CN108662322B - Rotational molding joint for hollow wall winding pipe - Google Patents
Rotational molding joint for hollow wall winding pipe Download PDFInfo
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- CN108662322B CN108662322B CN201810902558.7A CN201810902558A CN108662322B CN 108662322 B CN108662322 B CN 108662322B CN 201810902558 A CN201810902558 A CN 201810902558A CN 108662322 B CN108662322 B CN 108662322B
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- 238000001175 rotational moulding Methods 0.000 title claims abstract description 34
- 238000004804 winding Methods 0.000 title claims abstract description 26
- 238000007789 sealing Methods 0.000 claims abstract description 44
- 230000003014 reinforcing effect Effects 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 15
- 230000008569 process Effects 0.000 claims abstract description 12
- 239000000843 powder Substances 0.000 claims description 65
- 238000001816 cooling Methods 0.000 claims description 31
- 239000002994 raw material Substances 0.000 claims description 29
- 238000010438 heat treatment Methods 0.000 claims description 19
- 238000004519 manufacturing process Methods 0.000 claims description 15
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- 239000000203 mixture Substances 0.000 claims description 12
- 238000012216 screening Methods 0.000 claims description 12
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- 229920002943 EPDM rubber Polymers 0.000 claims description 3
- 229920000459 Nitrile rubber Polymers 0.000 claims description 3
- 239000003795 chemical substances by application Substances 0.000 claims description 3
- 239000011248 coating agent Substances 0.000 claims description 3
- 238000000576 coating method Methods 0.000 claims description 3
- 229920001684 low density polyethylene Polymers 0.000 claims description 3
- 239000004702 low-density polyethylene Substances 0.000 claims description 3
- 229920001084 poly(chloroprene) Polymers 0.000 claims description 3
- 229920000915 polyvinyl chloride Polymers 0.000 claims description 3
- 239000004800 polyvinyl chloride Substances 0.000 claims description 3
- 229920002379 silicone rubber Polymers 0.000 claims description 3
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- 238000005303 weighing Methods 0.000 claims description 3
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L25/00—Constructive types of pipe joints not provided for in groups F16L13/00 - F16L23/00 ; Details of pipe joints not otherwise provided for, e.g. electrically conducting or insulating means
- F16L25/14—Joints for pipes of different diameters or cross-section
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
- B29C41/02—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of definite length, i.e. discrete articles
- B29C41/04—Rotational or centrifugal casting, i.e. coating the inside of a mould by rotating the mould
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
- B29C41/34—Component parts, details or accessories; Auxiliary operations
- B29C41/52—Measuring, controlling or regulating
Abstract
The invention discloses a rotational molding joint of a hollow wall winding pipe, which comprises a joint body and a sealing ring arranged at a sleeving part of the joint body and a pipe main body, wherein the joint body comprises an outer cylinder and a reducing pipe positioning device, the middle part of the inner wall is provided with a reinforcing positioning rib, the reducing pipe positioning device is arranged on the side surface of the reinforcing positioning rib, the reducing pipe positioning device comprises a plurality of inner cylinders, the inner cylinders are coaxially arranged on one side surface of the reinforcing positioning rib and/or the other side surface of the reinforcing positioning rib, and the diameters of the inner cylinders are unequal; or the reducing pipe positioning device is a step surface arranged on the side surface of the reinforcing positioning rib, and the sealing ring comprises a sealing ring body and anti-falling teeth arranged on the outer surface of the sealing ring body; the rotational molding joint is prepared by adopting a novel process, so that free cutting of the hollow wall winding pipe can be realized, and the splicing of the reducing pipe can be realized, and the rotational molding joint has good sealing performance and long service life.
Description
Technical Field
The invention relates to the field of hollow wall winding pipes, in particular to a rotational molding joint of a hollow wall winding pipe.
Background
With the development of society and the advancement of science and technology, polymer materials are increasingly focused and applied to many fields, particularly municipal engineering, underground burying of pipelines is realized, steel pipes applied in the traditional method are replaced by hollow wall winding pipes, the hollow wall winding pipes have the advantages of high ring rigidity, strong impact resistance, simple process, low comprehensive cost and the like, but the hollow wall winding pipes applied in the existing market mostly adopt a hot melt connection mode and a bell and spigot mode, however, the mode is only suitable for the hollow wall winding pipes which are already molded, if the hollow wall winding pipes are cut off or lengthened for a small section, the problem of free cutting cannot be realized in the middle of the hollow wall winding pipes, and the pipelines connected by the hot melt connection technology are used underground for a period of time, so that collapse and breakage occur, and the service life is terminated. Meanwhile, the connector manufactured by the injection molding process adopted by the connector is of a single-layer solid structure, is suitable for manufacturing small products, has higher cost, and is not very suitable for manufacturing large-scale pipeline connectors.
