Patent Publication Number: US-2009229202-A1

Title: Half-shell for forming thermal break door and window frames or the like, associated section and associated assembly process

Description:
The present invention relates to the sector of aluminium or aluminium alloy sections for forming door and window frames or the like. In particular, it relates to a half-shell for forming a thermal break door or window frame, a section obtained by assembling two of these half-shells and a heat-insulating body, and an associated assembly process. 
     In the present description and in the claims the term “half-shell” shall be used to indicate a longitudinally elongated body with a substantially rectilinear axis which has any cross-sectional form and which, when assembled with another corresponding half-shell and a heat-insulating body, forms a section. Each half-shell is typically made of aluminium or aluminium alloy and is typically obtained by means of extrusion. As regards the above, in the present description and in the claims the term “section” shall be used to indicate the assembly consisting of two half-shells and a heat-insulating body. The heal-insulating body is also a longitudinally elongated with any cross-sectional form. Typically, this heat-insulating body is a part obtained by means of extrusion and made of a heat-insulating material. 
     For some time “thermal break” sections for forming thermal break door and window frames have been known. In thermal break sections, the aluminium part exposed externally is separated from the inner part by means of heat-insulating bodies. Inside these sections a thermal break chamber with walls consisting of heat-insulating material is formed. Generally, this material is a plastic material. Typically this plastic material is a polyamide. This chamber made partially of plastic material interrupts the transmission of the heat by means of conduction between the outer part and inner part and provides the frame with a high heat-insulating power. 
     In the thermal break sections which are known at present the thermal break chamber is formed by inserting the end of two polyamide bars inside special seats provided in two half-shells of the section. Alternatively, heat-insulating bodies with a tubular shape are used. Engagement of the polyamide bars or the tubular body is performed in the flat condition. In other words, the fixing points are positioned on two parallel surfaces. Each of the above-mentioned special seats is delimited by a pair of deformable longitudinal teeth or a deformable longitudinal tooth and a fixed shoulder. During insertion of the bars or the tubular body, the teeth are all open so as to allow, precisely, easy insertion of the bars or the tubular body, respectively. After inserting the bars or the tubular body inside the respective seats rolling is performed. The rolling machine compresses the teeth of either seat and ensures rigid joining together of the bars, or the tubular body, made of heat-insulating material and the half-shells. 
     Typically, before inserting the polyamide bars into the seats, at least a part of the bottom of the seats is knurled. Knurling of the bottom is performed in order to improve the so-called “pull-out strength”, i.e. fix more firmly the polyamide bars to the section. 
     The Applicant has noted that this knurling of the bottom of the receiving seats constitutes a further machining operation and involves the use of a special apparatus with knurling rollers. Inconveniently, the knurling apparatus must be adapted to the shape and form of the sections. 
     An even greater problem, which is associated with knurling of the bottom of the seats and has been identified by the Applicant, consists in the fact that this knurling operation requires time and hinders production-line assembly of the section. 
     Moreover, inconveniently, knurling of the bottom of the seats prevents sliding of the bars (or tubular body) inside the said seats. This constitutes a serious problem limiting productivity. 
     The Applicant aims to provide a section which can be assembled on a production line ensuring greater productivity, but which, at the same time, has high pull-out strength properties. The fact of being able to assemble a thermal break section on a production line constitutes a significant advantage and results in major advantages from a cost point of view. In fact, being able to dispense with performing a machining operation avoids the associated costs of the machining apparatus (knurling rollers) and reduces the machining times. 
     The above objects, together with others, are obtained owing to the fact that at least one second snug is provided on the tooth which locks the heat-insulating body. When the tooth is bent to lock the heat-insulating body, this second snug engages with the heat-insulating body and locks it firmly. In a preferred embodiment, the second snug engages with the heat-insulating body along a portion thereof which has a density less than that of the remainder of the heat-insulating body. This portion, which has, precisely, a density less than that of the remainder of the heat-insulating body, is compressed by the second snug and stably locks the heat-insulating body, preventing it from sliding. 
     According to a first aspect, the present invention provides a half-shell of a section configured so as to form a thermal break door or window frame, the half-shell comprising a seat which is configured so as to receive a portion of a heat-insulating body and lock this heat-insulating body with respect to the half-shell, and a tooth,
         wherein said seat comprises a bottom surface and two side walls,   wherein one is said two side walls is formed by said tooth which can be bent towards the bottom of the seat so as to lock the heat-insulating body in position,   wherein said tooth comprises a first snug projecting towards said seat,   wherein said tooth also comprises a second snug projecting towards the seat and designed to penetrate into said heat-insulating body.       

