Abstract:
Clam shell-type blow mold apparatus has a pair of opposed upper mold halves that cooperate to define a partial blow cavity. A one-piece bottom mold portion that completes the blow cavity is locked up against the top mold portion by a locking assembly to prevent separation of the bottom mold portion from the top mold portion during the high pressure blow cycle. The locking assembly includes a support ring for the bottom mold portion that has a number of radially outwardly projecting male lugs adapted to fit into female receiving notches on opposed halves of a lock ring on the upper mold portion. Individual ledges at the bottoms of the notches underlie the lugs of the support ring when the mold halves are fully closed so as to preclude separation of the support ring, and thus the bottom mold portion, from the lock ring and the upper mold portion. The notches in the support ring are interposed between pairs of bolt holes in the lock ring.

Description:
TECHNICAL FIELD 
   This invention relates to equipment used in the blow molding of thermoplastic articles, such as bottles. More particularly, it relates to improvements in clam shell-type blow mold apparatus that utilizes a pair of opposed mold halves and a cooperating bottom mold portion to define the blow cavity for the article. The invention especially pertains to an improved way of locking the bottom mold portion against separation from the upper portion of the mold during the blow cycle. 
   BACKGROUND AND SUMMARY 
   Blow molding machines that use clam shell-type mold apparatus to form the upper portion of a blow mold cavity and a cooperating bottom mold portion to complete the cavity are well known in the art. See, for example, U.S. Pat. No. 5,968,560 relating to a blow molding device for producing thermoplastic containers; U.S. Pat. No. 6,447,281 relating to a blow mold shell and shell holder assembly for a blow-molding machine; and U.S. Pat. No. 5,326,250 relating to opening and closing mechanism for a portfolio blow and blow-stretch mold. 
   Machines of this type operate at high speeds to maximize production throughput. As the opposing clam shell halves of the mold apparatus swing closed at the blow station during each blow cycle, push-up mechanism at the station below the clam shell halves must elevate a bottom portion of the mold up into proper position between the clam shell halves just before they close. Once closed, the clam shell halves grip and retain the bottom blow mold portion against separation from the rest of the mold during the high pressure blow cycle. Lock ring halves carried on the upper mold halves match up with complemental structure on a ring carried on the push up mechanism to retain the push up mechanism and thus the bottom mold portion in place when the upper mold halves fully close. 
   Obviously, the timing between the upper mold halves and the push-up mechanism is critical. If the timing is imperfect for any reason, the mold halves may close too soon and the mold surfaces of the bottom mold portion may be damaged by the lock ring segments as they prematurely enter the path of travel of the upwardly moving bottom mold portion. 
   The present invention provides a lock up arrangement in which the lock ring segments on the upper mold halves are configured to avoid encroachment into the path of travel of the lower mold portion even when the timing is imperfect between the upper mold halves and the push-up mechanism. A bottom mold portion that might be damaged by out-of-time lock ring segments of conventional design will be spared damage by the inventive segments due to the fact that they are configured to always remain out of the path of travel of the bottom mold portion even if the upper mold halves close prematurely. 
