JPS5927478B2 - How to make an elbow - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an elbow used in a blower duct or the like.

A conventional seed elbow is formed by welding a pair of half-shaped members a, which are obtained by dividing the elbow in half in the length direction, with flanges a on both sides, as shown in Fig. 1, or as shown in Fig. 2. As shown in the figure, a method is known in which a number of annular pieces C divided in the length direction of the elbow are formed in advance, and the pieces are sequentially joined to form the elbow.

However, in the case shown in Fig. 1, the member a is obtained by press working, making it difficult to obtain a large-diameter elbow, and in the case shown in Fig. 2, the number of steps is large, resulting in high costs. There is.

The object of the present invention is to provide a method for manufacturing an elbow without such inconveniences. It is made by winding the plate material in a spiral shape and binding the side edges that touch each other.

An example of implementing the present invention will be explained with reference to the attached drawings.

In FIG. 3, reference numeral 1 designates an elbow constructed by winding a long strip-shaped plate material 2 in a spiral shape and binding side edges 2a and 2b that contact each other. As shown in FIG. 5, both edges thereof are composed of meandering curves of the same shape, and the curves are offset from each other in the length direction.

This single curve is simply a curve representing one side of the conventional annular piece of the type shown in Fig. 2, which is formed by connecting a plurality of annular pieces, and is shifted by the winding angle α relative to the curve on the other side. .

The curve on the first side of this annular piece is shown in Figures 6a and b.If the radius of curvature is γ2 and the circumferential angle is θ, the radius of curvature on the center line of the elbow is D. /2+γ, the radius of curvature at positions X and Y displaced by an angle θ from that position is D
/2+γ-D/2cosθ, and the width of the annular piece whose central angle is φ at the radius of curvature is ((Di2+
γ)-D/2 cos θ) tanφ However, in the case of n annular pieces, φ is expressed as π/an.

However, a is a constant determined by the type of elbow, and is 4 for a 96' elbow and 6 for a 66' elbow.

Therefore, the curve is ((D/2+r) −D/2 co
sθ) tanπ//an.

Therefore, one example of cutting according to the present invention may be carried out as follows based on the curve.

That is, as shown in Fig. 5, take a line segment AOB corresponding to 10 circumferences of the elbow, divide it into n equal parts, and find the equal dividing point n1.
Draw a perpendicular line to n3...

Next, take the innermost width of the elbow along the perpendicular line in the opposite direction from both ends, and take the tip of the value of COSθ-0 in the above equation in the opposite direction, and connect the tips with P and Q. The intersection points of this straight line PQ and the perpendicular drawn to the line segment AOB are set as nl, n2, . . .

Then, take the values obtained by substituting the circumferential angle θ at the positions nl, n2, etc. above and below the perpendicular line, and set the points as 1tK2, 1, 2, etc. .

Thus obtained A, 1, 2...K, point f taken at a symmetrical position along the perpendicular line between points A and P, and ', 2'...B. When tied together, a plate piece a with curved edges on both sides is obtained, and when n pieces of this are connected in the length direction, a fourth plate piece a is obtained.
A desired plate material 2 as shown in the figure is obtained.

When winding the plate material 2 in a spiral shape, the plate material 2 is wound around the elbow with its side edges touching each other, and the curves forming the both side edges are offset from each other in the length direction. The elbow is not affected by the winding angle α, as shown in Figure 7a, where point A at one end of each plate piece a sequentially matches point B at the other end, and the axis of the elbow is not curved. You get an elbow.

That is, the axis line is curved as shown in Fig. 7, and the elbow does not occur, which causes problems in construction.

The illustrated one is one in which both side edges 2a and 2b are joined by seam folding, and numerals 4 and 4 indicate the seam folding.

However, it goes without saying that this connection can be achieved by welding or other means. In this way, according to the present invention, both edges are formed of meandering curves of the same shape, and the strip-like plate material is spirally wound and mutually connected. Since the side edges that come into contact with the plate are tied together, an elbow can be obtained by simply winding the plate material in a spiral shape, making continuous work possible.
Both side edges of the plate are made up of meandering curves of the same shape, and in particular, the curves are offset from each other in the length direction, which has the effect of providing an elbow that does not cause misalignment due to the winding angle.

[Brief explanation of the drawing]

In the drawings, Fig. 1a is a side view of a conventional example, Fig. 1 is a front view thereof, Fig. 2 is a side view of another conventional example, and Fig. 3a is a side view of an example implementing the method of the present invention. , Fig. 3 is a cross-sectional view taken along the I-1 line of Subaso, Fig. 4 is a plan view of the plate, Fig. 5 is a diagram illustrating cutting of the plate, and Fig. 6 is an explanatory diagram for deriving the equation of the curve. FIG. 7 is a diagram explaining the features of the method of the present invention. 1... Elbow, 2... Board material.

Claims (1)

[Claims] 1. It is characterized by having both side edges made of meandering curves with the same shape, and in which the curves are alternately staggered in the length direction of the strip-shaped plate material, which is wound in a spiral shape to bind the side edges that touch each other. Manufactured elbow bath