Abstract:
The present invention includes a mold apparatus for facilitating replacement of rotatable molds therein. First and second frames are provided forming a plurality of mold cells and each mold includes an upper and a lower mold section. The upper mold section is removably coupled to the upper frame, while the lower mold section is removably coupled to the lower frame. Using this arrangement, a mold may be removed by detaching all connections between it and the frames, while maintaining the frames closed. Similarly, a mold may be inserted into a mold cell and connected to the frames while maintaining the frames closed. The removal and insertion operations may be performed radially or axially, depending on frame configuration.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to mold apparatus and more particularly to apparatus for facilitating removal and replacement of a single mold in a multi-mold rotational mold configuration which, in addition, facilitates opening of all molds simultaneously. 
     A molding cycle includes the steps of bringing together two or more mold parts to form a mold having a cavity in which an article may be cast, placing particulate material inside the mold, heating the mold until the material inside is melted, rotating the mold about several different axes so that the entire cavity surface is coated with the melted material and then allowing the mold to cool so that the melted material hardens and forms an article. Rotation about several axis is accomplished by securing the mold to a multi-articular machine which can facilitate the required movement. 
     Each step in a molding cycle requires a finite amount of time, the total cycle time referred to hereinafter as a cycle period. Process efficiency is generally measured by the number of articles which can be formed in a given period which is directly related to the duration of the cycle period. 
     To increase process efficiency, the industry has designed mold apparatus which can form several articles during a single cycle period. The most common multi-mold apparatus include several (e.g. 10) molds which are mounted to a “spider” wheel system which includes matching rigid spider wheels. Where each article mold consists of first and second mold halves, each first mold half is secured to a first spider wheel and each second mold half is secured to a second spider wheel. The spider wheels are constructed such that when the wheels are secured together, each second mold half is aligned with a corresponding first mold half forming a mold cavity and the molds are arrayed radially about a rotation axis. 
     With particulate material in each first mold half, the spider wheels are secured together forming separate yet mechanically linked molds. The spider wheel system is then secured to a multi-articulate machine and the heating, rotating and cooling steps described above are performed. To remove articles from the molds after cooling, the second spider wheel is moved axially away from the first spider wheel simultaneously opening all mold halves. U.S. pat. No. 5,306,564 describes a typical spider wheel system. 
     Typically spider wheels include rigid legs spaced around their perimeters which cooperate to separate adjacent wheels and form a space therebetween where molds are mounted. While the spacer legs are necessary, the legs limit the types of molds which can be used with a particular spider to a single mold family. In other words, spider wheels are custom built to accommodate specific types of molds. 
     Sometimes it is desirable to replace either all or a subset of molds which are linked to a multi-articulate machine so that articles having different characteristics can be formed. To replace all molds in a first set with molds in a second set which have different characteristics, one solution has been spider wheel refabrication. Unfortunately, refabrication is extremely time consuming and labor intensive and is therefore relatively costly and thus avoided. 
     Another solution for replacing mold sets has been to detach a first set of spider wheels and replace the wheels with a second set of wheels specifically designed to accommodate the second set of molds. While replacement requires less time and less labor than refabrication, the extreme complexity of wheel-machine coupling systems makes even the replacement solution relatively labor intensive and time consuming. This is particularly true because spider wheel replacement typically extends the molding cycle period. 
     The cycle period is extended because system hardware does not facilitate wheel replacement simultaneously with one of the previously mentioned process steps (e.g. heating, rotating, cooling). Generally, mold systems do not facilitate wheel replacement while mold cavities are formed. Instead, replacement is only possible when spider wheels are decoupled from the multi-articulate machine. During a process cycle, except for at the beginning of the cycle when particulate material is placed inside a mold half and at the end of the cycle when a product is removed from a mold, the mold halves must be secured together. Particulate provision and product removal require minimal time and, in any event, require much less time than is needed to decouple spider wheels from a multi-articulate machine and recouple different wheels to the machine to accomplish replacement. Thus, mold replacement necessarily extends a molding process cycle and reduces process efficiency. 
     To replace a subset of molds on a wheel system the only solution is refabrication which, as indicated above, is time consuming and labor intensive and therefore expensive. 
