WO2023080798A1

WO2023080798A1 - Apparatus and method for molding thermoplastic material

Info

Publication number: WO2023080798A1
Application number: PCT/OM2021/050008
Authority: WO
Inventors: Mahmoud AL KINDI; Farooq AL JAHWARI; Mohammad AL SALMI; Said AL MUFARGI; Imad Ali
Original assignee: Sultan Qaboos University
Priority date: 2021-11-07
Filing date: 2021-11-07
Publication date: 2023-05-11

Abstract

An apparatus (100) for molding a thermoplastic material is provided. The apparatus (100) includes a housing (102) having a top end (116), a base end (118), and a bore (120) extending along a longitudinal axis (L) thereof. The housing (102) includes an opening (139) defined in a wall (140) which is coupled to a coupling member (104) to fluidly communicate the bore (120) with a vacuum source (201). A base cover (106) and a top cover (108) are fluid tightly engaged with the base end (118) and the top end (116) of the housing (102), respectively. The bore (120) of the housing (102), the base cover (106) and the top cover (108) together define a chamber (130) to receive the thermoplastic material and a specimen (132). The housing (102) includes a piston rod (112) slidably received through a hole (150) defined in the top cover (108) and connected to a piston (110) to move the piston (110) between a first position and to a second position to compress molten thermoplastic material.

Description

APPARATUS AND METHOD FOR MOLDING THERMOPLASTIC MATERIAL

TECHNICAL FIELD

[0001] The present disclosure relates to industrial molding processes, and more particularly, to an apparatus and a method for molding a thermoplastic material into a definite shape for industrial applications.

BACKGROUND

[0002] In recent years, several molding techniques have been widely used for polymer processing. The techniques used in the polymer processing may depend on the type of the polymer to be processed such as thermoplastics or thermosets. Some technologies such as a transfer molding and so on may be used for processing the thermosets. Moreover, technologies such as blow molding, and injection molding may be used for processing the thermoplastics. Air located between sample material particles during a melting process may trap as small bubbles within a melted material. Physical characteristics such as viscosity measurements are strongly influenced by such embedded air bubbles. Further, presence of air bubbles in a polymer product may cause adverse effects on the properties and performance of the polymeric product. Hence, removal of air bubbles from a molten thermoplastic material before getting compressed is a crucial step. This is particularly critical for intricate and thin products with viscus polymers (or their composites).

[0003] In a typical production process, a vacuum source used to process the polymer is just limited to the thermosets due to relatively low viscosity. The vacuum source removes air bubbles and humidity from the thermosets at low vacuum suction. Moreover, thermoset pellets may usually be made to dry in vacuum oven prior to processing. Whereas, thermoplastic melts are usually very viscus which may require high suction power. Moreover, different steps involving removal of the air bubbles and compressing the molten thermoplastic material into the polymer product may appear a cumbersome process. Thus, there is a need to develop a system including removal of air, humidity and compressing the thermoplastic material, all in one step. SUMMARY

[0004] In one aspect of the present disclosure, an apparatus for molding a thermoplastic material into a definite shape is disclosed. The apparatus includes a housing having a top end, a base end, and a bore extending along a longitudinal axis thereof between the top end and the base end. The housing includes an opening defined in a wall thereof along a transverse axis. The apparatus further includes a coupling member fluid tightly engaged with the opening and configured to fluidly communicate the bore with a vacuum source. The apparatus further includes a base cover configured to fluid tightly engage with the base end of the housing. The apparatus further includes a top cover configured to fluid tightly engage with the top end of the housing. The bore of the housing, the base cover and the top cover together define a chamber to receive the thermoplastic material and a specimen having the definite shape to be formed from the thermoplastic material. The apparatus further includes a piston slidably received within the chamber and configured to move between a first position and a second position. Moreover, the apparatus includes a piston rod slidably received through a hole defined in the top cover and connected to the piston. The piston rod moves the piston to the first position when the thermoplastic material is subjected to heat and vacuum pressure and moves the piston to the second position to compress molten thermoplastic material within the specimen.

[0005] In an embodiment, the apparatus includes a locking mechanism configured to hold the piston in the first position proximate the top end of the housing for a predefined time to melt the thermoplastic material and remove air and humidity from the molten thermoplastic material.

[0006] In an embodiment, the locking mechanism includes a pin configured to engage with a through hole defined in the piston rod.

[0007] In an embodiment, the top end of the housing includes a groove configured to engage with the top cover.

[0008] In an embodiment, the base end of the housing includes a protrusion configured to engage with the base cover.

[0009] In an embodiment, the base cover includes an indentation configured to engage with the protrusion of the housing.

