A corrugated pipe and a method for manufacturing the same

Abstract

The invention discloses a corrugated tube, comprising a tube body and a corrugated section arranged on the tube body. When viewed from a longitudinal section of the corrugated section in an extended state, the tube wall is formed by a left side wall, an arc-shaped wave crest wall and a right side wall which are alternately connected in sequence to present a continuous wave shape. The right side wall and the arc of the wave crest wall are in a smooth transition, while the left side wall intersects with the arc of the wave crest wall to form an inflection point convex to the inside of the tube wall. The right side wall is in a straight line segment shape or in an arc convex to the outside of the tube wall, and the curvature radius of the arc is much larger than the curvature radius of the arc of the wave crest wall. The left side wall is provided with two sections of a first arc and a second arc convex to the outside of the tube wall, the first arc intersects with the arc of the wave crest wall, and the inflection point is at the intersection of the first arc and the arc of the wave crest wall, and the curvature radius of the second arc is much larger than the curvature radius of the arc of the wave crest wall. Through the above scheme, the stretching of the corrugated tube is smoother, and the stability during shrinkage and shaping is not affected.

Description

Technical Field

[0001] The invention relates to the field of pipes, and more specifically, to a corrugated pipe with a corrugated wall suitable for ventilation and drainage equipment such as bathroom heaters, ventilators, range hoods, washing machines, etc. Background Art

[0002] Plastic telescopic tube is a widely used ventilation, exhaust and drainage component. It is an indispensable and important component for bathroom heaters, ventilators, sinks, washing machines and range hoods. The important feature of plastic telescopic tube is that it can be extended, contracted and bent under the action of external force to meet the requirements of various occasions.

[0003] The existing plastic corrugated pipe cannot be shaped by itself after being stretched or bent due to the effect of elasticity. Therefore, it has the disadvantages of poor strength, low pressure resistance, inconvenience in use, and narrow application range.

[0004] In view of the above problems, a structure is disclosed in the "telescopic bellows" disclosed in Chinese patent CN99225495.7. The bellows is composed of a cross-section of an upper oblique line segment wave wall, a lower oblique line segment wave wall, an arc wave peak connecting the upper and lower oblique line segment wave walls, and a triangular wave trough formed by the upper and lower oblique line segment wave walls themselves. Since the upper and lower oblique line segment wave walls are both straight lines, the upper and lower oblique line segment wave walls will bend in an arc shape after shrinking and folding. This bending deformation will generate a restoring force due to the fact that the upper and lower oblique line segment wave walls themselves are straight lines, thereby causing the disadvantage of being easy to spread out and difficult to fold.

[0005] With the development of technology, in order to solve the problem that the above-mentioned bellows are easy to spread out, a structure is disclosed in the "Plastic Telescopic Tube and Its Manufacturing Method" disclosed in Chinese Patent CN100523580. The upper and lower oblique line wave walls in the above-mentioned patent are mainly improved into convex wave walls, so that after the bellows are contracted, the wave wall on one side is bent back and fitted to the wave wall on the other side to achieve contraction. Since the wave wall on the bent side bypasses the dead point during the compression process, if it needs to be restored to its original state, the bellows needs to be stretched so that the wave wall on that side bypasses the dead point again to do work and restore the original convex shape, so that after contraction, the state of the bellows will remain stable.

[0006] Then, after adopting the bellows with the curved wave wall, although the bellows has a stable deformation ability after deformation, the wave wall on one side is folded back after contraction, and the wave wall after the folding will be convex to the wave wall on the other side in a reverse arc shape, and the curvature of the folding is very large. When the bellows needs to be opened, the folded wave wall will bypass the dead point again to restore the original convex shape. In this opening process, the force to overcome the folded wave wall bypassing the dead point is very large, and in the process of pulling the bellows from the contracted state to the stretched state, the force generated is instantaneous, which makes it very easy for the bellows to receive a large impulse and be broken. If the curvature of the wave wall is not enough, it will cause the problem of unstable state after contraction. Summary of the invention

[0007] The first object of the present invention is to provide a corrugated tube which has strong shrinkage and shaping ability and can be stretched and shrunk smoothly and labor-savingly.

