This invention relates in general to the forming of shapes or patterns on thermoplastic foam boards, sheets, blocks or slabs. More particularly, the present invention relates to methods and apparatuses for non-contact forming of thermoplastic-made foam boards, particularly of forming polystyrene foam boards, such as extruded polystyrene (XPS) foam boards, polyethylene foam boards, polyurethane foam boards or any other suitable thermoplastic foams, in which the forming mould or die does not come into contact with the thermoplastic foam board.
Thermoforming is a method of shaping articles in the presence of heat. Thermoforming normally consists of preheating a sheet of foam or non-foam thermoplastic material and bringing the preheated sheet in contact with the surface of a moulding element and forcing the preheated thermoplastic sheet to assume the configuration of the mould by impressing a second matching moulded element thereon which forces and presses the preheated thermoplastic material to generally conform to the space intermediate the machine mould elements.
One problem with the thermoforming technique for forming shapes or patterns on the surface of thermoplastic foam boards is that once the surface of the thermoplastic foam board is touched or contacted by a heated element, at or above the board materials melting point, particularly when the element has a surface area greater than ⅛th of an inch, material from the thermoplastic foam board tends to stick to the element and does not allow production to continue uninterrupted.
In the polystyrene foam industry, the process for forming shapes or patterns on the surface of polystyrene boards is normally performed most economically using hot wire cutters or machining. In such hot wire cutters, electrically isolated metal bars are energized electrically with voltage, e.g., 40 volts. Many high resistance wires, e.g., chrome nickel wires having an approximate 0.012 diam., are tensely held between the isolated metal bars. The current that flows through the high resistance wires heats them up so that they can therefore “melt” the polystyrene when it is passed through the heated wires. Hot wire processes work by using a heated wire that is generally less than about ⅛ inch thick which is capable of melting the thermoplastic material as it moves. Forming thermoplastic foam material such as XPS with heated elements having a surface area larger than the heated wires referred to before, results in residue from the melting sticking to the element and hindering production. The existing machining and hot wire methods currently in the art are used to cut out different patterns but, are generally slow and not good for continuous high production of forming surface patterns on thermoplastic foam. In addition, hot wire method produce significant scrap material. Furthermore, the use of the hot wire process may affect the vapour barrier properties of the XPS.
As stated in U.S. Pat. No. 3,917,770, another problem with the thermoforming of polystyrene foam is that “following the removal of the shaped article from the forming mould there is a tendency of the article to deform due to residual heat contained in the formed article causing forces of stress orientation to deform the still warm article. This problem is aggravated by polystyrene foam material since this material during extrusion and sheet forming operating conditions tends to be stress oriented. Thus when such stress oriented materials are subjected to reheating as during a moulding operation providing residual heat, they have a tendency to distort at elevated temperatures from a desired mould configuration thereby producing an undesired distortion or warpage in the final product.”
U.S. Pat. No. 3,917,770 describes a method of thermoforming foam polystyrene that prevents warping upon removal from moulds. According to this patent the foam polystyrene is formed by contacting a pre-heated foam sheet with matching male and female moulds at a lower temperature, i.e. a temperature below the melting point of the foam polystyrene. This only works for a certain thickness of XPS board otherwise, the extra heat required as the board thickness increases for the pre-heating process, deforms the material to a point where moulding it will be futile. Generally, the XPS board needs to be fairly thin (like coffee sleeves or foam egg cartons).
Despite the foregoing, there remains a need to develop improved methods and apparatuses for forming thermoplastic foam boards which overcome the disadvantages of the prior art and which allow for continuous, high throughput production as well as being able to form surfaces of relatively thicker thermoplastic foam boards. There is also a need to develop improved methods and apparatuses for forming thermoplastic foam boards that minimize warping upon removal from the die or mould.
The present invention provides methods and apparatuses for use in forming a surface of a thermoplastic block or board. The methods and apparatuses of the present invention may be used in applications such as in producing thermoplastic foam sub-floor tiles or exterior building insulation having a decorative or functional surface pattern, and in producing interior insulation tiles.
In one embodiment, the present invention provides for a method of forming a desired pattern on a thermoplastic foam board. In one embodiment, the method of forming a desired pattern on a thermoplastic foam board comprises: (a) providing a thermoplastic foam board having opposing first and second faces, (b) substantially placing the first face of the thermoplastic foam board relative to an element having the desired pattern, the element being heated to a temperature sufficient that the element can form the desired pattern on the thermoplastic foam board when the element is placed at a forming, non-contact distance from the first face of the thermoplastic foam board; (c) having the heated element and the thermoplastic foam board at the forming, non-contact distance thereby forming thermoplastic foam board; and (d) obtaining the thermoplastic foam board having the desired pattern.
