DESC:FIELD OF THE INVENTION
The present invention relates to the field of welding plastic components. In particular, the present invention relates to an apparatus and a method for welding two or more plastic components to obtain a composite plastic structure thereof, while avoiding deformation of the hollow plastic component during welding, wherein at least one of the plastic components is hollow.
DEFINITIONS
Plastic material – herein includes polypropylene, polyethylene, polyethylene terephthalate, nylon etc., but is not limited to these.
Welding – The term welding herein includes joining of two or more plastic components by heating the relevant portions thereof, wherein heating of the plastic components leads to softening and/or melting of portions of interest, and abutting the heated portions followed by cooling the abutted portions to form a bond thereat. The welding of two or more plastic components may be achieved by one or more known welding techniques, including but not limited to hot plate welding, radiation welding, etc.
Deformation – The term deformation includes change in shape or size or both shape and size of one or more plastic components during the welding process which may be due to softening or melting of the portions of the one or more plastic components or may be due to abutting of the portions of the one or more plastic components or both.
Welding pull strength – herein means the force required to separate the two welded plastic components.
BACKGROUND OF THE INVENTION
Vehicles are ubiquitous and inseparable part of our life. Vehicles are employed for transportation of people and cargo on large scale. Since the advent of the vehicles be it fossil fuel driven or electric vehicles, there have been attempts to improve the through put. That is attempts have been made to improve the fuel efficiency or fuel economy of the vehicles.
One way to improve the fuel economy or fuel efficiency of the vehicles is to reduce the vehicle’s weight. The weight of the vehicle is being reduced by incorporating light-weight material components instead of heavy metal components. The light-weight material components may be made of plastic, plastic-fiber composites, and the like, which have strength comparable with the metal counter parts but are light in weight as compared to the metal components.
For example, various pipes, or tubes, or conduits employed for conveying fluids such as air, fuel, oil, etc., have been replaced by plastic pipes, or tubes, or conduits (referred to as pipe(s) hereinafter) thereby reducing the overall weight of the vehicle and hence improving fuel efficiency thereof.
In this context, there is a frequent need for joining or welding these components. For the plastic components, there is a need for welding two or more plastic components or welding one plastic component to a metal component.
However, there are certain drawbacks associated with the conventional welding method for joining two or more plastic components.
For welding the two or more plastic components, the portions at which the welding is to be carried out are heated to a temperature such that the portions are softened or melted. Thereafter, the softened and/or melted portions are brought in contact with each other, wherein the softened and/or melted portions join to form a bond thereat.
It is observed that at the time of heating and when the portions are softened and/or melted, there is a tendency of the area at and around the softened and/or melted portions to drape or to deform. The deformation or draping may depend on the length of the portion, the thickness of the portion, the material of make of the portion, the weight of the portion, and the temperature to which it is heated.
Further, it is observed that at the time of abutting the two or more components, for a defect free welding or joining, it is necessary to abut the two or more components while applying some pressure. This pressure along with the softening and/or melting leads to further deformation of the portions under consideration.
The deformation or change in shape or size or both shape and size of the portions of the components being welded results in formation of defects which include improper welding of the components, gaps, cracks, etc., which is not desired.
To obviate the above-mentioned problems or disadvantages, it is necessary to support the plastic components. The support is in form of a solid rod or the like. The support solid rod is placed just below the portion to be heated which is physical contact with the portion being heated. This avoids deformation or draping of the portion being heated and welded. The support is provided even during the step of welding itself.
However, the use of solid rod support or the like is next to impossible in case when the plastic components to be welded are not straight. For example, for a hollow straight plastic pipe, it is easy to use a solid rod for supporting a portion thereof during welding. However, for a hollow plastic component which is not like the straight pipe, and have one or more bends and unreachable areas, it is difficult or impossible to use solid rod for support.
Therefore, there is an urgent need for providing a suitable alternative for supporting the portions of the plastic components during the step of welding together, wherein the support is such that it can reach even at areas which are at corners or bends of the plastic components. Further, there is a need to provide a method for welding plastic components together such that the plastic components can be welding without any deformation or draping.
OBJECTS OF THE INVENTION
Some of the objects of the presently disclosed invention, of which at the minimum one object is fulfilled by at least one embodiment disclosed herein, are as follows.
An object of the present invention is to provide an alternative, which overcomes at least one drawback encountered in the existing prior art.
Another object of the present invention is to provide a method for welding two or more plastic components together.
Still another object of the present invention is to provide a method for welding at least one hollow plastic component with another at least one plastic component.