[0010] In another aspect of the present disclosure, a method of molding a thermoplastic material into a definite shape is disclosed. The method includes positioning a specimen, having the definite shape to be formed from the thermoplastic material, within a chamber defined by an apparatus. The apparatus includes a housing having a top end, a base end, and a bore extending along a longitudinal axis thereof between the top end and the base end. The housing includes an opening defined in a wall thereof along a transverse axis. The apparatus further includes a base cover fluid tightly engaged with the base end of the housing. The apparatus further includes a top cover fluid tightly engaged with the top end of the housing. The bore of the housing, the base cover and the top cover together define the chamber to receive the specimen. The apparatus further includes a piston slidably received within the chamber and moves between a first position and a second position. The method further includes depositing the thermoplastic material within the chamber at a predefined height from a top surface of the specimen. The method further includes moving the piston to the first position proximate the top end of the housing. Moreover, the method includes heating the thermoplastic material to a predefined temperature and for a first predefined time. The method further includes vacuuming the chamber for a second predefined time at a predefined vacuum pressure to remove air and humidity from the molten thermoplastic material. Further, the method includes moving the piston to the second position to compress the molten thermoplastic material within the specimen at a predefined compression pressure for a third predefined time.

[0011] In an embodiment, the method includes fluidly connecting a coupling member to the opening. The coupling member fluidly communicates the bore with a vacuum source. [0012] In an embodiment, the method includes positioning the apparatus between a first compression plate and a second compression plate of a compression machine. The piston is connected to the first compression plate and the base cover is located on the second compression plate.

[0013] In an embodiment, the method includes connecting the piston to the first compression plate using a piston rod. The piston rod is slidably received through a hole defined in the top cover.

[0014] In an embodiment, the method includes locking the piston rod, via a locking mechanism, to hold the piston in the first position.

[0015] In an embodiment, the method includes cooling the compressed thermoplastic material and dismantling the housing, the base cover, the top cover, and the piston to remove the specimen from the chamber. [0016] In another aspect of the present disclosure, a system for molding a thermoplastic material into a definite shape is disclosed. The system includes a compression machine having a first compression plate and a second compression plate located distal to the first compression plate. The system further includes the apparatus disposed between the first compression plate and the second compression plate. The piston rod is configured to engage with the first compression plate and the base cover is configured to engage with the second compression plate. At least one of the first compression plate and the second compression plate applies heat to the thermoplastic material.

[0017] Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0018] A better understanding of embodiments of the present disclosure (including alternatives and/or variations thereof) may be obtained with reference to the detailed description of the embodiments along with the following drawings, in which:

[0019] FIG. 1A is a perspective view of an apparatus for converting a raw polymer material into a finished product, according to an embodiment of the present disclosure;

[0020] FIG. IB is an exploded view of the apparatus illustrating an arrangement of a top cover, a base cover, and a piston of the apparatus, according to an embodiment of the present disclosure;

[0021] FIG. 2 is a schematic planar view of a system illustrating a compression machine and the apparatus, according to an embodiment of the present disclosure; and

[0022] FIG. 3 is a schematic flow diagram of a method of molding a thermoplastic material into a definite shape, according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

[0023] Reference will now be made in detail to specific embodiments or features, examples of which are illustrated in the accompanying drawings. Wherever possible, corresponding or similar reference numbers will be used throughout the drawings to refer to the same or corresponding parts. Moreover, references to various elements described herein, are made collectively or individually when there may be more than one element of the same type. However, such references are merely exemplary in nature. It may be noted that any reference to elements in the singular may also be construed to relate to the plural and vice- versa without limiting the scope of the disclosure to the exact number or type of such elements unless set forth explicitly in the appended claim.

[0024] Referring to FIG. 1A, a perspective view of an apparatus 100 for converting a raw polymer material into a finished product through a compression molding process is illustrated, according to an embodiment of the present disclosure. The compression molding process may be defined as a molding process in which the molding material, such as the raw polymer material, is placed in a mold cavity, heated to change the state from solid to liquid or semiliquid, and exposed to force to cause the molten material to occupy the mold cavity. External pressing unit such as a mechanical, an electro-mechanical, a pneumatic, or a hydraulic pressing unit may be designed to apply the force to the molding material against the mold cavity. Desired temperature and pressure are maintained to extract compressed molding material. In some embodiments, molding process may include an extrusion molding, a blow molding, an injection molding, and a rotational molding. In the present disclosure, the apparatus 100 is used for molding a thermoplastic material into a definite shape. The thermoplastic material may include one or more of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polybenzimidazole, acrylic, nylon, teflon, and any other known polymer material.