[0008] To achieve the above-mentioned first purpose, the following technical means are used: a corrugated tube, comprising a tube body and a corrugated section arranged on the tube body, wherein the corrugated section, when viewed from a longitudinal section in its extended state, has a tube wall which is alternately connected in sequence by a left side wall, an arc-shaped crest wall and a right side wall to present a continuous wave shape, and there is a smooth transition between the arcs of the right side wall and the crest wall, while the left side wall intersects with the arc of the crest wall to form an inflection point convex to the inside of the tube wall, the right side wall is in the shape of a straight line segment or in the shape of an arc convex to the outside of the tube wall, and the curvature radius of the arc is much larger than the curvature radius of the arc of the crest wall, the left side wall is provided with two sections of a first arc and a second arc convex to the outside of the tube wall, the first arc intersects with the arc of the crest wall, and the inflection point is at the intersection of the first arc and the arc of the crest wall, and the curvature radius of the second arc is much larger than the curvature radius of the arc of the crest wall.

[0009] Further optimization is as follows: the curvature radius of the arc of the crest wall is 0.5-2mm, when the right wall is an arc, its curvature radius is 50-200mm, the first arc curvature radius of the left wall is 6-10mm, and the second arc curvature radius is 16-30mm.

[0010] Further optimization is as follows: from the horizontal projection, the distance from the bottom of the left wall to the crest is L1, and the distance from the crest to the bottom of the right wall is L2; ​​from the vertical projection, the distance from the crest to the trough is L3, satisfying L1: L2: L3 = 1: 1.1~1.2: 0.9~1.

[0011] Further optimization is as follows: the angle between the line between the two end points of the left side wall and the center line of the tube body is 45 to 60°, and the angle between the line between the two end points of the right side wall and the center line of the tube body is 2 to 5° smaller than the angle between the line between the two end points of the left side wall and the center line of the tube body.

[0012] A second object of the present invention is to provide a method for manufacturing the above-mentioned bellows.

[0013] To achieve the second objective, the following technical means are used: A method for manufacturing the bellows comprises the following steps:

[0014] a. Extruding the plastic into a tube blank through an extruder;

[0015] b. Put the tube blank into a telescopic tube forming mold with a set temperature while it is still hot, and make the two ends of the tube blank exposed outside the two ends of the forming mold. The mold cavity of the forming mold matches the shape of the finished telescopic tube in the extended state, and the length of the two ends of the mold cavity is longer than that of the finished telescopic tube in the extended state;

[0016] c. Place the air nozzle of the blowing device on the forming mold, close and lock the forming mold, and the two ends of the tube blank are clamped and sealed by the two ends of the forming mold. Then, blow air into the inner cavity of the tube blank through the air nozzle to inflate the tube blank into a semi-finished product. The inflation ratio during the inflation molding process is 1:2-3;

[0017] d. Open the forming mold, take out the semi-finished product and trim off the seals at both ends, and then compress the telescopic tube along the axial direction through compression molding to form a compressed and folded state.

[0018] The advantages of the present invention compared with the prior art are:

[0019] (1) The wave crest wall is set in an arc shape. When the corrugated section is stretched or contracted, the arc-shaped wave crest can evenly disperse the force, prevent partial stress concentration, and increase the service life of the bellows;

[0020] (2) The two-segment arc design of the right side wall allows the second arc with a larger curvature to collapse toward its center and fold over due to external force when it is folded toward the left side wall, which is equivalent to crossing a dead point. Therefore, after folding, the second arc also needs to overcome the resistance of the dead point to spread out, thereby better ensuring that the telescopic ring wall can maintain a folded state after folding. In addition, since the first arc with a smaller curvature is set on the right side wall, combined with the inflection point between the first arc and the intersection of the wave crest arc, the first arc will not be folded back due to force and will still present an outward convex form. Therefore, when the corrugated section shrinks, the first arc The arc will press against the left side wall, so that the left side wall and the right side wall will not be completely fitted together, showing that the outer tube section of the corrugated section is pushed open by the first arc, and the inner tube section is fitted after being folded back and centered by the second arc. When the corrugated section needs to be pulled apart, only the second arc needs to be restored and folded back, and since the first arc convexly presses against the left side wall, the stretching preparation state is already presented at the beginning, which can be more labor-saving and smooth, and the corrugated section can be pulled apart without overcoming a lot of resistance to do work, and there will be no instantaneous excessive force during stretching, thereby increasing the service life of the corrugated section.

