Patent Publication Number: US-2022227038-A1

Title: Permanent tooling for composite coil spring compression molding

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of and claims the benefit of U.S. application Ser. No. 16/682,846, filed Nov. 13, 2019, and titled “PERMANENT TOOLING FOR COMPOSITE COIL SPRING COMPRESSION”, the content of which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The present disclosure relates to tooling, and more specifically to tooling for forming variable taper components such as coil springs. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     Most commercially available tooling for variable taper components, such as composite coil springs, are destroyed after forming the variable taper component in order to remove the variable taper component from the trapped tooling. For example, and referring to  FIG. 1 , a variable taper composite coil spring  10  is shown, which includes a smaller diameter portion  12  at each end and a larger diameter portion  14  in the center. An inner mandrel (not shown) used to form this variable taper composite coil spring  10  is then “locked” inside after the variable taper composite coil spring  10  is formed/cured. Accordingly, the inner mandrel must be destroyed in order to remove the variable taper composite coil spring  10  from the inner mandrel. The inner mandrel is then remanufactured to produce each additional spring, which is costly and time consuming. 
     Other commercially available tooling uses a bismuth core mandrel that is melted out of the variable taper component after forming and then recast after each variable taper component is produced. This process greatly increases the part cost for each variable taper component. 
     The present disclosure addresses these issues with variable taper components, among other issues related to tooling for variable taper components, such as composite coil springs. 
     SUMMARY 
     In one form of the present disclosure, tooling for use in forming a variable taper component is provided. The tooling comprises an inner mandrel comprising a master insert defining opposed tapered edge faces, each opposed tapered edge face defining at least one locking feature, an external surface having a variable taper and a plurality of recesses configured to receive at least a portion of the variable taper component, and a tapered internal surface. The inner mandrel further comprises a plurality of interlocking pieces arranged concentrically around the master insert, each interlocking piece defining opposed tapered edge faces, one of the opposed tapered edge faces defining at least one locking feature and another of the opposed tapered edge faces defining at least one receiving feature to engage the at least one locking feature of an adjacent interlocking piece, an external surface defining a variable taper and a plurality of recesses configured to receive at least a portion of the variable taper component, and a tapered internal surface. Additionally, the inner mandrel comprises a tapered inner sleeve disposed against the tapered internal surfaces of the plurality of interlocking pieces and the master insert. The tooling further comprises an outer mandrel disposed around the inner mandrel, the outer mandrel defining a corresponding plurality of recesses configured to receive at least a portion of the variable taper component, wherein a maximum width of each of the interlocking pieces and the master insert is smaller than a minimum width of end portions of the variable taper component, and a central portion of the variable taper component is wider than the end portions. 
     In variations of this tooling, the opposed tapered edge faces of the master insert and the plurality of interlocking pieces are normal to an external surface of the central portion of the variable taper component, the locking feature is a linear tab and the receiving feature is a linear slot, the locking feature is a T-shaped tab and the receiving feature is a T-shaped slot, the locking feature and the receiving feature are magnetic, the variable taper is continuously variable along end portions of the tooling and is constant along a central portion of the tooling, the plurality of recesses in the master insert, the plurality of interlocking pieces, and the outer mandrel define a variable taper helix, the number of the plurality of interlocking pieces is four (4), the outer mandrel defines at least two (2) pieces, the tapered inner sleeve further comprises a removal feature, the at least one locking feature of the master insert and the plurality of interlocking features define a pitch that is equal to a pitch of the variable taper component. 
     In another variation of this tooling, a top member is disposed above the master insert and the plurality of interlocking pieces, the top member defining a locking feature and at least one of the plurality of interlocking pieces further defining a receiving feature disposed at an upper portion that engages the receiving feature of the top member. 
     In another form of the present disclosure, an inner mandrel for forming variable taper component is provided. The inner mandrel comprises a master insert defining opposed tapered edge faces, each tapered edge face defining at least one locking feature, an external surface having a variable taper and a plurality of recesses configured to receive at least a portion of the variable taper component, and a tapered internal surface. The inner mandrel further comprises a plurality of interlocking pieces arranged concentrically around the master insert, each interlocking piece defining opposed tapered edge faces, one of the opposed tapered edge faces defining at least one locking feature and another of the opposed tapered edge faces defining at least one receiving feature to engage the at least one locking feature of an adjacent interlocking piece, an external surface defining a variable taper and a plurality of recesses configured to receive at least a portion of the variable taper component, and a tapered internal surface. Additionally the inner mandrel comprises a tapered inner sleeve disposed against the tapered internal surfaces of the plurality of interlocking pieces and the master insert, wherein a maximum width of each of the interlocking pieces and the master insert is smaller than a minimum width of an end portion of the variable taper component, and a central portion of the variable taper component is wider than the end portions. 