[0025] Referring to FIGS. 1 and 2, an assembled and an exploded view, respectively, of the apparatus 100 are illustrated, according to various embodiments of the present disclosure. The apparatus 100 includes a housing 102, a coupling member 104, a base cover 106, a top cover 108, a piston 110, a piston rod 112, and a locking mechanism 114. In the present disclosure, the housing 102 is of a cylindrical shape. In some embodiments, the housing 102 may be of a cubical, a spherical, a polygonal or of any other shape known in the art. In some embodiments, the housing 102 may be made of metals such as cast iron, ceramics, plastics that show desired chemical and temperature resistance, aluminum, nickel, cobalt, copper, tin, or alloys such as stainless steel. The housing 102 includes a longitudinal axis ‘L’, which is otherwise known as the central axis of the apparatus 100, and a transverse axis ‘T’. The longitudinal axis ‘L’ and transverse axis ‘T’ are perpendicular to each other. The housing 102 includes a top end 116, a base end 118, and a bore 120 extending along the longitudinal axis ‘L’ thereof between the top end 116 and the base end 118. The bore 120 has a cylindrical shape similar to that of the housing 102. The top end 116 of the housing 102 includes a groove 122 configured to engage with the top cover 108. Moreover, the base end 118 of the housing 102 includes a protrusion 124 configured to engage with the base cover 106. The protrusion 124 is substantially a flat portion that is elevated relatively to a surface of the base end 118 of the housing 102.

[0026] The top cover 108 is configured to fluid tightly engage with the top end 116 of the housing 102. Particularly, the top cover 108 covers the top end 116 of the housing 102. In an embodiment, the top cover 108 includes a protrusion 126 to fluid tightly engage with the groove 122 defined at the top end 116 of the housing 102. The base cover 106 is configured to fluid tightly engage with the base end 118 of the housing 102. Particularly, the base cover 106 covers the base end 118 of the housing 102. The base cover 106 includes an indentation 128 configured to engage with the protrusion 124 of the housing 102. In some embodiments, the top cover 108 and the base cover 106 may have a groove and a protrusion, respectively, and, correspondingly, the top end 116 and the base end 118 may have a protrusion and an indentation, respectively, to cover the top end 116 and the base end 118 of the housing 102. In some embodiments, each of the top cover 108 and the base cover 106 may have a plurality of protrusions and indentations, respectively. In some embodiments, the top cover 108 and the base cover 106 may be fluid tightly engaged to the top end 116 and the base end 118, respectively, through snap-fits, a push-pull coupling mechanism, a push-push coupling mechanism, a threaded locking mechanism or through any other locking mechanisms known in the art. In some embodiments, the top cover 108 may be pivoted to the top end 116 of the housing 102 while the piston 110 and the piston rod 112 may be mechanically coupled to the top cover 108. In some embodiments, the base cover 106 and the housing 102 may be formed as a single unit. In some embodiments, the base cover 106 may be connected to the base end 118 of the housing 102 using threads or a mechanical interlocking system, such as a bayonet mechanism.

[0027] The bore 120 of the housing 102, the base cover 106 and the top cover 108 together define a chamber 130 to receive the thermoplastic material and a specimen 132 having the definite shape to be formed from the thermoplastic material. The specimen 132 includes a top surface 134 and a bottom surface 136. When the specimen 132 is positioned within the chamber 130, the top surface 134 of the specimen 132 faces the top end 116 of the housing 102 and the bottom surface 136 of the specimen 132 is in contact with the base cover 106 of the housing 102. The specimen 132 further includes a plurality of specimen cavities 138 extending between the top and bottom surfaces 134, 136. The specimen cavities 138 may be otherwise defined as the definite shape to be formed from the thermoplastic material. In the present disclosure, the specimen 132 includes five specimen cavities 138 of cylindrical shapes. In some embodiments, the specimen 132 may include a single cavity having a circular, an elliptical, a rectangular, a quadratic or a polygonal cross-sectional shape. In some embodiments, size and shape of each of the specimen cavities 138 may differ based on desired definite shape. In general, the number, size and shape of the specimen cavities 138 may be customized to arrive at the desired definite shape to be formed from the thermoplastic material. Moreover, more than one specimen 132 may be positioned within the chamber 130 depending on the size of the chamber 130. In some embodiments, a stack of specimen 132 may be positioned within the chamber 130 to receive a large number of compressed thermoplastic material at once. The specimen 132 may be made up of any alloy or metal such as stainless steel, bronze, and nichrome to withstand high temperature and pressure. In some embodiments, the specimen 132 may be made up of sand. In some embodiments, the apparatus 100 may include twin screw extruders which may allow the apparatus 100 being capable of achieving shear mixing.