Yet another object of the present invention is to provide a method for welding plastic components which overcomes the problem of deformation or draping during welding.
Another object of the present invention is to provide a method for welding plastic components which is simple, effective, time and cost efficient and further is more productive as compared with the conventional welding methods.
Other objects and benefits of the present invention will be more apparent from the following description, which is not intended to bind the scope of the present invention.
SUMMARY OF THE INVENTION
Disclosed is an apparatus and a method for welding two or more plastic components to obtain a composite plastic structure thereof, wherein at least one of the plastic components is hollow, while avoiding deformation of the hollow plastic component during welding.
In accordance with one aspect of the present invention, disclosed is a method for fabricating a composite plastic structure with reduced deformation. The method comprising the following steps:
A first plastic component defined by a wall and enclosing a space therewithin is formed or fabricated by known methods. The wall is having an operative first surface and a first profile. The first plastic component is sealed thereby configuring the first plastic component to receive and retain a pressurized fluid within the space. A valve is operably secured on the first plastic component, the valve is configured to facilitate injection and ejection of the pressurized fluid into and out of the space therethrough.
A second plastic component with an operative second surface having a second profile which being complimentary to the first profile is fabricated by employing known fabrication methods.
The pressurized fluid is injected into the space, at a first temperature, through the valve, wherein the pressurized fluid is injected to pressurize the first plastic component to a first pressure, wherein the first pressure is a pressure at which the wall of the first plastic component is stiffened.
A first localized portion of the wall of the first plastic component, and a second localized portion of the second plastic component are each heated to a temperature at which each of the first localized portion, and the second localized portion is softened.
The heated first localized portion and the heated second localized portion are brought in contact by juxtaposing the first plastic component with the second plastic component to form a connection therebetween, wherein the space is pressurized by the pressurized fluid at a second pressure, and at second temperature.
The connection so formed is allowed to cool to a temperature wherein the first localized portion, and the second localized portion harden while being connected.
After cooling, the pressurized fluid from the space is removed to obtain the composite plastic structure comprising the first plastic component welded to the second plastic component, wherein the welding is having a welding pull strength of 20 kgf to 200 kgf.
In accordance with one embodiment of the present invention, the welding pull strength is linked to various parameters by the following formula:
Wcs? [(W_c.W_t.A_p.T_H.T_g.T_h.T_ho)/S_g ]
Wherein,
Wcs – Welding pull strength
Wc – Wall cross section area
Wt – Wall thickness
Ap – Fluid pressure
TH – Temperature of the component
Tg – Glass transition temperature
Th – Time period for which the component is heated
Tho- Weld time
Sg – Sagging of wall
In accordance with another aspect of the present invention, disclosed is an apparatus for fabricating the composite plastic structure with reduced deformation.
The apparatus comprises a microcontroller, a memory associated with the microcontroller, the memory configured to store executables, tables, and data pertaining to operations relating to the fabrication of the composite plastic structure, a display connected to and in data communication with the microcontroller, the display is configured to display data pertaining to various parameters associated with the apparatus and welding process, a user interface connected to and in data communication with the microcontroller, the user interface being configured to receive one or more inputs from a user, which being received and processed by the microcontroller, a pressure transducer cooperating with the microcontroller, the pressure transducer being operatively connected to the first plastic component and configured to measure the pressure of the fluid within the space, a first movable jaw and a second movable jaw operatively and displaceably disposed on a support, the first and the second movable jaws being displaced by a displacing means selected from the group consisting of a motor, a pneumatic device, and a combination thereof, a first jig operatively connected to and in data communication with the microprocessor via a circuit interface and a motor and secured to the first moveable jaw, the first jig being configured to receive, support, and secure the first plastic component in a working position therein, a second jig operatively connected to and in data communication with the microprocessor via a circuit interface and a motor and secured to the second movable jaw, the second jig configured to receive, support, and secure the second plastic component in a working position therein, a first hot plate configured to heat the first plastic component, the first hot plate being associated with the first jig and heated by a heating coil and connected to and in data communication with the microprocessor, a second hot plate configured to heat the second plastic component, the second hot plate being associated with the second jig and heated by a heating coil and connected to and in data communication with the microprocessor, and a pressurized fluid source connected to and in fluid communication with the space of the first plastic component, the pressurized fluid source being configured to supply pressurized fluid at a predetermined pressure and temperature.