     There is, therefore, a need for a mold system which facilitates easy replacement of a mold in a spider wheel system. It would be particularly advantageous if molds could be replaced without separating mold halves and while the spider wheels are secured to an associated multi-articulate machine so that a mold could be removed from the wheels and replaced during a molding process cooling step thereby limiting the time between molding processes. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a mold apparatus for facilitating replacement of rotatable molds comprising first and second frames, wherein the first and second frames include first and second retainers, respectively. The apparatus also includes first and second mold portions which are positionable with respect to each other such that they form a mold, the first and second mold portions including first and second couplers, respectively, which are configured so as to be securely coupled to the first and second retainers, respectively, and a locking member linkable to the frames for securing the frames together so that the frames define a cell. 
     When the frames are secured together the mold is securable within the cell by securing the couplers to the retainers and the mold is removable from the cell by decoupling the couplers from the retainers. When the frames are not secured together and the couplers are coupled to the retainers, the frames are separable and when separated, the mold portions are in turn separated. 
     When the frames are secured together, the frames form a plurality of cells, the first and second frames include respective first and second retainers associated with each cell, and the mold includes a plurality of molds (e.g. a separate mold securable within each cell). 
     Preferably, the cells are arranged radially about an axis and to remove a mold, after decoupling the couplers associated with the mold to be removed from the retainers, the mold is axially lifted from an associated cell. In an alternative embodiment, a mold may be removed, after decoupling the couplers associated with the mold to be removed from the retainers, by radially sliding the mold from an associated cell. 
     The invention also includes a method for exchanging rotatable molds in a mold apparatus having an upper frame and a lower frame forming a plurality of cells, each retaining one of the rotatable molds, comprising the steps of detaching all connections between one of the rotatable molds and the frames, and removing the detached rotatable mold from the mold apparatus while maintaining the frames in a closed position. In one embodiment the detached mold is removed radially along a plurality of track and rail assemblies coupled to the frames. In an alternative embodiment, where the upper and lower frames are arranged about a rotation axis (i.e. the molds are radially spaced about the axis) the detached mold is axially removable. Each of the axial or radial removal methods further includes the steps of inserting a different mold into a location vacated by mold removal and connecting the different mold to the frames while maintaining frames closed. 
     The objects of the invention include: 
     (a) providing a rotatable mold apparatus and an associated method which permit independent removal of molds from, and insertion of molds into, cells defined by the apparatus without having to open the apparatus frames; 
     (b) providing an apparatus of the above kind which is simple and inexpensive to manufacture and use; 
     (c) providing an apparatus of the above kind which simplifies the process of swapping different molds within a single apparatus; 
     (d) providing an apparatus of the above kind which facilitates the use of molds having many different cavity characteristics; and 
     (e) providing a mold apparatus which facilitates mold replacement simultaneously with another molding process cycle step (e.g. cooling) so that mold replacement does not extend a cycle period. 
    
    
     These and other objects, advantages and aspects of the invention will become apparent from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there are shown preferred embodiments of the invention. Such embodiments do not necessarily represent the full scope of the invention and reference is made therefor, to the claims herein for interpreting the scope of the invention. 
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a top plan view of a first embodiment of the inventive mold apparatus; 
     FIG. 2 is a side perspective view of a cell of the mold apparatus in FIG. 1; 
     FIG. 3 is a side elevational view taken along line  3 — 3  of FIG. 1; 
     FIG. 4 is a cross-sectional view taken along line  4 — 4  of FIG. 3 depicting removal of a mold from a cell; 
     FIG. 5 is a cross-sectional view taken along line  5 — 5  of FIG. 4; 
     FIG. 6 is a cross-sectional view taken along line  6 — 6  of FIG. 4; 
     FIG. 7 is a top plan view of a second embodiment of the inventive mold apparatus; 
     FIG. 8 is a side perspective view of a cell of the mold apparatus in FIG. 7; 
     FIG. 9 is a top plan view of the upper frame of the mold apparatus in FIG. 7; 
     FIG. 10 is a cross-sectional view taken along line  10 — 10  of FIG. 9; 
     FIG. 11 is a cross-sectional view of an engaged fastener as in FIG. 10; and 
     FIG. 12 is a cross-sectional view of the fastener in FIG. 11, albeit disengaged. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Generally, the inventive apparatus includes an upper frame aligned with a lower frame which together define a plurality of cells, each for receiving and containing a separate removable mold. One of the significant advantages provided by the present invention is the ability to remove one or more molds from a mold apparatus without having to separate apparatus frames or remove the spider wheel from an associated multi-articulate machine. In addition, the present invention facilitates installation of one or more molds into the apparatus without having to open apparatus frames or removing the spider wheel from the machine. The invention includes embodiments which facilitate both radial and axial mold exchange. FIGS. 1 through 6 pertain to the first embodiment which facilitates radial mold exchange while FIGS. 7 through 12 pertain to the second embodiment which facilitates axial mold exchange. 