     In one embodiment, the other of said two side walls is also formed by a tooth which can be bent towards the bottom of the seat so as to lock the heat-insulating body in position and which comprises a first snug and a second snug projecting towards the seat and designed to penetrate into said heat-insulating body. 
     The first snug is preferably situated substantially at the free end of said tooth and said second snug is arranged underneath the first snug, in a position closer to the bottom of the seat. 
     Preferably, said second snug is formed substantially as an equilateral triangle with a rounded vertex. 
     According to another aspect, the present invention provides a section configured so as to form a thermal break door or window frame, said section comprising two half-shells of the above-mentioned type. 
     The heat-insulating body may comprise at least one portion which is more yielding than the remainder of the heat-insulating body. 
     According to yet another aspect, the present invention provides a process for forming a section so as to produce a thermal break door or window frame, comprising the following steps:
         a) providing two half-shells and a heat-insulating body,
           wherein each half-shall comprises; a seat which is configured to receive a portion of said heat-insulating body and lock this heat-insulating body with respect to the section, and at least one tooth,   wherein said seat comprises a bottom surface and two side walls,   wherein one of said two side walls is formed by said tooth which can be bent towards the bottom of the seat so as to lock the heat-insulating body in position,   wherein said tooth comprises a first snug projecting towards said seat,   wherein said tooth also comprises a second snug projecting towards the seat and designed to penetrate into said heat-insulating body;   
           b) inserting a portion of the heat-insulating body inside the seat;   c) bending the tooth so that the second snug penetrates into the heat-insulating body.       

     The process is typically performed continuously on a production line. 
     Preferably, the process does not envisage knurling the bottom of said seat. 
    
    
     
       A detailed description of the invention is now provided purely by way of a non-limiting example, to be read with reference to the accompanying sets of drawings, in which: 
         FIG. 1  is an enlarged cross-sectional view of a portion of a known half-shell for forming a section for a thermal break door or window frame; 
         FIG. 2  is an enlarged cross-sectional view of a portion of a half-shell according to an embodiment of the present invention; 
         FIG. 3  is an enlarged cross-sectional view of a bar of heat-insulating material according to an embodiment of the invention; 
         FIG. 3   a  is an enlarged cross-sectional view of a bar of heat-insulating material according to another embodiment of the invention; and 
         FIG. 4  is an enlarged cross-sectional view of a portion of an assembled section according to an embodiment of the invention. 
     
    
    