[0028] The housing 102 includes an opening 139 defined in a wall 140 thereof along the transverse axis ‘T’ . The wall 140 may be covered by an insulating material to avoid transfer of heat outside the apparatus 100. The wall 140 includes an outer surface 141 and an inner surface 141’. The inner surface 141’ defines the bore 120 of the housing 102. The wall 140 has a thickness ‘f defined between the outer surface 141 and the inner surface 141’. Dimensional specification of the groove 122 and the protrusion 124 at the top end 116 and the base end 118, respectively, of the housing 102 is defined within the thickness ‘t’ of the wall 140 of the housing 102. The opening 139 passes through the outer surface 141 and the inner surface 141’. In an example, the size of the opening 139, which is otherwise referred to as a diameter of the opening 139, may be in a range of 2/16 inch to 4/16 inch. In the present disclosure, size of the opening 139 is 3/16 inch. The size of the opening 139 may depend on the size of the housing 102 and the size of the bore 120. The coupling member 104 is fluid tightly engaged with the opening 139 and configured to fluidly communicate the bore 120 with a vacuum source 201 (shown in FIG. 2). In one embodiment, the coupling member 104 may be a hollow cylindrical member having a first end 142 configured to engage with the opening 139 of the housing 102 and a second end 144 configured to engage with the vacuum source 201. In another embodiment, the coupling member 104 may be integrally attached to the housing 102. In some embodiments, the coupling member 104 may include a valve arrangement to fluidly connect or disconnect the bore 120 with the vacuum source 201. Further, the valve arrangement may be used to control pressure within the chamber 130 to create a vacuum therein. The vacuum source 201 pulls air and humidity from the bore 120.

[0029] The piston 110 is slidably received within the chamber 130 and configured to move between a first position and a second position. In an embodiment, the piston 110 is a circular plate having a diameter smaller than a diameter of the bore 120 such that the piston 110 is slidably disposed within the chamber 130. A clearance between the diameter of the bore 120 defined by the inner surface 141’ of the housing 102 and the diameter of the piston 110 defined by a peripheral surface thereof may be defined in such a way that molten thermoplastic material is not leaked through the clearance. The piston 110 includes a flat surface 146 facing towards the specimen 132 and a top surface 148 opposite the flat surface 146 when the piston 110 is received within the chamber 130. The piston rod 112 is slidably received through a hole 150 defined in the top cover 108 and connected to the piston 110. In an embodiment, the piston rod 112 may have a cylindrical cross-section having a diameter smaller than a diameter of the hole 150 defined in the top cover 108 such that the piston rod 112 is freely received through the hole 150 of top cover 108. In alternate embodiments, the cross-sectional shape of the piston rod 112 may be oval, square, or any other polygon shape known in the art. The piston rod 112 includes a first end 152 connected to the top surface 148 of the piston 110 and a second end 154. In some embodiments, the piston 110 and the piston rod 112 may be detachably connected to each other. In some embodiments, the piston 110 and the piston rod 112 may be integrally attached with each other to form as a single component. The piston rod 112 moves the piston 110 to the first position when the thermoplastic material is subjected to heat and vacuum pressure and moves the piston 110 to the second position to compress molten thermoplastic material within the specimen 132. The first position and the second position of the piston 110 corresponds to a position of the piston 110 proximate the top end 116 and the base end 118, respectively, of the housing 102. [0030] The locking mechanism 114 is configured to hold the piston 110 in the first position proximate the top end 116 of the housing 102 for a predefined time to melt the thermoplastic material and remove air and humidity from the molten thermoplastic material. In an embodiment, the locking mechanism 114 includes a pin 156 configured to engage with a through hole 158 defined in the piston rod 112. The pin 156 includes a pin rod 160 having a first end 162 configured to insert through the through hole 158 of the piston rod 112 and a second end 164 attached with a cap 166. The through hole 158 is defined at a location in the piston rod 112 in such a way that the piston 110 is retained in the first position upon locking the piston rod 112 with the pin 156. In the first position of the piston 110, the pin 156 is inserted though the through hole 158 and rested on the top cover 108 such that the piston 110 is suspended at the first position. In some embodiments, the piston 110, the piston rod 112 and the pin 156 may be made up of a similar material depending on the customized need of the apparatus 100. In an example, the piston 110, the piston rod 112, the pin 156 may be made up of stainless steel, aluminum, cobalt, zinc, tin or any alloy. In some embodiments, the piston 110, the piston rod 112 and the pin 156 may be made up of different materials. In an example, the piston 110 may be made of a material different from the material of other parts of the housing 102, in particular, a material with lower heat conductivity to minimize the heat flow towards the piston rod 112.

[0031] Referring to FIG. 2, a schematic planar view of a system 202 for molding the thermoplastic material into the definite shape is illustrated, according to an embodiment of the present disclosure. The system 202 includes a compression machine 206 mounted on a supporting platform 208 and a control unit (not shown) in communication with the compression machine 206. The control unit is configured to communicate with the compression machine 206 electrically, hydraulically, mechanically, or a combination thereof to operate the compression machine 206. The compression machine 206 includes a first compression plate 210 and a second compression plate 212 located distal to the first compression plate 210. The system 202 also includes the apparatus 100 disposed between the first compression plate 210 and the second compression plate 212. The size and shape of the first and second compression plates 210, 212 may be similar or different depending on the customized needs of the system 202.