     1. Radial Embodiment 
     Referring now to the drawings, wherein like reference characters represent corresponding elements throughout the several views, and more specifically referring to FIGS. 1,  2  and  3  the inventive apparatus  10  which facilitates radial mold exchange includes an upper frame assembly  14 U, a lower frame assembly  14 L and a plurality of molds collectively referred to by numeral  12 . Generally, each of frames  14 U and  14 L are essentially identical and therefore, unless indicated otherwise, only frame  14 U will be described here in detail. Frame  14 U components are identified by a number followed by “U” while similar lower frame  14 L components are identified by an identical number followed by an “L”. 
     Frame  14 U includes a central coupling structure  18 U, a distal annular frame member  24 U and a plurality of radially extending equispaced “spoke” members (two of which are identified as  20 U and  22 U) which traverse the distance between structure  18 U and frame member  24 U. In addition, proximate structure  18 U, frame  14 U includes separate members which traverse the distance between adjacent spoke members (e.g.  20 U and  22 U), one of which is identified by numeral  30 U. Similarly, other support members  32 U,  28 U and  26 U traverse the distance between each two adjacent spoke members (e.g.  20 U and  22 U) at different radial distances from structure  18 U. 
     Frame  14 U further includes two track supporting members  19 U and  21 U positioned between each two adjacent spoke members  20 U,  22 U. Each support member  19 U,  21 U is preferably welded to members  32 U,  28 U and  26 U so that adjacent members  19 U and  21 U are parallel, a proximate end is adjacent member  30 U and a distal end is adjacent member  24 U. 
     Referring to FIG. 2, frame  14 U further includes three spacing/clamping members  34 U,  38 U (only two illustrated, in FIG. 1, location of a third is illustrated at numeral  36 U) for each two adjacent spoke members  20 U and  22 U. Each spacing member is rigidly linked at a proximal end to another frame member and extends perpendicular thereto. Member  34 U is centrally linked to member  30 U while members  36 U and  38 U are secured to spoke members  22 U and  20 U, respectively, adjacent annular member  24 U. As illustrated in FIG. 2, members  34 U,  36 U and  38 U mate and can be clamped to similar members which extend from frame  14 L. 
     Members  34 U,  36 U, and  38 U may comprise a plurality of different configurations and perform two different functions. First, members  34 U,  36 U and  38 U cooperate with members  34 L,  36 L and  38 L to separate upper frame members (e.g. spokes  20 U,  22 U) from lower frame members (e.g. spokes  20 L,  22 L). Second, although not illustrated in detail with respect to this first embodiment, distal ends of members  34 U,  36 U and  38 U are configured so that they securely and in a locking fashion receive adjacent distal ends of members  34 L,  36 L and  38 L, respectively. To this end, distal ends of members  34 U,  36 U and  38 U may each include a clamp or hook device to secure and lock to adjacent members  34 L,  36 L and  38 L. Alternatively, a subset of members  34 U,  36 U and  38 U may include a locking mechanism. Any type of locking mechanism should suffice which when locked, will maintain frames  14 U and  14 L together. For example, the locking member or mechanism may be as simple as a female/male mating arrangement with one or more bolts which extend through mating ends of adjacent members (e.g. through members  34 U and  34 L). 
     Although not illustrated, some other type of structure (e.g. hydraulically or pneumatically operated arms) is mechanically linked to each of upper and lower frames  14 U and  14 L, respectively, for, when members  34 U,  36 U and  38 U are not locked to members  34 L,  36 L and  38 L, lifting upper frame  14 U from lower frame  14 L. 