In one embodiment of the method of forming a desired pattern on a thermoplastic foam board, step (c) comprises moving the heated element from a start point to the forming, non-contact distance from the first face of the thermoplastic foam board and keeping the heated element at the forming non-contact distance for a time sufficient for forming the thermoplastic foam board.
In another embodiment of the method of forming a desired pattern on a thermoplastic foam board, step (c) comprises (i) moving the heated element from a start point to the forming, non-contact distance from the first face of the thermoplastic foam board; (ii) keeping the heated element for a time sufficient to start forming the thermoplastic foam board; (iv) as the thermoplastic foam board is being formed, moving the heated element towards the thermoplastic foam board while maintaining the heated element at the forming, non-contact distance from the surface of the thermoplastic foam board.
In another embodiment of the method of forming a desired pattern on a thermoplastic foam board, the method further comprises coupling the second face of the thermoplastic foam board to a substrate prior to placing the first face of the thermoplastic foam board relative to the element. In one aspect of the invention the substrate is substantially flat.
In another embodiment of the method of forming a desired pattern on a thermoplastic foam board, the thermoplastic is selected from polystyrene, polyethylene, polyurethane and polyvinyl chloride.
In another embodiment of the method of forming a desired pattern on a thermoplastic foam board, the thermoplastic is extruded polystyrene (XPS).
In another embodiment of the method of forming a desired pattern on a thermoplastic foam board, the thermoplastic foam board is 0.14 centimetres or more in thickness between the first face and the second face.
In another embodiment of the method of forming a desired pattern on a thermoplastic foam board, the thermoplastic foam board is 0.31 centimetres or more in thickness between the first face and the second face.
In another embodiment of the method of forming a desired pattern on a thermoplastic foam board, the method is a method of continuously forming the desired pattern on thermoplastic foam boards.
In one embodiment of the present invention, a method of manufacturing a subfloor panel having grooves is provided. In one embodiment, the method of manufacturing a subfloor panel having grooves comprises: (a) providing a thermoplastic foam board having opposing first and second faces, (b) substantially placing the first face of the thermoplastic foam board relative to an element capable of forming the grooves, the element being heated to a temperature sufficient that the element can form the thermoplastic foam board when the element is places at a forming, non-contact distance from the first face of the thermoplastic foam board; (c) having the heated element and the thermoplastic foam board at the forming non-contact distance thereby forming the projections on the thermoplastic foam board, and (d) obtaining the subfloor panel having the grooves.
In one embodiment of the method of manufacturing a subfloor panel Having grooves, step (c) comprises moving the heated element from a start point to the forming, non-contact distance from the first face of the thermoplastic foam board and keeping the heated element at the forming non-contact distance for a time sufficient for forming the grooves on the first surface of the thermoplastic foam board.
In another embodiment of the method of manufacturing a subfloor panel having grooves, step (c) comprises (i) moving the heated element from a start point to the forming, non-contact distance from the first face of the thermoplastic foam board; (ii) keeping the heated element for a time sufficient to start forming the grooves on the first face of the thermoplastic foam board; (iii) as the projections on the first face of the thermoplastic foam board are being formed, moving the heated element towards the first face of the thermoplastic foam board while maintaining the heated element at the forming, non-contact distance from the first face of the thermoplastic foam board.
In another embodiment of the method of manufacturing a subfloor panel having grooves, the method further comprises coupling the second face of the thermoplastic foam board to a substrate prior to placing the first face of the thermoplastic foam board relative to the element. In one aspect of the invention the substrate is substantially flat.
In another embodiment of the method of manufacturing a subfloor panel having grooves, the thermoplastic is selected from polystyrene, polyethylene, polyurethane and polyvinyl chloride.
In another embodiment of the method of manufacturing a subfloor panel having grooves, the thermoplastic is extruded XPS.
In another embodiment of the method of manufacturing a subfloor panel having grooves, the thermoplastic foam board is 0.31 centimetres or more in thickness between the first face and the second face.
In another embodiment of the method of manufacturing a subfloor panel having grooves, the method is a method of continuously manufacturing subfloor panels.
In another embodiment of the method of manufacturing a subfloor panel having grooves, the projections of the subfloor panel include a substantially flat top surface.
In one embodiment the present application provides for an apparatus for use in non-contact forming a thermoplastic foam board. In one embodiment, the apparatus for use in non-contact forming a thermoplastic foam board comprises (a) a means for supporting the thermoplastic foam board; (b) at least one element capable of being heated to a temperature sufficient that the element is capable of forming a desired pattern on the thermoplastic foam board when the heated element is placed at a forming non-contact distance from the thermoplastic foam board; and (c) means for determining the position of the thermoplastic foam board; and (d) means for controlling movement of the element towards the thermoplastic foam board whereby the element is kept at a distance of no less than the non-contact, forming distance from the thermoplastic foam board.