Through retrieval, the invention uses a clamp process to fix the connecting sleeve at two ends of a pipeline with two ends connected by adopting a clamp, but the process is more complicated in site construction and the quality is not easy to control. The Chinese patent with the publication number of CN202812542U is a double-bellmouth hollow wall winding pipe joint and a connecting mechanism, wherein bellmouths are arranged at two ends of the connecting mechanism, sealing rubber rings are arranged at the sleeving parts of the connecting mechanism and the pipe main body, and the connecting mechanism is manufactured by adopting an injection molding method, but the connecting mechanism does not have a positioning device when the connecting parts of the pipe main body are sealed by adopting the sealing rubber rings, and because the end surfaces of the pipe main body possibly have gaps, the rubber rings and even the connecting mechanism are easily shifted after long-time use, so that the sealing performance is poor, the service life is influenced, the connecting mechanism is not applicable when the connecting mechanism is connected with different pipe diameters, and the universality is not strong. There is also a chinese patent with publication number CN207486284U, a reducer union, which is only coaxially connected, and if there is a stepped connection on the ground, it is easy to collapse and break at the union, which affects the sealing effect.
Disclosure of Invention
In order to solve the problems, the invention discloses a rotational molding joint of a hollow wall winding pipe, which comprises a joint body and a sealing ring arranged at a sleeving position of the joint body and a pipe body, wherein the joint body comprises an outer cylinder and a reducing pipe positioning device, the middle part of the inner wall of the outer cylinder is provided with a reinforcing positioning rib, the reducing pipe positioning device is arranged on the side surface of the reinforcing positioning rib, the reducing pipe positioning device comprises at least one inner cylinder, the inner cylinder is coaxially arranged on one side surface of the reinforcing positioning rib and/or the other side surface of the reinforcing positioning rib, and the diameters of the inner cylinders are unequal; or the reducing pipe positioning device is a step surface arranged on the side surface of the reinforcing positioning rib, and the step surface is at least provided with 3 steps; the sealing ring comprises a sealing ring body and the anti-falling teeth arranged on the outer surface of the sealing ring body, so that pipes with different calibers can be realized, the connection is convenient, and the connection of the pipes can be realized rapidly and rapidly even if the operation is performed in a severe environment.
As a preferable scheme of the invention, the inner wall of the outer cylinder is set to be an arc surface, and/or the inner wall of the inner cylinder is set to be an arc surface, and/or the horizontal plane of each step is set to be an arc surface, so that the sealing performance of the joint can be enhanced when the joint is matched with a sealing ring, better adjustment can be realized according to small variable of the caliber of a pipe, the sealing performance of the joint is further improved, and/or the joint body adopts a rotational molding process, and the wall part of the joint body is of a hollow wall structure and has a certain noise reduction effect.
As a preferable scheme of the invention, the cross section shape of the anti-drop teeth is one or more selected from triangle, trapezoid, rectangle and wave, so that the sealing performance of the rotational molding joint is further improved.
As the preferable scheme of the invention, the opening ends of the outer cylinder and the inner cylinder and the connection parts of the outer cylinder, the inner cylinder and the reinforcing positioning ribs are round chamfer structures, so that the connection is safe and rapid, the scratching of hands during manual connection can be avoided, and the reliability is high.
As a preferable scheme of the invention, the anti-falling teeth are made of water-swelling rubber, and/or the sealing ring body is made of one of chloroprene rubber, nitrile rubber, ethylene propylene diene monomer rubber and silicone rubber, and only the anti-falling teeth swell when meeting water, so that the deformation caused by excessive swelling of the whole sealing ring is avoided, and the risk of outward turning and displacement of the sealing ring is reduced.
As the preferable scheme of the invention, the anti-falling teeth are arranged at equal intervals, the intervals are consistent with the intervals of the winding threads of the hollow wall winding pipe, the matching degree with the pipe is better, and the sealing property is further improved.