     Referring still to FIGS. 1,  2  and  3 , frames  14 U and  14 L together define a separate mold receiving cell  52  between each two adjacent spoke members (e.g.  20 U and  22 U) when frames  14 U and  14 L are clamped together in a closed configuration. Generally, a cell  52  is defined by the space bound by four spoke members  20 U,  22 U,  20 L and  22 L, associated members  30 U and  30 L and associated members  24 U and  24 L. Referring also to FIG. 4, when frames  14 U and  14 L are clamped together, all four track supporting member  19 U,  21  U,  19 L and  21  L are parallel and extend radially outward. 
     Referring also to FIGS. 4,  5  and  6 , a separate retainer or track  64 U,  64 L,  65 U and  65 L is secured (e.g. welded or screwed onto) to each of track supporting members  19 U,  19 L,  21  U and  21  L, respectively, so that four tracks are positioned within each cell  52 . Tracks  64 U and  65 U form a first retainer while tracks  64 L and  65 L form a second retainer. 
     Each of tracks  64 U,  65 U,  64 L and  65 L has identical characteristics and therefore, to simplify this explanation, only track  65 L will be described in detail. Referring to FIG. 5, track  65 L includes a flat bottom longitudinal member  67  and two lateral members  69  and  73  which extend in the same direction and perpendicular to member  67 . Distal ends of members  69  and  73  curve inwardly toward each other so that track  65 L generally forms a “C” shaped channel  79  which is restricted at the distal ends of members  69  and  73 . 
     Referring to FIGS. 1,  2 ,  3  and  4 , each mold  12  generally includes two mold portions or assemblies, an upper assembly  12 U and a lower assembly  12 L. Each of assemblies  12 U and  12 L are essentially identical and therefore, to simplify this explanation, only assembly  12 L is explained in detail. 
     Assembly  12 L includes a mold half  81 L and two couplers in the form of rail assemblies  83 L and  85 L. Couplers  83 L and  85 L are configured so as to be coupled to retainers  64 L and  65 L, respectively, such that when coupled, the relative positions of mold portion  81 L and frame member  14 L are invariably locked. Couplers  83 U and  85 U serve a similar purpose in coupling the invariable positions of mold portion  81 U and frame  14 U. Molds formed of halves like half  81 L are well known in the art and therefore are not explained here in detail, suffice it to say that when halves  81  L and  81  U are brought together (see FIG. 3) the halves  81 U and  81 L form a cavity into which meltable plastic particulate can be deposited for melting and forming a molded item. 
     Assemblies  83 L and  85 L (and for that matter  83 U and  85 U) have similar constructions and therefore, to simplify this explanation, only assembly  85 L is explained here in detail. Referring specifically to FIGS. 2,  5  and  6 , assembly  85 L includes an “L” shaped elongate member  62 , first and second bolts  66 ,  80 , first and second nuts  68 ,  82 , first and second springs  72 ,  86  and a coupler member or rail  74 . L shaped member  62  is sized to extend the length of track  65 L (see FIG. 2) and includes two members  91  and  93  which together form a 90° angle. Member  93  forms first and second apertures  95  and  97 , respectively, at opposite ends of its length. 
     Rail  74  is essentially the same length as track  65 L and has a width which is less than the distance between members  69  and  73  but greater than the distance between the restricted distal ends of members  69  and  73 . Rail  74  thickness is less than the distance between the restricted ends of members  69  and  73  and member  67 . Rail  74  forms first and second apertures  101  and  103  which are aligned with apertures  95  and  97  when assembly  85 L is constructed. Rail  74  also forms longitudinal surfaces  151  and  153  and lateral rail surfaces  155  and  157 . 
     Bolt  66  includes a wide head member  99  and a threaded distal end. Similarly, bolt  80  includes a wide head member  105  and a threaded distal end. To attach rail  74  to member  93 , the threaded ends of bolts  66  and  80  are placed through apertures  101  and  103 , through springs  72  and  86  and then through apertures  95  and  97 . Nuts  68  and  82  are then secured to the distal ends of bolts  66  and  80 , respectively. 
     Referring still to FIG. 5, member  91  is secured to mold half  81 L in any manner known in the art. As illustrated, a preferred method is to weld member  91  to half  81  L at two locations collectively identified by number  71 . 