In accordance with yet another aspect of the present invention, a composite plastic structure with reduced deformation is disclosed, the composite plastic structure comprising a first plastic component and a second plastic component welded together to define a weld bond having a welding pull strength is in the range of 20 kgf to 200 kgf, wherein the weld bond being formed by the method described herein above.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The present invention will now be described with the help of the accompanying drawing, in which
FIG. 1a illustrates an exemplary first plastic component, which is in form of a tubular plastic body employed in a vehicle engine for conveying a fluid like air therethrough.
FIG. 1b illustrates an exemplary second plastic component, which is in form of a plastic mesh like strip which is to be welded to the first plastic component of FIG. 1a.
FIG. 2 illustrates a schematic diagram of an apparatus employed for fabricating a composite plastic structure in accordance with the embodiments of the present invention.
FIG. 3 illustrates a schematic block diagram of various components of the apparatus employed for fabricating the composite plastic structure of FIG. 2.
LIST OF NUMERALS
102 - First plastic component
102a - Wall
102b - Space
102c - Operative first surface
102d - First profile
102e - Open end
102p1 - First localized portion
104 - Second plastic component
104c - Operative second surface
104d - Second profile
104p1 - Second localized portion
106 - Valve
108 - First jig
110 - Second jig
112 - Pressure transducer
114 - Sealing cover
200 - Apparatus
202 - Microcontroller
204 - Memory
206 - First movable jaw
208 - Second movable jaw
210 - Support
212 - First hot plate
214 - Second hot plate
216 - Pressurized fluid source
218 - Display
220 - User interface
DETAILED DESCRIPTION
All technical terms and scientific expressions used in the present invention have the same meaning as understood by a person skilled in the art to which the present invention belongs, unless and otherwise specified.
As used in the present specification and the claims, the singular forms “a,” “an” and “the” include plural references unless the context clearly dictates otherwise.
The term "comprising” as used in the present specification will be understood to mean that the list following is non-exhaustive and may or may not include any other extra suitable things, for instance one or more additional feature(s), part(s), component(s), process step(s), sub-step(s), and /or constituent(s) as applicable.
Further, the terms “about” and “approximately" used in combination with ranges of sizes of parts, particles, compositions of mixtures, and/or any other physical properties or characteristics, are meant to include small variations that may occur in the upper and/or lower limits of the ranges.
To overcome one or more disadvantages of the prior art, the present invention provides a suitable alternative for supporting the portions of the plastic components during the step of welding together, wherein the support is such that it can reach even at areas which are at corners or bends of the plastic components. Further, the present invention provides a method for welding plastic components together such that the plastic components can be welding without any deformation or draping.
Accordingly, the present invention provides an apparatus and a method for welding plastic components, wherein at least one of the plastic components is hollow while avoiding the deformation of the hollow plastic component during welding.
FIG. 1a illustrates an exemplary first plastic component (102), which is in form of a tubular plastic body employed in a vehicle engine for conveying a fluid like air therethrough. The first plastic component (102) comprises a tubular plastic body which is bent. The tubular plastic body has a first end which is closed and a second end (102e) which is open and is defined by a wall (102a). The wall (102a) encloses a space (102b) therewithin. The wall (102a) has an operative first surface (102c) which forms the operative outer surface of the tubular plastic body. The wall (102a) can be made of a plastic material comprising a single layer or multiple layers. The multiple layers may be of same or different material. In some cases, the wall (102a) may be reinforced by suitable reinforcing ribs. The reinforcing ribs may be plastic or metal or any other suitable material. For example, the wall (102a) may comprise two layers, a first outer layer made of polypropylene, and a second inner layer made of nylon. The wall (102a) material and number of layers depend on the application.
For example, if the first plastic component (102) is employed for conveying high pressure fluid, then the wall (102a) may comprise two layers and further may be reinforced. Any number of layers, ribs, and material of make is well within the ambit of the present invention.
The first plastic component (102) may have a specific profile (102d) (referred to as first profile hereinafter). The profile (102d) may be the profile of specific portion of the first plastic component (102) as is the case herein or may be the profile (102d) of the whole first plastic component (102). In FIG. 1a, the profile (102d) is in form of a substantially flat portion or area. The flat portion or area is referred to as first localized portion (102p1) herein. The first localized portion (102p1) is the portion of the first plastic component (102) which is welded to a second plastic component (104). The first localized portion (102p1) for the first plastic component (102) herein is a small portion of the first plastic component (102). However, it is to be noted that the first localized portion (102p1) may be a large portion or area or may be whole portion of the first plastic component (102). The open end (102e) is sealed or covered with a sealing cover (114), such that the space (102b) is closed completely. The space (102b) receives and stores a pressurized fluid.
