution and a method of manufacturing the bellows assembly. And more particularly to a bellows assembly having a conformal convolution with reduced stress and increased fatigue life with conformal convolution and a method of manufacturing the same.

The bellows is used extensively in areas requiring mechanical connection.

In particular, the bellows for a marine engine consists of a convolution that provides stretch-to-pipe flexibility and a flange that connects to the pipe at both ends of the convolution.

Since the bellows is intended to provide elasticity between the pipes, a large number of convolutions generally helps to reduce the stress, but the allowable length is determined for each part when applied to a marine engine, so that the number of convolutions can not be increased infinitely.

On the other hand, the bellows is an important factor in fatigue life that can withstand the operation of the ship engine for a long time. The fatigue life of the bellows is influenced by various factors such as external factors such as operating pressure and temperature, internal bellows material, bellows thickness, pitch of the acid of the convolution, height and shape of the mountain.

In order to improve the fatigue life of the bellows, it is necessary to reduce the stress applied to the bellows. For this purpose, it is important to design the number of convolutions and the connection with the flange.

1, generally, the welded portions of the bellows 2 and the flange 6 are formed by forming both end faces of the bellows 2 into a flat plate shape 4 and connecting the bellows 2 to the inner peripheral face 8 of the flange 6, As shown in Fig. According to this method, there is a convenience of welding, but the flat plate portion of the bellows does not contribute to the stress reduction and occupies only space, which limits the fatigue life improvement.

Prior Art Document: KR Patent Registration No. 1595859 (issued on February 19, 2016)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bellows and a method of manufacturing the bellows which can reduce stress and ensure fatigue life.

In order to achieve the above object, a bellows assembly having an adaptive convolution according to the present invention, which is devised to achieve the above object, has a structure in which a plurality of main convolutions are repeated in cycles, A bellows having a conforming convolution corresponding to a quarter pitch relative to the bellows; And a pair of flanges coupled to opposite ends of the bellows.

Further, an inner side surface of the flange facing the bellows is formed with an engaging groove into which an edge of the adaptive convolution is inserted and welded. The amplitude of the adaptive convolution is smaller than the amplitude of the adjacent main convolution. Wherein the engaging groove of the flange has a hook which engages with the hook of the adjoining convolution and the engaging groove of the flange has a depth in the flange thickness direction And a semicircular portion having a semicircular shape in cross section so as to be closer to the center of the flange and connected to the lower end of the triangular portion, A hook may be provided.

A method of manufacturing a bellows assembly having an adaptive convolution according to the present invention includes the steps of: (a) forming a convolution to have a pitch of 1.5 to 2.5 times the pitch of the bellows's convolution design in the final product; (b) truncating a plurality of main convolutions repeated in a period so that a corresponding convolution corresponding to a pitch of 1/4 of a pitch corresponding to a period of the main convolution is located; (c) machining the joint groove to be welded by inserting the edge of the conformal convolution on the inner surface of the pair of flanges, wherein the engagement groove has a conical shape in cross section so that the depth in the flange thickness direction becomes deeper toward the center of the flange A semicircular portion connected to the lower end of the triangular portion and having a semicircular shape in cross section so as to be closer to and away from the center of the flange, and a stepped portion including an end portion not connected to the triangular portion, ; (d) assembling a flange at both ends of the bellows to form hooks in the conforming convolution and hooking the coupling portions of the hooks to the flanges; (e) welding both end hook portions of the bellows to the engagement grooves of the flange; And (f) compressing the bellows to a design pitch.

According to the present invention, it is possible to reduce the stress and increase the fatigue life by forming a conformal convolution at both side ends of the bellows having a plurality of convolutions.

According to the present invention, a bellows having a conformal convolution is formed, the bellows is formed into a length greater than the design pitch, and then the bellows is assembled and welded to the bell groove of the bellows and the bellows is compressed at a designed pitch. The process is simplified.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a partial cross-sectional view of a typical bellows assembly,
FIG. 2 is a partially cutaway cross-sectional view of a bellows assembly with successive convolution according to an embodiment of the present invention; FIG.
FIG. 3 is a partially cutaway cross-sectional view of a bellows assembly having a driven convolution before compression as in FIG. 2,
Fig. 4 is a view showing only the bellows portion in Fig. 3,
Fig. 5 is an enlarged cross-sectional view of the coupling concavity of the bellows and the coupling groove of the flange in Fig. 2,
Figures 6 and 7 are photographs of a bellows assembly having a conforming convolution according to one embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same or similar components throughout the drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In addition, the preferred embodiments of the present invention will be described below, but it is needless to say that the technical idea of the present invention is not limited thereto and can be variously modified by those skilled in the art.

The bellows may refer to a corrugated portion including a plurality of convolutions, and may also refer to the whole joined to the flange. Hereinbelow, in order to avoid confusion, 'bellows' is used to refer only to the corrugated portion where the flange is not joined, and the bellows with the flange is referred to as the 'bellows assembly'.