A manufacturing process of a rotational molding joint of a hollow wall winding pipe comprises the following steps:
(a) And (3) batching: grinding the raw materials, firstly screening the raw materials by a 30-mesh filter screen to obtain first powder, continuously grinding the residual raw materials on the 30-mesh filter screen, secondly screening the raw materials by a 50-mesh filter screen to obtain second powder, continuously grinding the residual raw materials on the 50-mesh filter screen, thirdly screening the raw materials by a 80-mesh filter screen to obtain third powder, continuously grinding the residual raw materials on the 80-mesh filter screen to obtain fourth powder, fourthly screening the fourth powder by a 100-mesh filter screen, then placing the first powder, the second powder, the third powder and the fourth powder into an oven to be dried at a constant temperature of 120 ℃, weighing 100-200 parts of the first powder, 200-300 parts of the second powder, 200-300 parts of the third powder, 50-100 parts of the fourth powder and 5-10 parts of added color masterbatch according to parts by weight, and uniformly mixing to obtain a mixture;
(b) Preheating a die: uniformly coating a release agent on the inner wall of the die, then preheating the die at 90-110 ℃ for 2-5min, and then cooling to 50-60 ℃;
(b) Feeding: filling the weighed mixture into a cavity of a die, placing the die filled with the raw materials into a rotational molding machine, and rotating at a low rotation speed of 20-30r/min for 5-10 min;
(c) Heating: uniformly preheating the die for 5-10min at the preheating temperature of 120-150 ℃;
(e) Rotational molding: the temperature rising stage adopts four-section temperature rising and the temperature lowering stage adopts three-section temperature lowering; the temperature rising stage and the temperature lowering stage are matched with different rotation speeds;
(f) Demolding: cooling in a cooling chamber, demolding the product and taking out the product.
As a preferable scheme of the invention, the raw material in the step (a) is one or more of polyethylene, low density polyethylene, polyvinyl chloride, ABS, rubber modified polypropylene and polycarbonate.
As a preferable scheme of the invention, in the step (e), the four-stage temperature rise is carried out at 160-200 ℃ in the first stage, the temperature is kept for 5-10min, the rotating speed is 50-80r/min, the temperature is kept at 200-230 ℃ in the second stage, the rotating speed is 50-80r/min, the temperature is kept at 5-10min in the third stage, the temperature is kept at 230-260 ℃ in the third stage, the rotating speed is 50-80r/min, the temperature is kept at 260-280 ℃ in the fourth stage, the rotating speed is kept at 2-5min, and the rotating speed is 30-50r/min;
the three-stage cooling is that the temperature is reduced to 210-260 ℃ in the first stage, the temperature is kept for 2-5min, the rotating speed is 30-50r/min, the temperature is reduced to 150-210 ℃ in the second stage, the temperature is kept for 5-10min, the rotating speed is 20-30r/min, the temperature is reduced to 90-150 ℃ in the third stage, the temperature is kept for 5-10min, and the rotating speed is 10-20r/min; the heating time of each heating stage and the cooling time of each cooling stage are 5-8min;
as a preferred embodiment of the present invention, the method comprises the steps of: the cooling mode in the step (f) is one or a combination of strong wind cooling or water mist cooling.
The invention has the beneficial effects that: (1) The reducing pipe positioning device is arranged, so that pipes with different pipe diameters can be connected quickly and conveniently; (2) The inner wall is set to be a cambered surface, so that the difference of the micro pipe diameters of the pipes can be regulated, the sealing performance is greatly improved, the water seepage quantity accords with the standard in the strictest U.S. PVC pipe design construction manual, and the service life is up to 50 years; (3) According to the manufacturing process, powder materials with different sizes are adopted for mixing and rotational molding, powder particles with ordered sizes are arranged in a heating die, and as the thick and thin powder has long and short heat absorption melting time and is fast and slow, molten plastics can be orderly stacked and molded, the density is higher, and the tensile strength is enhanced; (4) The four-section type heating and three-section type cooling are adopted, different rotating speeds are matched in the heating stage and the cooling stage, and the stretching performance is greatly improved.