Further, the present invention is not limited to the first plastic component (102) as shown in FIG. 1a. The first plastic component (102) may have any shape, size, and configuration.
FIG. 1b illustrates an exemplary second plastic component (104), which is in form of a plastic rectangular shaped component which is to be welded to the first plastic component (102) of FIG. 1a. The second plastic component (104) has an operative second surface (104c) and has a second profile (104d). The second profile (104d) is complimentary to the first profile (102d), so that the welding of the two components (102, 104) is facilitated. Further, the second plastic component (104) has a second localized portion (104p1) which abuts and is welded to the first localized portion (102p1) of the first plastic component (102). The second profile (104d) is substantially flat.
Again, the present invention is not limited to the second plastic component (104) as above mentioned herein above and as illustrated in FIG. 1b. The second plastic component (104) may have any shape, size and configuration and is not limited in any manner to the shape of the second plastic component (104) illustrated in FIG. 1b.
In accordance with an aspect of the present invention, an apparatus (200) is disclosed, which is described with reference to FIG. 2, and FIG. 3, wherein FIG. 2 illustrates a schematic diagram of an apparatus employed for fabricating a composite plastic structure in accordance with the embodiments of the present invention, and FIG. 3 illustrates a schematic block diagram of various components of the apparatus employed for fabricating the composite plastic structure of FIG. 2.
The apparatus (200) for fabricating the composite plastic structure with reduced deformation comprises a microcontroller (202). The microcontroller (202) can be any microcontroller (202), which can receive, and execute one or more executables, which may be stored in a memory which is associated with the microcontroller (202) or in a memory (204) which is separately provided and is cooperating with the microcontroller (202). More specifically, the memory (204) is configured to store executables, tables, and data pertaining to operations relating to the fabrication of the composite plastic structure (100).
Further, a display (218) is connected to and in data communication with the microcontroller (202), the display (218) is configured to display data pertaining to various parameters associated with the apparatus and welding process. The display (218) can be any type of display, including but not limited to a CRT display, LED display, and an LCD display.
A user interface (220) is provided which is connected to and in data communication with the microcontroller (202), wherein the user interface (220) is configured to receive one or more inputs from a user, which being received and processed by the microcontroller (202). The user interface (220) may be a mouse or a keyboard or a touch screen display but is not limited to the above-mentioned user interfaces.
The apparatus (200) further includes a pressure transducer (112) which is cooperating with the microcontroller (202), the pressure transducer (112) is operatively connected to the first plastic component (102) and is configured to measure the pressure of the fluid within the space (102b). The pressure transducer (112) can be connected inline between a pressurized fluid source (216) and the first plastic component (102). The pressure transducer (112) can be any type of pressure transducer.
The apparatus (200) further comprises a first movable jaw (206) and a second movable jaw (208). The first movable jaw (206), and the second movable jaw (208) are operatively and displaceably disposed on a support (210). The first and second jaws can be displaced vertically (up and down) over the support (210) by employing a displacing means. The displacing means can include a suitable device selected from the group consisting of a motor, a pneumatic device, and a combination thereof. The first moveable jaw (206) is operatively disposed below the second moveable jaw (208).
Further, a first jig (108) is operatively connected to and in data communication with the microprocessor (202) via a suitable circuit interface and a motor. The first jig (108) is suitably and operably secured to the first moveable jaw (206). The first jig (108) is configured to receive, support, and secure the first plastic component (102) in a working position therein as shown in FIG. 2.
A second jig (110) is operatively connected to and in data communication with the microprocessor (202) via a suitable circuit interface and a motor and secured to the second movable jaw (208). The second jig (110) is configured to receive, support, and secure the second plastic component (104) in a working position therein as depicted in FIG. 2.
A first hot plate (212) is provided which is configured to heat the first plastic component (102). The first hot plate (212) is associated with the first jig (108) and heated by a heating coil and connected to and in data communication with the microprocessor (202). The temperature of the heating coil is controlled by the microprocessor (202). Similarly, a second hot plate (214) is provided which is configured to heat the second plastic component (102), the second hot plate (214) being associated with the second jig (110) and heated by a heating coil and connected to and in data communication with the microprocessor (202).
The apparatus (200) is provided with the pressurized fluid source (216) which is connected to and in fluid communication with the space (102b) of the first plastic component (102), the pressurized fluid source (216) is configured to supply pressurized fluid at a predetermined pressure and temperature via the valve (106).