   To this end, the present invention contemplates lock ring segments that are bolted to the bottom edge of upper mold halves as in the past. However, instead of the prior art approach wherein an inwardly projecting annular ledge on the segments protrudes into the path of travel of the bottom mold portion, the new lock ring segments are each provided with one or more outwardly recessed notches that present ledges located outside the profile of the bottom mold portion when the mold halves are closed. In turn, one or more outwardly projecting lugs on the ring that supports the bottom mold portion are configured to slip into the notches of the lock ring segments and onto the support ledges thereof when the mold halves close about the bottom mold portion and push-up mechanism. The lugs of the support ring are thus prevented by the ledges from moving away from the upper mold portion. The notches and their ledges are located between respective pairs of bolt locations on the lock ring segments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top plan view of a prior art clam shell-type mold apparatus in combination with opening and closing mechanism for that apparatus, the clam shell halves of the mold apparatus being illustrated in a closed position; 
       FIG. 1   a  shows the prior art apparatus and mechanism of  FIG. 1  in an opened position; 
       FIG. 2  is a vertical cross sectional view of the prior art mold apparatus of  FIG. 1  taken substantially along line  2 - 2  of  FIG. 1 , the lower mold portion being illustrated in its raised position cooperating with the upper mold halves to define a complete blow cavity; 
       FIG. 2   a  is a view of the prior art apparatus similar to  FIG. 2  but showing the lower mold portion in a withdrawn or lowered position; 
       FIG. 3  is an enlarged, exploded, isometric view of the prior art lock ring and support ring in combination with a bottom mold portion; 
       FIG. 4  is a vertical cross section view of mold apparatus incorporating a lock up arrangement in accordance with the principles of the present invention and showing the lower mold portion elevated into its fully raised position for cooperating with the upper mold halves in forming the internal blow cavity; 
       FIG. 4   a  is a vertical cross sectional view of the mold apparatus of  FIG. 4  but showing the lower mold portion withdrawn down out of the upper mold portion; 
       FIG. 5  is an enlarged, exploded isometric view of the lock ring and support ring of the present invention in conjunction with a bottom mold portion of a blow mold; and 
       FIG. 6  is an exploded top plan view of the lock ring and support ring of the present invention illustrating details of construction. 
   

   DETAILED DESCRIPTION 
   The present invention is susceptible of embodiment in many different forms. While the drawings illustrate and the specification describes certain preferred embodiments of the invention, it is to be understood that such disclosure is by way of example only. There is no intent to limit the principles of the present invention to the particular disclosed embodiments. 
   Prior Art Construction 
   The prior art mold apparatus  10  in  FIGS. 1 and 1   a  is opened and closed by opening and closing mechanism  12  which may take the form of that disclosed in U.S. Pat. Nos. 5,326,250 and 6,447,281. Accordingly, the disclosures of the &#39;250 and &#39;281 patents are hereby incorporated by reference in their entirety into the present specification. Mold apparatus  10  includes a pair of carrier halves  14  and  16  that are pivotally interconnected by a pivot  18  for movement by mechanism  12  between a closed position in  FIG. 1  and an open position in  FIG. 1   a . Carrier halves  14 ,  16  respectively support holder halves  20  and  22  which, in turn, support mold halves  24  and  26 . This construction is similar to that disclosed in U.S. Pat. No. 5,968,560, which patent is hereby incorporated by reference into the present specification. 
   As illustrated in  FIGS. 2 and 2   a , mold halves  24 ,  26  cooperate to partially define an internal mold cavity  28  when the mold halves  24 ,  26  are closed. Mold halves  24 ,  26  thus jointly present an upper mold portion which may be identified by the numeral  30 . A lower mold portion  32  is generally cup-shaped to present an upwardly facing cavity  34  that cooperates with cavity  28  to define a complete blow cavity for a bottle or other article to be blown when lower mold portion  32  is in its raised position as illustrated in  FIG. 2 . 
   Upper mold portion  30  is open at its bottom end so as to fully receive lower mold portion  32  when lower mold portion  32  is fully raised. Lower mold portion  32  fits up into a recess  36  in the bottom end of upper mold portion  30 , such recess  36  having a downwardly facing, annular shoulder  38  that is abuttingly engaged by the top edge  40  of bottom mold portion  32  when portion  32  is fully raised. Bottom mold portion  32  is raised and lowered between the positions of  FIG. 2  and  FIG. 2   a  by push-up mechanism broadly denoted by the numeral  42 , as well understood by those skilled in the art. 