Drawings
FIG. 1 is a schematic structural view of embodiment 1 of the present invention;
FIG. 2 is a schematic view showing the structure of the embodiment 2 of the present invention in which the inner cylinders have the same diameters;
FIG. 3 is a side view of FIG. 2;
FIG. 4 is a schematic view showing the structure of the inner cylinder of embodiment 2 of the present invention having different diameters;
FIG. 5 is a schematic view of the seal ring of the present invention;
FIG. 6 is a schematic illustration of coaxial connection of a reduced pipe according to embodiment 2 of the present invention;
FIG. 7 is a schematic illustration of coaxial connection of the same diameter tubing of example 2 of the present invention;
FIG. 8 is a schematic illustration of a non-coaxial connection of a reduced pipe according to embodiment 2 of the present invention;
fig. 9 is a schematic structural view of the present embodiment 3;
in the figure, 1-outer cylinder, 2-reinforced positioning rib, 3-inner cylinder, 301-first inner cylinder, 302-second inner cylinder, 4-sealing ring, 401-anti-disengaging tooth and 5-step surface.
Detailed Description
It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first", "a second", etc. may explicitly or implicitly include one or more such feature. In the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art in a specific case.
Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
Example 1
As shown in fig. 1, a rotational molding joint for a hollow wall winding pipe comprises a joint body and a sealing ring 4 arranged at the joint position of the joint body and a pipe body, wherein the joint body comprises an outer cylinder 1, the inner wall of the outer cylinder 1 is provided with a cambered surface, the middle part of the inner wall of the outer cylinder 1 is provided with a reinforcing positioning rib 2, and the outer cylinder and the reinforcing positioning rib are integrally molded in a rotational molding manner and are of a hollow wall structure.
Example 2
As shown in fig. 2-3, a rotational molding joint for a hollow wall winding pipe comprises a joint body and a sealing ring 4 arranged at the joint part of the joint body and a pipe main body, wherein the joint body adopts a rotational molding process and is a hollow wall and has a certain noise reduction effect. The joint body comprises an outer cylinder 1 and a reducing pipe positioning device, wherein the middle part of the inner wall is provided with a reinforcing positioning rib 2, the inner wall of the outer cylinder 1 is a cambered surface, so that the sealing performance of the joint body can be enhanced when the joint body is matched with a sealing ring, and the sealing performance of the joint body is further improved according to the fine adjustment of the caliber of the pipe; the reducing pipe positioning device is arranged on the side face of the reinforcing positioning rib 2 and comprises two inner cylinders 3, namely a first inner cylinder 301 and a second inner cylinder 302, wherein the first inner cylinder 301 and the second inner cylinder 302 are coaxially arranged on the two side faces of the reinforcing positioning rib 2 respectively, and the diameters of the first inner cylinder 301 and the second inner cylinder are equal; or may be provided with unequal diameters, as shown in fig. 4; the sealing ring 4 comprises a sealing ring body and a retaining tooth 401 arranged on the outer surface of the sealing ring body, and the rotational molding joint in the embodiment can be connected at will when pipes with different pipe diameters are connected, namely, the coaxial connection can be realized, and the coaxial connection can be realized according to the field construction environment without being coaxial, as shown in fig. 6-8.
The inner walls of the first inner cylinder 301 and the second inner cylinder 302 are both arc surfaces, so that the sealing performance is further improved;
as shown in fig. 5, the cross-sectional shape of the anti-slip teeth 401 is selected from one or more of triangle, trapezoid, rectangle, and wave.
The open ends of the outer cylinder 1 and the inner cylinder 3 and the connection parts of the outer cylinder 1, the inner cylinder 3 and the reinforcing positioning ribs 2 are round chamfer structures.
Example 3
As shown in fig. 9, this embodiment is further optimized based on embodiment 2, specifically, the reducing pipe positioning device is a step surface 5 disposed on a side surface of the reinforcing positioning rib 2, the step surface is provided with 5 steps, and as a preferred scheme of the present invention, a horizontal plane of each step is set as a cambered surface. The positioning device can also realize connection of pipes with different pipe diameters, has good sealing performance, and is rapid and convenient to operate in outdoor operation.
Example 4
As shown in fig. 5, this embodiment is further optimized based on embodiment 2, specifically, the anti-falling teeth 401 are made of water-swelling rubber, the sealing ring body is made of one of neoprene rubber, nitrile rubber, ethylene propylene diene rubber and silicone rubber, and only the anti-falling teeth swell when water is encountered, so that the deformation caused by excessive expansion of the whole sealing ring is avoided, and the risk of everting and shifting of the sealing ring is reduced.
The anti-falling teeth 401 are arranged at equal intervals, the intervals are consistent with the intervals of the winding threads of the hollow wall winding pipe, the matching degree with the pipe is better, and the sealing performance is further improved.