In accordance with another aspect of the present invention, a method is disclosed for welding the first plastic component (102) and the second plastic component (104), to obtain a composite plastic structure with reduced deformation. By employing the method of the present invention, the disadvantages of the conventional methods are obviated.
The first plastic component (102) is formed or fabricated by well-known methods such as the blow molding, wherein the first plastic component (102) is defined by the wall (102a) and enclosing the space (102b) therewithin, the wall (102a) having the operative first surface (102c) and having the first profile (102d).
The first plastic component (102) is received in the first jig (108) which being configured to support and secure the first plastic component (102), and the second plastic component (104) is received in a second jig (110) which being configured to support and secure the second plastic component (104).
The first plastic component (102) is sealed using the sealing cover thereby configuring the first plastic component (102) to receive and retain a pressurized fluid within the space (102b).
At least one aperture is configured on the first plastic component or the sealing cover.
Further, at least one fluid valve (106) is fixed over the aperture, wherein the valve (106) is configured to facilitate injection and ejection of the pressurized fluid into and out of the space (102b) therethrough. The valve (106) can be any type of valve, for example, the valve can be the one used for vehicle tyres. Any other type of valve is also well within the ambit of the present invention.
Further, the second plastic component (104) is provided with the operative second surface (104c) having the second profile (104d) which being complimentary to the first profile (102d).
The pressurized fluid is injected into the space (102b), at a first temperature, through the valve (106), wherein the pressurized fluid is injected to pressurize the first plastic component (102) to a first pressure, wherein the first pressure is a pressure at which the wall (102a) of the first plastic component (102) is stiffened. The first temperature and the first pressure are dependent on the material of the first plastic component, the shape and size of the first plastic component including the wall thickness, the temperature to which the first plastic component is heated during the welding process, and the area or the portion of the first plastic component which is heated.
A portion which is referred to herein as a first localized portion (102p1) of the wall (102a) of the first plastic component (102) is heated to a predetermined temperature using the hot plate (212), wherein the hot plate (212) is brought in contact with the first localized portion (102p1) and for a predetermined time. The temperature and time are such that the first localized portion (102p1) is softened or melted which is enough to obtain a bonding or welding of the first and the second plastic components.
Similarly, a second localized portion (104p1) of the second plastic component (104) is heated to a predetermined temperature and for a predetermined time period, wherein the temperature and time is such that the second localized portion (104p1) is softened or melted which is enough to obtain a bonding or welding of the first and the second plastic components.
Now the heated first plastic component (102), and the second plastic component (104) are brought in contact with each other by moving the respective movable jaws (206, 208), wherein the first localized portion (102p1) and the second localized portion (104p1) abuts each while being in softened or melted state to form a connection therebetween, and the space (102b) kept or maintained in pressurized state by the pressurized fluid at a second pressure, and at second temperature.
The first localized portion (102p1) and the second localized portion (104p1) are maintained in the abutted position for a predetermined time period the connection is allowed to cool to a temperature wherein the first localized portion (102p1), and the second localized portion (104p1) harden while being connected, thereby configuring the welding therebetween.
Finally, the pressurized fluid from the space (102b) is released to obtain the composite plastic structure comprising the first plastic component (102) welded to the second plastic component (104), wherein the welding having a welding pull strength is in the range of 20 kgf to 200 kgf.
In accordance with one embodiment of the present invention, the welding pull strength is linked to various parameters by the following formula:
Wcs? [(W_c.W_t.A_p.T_H.T_g.T_h.T_ho)/S_g ]
wherein,
Wcs – Welding pull strength
Wc – Wall cross section area
Wt – Wall thickness
Ap – Fluid pressure
TH – Temperature of the component
Tg – Glass transition temperature
Th – Time period for which the component is heated
Tho- Weld time
Sg – Sagging of wall (mm)
In accordance with one embodiment of the present invention, the first plastic component (102) comprises a tubular body having at least one open end (102e), and the first plastic component (102) is sealed by employing a sealing cover (114), and the first plastic component (102) is blow molded.
In accordance with one embodiment of the present invention, the first temperature is in the range of -15 °C to 40 °C, and the first pressure is in the range of 1.01 bar to 5 bar, and the second temperature is in the range of -15 °C to 40 °C, and the second pressure is in the range of 1.01 bar to 5 bar.