   Bottom portion  32  is maintained in its raised position not only by push-up mechanism  42 , but also by a locking assembly  44  that becomes effective for such purpose when mold apparatus  10  is fully closed. Locking assembly  44  includes as its primary components an upper lock ring  46  that is attached to the bottom edge  48  of upper mold portion  30  and a support ring  50  that rests upon push-up mechanism  42 . Lock ring  46 , as shown in detail in  FIG. 3 , comprises a pair of semi-circular halves  51  and  52  that are designed to be disposed in horizontally opposed relationship to one another when mold assembly  10  is closed so as to effectively form a complete ring. The two halves  51 ,  52  are identical to one another, each including a radially inwardly projecting ledge  54  having an upwardly facing surface  56 . Each half  51 ,  52  further includes a radially outwardly disposed, upright wall portion  58  having four upright bolt holes  60  passing therethrough. Bolt holes  60  receive corresponding bolts  62  ( FIGS. 2 and 2   a ) that threadably secure halves  51 ,  52  to bottom edge  48  of upper mold portion  30 . 
   On the other hand, support ring  50  is a one-piece component of generally cylindrical and annular overall configuration. Among other things, support ring  50  has a continuous annular lip  64  about its upper extremity that overhangs and projects outwardly beyond a smaller diameter main body portion  66 . The outer diameter of lip  64  is slightly less than the inner diameter of wall portion  58  of lock ring  46  when mold apparatus  10  is closed such that lip  64  can be fully surrounded by wall portion  58  and rest upon ledges  54  of lock ring halves  51 ,  52 . Thus, support ring  50  is precluded from downward movement out of lock ring  46 . 
   Bottom mold portion  32  has an undercut lower portion that presents a downwardly facing, annular shoulder  68  supported by the upwardly facing top surface of lip  64 . In addition, support ring  50  has a stepped bore  70  therethrough presenting a larger diameter upper portion and a smaller diameter lower portion that cooperatively define an upwardly facing, annular seat  72  underlying the bottom portion  32  to provide additional support. 
   New Locking Assembly 
     FIGS. 4 ,  4   a ,  5  and  6  disclose a new locking assembly  200  constructed in accordance with the principles of the present invention. With exception of the locking assembly  200 , the mold apparatus of  FIGS. 4-6  is the same as that illustrated in  FIGS. 1-3 . 
   Like locking assembly  44 , locking assembly  200  includes as its primary components a lock ring  202  that fastens to the bottom edge  48  of upper mold portion  30 , and a support ring  204  that rests upon the pedestal of push-up mechanism  42 . Lock ring  200  and support ring  204  are configured differently than lock ring  46  and support ring  50 , however. 
   To this end, lock ring  202  includes a pair of normally horizontally opposed, semi-circular lock ring halves  206  and  208  that are each provided with a plurality of, preferably four, upright bolt holes  210  for receiving corresponding bolts  212  as illustrated in  FIGS. 4 and 4   a . Bolts  212  pass through halves  206  and  208  and are threadably received by corresponding mold halves  24  and  26 . Each lock ring half  206 ,  208  has three circumferentially spaced notches  214 ,  216  and  218  therein which are interspersed between respective pairs of the four bolt holes  210  as illustrated particularly in  FIGS. 5 and 6 . Although it is within the concepts of the present invention to have a single notch in each lock ring half  206 ,  208 , three of such notches are preferred. In a preferred form of the invention, each notch  214 ,  216  and  218  has an open top formed in a top surface  220  of the lock ring half, although the notch could also be formed with a closed top. Each notch  214 ,  216 , and  218  also has a closed bottom that presents an outwardly extending ledge  222 . Each notch further has an upright back wall  224  that is recessed from an interior surface  226  of the lock ring half, as well as a pair of circumferentially spaced sidewalls  228  and  230  that extend upwardly from opposite lateral extremities of ledge  222 . Back wall  224  interconnects sidewalls  228  and  230 . 
   Support ring  204  comprises a generally cylindrical and annular body provided with an upright exterior surface  232  and a horizontal top end surface  234 . Two diametrically opposed sets of lugs  236 ,  238  and  240  project radially outwardly from opposite sides of the body adjacent upper end surface  234 . In the preferred embodiment lugs  236 ,  238  and  240  are flush with top end surface  234  but overhang and project radially outwardly beyond upright exterior surface  232 . Alternatively, the lugs could project above or below top surface  234 . Although each set of diametrically opposed lugs may comprise only a single such lug, in a preferred embodiment, three of such lugs are provided. The number of lugs corresponds to the number of notches provided in lock ring  202 . 