[0021] (3) The distance L1 from the bottom of the left wall to the crest, the distance L2 from the crest to the bottom of the right wall, and the distance L3 from the crest to the trough are set to satisfy the ratio of L1:L2:L3=1.1~1.2:1:0.9~1. When combined with the first arc and the second arc of the right wall, the effect of optimal labor-saving in stretching the corrugated section and stable shaping during shrinkage can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the overall external structure diagram of the bellows of this embodiment;

[0023] Figure 2 for Figure 1 A magnified view of part A;

[0024] Figure 3 is a cross-sectional view of the bellows of this embodiment;

[0025] Figure 4 for Figure 3 A magnified view of part B;

[0026] Figure 5 This is a partial enlarged analytical diagram of the corrugated section in the extended state;

[0027] Figure 6 It is a partially enlarged schematic diagram of the corrugated section in the contracted state.

[0028] In the figure, 1, tube body; 2, corrugated section; 3, right side wall; 4, crest wall; 5, left side wall; 51, first circular arc; 52, second circular arc; 6, inflection point. DETAILED DESCRIPTION

[0029] The invention will be further described in detail below with reference to the accompanying drawings and through specific embodiments. The following embodiments are merely illustrative and are not intended to limit the scope of protection of the present invention.

[0030] Example

[0031] A bellows, first see attached Figure 1 , including a tube body 1 and a corrugated section 2, wherein the corrugated section is described in detail in the attached Figure 2-6 From the longitudinal section of the extended state, the tube wall is formed by the left side wall 5, the arc-shaped wave crest wall 4 and the right side wall 3, which are connected alternately in sequence and present a continuous wave shape. The arc between the right side wall and the wave crest wall is a smooth transition, and the left side wall intersects with the arc of the wave crest wall to form an inflection point 6 convex to the inside of the tube wall. The right side wall is in the shape of a straight line segment or in the shape of an arc convex to the outside of the tube wall. In this embodiment, the right side wall is in an arc shape, and the curvature of the arc is 50-200 mm in radius. The curvature radius of the arc is much larger than 0.5-2mm of the crest wall. The left side wall is provided with two sections of a first arc 51 and a second arc 52 protruding outward from the tube wall. The first arc intersects with the arc of the crest wall. The inflection point is located at the intersection of the first arc and the arc of the crest wall. The curvature radius of the second arc is 16-30mm, which is much larger than the curvature radius of the arc of the crest wall, and the curvature radius of the first arc is 6-10mm, which is smaller than the curvature radius of the second arc.

[0032] The telescopic unit of the corrugated section consists of a left wall, a right wall and a wave crest wall. The analytical diagrams of the left wall, the right wall and the wave crest wall are shown in the attached Figure 5 , the angle α between the line between the two end points of the left wall and the center line of the tube body is 45-60°, and the angle β between the line between the two end points of the right wall and the center line of the tube body is 2-5° smaller than α. From the horizontal projection, the distance from the tail of the left wall to the crest is L1, and the distance from the crest to the tail of the right wall is L2. From the horizontal projection, the distance from the crest to the trough is L3, satisfying L1: L2: L3 = 1: 1.1-1.2: 0.9-1 is the best ratio. The corrugated section in this ratio is the smoothest when it expands and contracts.