[0032] In some embodiments, the first compression plate 210 is coupled to actuators 213. The actuators 213 may include a hydraulic actuator, a pneumatic actuator, a mechanical actuator, an electric actuator, or a combination thereof. The actuators 213 may allow the movement of the first compression plate 210 while keeping the second compression plate 212 firm or fixed during the compression process. In some embodiments, the actuators 213 may be coupled to the second compression plate 212 such that the second compression plate 212 may be movable while keeping the first compression plate 210 firm or fixed during the compression process. In some embodiments, the actuators 213 may be coupled to both the first and second compression plates 210, 212 such that both the first and second compression plates 210, 212 may move during the compression process according to inputs received from an operator. In the present disclosure, the piston rod 112 is configured to engage with the first compression plate 210 and the base cover 106 is configured to engage with the second compression plate 212. In some embodiments, the first compression plate 210 may have a coupling member to couple with the piston rod 112. Further, the second compression plate 212 may have an engaging mechanism to hold the base cover 106 of the apparatus 100. In some embodiments, the first and second compression plates 210, 212 may include protrusions, grooves or indentations according to corresponding structures provided by the base cover 106 and the piston rod 112. In the present disclosure, as shown in FIG. 2, one apparatus 100 is disposed between the first and second compression plates 210, 212. In some embodiments, a plurality of apparatuses 100 may be disposed between the first and second compression plates 210, 212 same time.

[0033] At least one of the first compression plate 210 and the second compression plate 212 applies heat to the thermoplastic material. Heating devices/heaters and coolers are present on the first and second compression plates 210, 212. Hereinafter, the heating devices/heaters and coolers may be interchangeable referred to as the heating unit and the cooling unit, respectively. In some embodiments, the cooling unit may be formed integrally with the heating unit. In some embodiments, the heating unit and the cooling unit may be constituted as separate units in the compression machine 206. Alternatively, the cooling unit may be adapted to receive the apparatus 100 and cool the apparatus 100, for example, in a cooling chamber. In some embodiments, the heating units and the cooling units may be embedded within the first and second compression plates 210, 212. In some embodiments, coolant may be any liquid coolant such as water or cold air. In some embodiments, the top cover 108, the base cover 106, the housing 102, and the piston 110 may also be equipped with internal heating and cooling channels/devices. The internal heating and cooling devices may include an electric resistance heater, cooling channels flushed with fluids, heat pipes, Peltier-elements, and inductive heating elements. The system 202 further includes the vacuum source 201 configured to fluidly communicate with the bore 120 of the apparatus 100. Particularly, the coupling member 104 is configured to fluidly communicate the chamber 130 with the vacuum source 201 through a connecting duct 214 made up of copper. In some embodiments, the connecting duct 214 may be made up of rubber, aluminum, cobalt, zinc, tin or any alloy. Type of a material used for making coupling member 104 may or may not be same as that of the connecting duct 214. The coupling member 104 may be fitted, glued, threaded, welded, inserted or locked with the connecting duct 214. In the present disclosure, the vacuum source 201 is a vacuum pump. In some embodiments, the vacuum source 201, the heating devices/heaters and the coolers may work based on manual inputs. In some embodiments, the vacuum source 201, the heating devices/heaters, and the coolers may be associated with sensors and control systems which may turn the vacuum source 201, the heating devices/heaters, and the coolers on and off automatically depending on program instruction set in the control unit.

[0034] Referring to FIG. 3, a schematic flow diagram of a method 300 of molding the thermoplastic material into the definite shape is illustrated, according to an embodiment of the present disclosure. The method 300 is described with reference to the apparatus 100 and the system 202 illustrated in FIG. 1A through FIG. 2. The order in which the method 300 is described is not intended to be construed as a limitation, and any number of the described method 300 steps can be combined in any order to implement the method 300. Additionally, individual steps may be removed or skipped from the method 300 without departing from the spirit and scope of the present disclosure. In an embodiment, the method 300 may be executed by the apparatus 100 and the system 202 of the present disclosure.