In accordance with one embodiment of the present invention, the first temperature, and the second temperature are same or wherein the first temperature, and the second temperature are different. The first and second temperature of the fluid may be different depending on the draping or the deformation of the area or portion of the first plastic component which is being heated. It is to be noted that the fluid temperature is chosen such that the fluid temperature is less than the ambient temperature. This facilitates in reducing the temperature of the inner surface of the wall (102a) of the first plastic component (102), which reduces the deformation and/or draping of the heated portion.
In accordance with one embodiment of the present invention, the first pressure, and the second pressure are same, or wherein the first pressure, and the second pressure are different. The first and second pressure may be different. The change in pressure may be made to correct the deformation upon heating and/or when the first and second components are abutted. The first pressure may be greater than the second pressure or vice versa.
In accordance with one embodiment of the present invention, the first plastic component (102), and the second plastic component (104) are each independently made from at least one plastic material selected from the group consisting of polypropylene, polyethylene, polyethylene terephthalate, nylon, and combinations thereof.
In accordance with one embodiment of the present invention, the first plastic component (102), the second plastic component (104), or both are made of one or more layers of the at least one plastic material.
In accordance with one embodiment of the present invention, the pressurized fluid is at least one selected from the group consisting of air, nitrogen, carbon dioxide, argon, helium, water, steam, and combinations thereof. It is to be noted that the fluids are not limited to these examples and any other fluid may be employed. In accordance with one embodiment of the present invention, the fluid is air as it is omnipresent and is economical to use. In accordance with one embodiment of the present invention, nitrogen may be used as the fluid wherein the nitrogen provides an inert atmosphere.
In accordance with one embodiment of the present invention, the step of heating the first localized portion (102p1), and the second localized portion (104p1) is each independently carried out by at least one method selected from the group consisting of direct heating, hot plate heating, induction heating, infrared radiation heating, and combinations thereof.
In accordance with one embodiment of the present invention, the pressure transducer (112) is operatively connected to the first plastic component (102), wherein the pressure transducer (112) is configured to measure the pressure of the fluid within the space (102b).
In accordance with yet another aspect of the present invention, a composite plastic structure with reduced deformation is disclosed which is fabricated by the method as described herein above. The composite plastic structure comprising a first plastic component (102) and a second plastic component (104) welded together to define a weld bond having a welding pull strength is in the range of 20 kgf to 200 kgf.
The present invention has been described with reference to two plastic components, however it is to be noted that the present invention can be used to weld more than two components at a time.
Further, the present invention has been described with reference to the first plastic component which is in form of a hollow plastic body, and the second plastic component which is a solid body with apertures thereon. However, it is to be noted that the present invention is not limited to this combination, and the components being welded may be all hollow (in case of multiple components), or at least one of the components may be hollow.
EXAMPLES
The present invention is now described with reference to the following examples which are provided for a clear understanding of the present invention and not for limiting the scope thereof.
Two plastic components as illustrated in FIG. 1a, and FIG. 1b were welded employing the method and apparatus as described herein in conjunction with the present invention. The table 1 herein below lists the various parameters and strengths achieved in five composite structures. The first plastic component and the second plastic component were made of polypropylene and had shape and profile as shown in FIG. 1a and FIG. 1b.
Table 1
Ex. T1 T2 Ap1 Ap2 TH1 TH2 Th1 Th2 Tho Tc Wcs Wt Tg Sg Wc K
1 -10 -10 1.1 1.1 200 200 20 20 10 300 50 2 80 1.5 30 No
2 15 10 1.15 1.15 210 210 20 20 10 300 55 2 80 1.5 30 No
3 20 20 1.2 1.2 215 225 20 20 10 300 60 2 80 1.5 30 No
4 20 15 1.2 1.2 220 220 20 20 10 300 50 2 80 1.5 30 No
5 10 20 1.3 1.3 220 220 20 20 10 300 70 2 80 1.5 30 No
6 30 30 1.2 1.2 220 220 20 20 10 300 20 2 80 1.5 30 No
7 35 35 1.2 1.2 225 225 20 20 10 300 25 2 80 1.5 30 No
8 40 40 1.2 1.2 230 230 20 20 10 300 30 2 80 1.5 30 No
T1 – First temperature (°C)
T2 – Second temperature (°C)
Ap1 – First pressure (bar)
Ap2 – Second pressure (bar)
TH1 – Temperature of the first component (°C)
TH2 – Temperature of the second component (°C)
Th1 – Time period for which the first component is heated (seconds)
Th2 – Time period for which the first component is heated (seconds)
Tho- Weld time (seconds)
Tc – Time period for which the connection was cooled (seconds)
Wcs – Welding pull strength (Kgf)
Wt – Wall thickness (mm)
Tg – Glass transition temperature (C)
Sg – Sagging of wall (mm)
Wc – Wall cross section area (mm2)
K – Deformation or any other problem with the welding (yes/no)
TECHNICAL ADVANCES AND ECONOMIC SIGNIFICANCE OF THE PRESENT INVENTION
The present invention provides several technical advances and advantages which include:
an apparatus and a method of the present invention
obviates need of a solid rod like support,
reduces or eliminates deformations or draping,
is easy to implement,
is simple,
is time and cost efficient, and
is more productive as compared with the conventional welding methods.