[0033] The specific ratios of L1, L2, and L3, as well as the minimum pulling force to pull the corrugated section apart when stretching it, and the experimental data on whether the left side wall is single-arc or double-arc are shown in the following table:

[0034]

[0035]

[0036] It can be seen from the above data that designing the left side wall into a double arc is more labor-saving than designing the left side wall into a single arc in the prior art. When the ratio of L1:L2:L3 is set close to 1:1.1~1.2:0.9~1, it is more labor-saving than other ratios. Moreover, since the second arc is reversed and shaped, the shaping ability of the corrugated tube in this embodiment will not be affected, thereby achieving strong shrinkage and shaping ability, and being able to stretch and shrink smoothly and labor-savingly.

[0037] The bellows manufacturing process of this embodiment is as follows:

[0038] a. Extruding the plastic into a tube blank through an extruder;

[0039] b. Put the tube blank into a telescopic tube forming mold with a set temperature while it is still hot, and make the two ends of the tube blank exposed outside the two ends of the forming mold. The mold cavity of the forming mold matches the shape of the finished telescopic tube in the extended state, and the length of the two ends of the mold cavity is longer than that of the finished telescopic tube in the extended state;

[0040] c. Place the air nozzle of the blowing device on the forming mold, close and lock the forming mold, and the two ends of the tube blank are clamped and sealed by the two ends of the forming mold. Then, blow air into the inner cavity of the tube blank through the air nozzle to inflate the tube blank into a semi-finished product. The inflation ratio during the inflation molding process is 1:2-3;

[0041] d. Open the forming mold, take out the semi-finished product and trim off the seals at both ends, and then compress the telescopic tube along the axial direction through compression molding to form a compressed and folded state.

[0042] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A corrugated tube, comprising a tube body and a corrugated section arranged on the tube body, wherein the corrugated section, when viewed from a longitudinal section in an extended state, has a tube wall which is alternately connected in sequence by a left side wall, an arc-shaped crest wall and a right side wall to present a continuous wave shape, and the right side wall and the arc of the crest wall have a smooth transition, while the left side wall intersects with the arc of the crest wall to form an inflection point convex to the inside of the tube wall, characterized in that: The right side wall is in the shape of a straight line segment or an arc bulging outward from the tube wall, and the curvature radius of the arc is much larger than the curvature radius of the arc of the crest wall. The left side wall is provided with two sections of a first arc and a second arc bulging outward from the tube wall, the first arc intersects with the arc of the crest wall, and the inflection point is located at the intersection of the first arc and the arc of the crest wall, the curvature radius of the second arc is much larger than the curvature radius of the arc of the crest wall, the curvature radius of the arc of the crest wall is 0.5-2mm, when the right side wall is an arc, its curvature radius is 50-200mm, and the curvature radius of the first arc of the left side wall is 6-10m m, the radius of curvature of the second arc is 16-30mm, from the horizontal projection, the distance from the bottom of the left wall to the crest is L1, the distance from the crest to the bottom of the right wall is L2, and from the vertical projection, the distance from the crest to the trough is L3, satisfying L1: L2: L3 = 1: 1.1 ~ 1.2: 0.9 ~ 1, the angle between the line between the two end points of the left wall and the center line of the tube body is 45 ~ 60 °, and the angle between the line between the two end points of the right wall and the center line of the tube body is 2 ~ 5 ° smaller than the angle between the line between the two end points of the left wall and the center line of the tube body.

2. A method for manufacturing a corrugated pipe as claimed in claim 1, characterized in that: The steps include: a. Extruding the plastic into a tube blank through an extruder; b. Put the tube blank into a telescopic tube forming mold with a set temperature while it is still hot, and make the two ends of the tube blank exposed outside the two ends of the forming mold. The mold cavity of the forming mold matches the shape of the finished telescopic tube in the extended state, and the length of the two ends of the mold cavity is longer than that of the finished telescopic tube in the extended state; c. Place the air nozzle of the blowing device on the forming mold, close and lock the forming mold, and the two ends of the tube blank are clamped and sealed by the two ends of the forming mold. Then, blow air into the inner cavity of the tube blank through the air nozzle to inflate the tube blank into a semi-finished product. The inflation ratio during the inflation molding process is 1:2-3; d. Open the forming mold, take out the semi-finished product and trim off the seals at both ends, and then compress the telescopic tube along the axial direction through compression molding to form a compressed and folded state.

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