Example 5
A manufacturing process of a rotational molding joint of a hollow wall winding pipe comprises the following steps:
(a) And (3) batching: grinding the raw materials, firstly screening the raw materials by a 30-mesh filter screen to obtain first powder, continuously grinding the residual raw materials on the 30-mesh filter screen, secondly screening the raw materials by a 50-mesh filter screen to obtain second powder, continuously grinding the residual raw materials on the 50-mesh filter screen, thirdly screening the raw materials by a 80-mesh filter screen to obtain third powder, continuously grinding the residual raw materials on the 80-mesh filter screen to obtain fourth powder, fourthly screening the fourth powder by a 100-mesh filter screen, then placing the first powder, the second powder, the third powder and the fourth powder into an oven to be dried at a constant temperature of 120 ℃, weighing 100 parts of the first powder, 300 parts of the second powder, 200 parts of the third powder, 50 parts of the fourth powder and 5 parts of additive color masterbatch according to parts by weight, and uniformly mixing to obtain a mixture;
(b) Preheating a die: uniformly coating a release agent on the inner wall of a die, then preheating the die at 110 ℃ for 5min, and then cooling to 50 ℃;
(b) Feeding: filling the weighed mixture into a cavity of a die, placing the die filled with the raw materials into a rotational molding machine, and rotating at a low rotation speed of 25r/min for 5min;
(c) Heating: the die is uniformly preheated for 5min, and the preheating temperature is 120 ℃;
(e) Rotational molding: the four-stage heating is adopted to heat up to 160 ℃ in the first stage, the temperature is kept for 5min, the rotating speed is 50r/min, the temperature is kept for 10min in the second stage, the rotating speed is 60r/min, the temperature is kept for 10min in the third stage, the temperature is kept for 258 ℃, the rotating speed is 70r/min, the temperature is kept for 3min in the fourth stage, and the rotating speed is 35r/min;
the three-stage cooling is that the temperature is reduced to 210 ℃ in the first stage, the temperature is kept for 3min, the rotating speed is 40r/min, the temperature is reduced to 160 ℃ in the second stage, the temperature is kept for 10min, the rotating speed is 25r/min, the temperature is reduced to 100 ℃ in the third stage, the temperature is kept for 7min, and the rotating speed is 15r/min; the heating time of each heating stage and the cooling time of each cooling stage are 5min;
(f) Demolding: cooling with strong wind in a cooling chamber, demolding the product, and taking out the product.
The raw material in the step (a) is low-density polyethylene.
Example 6
The embodiment is further optimized based on the embodiment 5, specifically, 100 parts of first powder, 300 parts of second powder, 200 parts of third powder, 60 parts of fourth powder and 5-10 parts of additive color masterbatch are weighed and uniformly mixed in the step (a) to obtain a mixture; other steps were consistent with example 5.
Example 7
The embodiment is further optimized based on the embodiment 5, specifically, 100 parts of first powder, 300 parts of second powder, 200 parts of third powder, 70 parts of fourth powder and 5 parts of additive color masterbatch are weighed in the step (a) and uniformly mixed to obtain a mixture; other steps were consistent with example 5.
Example 8
The embodiment is further optimized based on the embodiment 5, specifically, 100 parts of first powder, 300 parts of second powder, 200 parts of third powder, 80 parts of fourth powder and the additive color master batch 5 are weighed in the step (a) and uniformly mixed to obtain a mixture; other steps were consistent with example 5.
Example 9
The embodiment is further optimized based on the embodiment 5, specifically, 100 parts of first powder, 300 parts of second powder, 200 parts of third powder, 90 parts of fourth powder and 5 parts of additive color masterbatch are weighed in the step (a) and uniformly mixed to obtain a mixture; other steps were consistent with example 5.
Example 10
The embodiment is further optimized based on the embodiment 5, specifically, 100 parts of first powder, 300 parts of second powder, 200 parts of third powder, 100 parts of fourth powder and 5 parts of additive color masterbatch are weighed in the step (a) and uniformly mixed to obtain a mixture; other steps were consistent with example 5.
Comparative example 1
The difference between the comparative example 1 and the example 4 is that 650 parts of 50 mesh powder and 5 parts of additive color masterbatch are weighed and evenly mixed in the step (a) to obtain a mixture; other steps were consistent with example 5.