[0035] At step 302, the method 300 includes positioning the specimen 132 having the definite shape to be formed from the thermoplastic material, within the chamber 130 defined by the apparatus 100. The apparatus 100 includes the housing 102 having the top end 116, the base end 118, and the bore 120 extending along the longitudinal axis ‘L’ thereof between the top end 116 and the base end 118. The housing 102 includes the opening 139 defined in the wall 140 thereof along the transverse axis ‘T’. The apparatus 100 includes the base cover 106 fluid tightly engaged with the base end 118 of the housing 102. The apparatus 100 further includes the top cover 108 fluid tightly engaged with the top end 116 of the housing 102. The bore 120 of the housing 102, the base cover 106 and the top cover 108 together define the chamber 130 to receive the specimen 132. Moreover, the apparatus 100 includes the piston 110 slidably received within the chamber 130 and moves between the first position and the second position. During the molding process, the base cover 106 is fluid tightly engaged with the base end 118 of the housing 102 as such the base end 118 of the housing 102 is covered to receive the specimen 132. The specimen 132 is then inserted from the top end 116 of the housing 102 and placed in the bore 120 over the base cover 106. The specimen 132 may be positioned within the chamber 130 with the help of tools or handles. When the specimen 132 is positioned within the chamber 130, the bottom surface 136 of the specimen 132 contacts with the base cover 106 as such the base cover 106 and the specimen 132 are in close contact with each other without any air gap to transfer heat more efficiently. [0036] At step 304, the method 300 includes depositing the thermoplastic material within the chamber 130 at a predefined height from the top surface 134 of the specimen 132. The thermoplastic material may be placed manually or by using tools such as tong. The thermoplastic material may exist in forms such as pellets or large crystals or solids having regular or irregular forms. In some embodiments, pellets of the thermoplastic material may cover some area of the specimen cavities 138. The exceeding part of the thermoplastic material outside the specimen cavities 138 may define the predefined height. In some embodiments, large crystal or solid thermoplastic material may not cover any space inside the specimen cavities 138. In this case, the predefined height may be defined by the actual height of the large crystal or the solid thermoplastic material placed over the top surface 134 of the specimen 132. In some embodiments, the predefined height may be defined as a height defined within the chamber 130 from the top surface 134 of the specimen 132. The predefined height may be defined based on various factors including, but not limited to, volume of the bore 120, size of the specimen 132, and the specimen cavities 138 or the definite shape to be formed from the thermoplastic material. In some embodiments, the predefined height may be in a range of 1.5 - 3.0 Centimeter (cm). In the present disclosure, the predefined height is 2 cm. In some embodiments, the method 300 further includes receiving the piston 110 within the chamber 130 followed by fluidly tightly coupling the top cover 108 with the top end 116 of the housing 102 upon depositing the thermoplastic material within the chamber 130. The piston rod 112 is freely inserted through the hole 150 defined in the top cover 108 such that the piston 110 is movably disposed within the chamber 130. [0037] At step 306, the method 300 includes moving the piston 110 to the first position proximate the top end 116 of the housing 102. The method 300 further includes locking the piston rod 112, via the locking mechanism 114, to hold the piston 110 in the first position. The method 300 further includes fluidly connecting the coupling member 104 to the opening 139. The coupling member 104 fluidly communicates the bore 120 with the vacuum source 201. The method 300 further includes positioning the apparatus 100 between the first compression plate 210 and the second compression plate 212 of the compression machine 206. The piston 110 is connected to the first compression plate 210 and the base cover 106 is located on the second compression plate 212. The method 300 also includes connecting the piston 110 to the first compression plate 210 using the piston rod 112. The piston rod 112 is slidably received through the hole 150 defined in the top cover 108. The method 300 may further include pressing the first compression plate 210 until a predefined pressure is attained within the chamber 130. In an example, the predefined pressure may be referred to as a contact pressure caused by the first and second compression plates 210, 212 on the apparatus 100. The predefined pressure may also lead to rise in temperature within the chamber 130. The predefined pressure may be set up in the chamber 130 before melting of the thermoplastic material takes place. The predefined pressure may be in a range of 4 to 6 metric tons. In the present disclosure, the predefined pressure may be 5 metric tons.

[0038] At step 308, the method 300 includes heating the thermoplastic material to a predefined temperature and for a first predefined time. The predefined temperature is attained by the activation of the heating devices/heaters. The predefined temperature may be referred to as a temperature at which the thermoplastic material is expected to be melted and the first predefined time refers to time taken by the thermoplastic material to completely change the physical state thereof into a liquid state. In some embodiments, the first and second compression plates 210, 212 may be set to the predefined temperature to heat the thermoplastic material. In some embodiments, the first and second compression plates 210, 212 may be set to different temperatures and the differential temperature may be equivalent to the predefined temperature. The predefined temperature and the first predefined time may be in a range of 300 - 400 degree Celsius (°C) and 10 - 20 minutes, respectively. In the present disclosure, the predefined temperature is 350°C and the first predefined time is 15 minutes.

[0039] At step 310, the method 300 includes vacuuming the chamber 130 for a second predefined time at a predefined vacuum pressure to remove air and humidity from the molten thermoplastic material. The molten thermoplastic material is generally viscous. The second predefined time may be referred to as a time taken by the vacuum source 201 to suck air and humidity out of the chamber 130 leaving the molten thermoplastic material dry. The predefined vacuum pressure may be referred to as a pressure that may be lower than ambient pressure. After completion of the second predefined time, the vacuum source 201 turns off. Turning off the vacuum source 201 leads to release in the predefined vacuum pressure within the chamber 130. The locking mechanism 114 is further unlocked by releasing the pin 156 out of the piston rod 112.