it is a clean process
,CLAIMS:We claim:
A method for fabricating a composite plastic structure with reduced deformation, the method comprising the following steps:
forming a first plastic component (102) defined by a wall (102a) and enclosing a space (102b) therewithin, the wall (102a) having an operative first surface (102c) and having a first profile (102d);
sealing the first plastic component (102) thereby configuring the first plastic component (102) to receive and retain a pressurized fluid within the space (102b);
operably securing a valve (106) on the first plastic component (102), the valve (106) configured to facilitate injection and ejection of the pressurized fluid into and out of the space (102b) therethrough;
forming a second plastic component (104) with an operative second surface (104c) having a second profile (104d) which being complimentary to the first profile (102d);
injecting the pressurized fluid into the space (102b), at a first temperature, through the valve (106), wherein the fluid is injected to pressurize the first plastic component (102) to a first pressure, wherein the first pressure is a pressure at which the wall (102a) of the first plastic component (102) is stiffened;
heating a first localized portion (102p1) of the wall (102a) of the first plastic component (102), and a second localized portion (104p1) of the second plastic component (104) to a temperature at which each of the first localized portion (102p1), and the second localized portion (104p1) is softened;
abutting the first localized portion (102p1) and the second localized portion (104p1) by juxtaposing the first plastic component (102) with the second plastic component (104) to form a connection therebetween, wherein the space (102b) is pressurized by the pressurized fluid at a second pressure, and at second temperature;
allowing the connection to cool to a temperature wherein the first localized portion (102p1), and the second localized portion (104p1) harden while being connected; and
releasing the pressurized fluid from the space (102b) to obtain the composite plastic structure comprising the first plastic component (102) welded to the second plastic component (104), wherein the welding having a pull strength of 20 kgf to 200.
The method as claimed in claim 1, wherein the first plastic component (102) is received in a first jig (108) which being configured to support and secure the first plastic component (102), and the second plastic component (104) is received in a second jig (110) which being configured to support and secure the second plastic component (104).
The method as claimed in claim 1, wherein the welding pull strength is given by the following formula:
Wcs? [(W_c.W_t.A_p.T_H.T_g.T_h.T_ho)/S_g ]
Wherein,
Wcs – Welding pull strength
Wc – Wall cross section area
Wt – Wall thickness
Ap – Fluid pressure
TH – Temperature of the component
Tg – Glass transition temperature
Th – Time period for which the component is heated
Tho- Weld time
Sg – Sagging of wall.
The method as claimed in claim 1, wherein the first plastic component (102) comprising a tubular body having at least one open end (102e), and the first plastic component (102) is sealed by employing a sealing cover (114), and the first plastic component (102) is blow molded.
The method as claimed in claim 1, wherein the first temperature is in the range of -15 °C to 40 °C, and the first pressure is in the range of 1.01 bar to 5 bar, and the second temperature is in the range of -15 °C to 40 °C, and the second pressure is in the range of 1.01 bar to 5 bar.
The method as claimed in claim 1, wherein
the first temperature, and the second temperature are same or wherein the first temperature, and the second temperature are different, and
the first pressure, and the second pressure are same, or wherein the first pressure, and the second pressure are different.
The method as claimed in claim 1,
wherein the first plastic component (102), and the second plastic component (104) are each independently made from at least one plastic material selected from the group consisting of polypropylene, polyethylene, polyethylene terephthalate, nylon, and combinations thereof, and
wherein the first plastic component (102), the second plastic component (104), or both are made of one or more layers of the at least one plastic material.
The method as claimed in claim 1,
wherein the pressurized fluid is at least one selected from the group consisting of air, nitrogen, carbon dioxide, argon, helium, water, steam, and combinations thereof,
wherein the step of heating the first localized portion (102p1), and the second localized portion (104p1) is each independently carried out by at least one method selected from the group consisting of direct heating, hot plate heating, induction heating, infrared radiation heating, and combinations thereof, and
wherein a pressure transducer (112) is operatively connected to the first plastic component (102), wherein the pressure transducer (112) is configured to measure the pressure of the fluid within the space (102b).