Example 11
The embodiment is further optimized based on the embodiment 5, specifically, in the step (e), four-stage heating is adopted to heat up to 180 ℃ in the first stage, heat up to 5min in the heat preservation, the rotating speed is 60r/min, heat up to 220 ℃ in the second stage, heat up to 10min in the heat preservation, the rotating speed is 70r/min, heat up to 260 ℃ in the third stage, heat up to 10min in the heat preservation, the rotating speed is 80r/min, heat up to 265 ℃ in the fourth stage, heat up to 3min in the heat preservation, and the rotating speed is 30r/min;
the three-stage cooling is that the temperature is reduced to 200 ℃ in the first stage, the temperature is kept for 3min, the rotating speed is 35r/min, the temperature is reduced to 150 ℃ in the second stage, the temperature is kept for 10min, the rotating speed is 20r/min, the temperature is reduced to 90 ℃ in the third stage, the temperature is kept for 5min, and the rotating speed is 10r/min; the temperature rise time per temperature rise stage and the temperature reduction time per temperature reduction stage were both 5min, and the other steps were the same as in example 5.
Example 12
The embodiment is further optimized based on the embodiment 5, specifically, in the step (e), four-stage heating is adopted to heat up to 180 ℃ in the first stage, heat up to 5min in the heat preservation, the rotating speed is 60r/min, heat up to 220 ℃ in the second stage, heat up to 10min in the heat preservation, the rotating speed is 70r/min, heat up to 260 ℃ in the third stage, heat up to 10min in the heat preservation, the rotating speed is 80r/min, heat up to 265 ℃ in the fourth stage, heat up to 3min in the heat preservation, and the rotating speed is 30r/min;
the three-stage cooling is that the temperature is reduced to 200 ℃ in the first stage, the temperature is kept for 3min, the rotating speed is 35r/min, the temperature is reduced to 150 ℃ in the second stage, the temperature is kept for 10min, the rotating speed is 20r/min, the temperature is reduced to 90 ℃ in the third stage, the temperature is kept for 5min, and the rotating speed is 10r/min; the temperature rise time per temperature rise stage was 7min and the temperature decrease time per temperature decrease stage was 7min, and the other steps were the same as in example 5.
Example 13
The embodiment is further optimized based on the embodiment 5, specifically, in the step (e), four-stage heating is adopted to heat up to 180 ℃ in the first stage, heat up to 5min in the heat preservation, the rotating speed is 60r/min, heat up to 220 ℃ in the second stage, heat up to 10min in the heat preservation, the rotating speed is 70r/min, heat up to 260 ℃ in the third stage, heat up to 10min in the heat preservation, the rotating speed is 80r/min, heat up to 265 ℃ in the fourth stage, heat up to 3min in the heat preservation, and the rotating speed is 30r/min;
the three-stage cooling is that the temperature is reduced to 200 ℃ in the first stage, the temperature is kept for 3min, the rotating speed is 35r/min, the temperature is reduced to 150 ℃ in the second stage, the temperature is kept for 10min, the rotating speed is 20r/min, the temperature is reduced to 90 ℃ in the third stage, the temperature is kept for 5min, and the rotating speed is 10r/min; the heating time per heating stage was 8min and the cooling time per cooling stage was 8min, and the other steps were the same as in example 5.
Comparative example 2
The difference between this comparative example and example 4 is that the temperature is raised to the temperature in the step (e): 260 ℃ and heating time: 22 minutes; heat preservation temperature: 200 ℃, and the heat preservation time is as follows: 5 minutes, the rotating speed is 50r/min, the temperature is reduced to 100 ℃, and the temperature reduction time is 10 minutes.
Comparative example 3 was a conventional connection using a thermal fuse for thermal fusion.
Samples prepared according to the process of example 4 and having a pipe diameter of 300mm in examples 1-3 described above were subjected to a water shut-off test according to European Standard prEN13476-3 (7 months 2000) and the test results are shown in Table 1 below:
table 1 water permeability test results of samples
| Seepage volume (m) 3 ) | |
| Example 1 | 0.38 |
| Example 2 | 0.48 |
| Example 3 | 0.38 |
| Example 4 | 0.18 |
| Comparative example 3 | 1.45 |
According to the results shown in Table 1, the test results of the water-blocking tests of the patterns of examples 1 to 4 meet the standards, but the test results of comparative example 3 exceed the standards, so that it can be seen that the sealing performance of the invention is excellent, whereas the sealing performance of the traditional hot melting mode is poor, the hot melting mode is easily affected by operators, the stability is poor, the operation is inconvenient in a severe environment, the influence factors are large, the product performance of the invention is excellent, the repetition rate of the new manufacturing process is high, and the stability is good.