[0040] At step 312, the method 300 includes moving the piston 110 to the second position to compress the molten thermoplastic material within the specimen 132 at a predefined compression pressure for a third predefined time. The first compression plate 210 may press the piston 110 downward towards the molten thermoplastic material. The second position may refer to a position of the piston 110 in which the flat surface 146 of the piston 110 touches the molten thermoplastic material. At the second position of the piston 110, the molten thermoplastic material is pushed towards the specimen 132 and further inside the specimen cavities 138. The second position of the piston 110 keeps on varying as the molten thermoplastic material gets into the specimen cavities 138. Distance between the top surface 134 of the specimen 132 and the piston 110 keeps on decreasing as the molten thermoplastic material fills the specimen cavities 138. Eventually, the flat surface 146 of the piston 110 may touch the top surface 134 of the specimen 132. The predefined compression pressure may be referred to as a pressure maintained on the piston 110 after the molten thermoplastic material is pushed into the specimen cavities 138. Moreover, the third predefined time may be referred to as a time taken by the system 202 to maintain the predefined compression pressure on the piston 110. In some embodiments, the predefined compression pressure and the third predefined time may be in a range of 4 - 5 metric tons and 3 - 8 minutes, respectively. In the present disclosure, the predefined compression pressure and the third predefined time are 3 metric tons and 5 minutes, respectively.

[0041] The method 300 further includes cooling the compressed thermoplastic material. After the third predefined time, the system 202 turns off the heating devices/heaters and activates the cooling unit. The cooling unit lowers the temperature of the compressed thermoplastic material and allow the molten thermoplastic material to dry and regain its solid state. The method 300 further includes dismantling the housing 102, the base cover 106, the top cover 108, and the piston 110 to remove the specimen 132 from the chamber 130. The compressed thermoplastic material may be ejected by placing a rod having diameter similar to a diameter of the specimen 132 and hitting the rod with a hammer. In some embodiments, the specimen cavities 138 may be layered by a non-adhesive material before the specimen 132 is positioned in the bore 120, thus the non-adhesive material allows easy ejection of the compressed thermoplastic material when the housing 102 is dismantled. In some embodiments, foils of similar shapes as of the specimen cavities 138 having one open end may also be inserted in the specimen cavities 138 before depositing the thermoplastic material in the bore 120 so that the compressed thermoplastic material may be ejected by just pulling the foil up from the top surface 134 of the specimen 132. In some embodiments, the specimen 132 may be dipped inside any coolant which may allow ejection of the compressed thermoplastic material without any labor or tools.

Industrial applicability

[0042] The present disclosure allows vacuum assistance to the thermoplastic material molding process. An immaculate and efficient compressed thermoplastic material is obtained in one single process which include removal of air and humidity from the molten thermoplastic material and molding the thermoplastic material into the compressed thermoplastic material. The compressed thermoplastic material is obtained in very less time. Constrained space of the chamber 130 allows vacuuming and compression of the thermoplastic material. A simple and compact design of the apparatus 100 mitigates the need of implementing any advanced manufacturing techniques. The apparatus 100 including the vacuum source 201 helps to achieve zero pre-processing of the thermoplastic material before being received by the chamber 130, which further avoid usage of vacuum ovens for preprocessing of the thermoplastic material. Use of the vacuum source 201 avoids any need for complex and expensive mechanical or hydraulic constructions. The present disclosure helps in cost cutting by reducing number of steps which are otherwise performed in the known molding process. The predefined vacuum pressure allows suction of the highly viscous molten thermoplastic material. A large number of the compressed thermoplastic material may be obtained at once depending on the count of the specimen cavities 138. The apparatus 100 may allow formation of nano/micro, very thin and intricate compressed thermoplastic material without any defects or flaws. The compressed thermoplastic material may be obtained in any desirable shape by just changing the shape of the specimen cavities 138 while keeping the apparatus 100 same. The nature of the material used to make the apparatus 100 allows to withstand high temperature and pressure without rupturing or getting damaged. The size of the assembled and disassembled apparatus 100 makes the apparatus 100 portable. The top cover 108 acts as a sealant as well as a placement for the piston 110. Further, the base cover 106 also acts as a sealant. The top cover 108 provides tight air connection with the piston rod 112. The locking mechanism 114 holds the piston 110 to the first position which further leads to smooth molding processing.

[0043] While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.