An apparatus (200) for fabricating the composite plastic structure with reduced deformation as claimed in claim 1, wherein the apparatus (200) comprising:
a microcontroller (202);
a memory (204) associated with the microcontroller (202), the memory (204) configured to store executables, tables, and data pertaining to operations relating to the fabrication of the composite plastic structure (100);
a display (218) connected to and in data communication with the microcontroller (202), the display (218) configured to display data pertaining to various parameters associated with the apparatus and welding process;
a user interface (220) connected to and in data communication with the microcontroller (202), the user interface (220) configured to receive one or more inputs from a user, which being received and processed by the microcontroller (202);
a pressure transducer (112) cooperating with the microcontroller (202), the pressure transducer (112) operatively connected to the first plastic component (102) and configured to measure the pressure of the fluid within the space (102b);
a first movable jaw (206) and a second movable jaw (208) operatively and displaceably disposed on a support (210), the first and the second movable jaws (206, 208) being displaced by a displacing means selected from the group consisting of a motor, a pneumatic device, and a combination thereof;
a first jig (108) operatively connected to and in data communication with the microprocessor (202) via a circuit interface and a motor and secured to the first moveable jaw (206), the first jig (108) configured to receive, support, and secure the first plastic component (102) in a working position therein;
a second jig (110) operatively connected to and in data communication with the microprocessor (202) via a circuit interface and a motor and secured to the second movable jaw (208), the second jig (110) configured to receive, support, and secure the second plastic component (104) in a working position therein;
a first hot plate (212) configured to heat the first plastic component (102), the first hot plate (212) being associated with the first jig (108) and heated by a heating coil and connected to and in data communication with the microprocessor (202);
a second hot plate (214) configured to heat the second plastic component (102), the second hot plate (214) being associated with the second jig (110) and heated by a heating coil and connected to and in data communication with the microprocessor (202); and
a pressurized fluid source (216) connected to and in fluid communication with the space (102b) of the first plastic component (102), the pressurized fluid source (216) configured to supply pressurized fluid at a predetermined pressure and temperature.
A composite plastic structure with reduced deformation, the composite plastic structure comprising a first plastic component (102) and a second plastic component (104) welded together to define a weld bond having a welding pull strength is in the range of 20 kgf to 200 kgf, wherein the weld bond being formed by following the steps:
forming a first plastic component (102) defined by a wall (102a) and enclosing a space (102b) within the wall (102a), the wall (102a) having an operative first surface (102c) and having a first profile (102d);
sealing the first plastic component (102) configuring the first plastic component (102) to receive and retain a pressurized fluid within the space (102b);
operably securing a valve (106) on the first plastic component (102), the valve (106) configured to facilitate injection and ejection of the pressurized fluid into and out of the space (102b) therethrough;
forming a second plastic component (104) with an operative second surface (104c) having a second profile (104d) which being complimentary to the first profile (102d);
receiving the first plastic component (102) in a first jig (108) which being configured to support and secure the first plastic component (102);
receiving the second plastic component (104) in a second jig (110) which being configured to support and secure the second plastic component (104);
injecting the pressurized fluid into the space (102b), at a first temperature, through the valve (106), wherein the fluid is injected to pressurize the first plastic component (102) to a first pressure, wherein the first pressure is a pressure at which the wall (102a) of the first plastic component (102) is stiffened;
heating a first localized portion (102p1) of the wall (102a) of the first plastic component (102), and a second localized portion (104p1) of the second plastic component (104) to a temperature at which each of the first localized portion (102p1), and the second localized portion (104p1) is softened;
abutting the first localized portion (102p1) and the second localized portion (104p1) by juxtaposing the first plastic component (102) with the second plastic component (104) to form a connection therebetween, wherein the space (102b) is pressurized by the fluid at a second pressure, and at second temperature;
allowing the connection to cool to a temperature wherein the first localized portion (102p1), and the second localized portion (104p1) harden while being connected; and
releasing the fluid from the space (102b) to obtain the composite plastic structure comprising the first plastic component (102) welded to the second plastic component (104).
Dated this 06 October 2022
For the Applicant,

Deepak Pradeep Thakur
Applicant’s Patent Agent
IN/PA – 3687
To,
The Controller of Patents
The Patent Office, At Mumbai