The compressive strength and tensile strength properties of examples 5-13 and comparative examples 1-2 were tested as described above, see Table 2 below:
table 2 test results of the properties of the samples
| Tensile Strength (Mpa) | Elongation (%) | |
| Example 5 | 28.12 | 600 |
| Example 6 | 29.15 | 600 |
| Example 7 | 30.21 | 700 |
| Example 8 | 28.89 | 600 |
| Example 9 | 26.02 | 550 |
| Example 10 | 25.01 | 500 |
| Comparative example 1 | 15.20 | 300 |
| Example 11 | 27.98 | 550 |
| Example 12 | 29.13 | 600 |
| Example 13 | 30.12 | 600 |
| Comparative example 2 | 18.56 | 350 |
As can be seen from Table 2, the mixed powder with different particle sizes is used as the raw material, the tensile strength and the elongation of the test sample are both better than those of the comparison example 1 with 50 meshes as the powder, the test value of the best example 6 is nearly twice that of the comparison example 1, and the mixed raw material with different particle sizes can be more orderly piled up and molded due to the fact that the heat absorption melting time of the coarse and fine powder is long and short, the density is higher, and the tensile strength is enhanced; meanwhile, as can be seen from the table 2, the sample performance prepared by adopting the four-section type temperature rising and three-section type temperature reducing modes and matching different rotating speeds is far better than that of the traditional temperature rising mode (comparative example 2), the product performance is outstanding, and compared with the injection molding technology adopted in the past, the rotational molding technology has the advantages of low economic cost and suitability for preparing large products, and the connector with a hollow structure has the noise reduction and buffering functions to a certain extent.
The above embodiments only describe the optimal use of the existing apparatus, but similar common mechanical means are used to replace the elements in the present embodiment, which all fall within the scope of protection.
Claims (8)
1. A manufacturing process of a rotational molding joint of a hollow wall winding pipe is characterized by comprising the following steps of: the rotational molding joint for the hollow wall winding pipe comprises a joint body and a sealing ring (4) arranged at the sleeving position of the joint body and the pipe body, wherein the joint body comprises an outer cylinder (1) and a reducing pipe positioning device, the middle part of the inner wall of the outer cylinder (1) is provided with a reinforcing positioning rib (2), the reducing pipe positioning device is arranged on the side surface of the reinforcing positioning rib (2), the reducing pipe positioning device comprises at least one inner cylinder (3), the inner cylinder (3) is coaxially arranged on one side surface of the reinforcing positioning rib (2) and/or the other side surface of the reinforcing positioning rib (2), and the diameters of the inner cylinders (3) are different; the sealing ring (4) comprises a sealing ring body and a release stopping tooth (401) arranged on the outer surface of the sealing ring body; the inner wall of the outer cylinder (1) is set to be an arc surface, the inner wall of the inner cylinder (3) is set to be an arc surface, the joint body adopts a rotational molding process, and the wall part of the joint body is of a hollow wall structure;
the manufacturing process comprises the following steps:
(a) And (3) batching: grinding the raw materials, firstly screening the raw materials by a 30-mesh filter screen to obtain first powder, continuously grinding the residual raw materials on the 30-mesh filter screen, secondly screening the raw materials by a 50-mesh filter screen to obtain second powder, continuously grinding the residual raw materials on the 50-mesh filter screen, thirdly screening the raw materials by a 80-mesh filter screen to obtain third powder, continuously grinding the residual raw materials on the 80-mesh filter screen to obtain fourth powder, fourthly screening the fourth powder by a 100-mesh filter screen, then placing the first powder, the second powder, the third powder and the fourth powder into an oven to be dried at a constant temperature of 120 ℃, weighing 100-200 parts of the first powder, 200-300 parts of the second powder, 200-300 parts of the third powder, 50-100 parts of the fourth powder and 5-10 parts of added color masterbatch according to parts by weight, and uniformly mixing to obtain a mixture;
(b) Preheating a die: uniformly coating a release agent on the inner wall of the die, then preheating the die at 90-110 ℃ for 2-5min, and then cooling to 50-60 ℃;
(b) Feeding: filling the weighed mixture into a cavity of a die, placing the die filled with the raw materials into a rotational molding machine, and rotating at a low rotation speed of 20-30r/min for 5-10 min;
(c) Heating: uniformly preheating the die for 5-10min at the preheating temperature of 120-150 ℃;
(e) Rotational molding: the temperature rising stage adopts four-section temperature rising and the temperature lowering stage adopts three-section temperature lowering; the temperature rising stage and the temperature lowering stage are matched with different rotation speeds;
(f) Demolding: cooling in a cooling chamber, demolding the product and taking out the product.