     In a variation of this inner mandrel, a top member is disposed above the master insert and the plurality of interlocking pieces, the top member defining a locking feature and at least one of the plurality of interlocking pieces further defining a receiving feature disposed at an upper portion that engages the receiving feature of the top member. 
     In another variation of this inner mandrel, the tapered inner sleeve further comprises a removal feature. 
     In yet another form of the present disclosure, a method of forming a variable taper component is provided. The method comprises placing a variable taper component preform around the inner mandrels as described herein and forming a variable taper component from the variable taper component preform. 
     In a variation of this method, prior to the forming step, an outer mandrel is placed around the variable taper component preform and the inner mandrel, the outer mandrel defining a corresponding plurality of recesses configured to receive at least a portion of the variable taper component preform. This variation may further comprise injecting a material into the recesses of the inner mandrel and the outer mandrel, wherein the forming step comprises injection molding. 
     In another form of this method, the forming step comprises compression molding. Additionally, a composite coil spring, among other variable taper components, is formed according to the methods of the present disclosure. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a variable taper composite coil spring according to the prior art; 
         FIG. 2  is a perspective view of tooling for forming a variable taper component constructed according to the teachings of the present disclosure; 
         FIG. 3  is a perspective view of an inner mandrel and a variable taper component constructed according to the teachings of the present disclosure; 
         FIG. 4A  is an exploded view of  FIG. 3 ; 
         FIG. 4B  is a perspective view of an alternate form of the tapered inner sleeve constructed in accordance with the teachings of the present disclosure; 
         FIG. 4C  is a perspective view of the underside of an alternate top member constructed in accordance with the teachings of the present disclosure; 
         FIG. 4D  is a perspective view of the top member of  FIG. 4C  engaging an interlocking piece and constructed in accordance with the teachings of the present disclosure; 
         FIG. 4E  is a perspective view of the top member of  FIG. 4C  engaging three (3) interlocking pieces and constructed in accordance with the teachings of the present disclosure; 
         FIG. 5A  is a side view illustrating an external portion of a master insert of tooling constructed in accordance with the teachings of the present disclosure; 
         FIG. 5B  is a side view illustrating an internal portion of the master insert of  FIG. 5A ; 
         FIG. 5C  is a rotated side view of the master insert of  FIG. 5A ; 
         FIG. 5D  is another rotated side view of the master insert of  FIG. 5A ; 
         FIG. 5E  is the same view as  FIG. 5D , illustrating a variable taper of an external surface of the master insert of  FIG. 5A ; 
         FIG. 5F  is a top view of the master insert of  FIG. 5A ; 
         FIG. 5G  is a perspective top view of the master insert of  FIG. 5A ; 
         FIG. 6A  is a rotated side view of an interlocking piece constructed in accordance with the teachings of the present disclosure; 
         FIG. 6B  is another rotated side view of the interlocking piece of  FIG. 6A ; 
         FIG. 6C  is another rotated side view of the interlocking piece of  FIG. 6A ; 
         FIG. 6D  is a side view of the interlocking piece of  FIG. 6A ; 
         FIG. 6E  is a top view of the interlocking piece of  FIG. 6A ; 
         FIG. 6F  is a top perspective view of the interlocking piece of  FIG. 6A ; 
         FIGS. 7A through 7L  illustrate a sequence of disassembling and removing an inner mandrel from a variable taper component according to the teachings of the present disclosure; 
         FIG. 8  is a perspective view of a portion of an outer mandrel constructed according to the teachings of the present disclosure; and 
         FIG. 9  illustrates alternative locking features of the master insert and/or interlocking pieces constructed according to the teachings of the present disclosure. 
     
    
    
     The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     Referring to  FIGS. 2 through 4 , tooling  20  for use in forming a variable taper component  30  is shown. The tooling  20  generally comprises an inner mandrel  40  comprised of several pieces, which are described in greater detail below, and in some forms includes an outer mandrel  120 . 