     With reference initially to  FIG. 1 , this shows an enlarged cross-sectional view of a portion of a known half-shell  1  for forming a section for a thermal break door or window frame. In particular, it shows an enlarged view of a seat  2  designed to receive the end of a heat-insulating body (not shown in  FIG. 1 ). The seat  2  defines a roughly trapezoidal space and is delimited by a bottom surface  21  and by two sides  22 ,  23 . The first side  22  is a fixed shoulder, while the second side  23  is formed by a deformable tooth  3 . In other embodiments (not shown), the shoulder is replaced by another deformable tooth and therefore the seat  2  is delimited by two deformable teeth  3 . Typically, a groove  24  is provided in the zone where the bottom  21  of the seat  2  joins the deformable tooth  3 . The deformable tooth  3  of the seat  2  which receives the heat-insulating body terminates in a snug  31  which extends towards the inside of the seat  2 . 
     In order to assemble a section  1  and a heat-insulating body (not shown in  FIG. 1 ) inserted partially inside its seat, the locking tooth  3  is rotated so that the projecting snug  31  moves towards the bottom  21  of the seat  2 . Obviously, in the case where the seat  2  is delimited by two teeth  3 , both are rotated towards the bottom  21 . In this way the heat-insulating body is prevented from coming out of its seat and sliding of the heat-insulating body with respect to the section  1  is limited. In the known sections, typically, part of the bottom  21  of the seat  2  is knurled so as to further improve the pull-out strength. 
       FIG. 2  shows a cross-sectional view of a portion of a half-shell  1  according to an embodiment of the present invention for forming a section of a thermal break door or window frame. In particular it shows an enlarged view of a seat  2  designed to receive the end of a heat-insulating body (not shown in  FIG. 2 ). The seat  2  defines a roughly trapezoidal space and is delimited by a bottom surface  21  and by two sides  22 ,  23 . The first side  22  is a fixed shoulder, while the second side  23  is formed by a deformable tooth  3 . In other embodiments (not shown), the shoulder is replaced by another deformable tooth  3  and therefore the seat  2  is delimited by two deformable teeth  3 . Typically, a groove  24  is provided in the zone where the bottom  21  of the seat  2  joins the deformable tooth  3 . The deformable tooth  3  of the seat  2  which receives the heat-insulating body terminates in a first snug  31  which extends towards the inside of the seat  2 . According to the present invention, in addition to the first snug, at least one second snug  4  designed to penetrate into the heat-insulating body is provided, as will be explained more fully below. 
     Preferably, the second snug  4  is provided in a lower position than the first snug  31 , in the side of the tooth  3  which delimits the seat  2 . In other words, said second snug  4  is provided between the groove  24  and the first snug  31 . Preferably, the second snug  4  is substantially triangular with a rounded vertex. Conveniently, the second snug  4  projects from the inner side of the tooth  3  by about 0.20 to 0.50 mm. In a particular advantageous embodiment, the second snug  4  projects from the inner side of the tooth  3  by about 0.35 mm. Preferably, the first snug  31  and the second snug  4  project by the same amount from the inner side of the tooth  3 . 
     As mentioned above, preferably, the second snug  4  is substantially triangular with a rounded vertex. Preferably, the second snug  4  is formed roughly as an equilateral triangle. Preferably, the vertex is rounded with a radius of between 0.1 mm and 0.3 mm. In a preferred embodiment, the rounding radius of the vertex is equal to about 0.2 mm. Obviously, the second snug  4  may have any cross-sectional form, i.e. not necessarily that of an isosceles triangle with a rounded vertex. It could have a form with a sharp corner and a square, pentagonal, hexagonal or similar cross-section. 
     In a preferred embodiment an interaxial distance between the first snug  31  and the second snug  4  ranges between 0.5 mm and 1.5 mm. Conveniently, the interaxial distance is equal to about 1.0 mm. 
       FIG. 3  shows a cross-section of a constructional form of a heat-insulating body  5  designed to form a section according to an embodiment of the present invention. Viewed in cross-section, the heat-insulating body  5  comprises an elongated central part  51 , two approximately trapezoidal heads  52  and two sections  53  which connect the heads  52  to the ends of the central part  51 . The central part  51  and the two connecting sections  53  form roughly an Q (omega) shape. The two approximately trapezoidal heads  52  are configured so as to engage inside the seats  2 . In an alternative, shown in  FIG. 3   a , the bar of heat-insulating material has a substantially straight, I-shaped, cross-sectional form. In any case, for the purposes of the present invention, the body of heat-insulating material could have any open or closed (tubular) cross-sectional form. 