2. The process for manufacturing a hollow wall wound pipe rotational molding joint according to claim 1, wherein: the cross section shape of the anti-falling teeth (401) is one or more selected from triangle, trapezoid, rectangle and wave.
3. A process for manufacturing a hollow wall wound pipe rotational moulding joint according to claim 2 wherein: the opening ends of the outer cylinder (1) and the inner cylinder (3) and the connection parts of the outer cylinder (1), the inner cylinder (3) and the reinforcing positioning ribs (2) are of round chamfer structures.
4. A process for manufacturing a hollow wall wound pipe rotational moulding joint according to claim 3 wherein: the anti-falling teeth (401) are made of water-absorbing expansion type rubber, and the sealing ring body is made of one of chloroprene rubber, nitrile rubber, ethylene propylene diene monomer rubber and silicone rubber.
5. The process for manufacturing a rotational molding joint for hollow-wall wound pipes as claimed in claim 4, wherein: the anti-falling teeth (401) are arranged at equal intervals, and the intervals are consistent with the intervals of winding threads of the hollow wall winding pipe.
6. The process for manufacturing a hollow wall wound pipe rotational molding joint according to claim 1, wherein: the raw materials in the step (a) are one or more of polyethylene, low-density polyethylene, polyvinyl chloride, ABS, rubber modified polypropylene and polycarbonate.
7. The process for manufacturing a hollow wall wound pipe rotational molding joint according to claim 1, wherein: the four-stage temperature rise in the step (e) is 160-200 ℃ in the first stage, the temperature is kept for 5-10min, the rotating speed is 50-80r/min, the temperature is kept for 5-10min in the second stage, the rotating speed is 50-80r/min, the temperature is kept for 5-10min in the third stage, the rotating speed is 50-80r/min, the temperature is kept for 2-5min in the fourth stage, and the rotating speed is 30-50r/min;
the three-stage cooling is that the temperature is reduced to 210-260 ℃ in the first stage, the temperature is kept for 2-5min, the rotating speed is 30-50r/min, the temperature is reduced to 150-210 ℃ in the second stage, the temperature is kept for 5-10min, the rotating speed is 20-30r/min, the temperature is reduced to 90-150 ℃ in the third stage, the temperature is kept for 5-10min, and the rotating speed is 10-20r/min; the heating time of each heating stage and the cooling time of each cooling stage are 5-8min.
8. The process for manufacturing a hollow wall wound pipe rotational molding joint according to claim 1, wherein: the method comprises the following steps: the cooling mode in the step (f) is one or a combination of strong wind cooling or water mist cooling.
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| CN112344108B (en) * | 2020-11-27 | 2023-06-23 | 际华三五一七橡胶制品有限公司 | Nodular cast iron pipe with prefabricated heat preservation |
| CN112524356B (en) * | 2020-12-04 | 2023-04-07 | 成都中企动力技术服务有限公司 | Double-end socket sealing structure and sealing test method for hollow structure wall winding pipe |
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| JP2005256946A (en) * | 2004-03-11 | 2005-09-22 | T Two:Kk | Hose connecting means |
| CN202228841U (en) * | 2011-09-21 | 2012-05-23 | 李天洪 | Bell and spigot connecting device of hollow wall winding pipe |
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| US10137537B2 (en) * | 2014-03-13 | 2018-11-27 | Frederick M. Mako | System and method for producing chemicals at high temperature |
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| JP2000199594A (en) * | 1999-01-07 | 2000-07-18 | Sekisui Chem Co Ltd | Coupling made of resin |
| JP2005256946A (en) * | 2004-03-11 | 2005-09-22 | T Two:Kk | Hose connecting means |
| KR20120110410A (en) * | 2011-03-29 | 2012-10-10 | 아론카세이 가부시키가이샤 | Pipe joint |
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