     The inner mandrel  40  comprises a master insert  60 , a plurality of interlocking pieces  80 , and a tapered inner sleeve  100 . As shown, the plurality of interlocking pieces  80  are arranged concentrically around the master insert  60 , and each of the components of the inner mandrel  40  are designed to be assembled and disassembled in a specific order so that they may be reused for each subsequent forming operation to produce the variable taper component  30 , which is described in greater detail below. 
     Referring first to  FIGS. 5A-5G , the master insert  60  is illustrated in greater detail. The master insert  60  defines opposed tapered edge faces  62 , an external surface  66 , and a tapered internal surface  72 . Each opposed tapered edge face  62  defines at least one locking feature  64 , which is configured to engage a corresponding receiving feature in the adjacent interlocking pieces, which is illustrated and described in greater detail below. Although a total of four (4) locking features  64  are shown, two (2) on each opposed tapered edge face  62 , it should be understood that any number of locking features may be employed, and in a number of locations besides those illustrated, while remaining within the scope of the present disclosure. 
     The external surface  66  includes a variable taper  68  (represented by an offset phantom profile in  FIG. 5E ) as shown and a plurality of recesses  70  configured to receive at least a portion of the variable taper component  30 . The variable taper  68  is relative to a longitudinal axis X of the inner mandrel  40  and should be construed to mean that the geometry, or profile, of the external surface  66  increases and decreases along the longitudinal axis X. Further, it should be understood that the variable taper need not be symmetrical about a central portion of the inner mandrel  40  as shown herein and may further be continuously variable or have zones having the same taper transitioning to zones having a different taper while remaining within the scope of the present disclosure. In one form, the taper is continuously variable from the center portion to the end portions while remaining constant along a central portion of the tooling  20 . 
     Generally, the variable taper  68  of the external surface  66  corresponds to the geometry of the variable taper component  30  being formed from the tooling  20 , which has smaller end portions and a larger center portion as previously described. 
     Referring now to  FIG. 4A  and  FIGS. 6A-6F , one of the interlocking pieces  80  is shown in greater detail. Each interlocking piece  80  defines opposed tapered edge faces  82 , an external surface  88 , and a tapered internal surface  94 . One of the opposed tapered edge faces  82  of each interlocking piece  80  defines at least one locking feature  84 , and another of the opposed tapered edge faces  82  defines at least one receiving feature  86  to engage the at least one locking feature  84  of an adjacent interlocking piece  80 . Similar to the master insert  60  as described above, although a total of two (2) locking features  84  are shown with two (2) corresponding receiving features  86  on each interlocking piece  80 , it should be understood that any number of locking features and receiving features may be employed, and in a number of locations besides those illustrated, while remaining within the scope of the present disclosure. 
     The external surface  88  defines a variable taper  90  (represented by an offset phantom profile in  FIG. 6B ) and a plurality of recesses  92  configured to receive at least a portion of the variable taper component  30 . Notably, due to the plurality of recesses  92  configured to receive the variable taper component  30  and the tapered internal surface  94 , each interlocking piece  80  of inner mandrel  40  is unique. 
     Generally, each of the opposed tapered edge faces  62  of master insert  60  and the opposed tapered edge faces  82  of the interlocking pieces  80  are normal to an external surface of a central portion  34  of the variable taper component  30  for ease of removal, which is illustrated and described in greater detail below. Further, a maximum width of each of the interlocking pieces  80  and the master insert  60  is smaller than a minimum width of end portions  32  of the variable taper component  30 , also for ease of removal. Additionally, at least one locking feature  64  of the master insert  60  and at least one locking feature  84  of the plurality of interlocking features  80  define a pitch that is equal to a pitch of the variable taper component. In other words, the locking features  64 / 84  are at angle relative to each other across the master insert  60  and the interlocking pieces  80  that matches the angle of the variable taper component, in one form of the present disclosure. 
     Now referring back to  FIG. 4A , the tapered inner sleeve  100  in one form is hollow and generally defines a portion of a geometrical cone. However, it should be understood that the tapered inner sleeve  100  could be hollow or solid, and could further include a removal feature as described in greater detail below. The external surface of the tapered inner sleeve  100  is generally configured to mate to the tapered internal surfaces  72  and  94  of the master insert  60  and interlocking pieces  80 , respectively. Further, the tapered inner sleeve has a wider proximal end portion  102  and a narrower distal end portion  104 , thus forming the taper. 