FIG. 2 is a partial cutaway cross-sectional view of a bellows assembly having a conforming convolution according to an embodiment of the present invention, FIG. 3 is a partial cutaway cross-sectional view of a bellows assembly having successive convolutions prior to compression, 4 is a view showing only the bellows portion in Fig. FIG. 5 is an enlarged cross-sectional view of the coupling groove of the bellows and the flange in FIG. 2. FIG. Figures 6 and 7 are photographs of a bellows assembly having a conforming convolution according to one embodiment of the present invention.

A bellows assembly having a conformal convolution according to an embodiment of the present invention includes a bellows 102 and a flange 110, referring to FIGS.

5 and 6, in the present invention, the flange has a flange protruding from a bellows cylinder having an outer diameter larger than that of the bellows and formed of a plurality of main convolutions and successive convolutions, And is connected to the inner surface rather than the outer surface.
The bellows 102 includes a main convolution 104 having a corrugated shape.
Referring to FIG. 4, the main convolution 104 is repeatedly formed in a plurality of cycles. The period of the main convolution 104 is a distance from a mountain to a mountain, or a distance from a goal to a goal, or a distance from a specific point to a point immediately after the same point appears, and is defined as one pitch.

delete

At both ends of the bellows 102, a conforming convolution 106 is formed.

The resulting convolution 106 has a smaller pitch than the other main convolution. For example, in FIG. 4, a successive convolution having a quarter pitch to one pitch corresponding to the period of the main convolution is shown, but the present invention is not limited thereto.

The degree of contributing to the stress reduction varies depending on various values such as 3/4 pitch, 2/3 pitch, 1/2 pitch, 1/3 pitch, 1/4 pitch, and the like. It is impossible to increase the pitch of the suffix convolution indefinitely because the allowable length is determined in the design.

In the present invention, it is confirmed that the extension convolution is formed at 1/4 pitch on both sides of the bellows, which is optimum for the stress reduction while satisfying the design specifications of the ship engine. This will be described later.

The connected convolution 106 is formed to be smaller than the amplitude of the adjacent main convolution. When the additive convolution is formed at a quarter pitch, the amplitude of the adjacent convolution has 1/2 of the amplitude of the adjacent main convolution.

The extension convolution 106 has a hook portion 108 having a hook-shaped cross section. The hook portion 108 is engaged with the hook 126 of the engaging groove 120 of the flange 110.

The flange 110 is coupled to both ends of the bellows 102.

The flange 110 has an inner side surface facing the bellows 102 and an engaging groove 120 to which the edge of the adaptive convolution 106 is inserted and welded.

The coupling groove 120 includes a triangular portion 122 and a semicircular portion 124 and a hook 126.

The triangular part 122 has a conical shape in section so that the depth of the flange 110 in the thickness direction thereof becomes deeper toward the center of the flange 110.

The semicircular part 124 is connected to the lower end of the triangular part 122 and has a semicircular shape in cross section so as to approach the center of the flange 110 and then move away from the center.

The hook 126 is provided at an end (the right end on the basis of FIG. 5) which is not connected to the triangular portion 122 of the semicircular portion 124. The hook 126 engages the hook portions 108 of the conformed convolution 106 to engage with each other such that the fitted convolution 106 is securely welded to the flange 110.

The end of the extension convolution 106 may be welded to the inner surface of the flange without a hook portion as shown in Fig. 5, but in this case, it is difficult to secure sufficient strength, and welding work is difficult. Therefore, it is preferable that the end of the driven convolution 106 is provided with the hook portion 108 as shown in Fig. That is, the strength is secured by the coupling of the hook portion and the hook, and the welding space is ensured by the triangular portion and the semicircular portion.

The physical properties of the bellows are specified in detail in the EJMA standard (10th Edition).

The EJMA standard specifies that when a circular bellows with a constant shape and size of convolution is subjected to a certain axial displacement, lateral movement, and angular rotation under given pressure, Maximum buckling stress, buckling potential, load to be received by members around the bellows, and limitations.

In the case of bellows in which the shape and size of the convolution are not constant, this EJMA standard can not be applied. However, it is considered that the shape and size of the convolutions are separated and the bellows is regarded as one bellows. A method of repeating the calculation process for a necessary number of times can be used.

In the case of the bellows having the adaptive convolution like the present invention, it can be interpreted that it includes an incomplete convolution (hereinafter referred to as a first-order convolution, a second-order convolution) on both sides of the main convolution, I interpreted the behavior of the bellows.

Three types of bellows were analyzed according to the EJMA standard. The bellows were analyzed for the total stress due to lateral and axial stresses (Fatigue Life Cycle) ) Were calculated.

The three forms are: (1) a bellows with an integral nine mountains, (2) a bellows with an incomplete quarter-circle on one side of the bellows with an integral nine mountains, (3) And bellows (corresponding to the present invention) to which respective convex convolutions each having an incomplete 1/4 acid are connected to both sides of the bellows having nine mountains.

The results are summarized as follows.