     The body of heat-insulating material  5  is generally made of polyamide, PVC, ABS or other plastic which is substantially rigid and cannot be easily compressed. The Applicant has established that an advantageous material in terms of weight and (low) thermal conductivity is Tefanyl. According to a preferred embodiment of the present invention, the heat-insulating body  5  comprises a portion  54  thereof made of soft material. This portion  54  of softer material may be in the form of a cord with a roughly circular cross-sectional form suitable for housing inside a special cavity formed in the body of heat-insulating material  5 . Generally, for the purposes of the present invention, “softer material” is understood as meaning a material suitable for being compressed more easily than the remainder of the heat-insulating body. Typically, this material has a density less than that of the remainder of the heat-insulating body  5 . In one embodiment, the cross-section of the cavity which receives the cord  54  is substantially circular with a diameter of between about 1.0 mm and 1.5 mm. In a preferred embodiment, the diameter of the cavity is equal to about 1.2 mm. Preferably, the cord is obtained by means of co-extrusion. 
     This cord may consist of glue or the like which can be activated when exposed to a certain pressure and/or to a certain temperature. 
     According to a first embodiment, the portion  54  of softer material projects slightly from the profile of the body of heat-insulating material  5 . The amount of this projection may be in the region of 0.1 mm to 0.2 mm and preferably is equal to about 0.15 mm. In a possible variant, the portion  54  of softer material is substantially flush with the profile of the body of heat-insulating material  5 . In a further embodiment, the portion  54  of softer material is inset with respect to the profile of the body of heat-insulating material  5 . 
     The number and position of the portions  54  of softer material depends on the number of second snugs  4  and their position. In one embodiment (that shown in  FIG. 3 ) two portions  54  of softer material are provided since each receiving seat  2  is formed by a fixed shoulder and by a deformable tooth  3  and only the latter is provided with a second snug  4 . In other embodiments (not shown), for each head  52 , two portions  54  of softer material, one on each opposite side of each head, may be provided. In other embodiments (not shown), for each side of each head  52 , two (or more) portions  54  of softer material may be provided. 
     The portions  54  of softer material may be made with a substantially flexible PVC, a rubber, an adhesive, a mastic or similar material. A material which is considered particular suitable for the purpose is resin from the family NORYL® available, for example, from GE plastics, which has its head office in Pittsfield, Mass., United States of America, a division of General Electric. For example, the resin NORYL PPX7110 (unreinforced), the resin NORYL PPX7112 (paintable/unreinforced), the resin NORYL PPX7115 (unreinforced), the resin NORYL PPX630 (30% reinforced) or the resin NORYL PPX640 (40% reinforced) may be used. Advantageously these resins have a better transmittance than polyamide or a similar material. 
       FIG. 4  shows an enlarged cross-section of a portion of a section according to an embodiment of the invention, comprising a heat-insulating body  5  and two half-shells  1 . In particular assembly of the heat-insulating body  5  on the half-shells  1  is shown: inside each seat  2  the tooth passes from its initial position (where it allows the head  52  of the body  5  of heat-insulating material to be inserted inside the respective seat  2 ), into its locking position (indicated by broken lines). As can be noted, in the locking position, the second snug  4  of each tooth  3  has penetrated into the respective portion  54  of softer material, firmly fixing the body  5  of heat-insulating material to the section. Penetration of the second snug occurs, advantageously, in succession after penetration of the first snug. 
     It should, however, be pointed out that, for the purposes of the present invention, the body of heat-insulating material does not necessarily have the portions  54 . The latter could not be present but, the body of heat-insulating material would nevertheless be firmly and stately fixed to the half-shells. 
     The Applicant has measured the pull-out strength—in accordance with that stipulated by the standard UNI ENI 14024 category W—of the half-shells  1  when assembled with the body of heat-insulating material according to the embodiment of  FIG. 4 . According to this standard, the minimum pull-out value must be 24 Newton per mm. The Applicant has measured a pull-out strength value of about 400 to 500 kg on a 10 cm sample, i.e. far greater than that stipulated by the above-mentioned standard. 
     In an alternative embodiment, the body of heat-insulating material is formed by co-extruding a first material which has a first density with a second material which has a second density less than the first density. 
     Advantageously, according to the invention, machining of the half-shells with knurling of the bottom of the seat is avoided. The section, together with the second snug (or with more than one second snug), is obtained by means of drawing and the assembly process may be performed continuously on a production line. This results in a considerable reduction in costs and machining time. 
     As a result of the present invention it is possible to perform on a production line assembly with a productivity substantially twice that of the productivity for assembly of the half-shells where the bottom of the seats is knurled. 
     The two half-shells may be obtained by means of extrusion separately and independently of one another or may be obtained by means of a single die with subsequent cutting of a bridge-piece joining them together.