     Referring to  FIG. 4B , in an alternate form, the tapered inner sleeve  100 ′ includes a removal feature  101 , which is configured to assist in removing or inserting the tapered inner sleeve  100  within the assembled master insert  60  and plurality of interlocking pieces  80 . In this form, the removal feature  101  is a handle that extends across and interior portion of the tapered inner sleeve  100 , which can be grasped by an operator or a machine/robot. It should be understood that this particular handle configuration is merely exemplary, and a wide variety of removal features may be employed while remaining within the scope of the present disclosure. 
     Referring now to  FIGS. 4C-4E , in another alternate form, a top member  130  is disposed above the master insert  60  (not shown) and the plurality of interlocking pieces  80 , the top member  130  defining a locking feature  132  and at least one of the plurality of interlocking pieces  80  further defining a receiving feature  134  disposed at an upper portion that engages the locking feature  132  of the top member  130 . (Only one (1) interlocking piece  80  is shown in  FIG. 4D  and only three (3) interlocking pieces are shown in  FIG. 4E  for purposes of clarity). The locking feature  132  in this form defines a center rail  136  on a platform  138 , and a rear wall  140 . With this configuration of a locking feature  132 , the center rail  136  provides circumferential positioning, the platform  138  provides axial positioning, and the rear wall  140  provides radial positioning for the respective interlocking piece  80 . With this alternate top member  130 , the individual pieces/components of the inner mandrel  40  can be more securely locked together. 
     It should be understood that the specific locking feature  132  illustrated and described herein is merely exemplary, and thus other locking features may be employed while remaining within the scope of the present disclosure. Also, it should be understood that the locking features and receiving features illustrated and described throughout may be interchanged and placed on either of the adjacent components being locked together. 
     As further shown in  FIGS. 4D and 4E , an alternate marking indicia  142  may be provided on components of the inner mandrel  40 . For example, a numbering system can be used on each of the master insert  60  and the interlocking pieces  80  (shown with the numerals “3” and “4” and “5”) to assist an operator or machine vision system as to which pieces should be assembled and disassembled in which particular order. 
     Generally, to assemble the inner mandrel  40 , each of the interlocking pieces  80  are engaged with each other first, and the master insert  60  is then slid into place via the locking features  84  and receiving features  86 . The tapered inner sleeve  100  is then slid into the center of the inner mandrel  40 , and by virtue of its taper, forces each of the interlocking pieces  80  and the inner mandrel  40  together in an interlocking fashion. 
     Referring now to  FIGS. 4 and 7A through 7L , the inner mandrel  40  is configured to be disassembled and reused after forming a variable taper component  30 . In  FIG. 7A , the variable taper component  30  has been formed around the inner mandrel  40 . After the variable taper component  30  is formed, as shown in  FIG. 7B , the tapered inner sleeve  100  is translated (along the longitudinal axis X) or pulled out of the center of the inner mandrel  40 . Since the tapered inner sleeve  100  presses against tapered internal surfaces  72  and  94 , the removal of tapered inner sleeve  100  allows the master insert  60  to move. Accordingly, in  FIG. 7C , the master insert  60  is moved inwardly, away from the variable taper component  30  and towards the center of the inner mandrel  40 , and the locking features  64  slidably decouple from receiving features  86  of the adjacent interlocking pieces. As shown in  FIG. 7D , master insert  60  can then be removed, or pulled out from the center of the inner mandrel  40 . 
     Because the master insert  60  couples to opposed tapered edge faces  82  and receiving features  86  of adjacent interlocking pieces  80 , the removal of the master insert  60  then allows at least one interlocking piece  80  to move. As shown in  FIG. 7E , locking features  84  of one interlocking piece can be slidably decoupled from receiving features  86  of an adjacent interlocking piece  80 , and the interlocking piece  80  can then be moved inwardly, away from the variable taper component  30  and towards the center of the inner mandrel  40 , for its removal as shown in  FIG. 7F . 
     This procedure for removing an interlocking piece  80  is then repeated as shown in  FIGS. 7G through 7L , so that the remaining interlocking pieces  80  can be removed, thus freeing the variable taper component  30  from the inner mandrel  40 . Advantageously, the inner mandrel  40  can be removed and reused in forming another variable taper component  30  without being destroyed. 