     Referring now to FIGS. 2 and 6, stop assemblies (only two  107 L and  109 L illustrated) are provided at the proximate ends of each track  64 U,  64 L,  65 U and  65 L. The stop assemblies are of similar construction and therefore only assembly  109 L is explained here in detail. Assembly  109 L includes a bolt  111 , a square stop member  113  and an anchor member  115 . Stop member  113  is approximately the width of track  65 L and has a similar length dimension. Anchor member  115  is approximately the same width and thickness as rail  74  so that member  115  fits within channel  79 . Member  115  forms an aperture  117  as does stop member  113  (i.e. aperture  119 ). Aperture  117  is threaded so as to securely receive the threaded end of bolt  111 . 
     To secure assembly  109 L to the proximate end of track  65 L, anchor member  115  is placed within channel  79  at the proximal end of track  65 L, apertures  117  and  119  are aligned, bolt  111  is placed through aperture  119  and is received in aperture  117 . Bolt  111  is tightened until the distal restricted ends of members  69  and  73  are clamped between anchor member  115  and stop member  113 . 
     Referring now to FIGS. 2 through 6, assuming initially that the upper and lower frames  14 U and  14 L, respectively are clamped together, and that a mold  12  is outside cavity  52  (i.e. disattached from the frames), nuts  68  and  82  are loosened on each attachment assembly so that the distance between each rail  74  and a facing surface of an associated member  93  is greater than the thickness of the distal restricted ends of track members  69  and  73 . Then, as best seen in FIGS. 3 and 4, to position mold  12  within cavity  52 , rails  74  are aligned with adjacent track cavities  73  (see also FIG. 5) and mold  12  is forced radially inward toward structure  18 U (see FIG.  1 ). Eventually the distal ends of rails  74  contact stop members  113  and further inward motion is impeded. At this point, the mold  12  is in the position illustrated in FIG.  2 . Rail  74  lateral surfaces  155  and  157  and track  64 U,  64 L,  65 U and  65 L lateral members  69  and  73  (see FIG. 5) impede lateral motion while rail  74  longitudinal surfaces  151  and  153  and track longitudinal member  67  impede longitudinal motion of mold  12 . To impede radial movement of mold  12 , nuts  68  and  82  are tightened so that the restricted ends of members  69  and  73  are clamped between rail  74  and a facing surface of an adjacent member  93 . Once mold  12  is secured in this fashion, radial mold motion is impeded. 
     To remove mold  12  from cavity  52 , the above process is reversed. To this end, bolts  68  and  82  are loosened and mold  12  is slid radially out of cavity  52  along tracks  64 U,  64 L,  65 U and  65 L. 
     Referring to FIGS. 1,  2  and  3 , when molds  12  are secured (i.e. nuts  68  and  82  are tightened) in their respective cavities  52 , by decoupling all claiming members  34 U from  34 L,  36 U from  36 L and  38 U from  38 L, upper frame  14 U can be decoupled from lower frame  14 L. In this case, assuming mold halves  81 U and  81 L are not independently coupled together, frames  14 U and  14 L can be separated, thereby separating all upper mold halves  81 U from adjacent lower mold halves  81 L. 
     Thus, it should be appreciated that this inventive first system facilitates normal rotational molding procedures whereby a plurality of molds  12  can be simultaneously opened and closed to facilitate rapid deposit of mold particulate material and rapid removal of manufactured products after melting, rotation and hardening. In addition, the inventive apparatus advantageously facilitates removal of any number of the molds  12  separately from frames  14 U and  14 L by detaching rails  74  from adjacent tracks and radial removal of the associated mold  12 . Thus, as illustrated in FIG. 1, many different mold forms can be used with and swapped in and out of a single frame apparatus even while frames  14 U and  14 L are secured (e.g. while manufactured parts are cooling) thereby saving time. 
     II. Axial Embodiment 
     The second embodiment is similar to the first embodiment described above in that it includes upper and lower frames  114 U and  114 L, respectively, which can be either locked together to form mold receiving cells, or can be unlocked and separated so that a plurality of mold halves which are coupled to frames  114 U and  114 L can be separated for insertion of particulate molding material or removal of molded products. In addition, even while frames  114 U and  114 L are locked together, one or more molds linked thereto can be delinked and removed from the frames and, if desired, can be replaced. What is different between the second and first embodiments is that, instead of facilitating radial mold removal as in the first embodiment, with the second embodiment molds are removed axially. 