These and other aspects of the invention will become apparent from the detailed description by reference to the following Figures.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Also, unless indicated otherwise, except within the claims, the use of “or” includes “and” and vice versa. Non-limiting terms are not to be construed as limiting unless expressly stated or the context clearly indicates otherwise (for example “including”, “having” and “comprising” typically indicate “including without limitation”). Singular forms including in the claims such as “a”, “an” and “the” include the plural reference unless expressly stated otherwise. In this specification and in the claims that follow, reference will be made to a number of terms that shall be defined to have the meanings below. All numerical designations, e.g., dimensions and weight, including ranges, are approximations that typically may be varied (+) or (−) by increments of 0.1, 1,0, or 10.0, as appropriate. All numerical designations may be understood as preceded by the term “about”.
In this document the term “forming” means creating a contoured surface configuration, pattern, or shape on a surface of a thermoplastic foam board, sheet, block or slab. Forming may include forming a decorative or functional configuration, pattern or shape on the surface of a thermoplastic foam board, sheet, block or slab.
The term “thermoplastic” refers to a polymer that is capable of softening or fusing when heated and of hardening again when cooled. Examples of thermoplastics include polystyrene, polyethylene, polyurethane and polyvinyl chloride. For the purpose of this document, thermoplastic includes also extruded polystyrene (XPS).
In this document the term “blank” refers to an unformed (i.e. a blank) thermoplastic foam board. The blank may be presented in a number of suitable shapes including block, board, sheet, or slab. For simplicity in this document the term “board” will be used in reference to the number of suitable shapes. The board may have opposing first and second faces or surfaces.
With reference to
In one embodiment, the present invention relates to apparatuses for forming a blank.
The present invention allows the continuous production of forming of boards of foam thermoplastic blanks, such as production of XPS foam insulation boards. The process for forming the surfaces of thermoplastic foam boards according to one embodiment includes heating an element having a desired pattern, form or shape, up to a desired temperature (usually melting point of the blank, or higher) and moving the heated element towards the surface of the blank to be formed and to a desired distance from the surface of the board, but without contacting the surface of the blank being formed. The element may be a die or a mould.
Referring to
In one embodiment of the present invention, the die or plate carrying the die, may be the top or upper part of a standard mechanical press, and may be a slidable top ram plate. With reference to
In one embodiment, the apparatus of the present invention may be linked to robots which may allow for high throughput and automation of the apparatus and automation of processes according to the present invention. For example, robots for loading of a blank on the base of the apparatus, and for unloading of the formed thermoplastic foam board, may be incorporated into a system which includes the apparatus of the present invention. The apparatus may also include locating means 118 for determining the location or position of face 107. Information from the locating means may be used to avoid contact of the die 108 with the board 109. Locating means may include light sensors, ultrasound sensors and so Forth. The die, the power source, the brake, the robots, the locating means and other components of the apparatus of the present invention may be programmable and automatically controlled by linking the die, power source, the locating means, robots and other components of the apparatus of the present invention to a computer unit. The computer unit may then control loading of a blank on the base of the apparatus, unloading of the formed thermoplastic foam board, temperature of the die, speed of the die, movement of the die, distance of the die from the blank, and so forth.
The plate and die may include venting apertures for allowing venting of gases that may be produced when forming blanks (not shown). In aspects of the present invention, the apertures may be part of the pattern of the die. The final formed product may include areas that may have the pre-formed thickness of the board, (i.e. areas of the board which may not be formed because they were aligned with a venting aperture and not exposed to sufficient heat).
Referring to
In aspects of the present invention, the die may be made of an efficient thermal conductor such aluminium or aluminium alloy, or any other suitable material.
Method of Forming Thermoplastic Foam Boards
In one embodiment, the present invention relates to a method for forming a surface of a thermoplastic foam board. The forming method may include (a) providing a thermoplastic foam board having opposing first and second faces, (b) substantially placing the first face of the thermoplastic foam board relative to an element having the desired pattern, the element being heated to a temperature sufficient that the element can form the desired pattern on the thermoplastic foam board when the element is placed at a forming, non-contact distance from the first face of the thermoplastic foam board; (c) having the heated element and the thermoplastic foam board at the forming non-contact distance thereby forming thermoplastic foam board; and (d) obtaining the thermoplastic foam board having the desired pattern.