     Referring to  FIG. 8 , a side view of one half of the outer mandrel  120  from is shown. The outer mandrel  120  comprises a face  122  and an internal surface  124 . The internal surface  124  defines a corresponding plurality of recesses  126  configured to receive at least a portion of variable taper component  30 . Generally, the internal surface  124  is configured to couple, or conform to the variable taper component  30  and the external geometries of the master insert  60  and interlocking pieces  80 . Accordingly, the tooling  20  can be used in a variety of manufacturing operations such as, by way of example, compression molding or injection molding. Although a two-piece outer mandrel  120  is shown herein, it should be understood that any number of pieces, or alternatively a conformal bladder or other tooling design, may be employed for the outer mandrel while remaining within the scope of the present disclosure. 
     In a compression molding application, the inner mandrel  40  is first assembled, and then a variable taper component preform (not shown) is placed within the recesses  70  and  92  of the master insert  60  and the interlocking pieces  80 , respectively. The outer mandrel  120  is then placed around the variable taper component preform and the inner mandrel  40 , and this assembly is placed in a compression molding die/tool. After forming, the outer mandrel  120  is removed first, and then the inner mandrel  40  is disassembled as described above. The variable taper component  30  can then be removed for further processing without destroying any tooling. 
     Similarly, for injection molding, the inner mandrel  40  and the outer mandrel  120  are assembled together (and positioned relative to each other with tooling features not shown), and then this assembly is placed into an injection molding tool. Molten resin, or molten resin with embedded fibers, can then be injected into the recesses  70  and  92  of the master insert  60  and the interlocking pieces  80 , respectively, and the recesses  126  of the outer mandrel  120 , to form the variable taper component  30 . The outer mandrel  120  and inner mandrel  40  are removed as set forth above. 
     It should be understood that compression molding and injection molding are merely two examples of forming a variable taper component, and other processes are to be considered within the scope of the present disclosure. Further, a variety of part types may be formed using the innovative tooling  20  according to the teachings of the present disclosure. For example, a composite coil spring can be formed according to the teachings herein. The composite coil spring may comprise continuous or discontinuous fibers, which may be glass or carbon by way of example, in a curable resin matrix. The curable resin matrix can be either thermoset or thermoplastic. 
     Further, as illustrated herein, the plurality of recesses  70 / 92 / 126  in the master insert  60 , the plurality of interlocking pieces  80 , and the outer mandrel  120 , respectively, define a variable taper helix in one form of the present disclosure. 
     The master insert  60 , interlocking pieces  80 , tapered inner sleeve  100 , outer mandrel  120  and components thereof (e.g. locking feature, receiving feature, among others) can be made of any material that can withstand the processing temperatures and pressures when forming the variable taper component  30 . As such, a tool steel is contemplated in one form, although other materials such as ceramics (e.g. alumina, carbides graphite, magnetic, nitrides, non-oxide, oxide, sand, silica, zirconia, among others), composites, other metals (e.g. aluminum-based, iron-based, magnetic, nickel-based, titanium-based, among others), polymers and combinations of these materials may comprise the master insert, interlocking pieces, tapered inner sleeve, and outer mandrel. Moreover, different materials can be used for each of the master insert  60 , interlocking pieces  80 , tapered inner sleeve  100 , and outer mandrel  120  while remaining within the scope of the present disclosure. 
     Referring now to  FIG. 9 , alternative forms of locking features  64  of a master insert  60  are shown. It should be understood that these locking features  64 , and combinations thereof, may also be used with the locking features  84  of the interlocking pieces  80  while remaining within the scope of the present disclosure. In the first form, the locking feature  64  is a linear tab, while the receiving feature  86  (shown in  FIG. 4A ) is a linear slot. In an alternate form, the locking feature  64 ′ is a T-shaped tab, while the receiving feature (not shown) is a T-shaped slot. In yet another form, the locking features may be magnetic, whether physical interlocking or exclusively magnetically interlocking. It should be understood that these exemplary variations, among others, may be employed to interlock the components of the inner mandrel  40  while remaining within the scope of the present disclosure. 
     Unless otherwise expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other characteristics are to be understood as modified by the word “about” or “approximately” in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice; material, manufacturing, and assembly tolerances; and testing capability. 
     As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.” 
     The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.