     Referring to FIGS. 7 through 9, each of frames  114 U and  114 L are very similar. To the extend that frames  114 U and  114 L are similar, only frame  114 U will be explained in detail and differences will be identified throughout. Upper frame  114 U includes a central coupling structure  118 , a distal annular frame member  124 U and a plurality of radially extending equispaced spoke members (two of which are identified as  120 U and  122 U) which traverse the distance between structure  118 U and member  124 U. Frame  114 U also includes brace members (one identified as  130 U) between adjacent spoke members and proximate structure  118 U. 
     Unique to frame  114 U, and not included on frame  114 L, frame  114 U forms two angle members, exemplary angle members are identified by numerals  111 U and  113 U, each member  111 U and  113 U extending from annular member  124 U to proximate end of one of members  120 U and  122 U, respectively. Also unique to frame  114 U, frame  114 U forms two extension members  115 U and  117 U between each two spoke members. Referring also to FIG. 10, each of members  111 U,  113 U,  115 U and  117 U forms an aperture, the aperture in member  113 U identified by numeral  131  and the aperture in member  117 U identified by numeral  113 . 
     Referring to FIG. 8, lower frame  114 L also has some unique structure including three additional support members  119 L,  121 L and  123 L between each two adjacent spoke members  119 L,  121 L and  123 L spaced apart between member  130 L and member  124 L, each traversing the distance between adjacent spoke members. Two apertures are formed in opposite ends of each of members  119 L and  123 L, one aperture  151  in member  119 L and one aperture  153  in member  123 L illustrated (see FIG.  10 ). 
     Referring to FIGS. 8 and 10, three separating assemblies are associated with each adjacent pair of spoke members and are positioned between frames  114 U and  114 L. In FIG. 8, only one stop assembly  159  is illustrated, view of the second and third assemblies blocked. Each assembly  159  includes a rigid stop and an adjustable stop linked at separate ends to frames  114 U and  114 L. The location of the other two stop assemblies associated with spoke members  120 U and  122 U are identified by ends  161  and  163  in FIG.  9 . 
     In addition, referring still to FIG. 8, a plurality of locking assemblies are also linked between frames  14 U and  14 L, a separate locking assembly located adjacent each separate assembly. Two locking assemblies  155  and  157  are illustrated, however, the location of the other locking assemblies associated with adjacent spoke members  122 U and  12 U is identified by end  165  in FIG.  9 . When frames  114 U and  114 L are brought together locking assemblies  155 , 157  and  165  can be used to lock the frames  114 U and  114 L together. While any locking assembly would suffice, a preferred assembly includes a bolt which extends though an upper frame member and is secured in a bolt receiving member which is securely attached to a similarly positioned and opposing lower frame member. For example, in FIG. 8, assembly  155  generally includes a bolt  220  which extends through member  122 U and is threadably secured within a receiving member  222  which is in turn secured to member  122 L. To lock frames  114 U and  114 L together, bolts  220  are tightened until the stops  159  make contact. 
     Referring to FIGS. 7,  8  and  10 , when frames  114 U and  114 L are locked together, mold receiving cells are formed between each proximate four spoke members  120 U,  120 L,  122 U and  122 L, associated members  130 U and  130 L and associated members  124 U and  124 L, one cell identified by number  224 . 
     Referring to FIGS. 7,  8  and  9 , according to the second inventive embodiment, each mold  112  includes two separate mold assemblies  112 U and  112 L. Each assembly  112 U and  112 L includes a mold half similar to the mold halves described above with respect to the first embodiment, and a coupler assembly secured to each mold half. The coupler assembly secured to the upper mold half is identified as  171  while the coupler assembly secured to the lower mold half is identified as  173 . 
     Assembly  173  includes four member  176 , 177 , 178  and  179  which form a trapezoid wherein opposite members  176  and  178  are parallel and spaced apart a distance equal to the distance between members  123 L and  119 L and where the distance between opposing members  177  and  179  is such that coupler assembly  173  can fit between adjacent spokes  120 U and  122 U and also between opposing members  115 U and  117 U when axially passed therethrough. The lower mold half is secured to assembly  173 . 