Claims

1. An apparatus (100) for molding a thermoplastic material into a definite shape, the apparatus (100) comprising: a housing (102) having a top end (116), a base end (118), and a bore (120) extending along a longitudinal axis (L) thereof between the top end (116) and the base end (118), wherein the housing (102) comprises an opening (139) defined in a wall (140) thereof along a transverse axis (T); a coupling member (104) fluid tightly engaged with the opening (139) and configured to fluidly communicate the bore (120) with a vacuum source (201); a base cover (106) configured to fluid tightly engage with the base end (118) of the housing (102); a top cover (108) configured to fluid tightly engage with the top end (116) of the housing (102), wherein the bore (120) of the housing (102), the base cover (106) and the top cover (108) together define a chamber (130) to receive the thermoplastic material and a specimen (132) having the definite shape to be formed from the thermoplastic material; a piston (110) slidably received within the chamber (130) and configured to move between a first position and a second position; and a piston rod (112) slidably received through a hole (150) defined in the top cover (108) and connected to the piston (110), wherein the piston rod (112) moves the piston (110) to the first position when the thermoplastic material is subjected to heat and vacuum pressure and moves the piston (110) to the second position to compress molten thermoplastic material within the specimen (132).

2. The apparatus (100) according to claim 1 further comprising, a locking mechanism (114) configured to hold the piston (110) in the first position proximate the top end (116) of the housing (102) for a predefined time to melt the thermoplastic material and remove air and humidity from the molten thermoplastic material.

3. The apparatus (100) according to any one of the preceding claims, wherein the locking mechanism (114) comprises a pin (156) configured to engage with a through hole (158) defined in the piston rod (112).

4. The apparatus (100) according to any one of the preceding claims, wherein the top end (116) of the housing (102) comprises a groove (122) configured to engage with the top cover (108).

5. The apparatus (100) according to any one of the preceding claims, wherein the base end (118) of the housing (102) comprises a protrusion (124) configured to engage with the base cover (106).

6. The apparatus (100) according to any one of the preceding claims, wherein the base cover (106) comprises an indentation (128) configured to engage with the protrusion (124) of the housing (102).

7. A method (300) of molding a thermoplastic material into a definite shape, the method (300) comprising: positioning a specimen (132), having the definite shape to be formed from the thermoplastic material, within a chamber (130) defined by an apparatus (100), wherein the apparatus (100) comprises: a housing (102) having a top end (116), a base end (118), and a bore (120) extending along a longitudinal axis (L) thereof between the top end (116) and the base end (118), wherein the housing (102) comprises an opening (139) defined in a wall (140) thereof along a transverse axis (T); a base cover (106) fluid tightly engaged with the base end (118) of the housing (102); 19 a top cover (108) fluid tightly engaged with the top end (116) of the housing (102), wherein the bore (120) of the housing (102), the base cover (106) and the top cover (108) together define the chamber (130) to receive the specimen (132); and a piston (110) slidably received within the chamber (130) and moves between a first position and a second position; depositing the thermoplastic material within the chamber (130) at a predefined height from a top surface (134) of the specimen (132); moving the piston (110) to the first position proximate the top end (116) of the housing (102); heating the thermoplastic material to a predefined temperature and for a first predefined time; vacuuming the chamber (130) for a second predefined time at a predefined vacuum pressure to remove air and humidity from molten thermoplastic material; and moving the piston (110) to the second position to compress the molten thermoplastic material within the specimen (132) at a predefined compression pressure for a third predefined time.

8. The method (300) according to claim 7 further comprising, fluidly connecting a coupling member (104) to the opening (139), wherein the coupling member (104) fluidly communicates the bore (120) with a vacuum source (201).

9. The method (300) according to any one of claims 7-8 further comprising, positioning the apparatus (100) between a first compression plate (210) and a second compression plate (212) of a compression machine (206), wherein the piston (110) is connected to the first compression plate (210) and the base cover (106) is located on the second compression plate (212). 20

10. The method (300) according to any one of claims 7-9 further comprising, connecting the piston (110) to the first compression plate (210) using a piston rod (112), wherein the piston rod (112) is slidably received through a hole (150) defined in the top cover (108).

11. The method (300) according to any one of claims 7-10 further comprising, locking the piston rod (112), via a locking mechanism (114), to hold the piston (110) in the first position.

12. The method (300) according to any one of claims 7-11 further comprising: cooling compressed thermoplastic material; and dismantling the housing (102), the base cover (106), the top cover (108), and the piston (110) to remove the specimen (132) from the chamber (130).

13. A system (202) for molding a thermoplastic material into a definite shape, the system (202) comprising: a compression machine (206) having a first compression plate (210) and a second compression plate (212) located distal to the first compression plate (210); and an apparatus (100) according to claim 1 disposed between the first compression plate (210) and the second compression plate (212), wherein the piston rod (112) is configured to engage with the first compression plate (210) and the base cover (106) is configured to engage with the second compression plate (212), and wherein at least one of the first compression plate (210) and the second compression plate (212) applies heat to the thermoplastic material.