Stress (MPa) Fatigue Life (Times) (One) 1327.74 6842 (2) 1258.93 8822 (3) 1220.76 10246

Referring to the above results, it can be confirmed that the case (3) corresponding to the present invention shows the minimum stress value and the maximum fatigue life value.

Hereinafter, a method of manufacturing a bellows assembly having adaptive convolution according to an embodiment of the present invention will be described.

 Cutting a plurality of main convolutions repeated at a period so that a successive convolution corresponding to a pitch of 1/4 of a pitch corresponding to a period of the main convolution is positioned; (c) machining the joint groove to be welded by inserting the edge of the conformal convolution on the inner surface of the pair of flanges, wherein the engagement groove has a conical shape in cross section so that the depth in the flange thickness direction becomes deeper toward the center of the flange A semicircular portion connected to the lower end of the triangular portion and having a semicircular shape in cross section so as to be closer to and away from the center of the flange, and a stepped portion including an end portion not connected to the triangular portion, ; (d) assembling a flange at both ends of the bellows to form hooks in the conforming convolution and hooking the coupling portions of the hooks to the flanges; (e) welding both end hook portions of the bellows to the engagement grooves of the flange; And (f) compressing the bellows to a design pitch.

First, the convolutions are formed to have a pitch of 1.5 to 2.5 times the pitch of the bellows's convolutions in the final product.

Next, at the ends of the plurality of main convolutions that are repeated in the period, the overlap convolution corresponding to 1/4 pitch relative to one pitch corresponding to the period of the main convolution is cut.

Next, engaging grooves are formed on the inner surfaces of the pair of flanges.

Specifically, the edges of the conforming convolution are respectively inserted into the inner surfaces of the pair of flanges to process the joint groove to be welded. The engagement groove has a conical shape in cross section so that the depth in the flange thickness direction becomes deeper toward the center of the flange And a semicircular portion having a semicircular cross section and a portion not connected to the triangular portion of the semicircular portion so as to be closer to and away from the center of the flange.

Next, a hook portion is formed at the edge of the adjoining convolution, and the flange is assembled at both ends of the bellows so that the hook is caught in the coupling groove of the flange.

Next, the both-end hook portion of the bellows is welded to the engaging groove of the flange.

Finally, compress the bellows to the design pitch.

It will be apparent to those skilled in the art that various modifications, substitutions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. will be. Therefore, the embodiments disclosed in the present invention and the accompanying drawings are intended to illustrate and not to limit the technical spirit of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments and the accompanying drawings . The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

102 - Bellows 104 - Main convolution
106 - Convolution 108 - Hook part
110 - Flange 120 - Coupling groove
122 - triangular part 124 - semicircular part
126 - Hook

Claims (3)

A bellows having a plurality of main convolutions repeated at regular intervals and having a corresponding convolution corresponding to a pitch of one quarter of a pitch corresponding to the period of the main convolution at both ends; And
A pair of flanges coupled to opposite ends of the bellows,
Lt; / RTI >
The flange has a larger outer diameter than the bellows and has a flange protruding from a bellows cylinder formed by a plurality of main convolutions and a conformal convolution. Both ends of the bellows are connected to the inner side of the flange,
An inner circumferential surface of the flange facing the bellows is formed with an engaging groove into which an edge of a conformal convolution is inserted and welded,
The amplitude of the coupled convolution is smaller than the amplitude of the adjacent main convolution,
A hook portion having a hook-shaped cross section is provided at an edge of the accommodated convolution,
The coupling groove of the flange has a hook engaged with the hook portion of the accompanying convolution,
The coupling groove of the flange has a triangular portion having a conical shape in cross section so that the depth in the thickness direction of the flange becomes deeper toward the center of the flange and a triangular portion having a semicircular shape in cross section so as to be closer to the center of the flange, Wherein a hook is provided at an end portion not connected to the triangular portion of the semicircular portion so as to secure the strength by the engagement of the hook portion and the hook and to secure the welding space by the triangular portion and the semicircular portion, ≪ / RTI > delete (a) shaping the convolution to have a pitch of 1.5 to 2.5 times the pitch of the bellows in the final finished product;
(b) truncating a plurality of main convolutions repeated in a period so that a corresponding convolution corresponding to a pitch of 1/4 of a pitch corresponding to a period of the main convolution is located;
(c) machining the joint groove to be welded by inserting the edge of the conformal convolution on the inner surface of the pair of flanges, wherein the engagement groove has a conical shape in cross section so that the depth in the flange thickness direction becomes deeper toward the center of the flange A semicircular portion connected to the lower end of the triangular portion and having a semicircular shape in cross section so as to be closer to and away from the center of the flange, and a stepped portion including an end portion not connected to the triangular portion, ;
(d) assembling a flange at both ends of the bellows to form a hook at the edge of the conformal convolution and hooking the coupling portion of the flange into the flange;
(e) welding both end hook portions of the bellows to the engagement grooves of the flange; And
(f) compressing the bellows to a design pitch
Wherein the bellows assembly has a concave surface.

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