   Each lug  236 ,  238  and  240  is provided with an outermost peripheral edge  244  and a pair of opposite side edges  246  and  248  that extend outwardly from upright surface  232  and connect with outer peripheral edge  244 . In a preferred embodiment, the side edges  246 ,  248  of each intermediate lug  238  project generally radially outwardly while converging slightly as outer edge  244  is approached. On the other hand, with respect to the outer lugs  236  and  240  of each set, the outer edge  248  thereof has a relief bevel incorporated therein so that such edges slope more dramatically than the inner edges  246  thereof. As will be seen, such relief bevel facilitates closure of the mold halves and lock ring halves around support ring  204  during operation. 
   Support ring  204  is provided with a stepped central bore therethrough presenting an upper enlarged diameter bore portion  250  and a lower reduced diameter bore portion  252 . Such two portions  250 ,  252  thus cooperate to define an upwardly facing, annular seat  254  within the interior of support ring  204  that serves as one portion of a support surface for bottom mold portion  32 . Another portion of such support surface is presented by the top end surface  234  of support ring  204 . 
   Operation 
   The manner of use of locking assembly  200  should be apparent from the foregoing detailed description. Therefore, the operation of the apparatus will only be briefly described. Further, although the present invention has been shown and described in connection with a base cup style bottom mold portion  32 , it has equal utility in connection with a bottom mold portion that comprises a standard push up for a champagne base. 
     FIG. 2   a  illustrates the fact that in the prior art, ledges  54  of lock ring halves  51 ,  52  may project into the profile of the bottom mold portion  32 , depending upon the diameter of the particular bottom mold portion involved. In the illustrated example of the prior art, ledges  54  directly overlie the upper edge  40  of bottom mold portion  32  when bottom mold portion  32  is fully withdrawn and upper mold potion  30  is completely closed. Although, ideally, in the prior art the upper mold portion  30  is never closed until bottom mold portion  32  has been fully received within recess  36  as illustrated in  FIG. 2 , in practice there may be times when upper mold portion  30  closes prematurely so as to encroach upon the path of travel of bottom mold portion  32  before bottom mold portion  32  has been fully raised. This can cause serious damage to bottom mold portion  32  and other parts of the machine, as well as significant and costly down time. 
   On the other hand, as illustrated in  FIG. 4   a  in the present invention, using the same size bottom mold portion  32 , no portion of upper lock ring  202  overlies the upper edge  40  of bottom mold portion  32 . Instead, the supporting ledges  222  of lock ring halves  206 ,  208  are disposed radially outside of the profile of bottom mold portion  32 . Consequently, even if top mold portion  30  should happen to close too soon, bottom mold portion  32  will not be engaged and damaged by lock ring  202 . Although lock ring halves  206 ,  208  might improperly engage and damage support ring  204 , that part is easily replaced and contains no delicate mold surfaces. Likewise, lock ring  202  is a relatively inexpensive component that is easily replaced in the event of damage thereto. 
   As shown in  FIG. 4 , when bottom mold portion  204  is fully raised and top mold portion  30  has closed, the male portions of support ring  204 , i.e. lugs  236 ,  238  and  240 , project into the female portions on lock ring  202 , i.e. notches  214 ,  216  and  218 . Lugs  236 ,  238  and  240  thus come into overlying relationship with ledges  222  of notches  214 ,  216  and  218  such that ledges  222  preclude separation of support ring  204 , and thus bottom mold portion  32 , from top mold portion  30 . It will be appreciated that the relieved or beveled portions of side edges  248  on outer lugs  236  and  240  facilitate entry of outer lugs  236  and  240  into their respective notches  214  and  218  as upper mold halves  24  and  26  swing about pivot  18  from their open condition of  FIG. 1   a  to their closed condition of  FIG. 1 . 
   The inventor(s) hereby state(s) his/their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of his/their invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set out in the following claims.