     Importantly when assembly  173  is formed with the dimensions indicated, assembly  173  can fit between members  120 U,  122 U,  130 U and  124 U but will be stopped when members  176  and  178  contact members  119 L and  122 L, respectively. Two linking assemblies  180 , 181  are provided at the ends of member  176  which, when member  176  is adjacent member  119 L, align with the apertures in member  119 L. Similarly, two linking assemblies  182  and  183  are provided in member  178  which, when member  178  is adjacent member  123 L, align with the apertures in member  123 L. 
     Referring still to FIG. 8, coupler assembly  171  includes a lattice of members which is secured to the upper mold half. While a specific lattice design is illustrated, the important aspect of assembly  117  is that distal ends of some members extend outwardly such that the ends contact members  111 U,  113 U,  115 U and  117 U. Said distal ends are identified by numerals  230 ,  231 ,  232  and  233 . A linking assembly  185 , 186 , 187 , and  188  is provided at each of distal ends  231 ,  230 ,  232  and  233 , respectively, which aligns with an aperture in a member  115 U,  117 U,  113 U and  111 U, respectively. 
     Thus, for each mold  112  there are eight aperture/linking assembly pairs, four pairs associated with each coupler assembly  171  and  173 . First, second, third and fourth pairs comprise linking assemblies associated with assembly  173  and apertures associated with members  111 U,  113 U,  115 U and  117 U, respectively. The fifth and sixth pairs are associated with members  176  and  119 L and the seventh and eighth pairs are associated with members  178  and  123 L. As all linking assemblies are essentially of the same construction, only one assembly  182  will be explained here to simplify this explanation. 
     Referring to FIGS. 11 and 12, a pair of cross-sectional views show linking assembly  182  in engaged and disengaged positions, respectively. Referring to FIG. 11, assembly  182  includes upper tubular member  190  connected to member  177  at spot weld  194 . Another tubular member  196  is welded within aperture  153  of member  123 L. A socket head cap screw  198  and receiver  200  are connected within the tubular cavity formed between members  190  and  196 . Specifically, socket head cap screw  198  is threadably engageable with the internal threads of receiver  200 . A washer  202  is provided between the head of the socket head cap screw  198  and member  190 . A clevis pin  204  is inserted through apertures in tubular member  196  and receiver  200 , thereby retaining receiver  200  within tubular member  196 . Use of receiver  200  is particularly beneficial as receivers  200  with stripped threads can be easily replaced. 
     In operation, referring to FIGS. 7 through 12, assuming frames  114 U and  114 L are locked together and at least one mold  112  is secured within a mold cell  224 , to remove the mold  112  without separating frames  114 U and  114 L, each socket head cap screw  198  associated with each linking assembly is loosened. Then, mold  112  is pulled axially from an associated cell along the direction indicated by arrow  240  (see FIG.  10 ). Thereafter mold  112  can be opened separately of frames  114 U and  114 L. 
     To replace a mold within a cell, the mold is simply dropped down into the cell (i.e. in the direction opposite arrow  240  until members  176  and  178  contact members  119 L and  123 L, respectively, and distal ends  231 ,  230 ,  232  and  233  contact members  115 U,  117 U,  113 U and  111 U. At this point all linking assemblies should be aligned with associated apertures. Then socket head cap screws  198  are secured within adjacent retainers  200 . 
     As with the first embodiment, when mold halves  112 U and  112 L are secured to frames  114 U and  114 L, respectively, locking assemblies (see  155 ,  157  in FIG. 8) can be unlocked and an overhead hoist (not illustrated) can be used to separate all molds at once. 
     It should be understood that the methods and apparatuses described above are only exemplary and do not limit the scope of the invention, and that various modifications could be made by those skilled in the art that would fall under the scope of the invention. For example, while various preferred locking and linking assemblies have been described above, clearly any types of such assemblies which can maintain respective components secured together during a molding process cycle are contemplated. In addition, other frame designs are contemplated, the important aspect of the invention being that separate molds can be individually removed from linked frames without having to open all mold halves or remove the spider wheel from the machine and during a typical process cycle step so that the cycle period is not substantially extended to facilitate replacement. 
     To apprise the public of the scope of this invention, we make the following claims: