Patent Document

TECHNICAL FIELD 
     The present invention relates to die casting and molding processes. More particularly, the present invention is related to the adjustment of wear plates on a mold and the alignment maintenance of mold halves during repeated cycle use thereof. 
     BACKGROUND OF THE INVENTION 
     Compression molding is an example high-volume molding process that may be used to produce complex components from a single set of mold halves. In general, a mold consists of a cavity half and a core half. During the compression molding process the alignment of the cavity half and the core half are maintained as the halves are brought together. Prior to the mold being closed, or in other words, prior to the mold halves being completely mated and in contact with each other, material is placed or injected into a mold cavity formed by the mold halves. Inner contour surfaces of the mold halves within a cavity area form the mold cavity. The mold is then compressed or completely closed through applied force to spread the injected material and fill the mold cavity. Pressure is applied until the injected material is cured to form a component in the shape of the mold cavity. 
     A compression mold assembly typically consists of leader pins and/or guides and compression locks, which are used to align and maintain alignment of the mold halves. The guides provide a semi-tight or rough alignment of the mold halves. The compression locks provide a tight or fine alignment of the mold halves. During the compression molding process the cavity half tends to rub on the guides and the adjacent surfaces of the core half in the compression lock areas. Wear plates have been incorporated in the stated areas to prevent chafing or galling of the contact surfaces of the mold halves. Thus, as the mold closes, the wear plates on the core half rub on and against adjacent surfaces on the cavity half or vice versa. Although the wear plates prevent galling on the mold contact surfaces, they wear over time. The fitting between the mold halves or between the wear plates and the adjacent mold half can become loose in the lock areas. The loose fit results in inaccurate alignment of the mold halves, which causes the mold halves to shift relative to each other. This shift can cause damage to the mold halves or a change in the parting line gap between the mold halves, which in turn can result in scrap parts. 
     Typically, shims are added to the backside of the wear plates to compensate for the wear on the wear plates. To add the shims the mold is opened and the mold halves are separated. The opening and separation causes the loss of accurate alignment of the mold halves. In addition, it is difficult to determine when, where, and how many shims are needed. The stated determinations can be further hindered due to wear on the guides, and the ability of the guides to be deflected during the closing of the mold. A considerable amount of downtime can be extended in adjusting the position of the wear plates. 
     Thus, there exists a need for an improved compensation technique in maintaining the consistent alignment of mold halves during a high-volume molding process that minimizes downtime. 
     SUMMARY OF THE INVENTION 
     In one embodiment of the present invention a locking system is provided for a mold that includes a first mold half, a second mold half, and a lock assembly. The lock assembly is coupled to one of the mold halves. The lock assembly includes a wear plate, that is disposed between the first mold half and the second mold half. An adjustment element is disposed between the wear plate and one of the mold halves. The lock assembly also includes a wear plate locking fastener that locks the position of the wear plate. In addition, an adjustment fastener, separate from the locking fastener, adjusts the position of the wear plate. 
     Another embodiment of the present invention provides a method of adjusting locks within a lock assembly of a mold that includes engaging angled locks of the mold. The wear plate is positioned against and in a contact position with one of the mold halves while the mold is in a closed state. The mold is opened. The wear plate is locked in the contact position. 
     The embodiments of the present invention provide several advantages. One such advantage is the provision of a wear plate for a mold that may be position adjusted while the mold is in a closed state. This allows for accurate placement of the wear plates prior to locking the wear plates in position. The decreases set time of the wear plates. 
     Another advantage provided by an embodiment of the present invention is the incorporation of angled mold locks. Angled mold locks provide a fine accurate alignment of mold halves without the wear and/or galling commonly associated with the mating of mold halve surfaces. 
     The above stated advantages provide an efficient, easy, and consistent technique of maintaining alignment of mold halves in a high-volume production process. 
     The present invention itself, together with further objects and attendant advantages, will be best understood by reference to the following detailed description, taken in conjunction with the accompanying drawing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of this invention reference should now be had to the embodiments illustrated in greater detail in the accompanying figures and described below by way of examples of the invention wherein: 
         FIG. 1  is a side sectional view of an injection compression molding system incorporating a compression wear plate lock adjustment system in accordance with an embodiment of the present invention. 
         FIG. 2  is a top and block diagrammatic view of a compression wear plate lock adjustment system of  FIG. 1 . 
         FIG. 3  is a side cross-sectional view of the mold of  FIG. 1  as viewed through section A—A of  FIG. 2 . 
         FIG. 4  is a top close-up view of one of the adjustable compression wear plate locks as viewed through section B—B of  FIG. 3 . 
         FIG. 5  is a side close-up view of the adjustable compression wear plate lock of  FIG. 4  as viewed through section C—C of  FIG. 4 . 
         FIG. 6  is a top close-up view of a compression wear plate lock adjustment system illustrating wear gaps and adjustment thereof in accordance with an embodiment of the present invention. 
         FIG. 7  is a side cross-sectional view of a mold incorporating adjustable compression wear plate locks and angled mold locks in accordance with another embodiment of the present invention. 
         FIG. 8  is a logic flow diagram illustrating a method of maintaining alignment of mold halves in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In each of the following figures, the same reference numerals are used to refer to the same components. While the present invention is described primarily with respect to a mold half alignment technique as applied to an injection/compression molding process, the present invention may be adapted to various processes including injection molding, compression molding, die casting, and other molding and casting processes that utilize multiple mold elements to form one or more mold cavities. The present invention may be applied to molds used to form complex shaped and deep contoured components, such as instrument panels, bumpers, door panels, interior trim panels, and other components known in the art. The present invention may apply to automotive, aeronautical, nautical, railway, commercial, and residential industries, as well as to other industries that utilize similar molding processes. 
     In the following description, various operating parameters and components are described for one constructed embodiment. These specific parameters and components are included as examples and are not meant to be limiting. 
     Referring now to  FIG. 1 , a side sectional view of an injection/compression molding system  10  incorporating a compression wear plate lock adjustment system  12  in accordance with an embodiment of the present invention is shown. The adjustment system  12  has a mold  14  with adjustable compression wear plate locks  16  and angled mold locks  18 . The mold  14  has a cavity mold half  20  and a core mold half  22 . The cavity mold half  20  is mounted on a stationary platen  24 . The core mold half  22  is mounted on a moveable platen  26  that is translated along a mold closing line  28 . The core mating surface  30  of the core mold half  22  remains parallel to the cavity mating surface  32  of the cavity mold half  20  during actuation thereof. The mold closing line  28  extends perpendicular to the mating surfaces  30  and  32 . The cavity mold half  20  and the core mold half  22  may be mounted on either of the platens  24  and  26 . 
     In operation, as the mold  14  is closed the wear plate locks  16  and the angled mold locks  18  assure proper alignment of the mold halves  20  and  22 . The wear plate locks  16  are integrally formed and are attached to one of the halves  20  and  22  and are in contact with the other half when the mold  14  is closed. For example, the wear plate locks  16  may be attached to the core mold half  22  and be in contact with the cavity mold half  20  when the mold  14  is closed or vice versa. The wear plate locks  16  include wear plates that are attached to one of the halves  20  and  22 , which is referred to as the lock mounting half, and are in contact with and adjacent to the other half or adjacent half. As the mold  14  is closed wear surfaces of the wear plates rub against the adjacent mold half and overtime form wear gaps therebetween. Adjustability of the wear plate locks compensates for the wear gaps. Sample wear plates are best seen in  FIGS. 2–7  and example wear gaps G 2  are shown in  FIG. 6 . The angled mold locks  18  are coupled to the mold halves  20  and  22 . The wear plate locks  16 , the angled locks  18 , and the use thereof is described below in detail with respect to  FIGS. 2–8 . 
     The injection compression molding system  10  is shown for example purposes only. The injection compression molding system  10  includes an injection side  30  and a die/part actuation side  32 , which are controlled by a controller  33 . The injection side  30  includes a rotation servo motor  34  and an injection servo motor  36 , which are coupled to and are used to rotate and translate a screw  38 . The rotation and translation of the screw  38  causes the resin material  40  from within a hopper  42  to be injected into the mold  14 . The injected resin  40 , through applied heat and pressure, cures to form a part. 
     The die/part actuation side  32  includes a die actuation motor  44 , which is used to open and close the mold  14 . The die actuation motor  44  is coupled to the moveable die  26  via a drive shaft  46 . The die actuation motor  44  rotates the drive shaft  46  to translate the core mold half  22 , thus, opening or closing the mold  14 . The die/part actuation side  32  may also include a part separation motor  48  and a part removal motor  50 . The part separation motor  48  is coupled to an ejection member  52 , which is used to separate the part from the core mold half  22  upon forming and cooling of the part. The part removal motor  50  is coupled to a part removing arm  54  and a pad  56 . The pad  56  is used to grab the part and remove it from the mold  14  upon curing thereof. 
     During operation of the injection compression molding system  10 , the mold  14  is closed by translating the core mold half  22  towards the cavity mold half  20 . Before the mold  14  is completely closed, the material  40 , which may be in the form of a thermoplastic or thermosetting resin, is injected into the mold cavity  58 . The further closing of the mold  14  compresses and thus spreads out the injected material within the mold cavity  58 . The wear plate locks  16  maintain alignment of the mold halves  20  and  22  during this injection/compression process. Heat and pressure may be continuously applied until the injected material is cured to form the part. 
     Referring now to  FIG. 2 , a top and block diagrammatic view of the compression wear plate lock adjustment system  12  is shown. The lock adjustment system  12  includes the guide pins  60 , the wear plate locks  16 , and the angled mold locks  18 . As the mold  14  is closed, the guide pins  60  provide an initial rough alignment of the core mold half  22  with the cavity core half  20 . The wear plate locks  16  provide an intermediate fine alignment of the core mold half  22  with the cavity core half  20 . The angled mold locks  18  provide a final precise alignment of the core mold half  22  with the cavity mold half  20  when the mold is in a fully closed state. Although the following is described with respect to the wear plate locks  16  being mounted on the core mold half  22 , they may be mounted on the cavity mold half  20 , as shown in  FIG. 7 . 
     Although a particular number of each of the locks  16  and  18  is shown and the locks  16  and  18  are shown at certain locations on the mold  14 , any number of each lock may be used and the locks  16  and  18  may be located in various other locations on the mold  14 . The wear plate locks  16  may be located on or at the corners  62  of the mold  14 , as shown, or may be located on the sides  64  of the mold  14 . The angled mold locks  18  may be located along the sides  64 , as shown, or may be located on the corners  62 . The angled mold locks  18  may also be located within the mold  14  such that all of the edges  66  of the angle mold locks  18  are within the outer periphery  68  of the mold  14 . 
     Referring now to  FIGS. 3–5 , a side cross-sectional view of the mold  14  and a top close-up view and a side close-up view of one of the adjustable compression wear plate locks  16  are shown. The guide pins  60 , as shown, extend from lock towers  70 , which are integral portions of the core mold half  22 . The guide pins  60  extend within pin reception holes  72  in the cavity mold half  20 . The guide pins  60  and the pin reception holes  72  may be in various locations on the halves  20  and  22 . The guide pins  60  may be located on or off of the lock towers  70  and also or alternatively on the cavity mold half  20  and have respective pin reception holes  72  in the core mold half  22 . The guide pins  60  may be of various types, styles, and formed of various materials. 
     The wear plate locks  16  are in the form of locking assemblies and include one or more wear plates  80  that provide contact rubbing surfaces  82  between the mold halves  20  and  22 . Two wear plates in perpendicular relationship are shown per each corner wear plate lock. As the mold  14  is closed the mold contact surfaces  83  of the cavity mold half  22  rub on the contact rubbing surfaces  82 . The wear plates  80  are locked in position relative to the core mold half  22  via locking fasteners  84 . The position of the wear plates  80  is adjustable via adjustment blocks or elements  86  and wedge adjustment fasteners  88 . The adjustment elements  86  are coupled between the wear plates  80  and the lock towers  70  and/or the core mold half  22 . In the embodiment shown, the adjustment elements  86  are in the form of wedges. The adjustment fasteners  88  extend through associated recessed holes  90  in the adjustment elements  86  and into the wedge adjustment towers  92 . The wedge adjustment towers  92  are an integral portion of the core mold half  22 . 
     The wear plates  80  are, in general, formed of a material that is softer than that of the mold halves  20  and  22  to prevent wear on the mold halves  20  and  22 . The surfaces  82  and  83  are formed of dissimilar materials to prevent galling. Although the wear plates  80  are shown in rectangular form, they may be of various shapes. The wear plates  80 , the mold halves  20  and  22 , and the guide pins  60  may be formed of various materials, such as steel, aluminum, brass, or other suitable materials. In one embodiment, the guide pins  60  are formed of a hardened steel, which is slid into bushings  85  (only one is shown) formed of brass that are located within the cavity mold halve  20 , as shown in  FIG. 3 . 
     The adjustment elements  86  are tapered to cause the wear plates  80  to shift in a direction approximately lateral or perpendicular to the shift direction of the adjustment elements  86 . Arrows  94  show shift directions of the adjustment elements  86 . Arrows  96  show shift directions of the wear plates  80 . Each adjustment element  86  has a single tapered side  100  adjacent the lock towers  70 . This allows for unidirectional shifting of the wear plates  80 . In shifting the adjustment elements  86 , the adjustment gaps G 1  between the wedge adjustment towers  92  and the adjustment elements  86  are increased or decreased in size. The adjustment fasteners  88  are rotated to shift the adjustment elements  86  toward or away from the wedge adjustment towers  92 . The shifting of the adjustment elements  86  causes the wear plates  80  to shift toward or away from the lock towers  70  and the cavity mold half  20  as desired. The adjustment fasteners  88  are externally accessible and visible with respect to and when the mold  14  is closed. 
     The locking fasteners  84  extend through associated slotted holes  102  in the wear plates  80 , through the adjustment elements  86 , and into the lock towers  70 . The locking fasteners  84  lock the wear plates  80  on and in position relative to the lock towers  70 . The locking fasteners  84  also lock the adjustment elements  86  into a selected position. The slotted holes  102  allow for unidirectional positioning of the wear plates  80  and the adjustment elements  86  with respect to the lock towers  70 . The fasteners  84  and  88  may be in the form of threaded bolts, as shown, or may be in some other form known in the art. 
     The angled mold locks  18  may be integrally formed as part of the mold halves  20  and  22 , as shown. The angled mold locks  18  include a receiving half  110  and a projecting half  112  that engages therewith. The projecting half  112 , in effect, is keyed to match the receiving half  110 . The projecting half  112  fits within the receiving half  110 . In one embodiment, the halves  110  and  112  include angled locking surfaces  114  and  116  that are approximately 15° from the mold closing line  28  and extend along a displacement closing direction of the mold halves  20  and  22 . Angles α and β are shown and represent the locking surface angles for the receiving surface  114  and the projecting surface  116 , respectively. Of course, angles α and β may be different than that shown depending upon the application. In an alternative embodiment, the receiving half  110  is an integral part of the core mold half  22  and the projecting half  112  is an integral part of the cavity mold half  20 . 
     Referring now to  FIG. 6 , a top close-up view of a compression wear plate lock adjustment system  120  illustrating wear gaps G 2  and adjustment thereof in accordance with an embodiment of the present invention is shown. During repeated use of the mold  122 , the wear plate surfaces  124  wear overtime creating the wear gaps G 2  between the wear plates  126  and the adjacent mold half  128 . The wear gaps G 2  may be compensated for through manual or systematic adjustment of the fasteners  130  and  132  in the adjustment system  120 . 
     The adjustment system  120  may include one or more gap sensors  134 , a controller  136 , and a gap adjustment actuating mechanism  138 . The gap sensors  134  are used to detect the size of the wear gaps G 2 . The controller  136  in response to the wear gap size shifts the wear plates  126  by shifting the adjustment elements  140  via the actuating mechanism  138 . The gap sensor  134  may be coupled within one of the mold halves, as shown, or within the wear plates  126 , the adjustment elements  140 , and the lock towers  142 . The gap sensor  134  may be in the form of an infrared sensor, a contact sensor, a radar sensor, an ultrasonic sensor, or other gap or contact sensor known in the art. The gap sensor  134  may also be replaced with a pressure sensor. The position of the wear plates  126  may be adjusted in response to the applied pressure of the wear plates  126  on the adjacent mold half. Although the adjustment mechanism  138  may be coupled to the adjustment fasteners  132  and to the locking fasteners  130 . The adjustment mechanism  138  may have linkages, robotic members, motors, and coupling members (all of which are not shown), as well as other devices known in the art for moving, rotating, loosening, tightening, or altering the state and position of the fasteners  130  and  132 . 
     The controller  136  may be microprocessor based such as a computer having a central processing unit, memory (RAM and/or ROM), and associated input and output buses. The controller  136  may be an application-specific integrated circuit or may be formed of other logic devices known in the art. The controller  136  may be a portion of a central main control unit, a control circuit having a power supply, or may be a stand-alone controller as shown. 
     Referring now to  FIG. 7 , a side cross-sectional view of a mold  150  incorporating adjustable compression wear plate locks  152  and angled mold locks  154  in accordance with another embodiment of the present invention is shown. The wear plate locks  152  are similar to the wear plate locks  16  and are fastened to the cavity mold half  158  as opposed to the core mold half  160 . The lock fasteners  162  extend through the wear plates  164  (only one is shown), through the adjustment elements  166  (only one is shown), and into the cavity mold half  158 . 
     Referring now to  FIG. 8 , a logic flow diagram illustrating a method of maintaining alignment of mold halves in accordance with an embodiment of the present invention is shown. This method may be utilized during a high-volume manufacturing or production process. 
     In step  200 , a mold, such as the mold  14 , is opened. The opening of the mold provides access to locking fasteners, such as the locking fasteners  84 , of adjustable compression wear plate locks, such as the wear plate locks  16 . 
     In step  202 , wear plates, such as wear plates  80 , of the wear plate locks are unlocked. The locking fasteners are loosened or backed-off to allow for the wear plates to be repositioned. In step  204 , adjustment elements, such as the adjustment elements  86 , are backed-off to assure that the wear plates are not in contact with the adjacent mold half or mold contact surfaces, such as surfaces  83 . 
     In step  206 , the mold is closed and the angled mold locks, such as the angled mold locks  18 , are engaged. In step  208 , the wear plates are brought into contact with the mold contact surfaces. In one embodiment, the adjustment fasteners are tightened, thereby, shifting the adjustment elements toward the wedge adjustment towers. The shift in the adjustment elements causes the wear plates to be shifted against the adjacent mold half. This position of the wear plates is referred to as the contact position. 
     In step  210 , the mold is opened, thus separating the mold halves. In step  212 , the wear plates are locked in the contact position. The locking fasteners are tightened to prevent movement of the adjustment elements and the wear plates. 
     The above-described steps are meant to be illustrative examples; the steps may be performed sequentially, synchronously, simultaneously, or in a different order depending upon the application. 
     The present invention provides a quick, easy, and consistent compression lock adjustment system. The present invention eliminates the need for shims as are often utilized between lock towers and wear plates. The present invention maintains accurate alignment between a core mold half and a cavity mold half including during wear plate position adjustment. The present invention allows for the position of the wear plates to be adjusted while the associated mold is in a closed state. This allows one to precisely determine the appropriate position of the wear plates. 
     While the invention has been described in connection with one or more embodiments, it is to be understood that the specific mechanisms and techniques which have been described are merely illustrative of the principles of the invention, numerous modifications may be made to the methods and apparatus described without departing from the spirit and scope of the invention as defined by the appended claims.

Technology Category: b