The method of the present invention may be carried out manually or automatically. In one embodiment of the method of the present invention, locating means 118 may be used to locate face 107 relative to die 108. The signal from the locating means may be send to a computer unit which may control movement of the die so as to avoid contact between the thermoplastic foam board being formed and die 108.
It should be understood that the forming process of the present invention may work with the heated element moving upwards and the thermoplastic material above the element, or with the heated element moving downwards and the thermoplastic material below the element. Sideways movement are also covered by the methods of the present invention.
The temperature of the forming element, type of thermoplastic material to be formed and speed of the heated element towards the thermoplastic foam board may be correlated. The thermoplastic material's melt point may be related to the temperature of the element and the temperature of the element may relate to the speed it travels towards the thermoplastic material. The temperature of the element may be the melting point of the blank, or higher.
The element, mould or die, after reaching the depth of the desired shape, may return to its starting, home position. The formed product may then be removed and the process may be repeated. Because no residue of the thermoplastic material attaches to the element, the method of the present invention allow for a continuous, uninterrupted process. In one embodiment, the blank to be formed may be thicker than ⅛th of an inch (about 0.14 centimetres). In another embodiment, the blank may be thicker than ⅛th of an inch (about 0.31 centimetres).
As described above, to keep the blank 106 substantially flat during the forming process of the present invention, face 111 of the blank 106 opposite to the face 107 to be formed, may be substantially coupled, fixed, or adhered to a substrate 109 which may be a substantially flat board made of wood or any other suitable material, prior forming the surface 107 of the blank 106. The blank 106 may then be placed on the surface 104 of the bed 102 by placing the substrate 109 on the surface 104, such that face 107 of blank 106 may be exposed to die 108. It should be understood that the blank may be formed without being adhered first to the substrate but, in this case, the forming apparatus may need to include means for holding the blank substantially flat. For example a vacuum table that sucked the board substantially flat before forming. Having the blank adhered to a substrate, may also serve to prevent warping of the blank after it is formed.
The apparatuses and methods of the present invention may be suitable to form shapes or patterns into surfaces of foam boards of polyethylene, polyvinyl chloride, polyurethane sheets, or polystyrene such as XPS insulation boards. Almost any thermoplastic may be used.
For example, the methods of the present invention may be used for the manufacturing of a foundation insulation panel. In one embodiment, the method of manufacturing a foundation insulation panel may include (a) substantially placing a first face of a thermoplastic foam board relative to a die capable of forming grooves on the first face of the thermoplastic foam board, the die being heated to a temperature sufficient that the die can form the first face of the thermoplastic foam board when the die is placed at a forming, non-contact distance from the first face of the thermoplastic foam board; (b) having the heated die and the first face of the thermoplastic foam board at the forming non-contact distance; (c) forming the grooves on the first face of the thermoplastic foam board, and (d) obtaining the thermoplastic foundation insulation board having grooves on the first face.
In one embodiment, step (b) may include moving the heated die from a start point to the forming, non-contact distance from the first face of the thermoplastic foam board and keeping the heated die at the forming non-contact distance for a time sufficient for forming the grooves on the first surface of the thermoplastic foam board. In another embodiment, (b) may include (i) moving the heated die from a start point to the forming, non-contact distance from the first face of the thermoplastic foam board; (ii) keeping the heated die for a time sufficient for forming the grooves on the first face of the thermoplastic foam board; (iv) as the first face of the thermoplastic foam board is being formed, moving the heated die towards the first face of the thermoplastic foam board while maintaining the heated die at the forming, non-contact distance from the first face of the thermoplastic foam board.
In another embodiment of the method of manufacturing a foundation insulation board, the second face of the thermoplastic foam board may be adhered, coupled or fixed to a substantially flat substrate prior to placing the first face of the thermoplastic foam board relative to the die.
Advantages of the invention may include: (i) the continuous production of forming surface area shapes onto thermoplastic foam boards (5-12 second cycle time in the case of XPS); the methods of the present invention allow to continuously and repeatably produce formed thermoplastic foam boards, since there is no sticking of thermoplastic material on the forming element which would necessitate to be removed; (ii) no production of scrap thermoplastic material; (iii) high throughput production of thermoplastic products such as floating or non-floating XPS sub-floor panels; (iv) less expensive start up costs than injection and reaction moulding; (v) in many cases less expensive part costs than injection and reaction moulding; (vi) as a result of the methods of the present invention, the heated element (die or mould) seals the outer skin of the thermoplastic material, which effectively keeps at least same vapour barrier properties of the untreated thermoplastic material.
This application claims the benefit of the filing date of U.S. Provisional Application No. 61/564,960, filed Nov. 30, 2011, the content of which is specifically incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
61564960 | Nov 2011 | US |