Abstract:
A nozzle retaining clip for retaining a nozzle assembly with a material distributing manifold comprises an attachment portion for attaching the clip to the manifold and an engagement portion for engaging a nozzle assembly abutted to the manifold. Two clips located to engage opposite sides of a nozzle assembly abutted to the manifold member are effective to retain the nozzle assembly and to allow the manifold and nozzle assembly to move relative to one another while the clips and nozzle assembly remain engaged. A first alternative clip achieves only surface contact and a second alternative clip allows protrusion of a segment of a nozzle assembly periphery through the clip. Advantageously, the clip comprises at least one locating tap to restrain movement of the clip relative to a manifold. An apparatus for injection molding comprises a manifold and nozzle assembly construction comprising clips in accordance with the invention.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to injection molding. In particular, this invention pertains to manifold and nozzle assembly constructions for facilitating assembly of mold components comprising a mold assembly. 
     2. Description of Related Art 
     It is known to provide injection molding equipment comprising constructions of a manifold and associated nozzle assemblies wherein nozzle assemblies are attached to a material distributing manifold to facilitate installation of the manifold and nozzle assembly in a mold assembly. As is known, components of a mold assembly include members to receive a manifold and members to receive at least a portion of at least one nozzle assembly and that further comprise a mold die element that defines at least a portion of a mold cavity.  FIGS. 1   a  and  1   b  illustrate an example of a manifold and nozzle assembly construction and portions of a mold component in which such constructions are installed. Considering  FIG. 1   b , plates MP 1  and MP 2  define a space in which a manifold block MB, comprising manifold and nozzle assembly construction MNA ( FIG. 1   a ), is received. A mold retainer plate MP 3  supports a mold die block MD comprising at least a portion of a mold cavity such as cavity space MC. Each nozzle assembly, such as nozzle assemblies NA 1  and NA 2 , is partially received in a recess such as nozzle well WN in a mold die block such as mold die block MD. 
     Continuing with reference to  FIGS. 1   a  and  1   b , nozzle assemblies NA 1  and NA 2  are retained with manifold block MB by threaded retainers such as retaining nut RN 1  ( FIG. 1   b ). Retaining nut RN 1  is at least partially received in nozzle receiving bore MR of manifold block MB and retains nozzle assembly NA 1  so that sealing contact is achieved between the inlet end of nozzle assembly NA 1  and the ceiling of receiving bore MR. Desired sealing contact of the nozzle inlet end face with the ceiling of nozzle receiving bore MR is achieved by compressive forces exerted by the threaded connection of retaining nut RN 1  with manifold block MB. As shown in  FIG. 1   b , a passage PM within manifold block MB is in fluid communication with a nozzle passage PN (shown in phantom (dashed lines)) through a nozzle assembly NA 1 . The outlet of nozzle passage PN is in fluid communication with mold cavity space MC through an opening (so-called “gate” MG) in mold die block MD. In manifold and nozzle assembly constructions comprising more than one nozzle assembly, a connecting passage, such as passage PC, conveys material from manifold passage PM to nozzle passage PN. Nozzle assemblies such as nozzle assembly NA 1  advantageously comprise tip elements such as nozzle tip member NT having a passage there-through in fluid communication with nozzle passage PN and from which material exits the nozzle assembly. Sealing contact is made between nozzle assembly NA 1  and nozzle well WN proximate the nozzle tip to prevent material from exiting the mold die block through nozzle well WN. 
     It is to be understood that flowable condition of material within manifold block MB and nozzle assembly NA 1  is achieved by maintaining manifold block MB and nozzle assembly NA 1  at suitably elevated temperatures. To that end, heating elements may be provided such as nozzle heater NH surrounding the elongated shank of nozzle assembly NA 1 . Likewise, heating elements may be provided in manifold block MB. Heat transfer from manifold block MB and nozzle assembly NA 1  to surrounding members is reduced by minimizing contact therebetween. Hence, manifold block MB is supported between plates MP 1  and MP 2  with spacers (not shown) and nozzle assembly NA 1  is spaced apart from sidewalls of nozzle well WN by precisely locating nozzle receiving bores MR in manifold block MB. 
     Sealing contact between nozzle assembly NA 1  and mold members is dependent, at least in part, on alignment of nozzle assembly NA 1  relative to the mold members. In particular, substantial parallelism between the face of the nozzle end surrounding the nozzle inlet and the ceiling of receiving bore MR surrounding the outlet of connecting passage PC is effective to maintain sealing contact therebetween when nozzle assembly NA 1  is abutted to the ceiling of receiving bore MR. Likewise, desired sealing contact between nozzle assembly NA 1  and nozzle well WN is achieved by abutment of an element of the nozzle assembly, such as a nozzle flange NF. Provided the longitudinal centerline of nozzle assembly NA 1  is substantially parallel to the longitudinal centerline of nozzle well WN, sealing contact between nozzle flange NF and the sidewall of nozzle well WN will be realized. 
     As indicated, an advantage of manifold and nozzle assembly constructions illustrated in  FIGS. 1   a  and  1   b  is that they are susceptible of pre-assembly to facilitate installation in mold components. A disadvantage of such constructions arises in consequence of thermal expansion in use that can result in forces that tend to cause tilting of nozzle assemblies relative to other mold component members. By virtue of deliberate thermal isolation of manifold and nozzle assembly construction MNA, manifold block MB will undergo different thermal expansion than other members of the mold component as temperature of the mold component is raised to a desired operating temperature. Considering the arrangement illustrated in  FIG. 1   b , it will be understood that by virtue of attachment of nozzle assembly NA 1  to manifold block MB by retaining nut RN 1 , nozzle assembly NA 1  is fixed in position relative to manifold block MB. Furthermore, by virtue of contact of nozzle sealing flange NF with the sidewall of nozzle well WN, nozzle assembly NA 1  is fixed in position relative to mold die bock MD. Under circumstances where thermal expansion of manifold block MB effects a change of position of receiving bore MR, (the change of position being illustrated in phantom (dashed lines) in  FIG. 1   b ) a transverse force EF is applied to the inlet end of nozzle assembly NA 1 . Unless there is a corresponding change of position of nozzle well WN, a corresponding force will not be applied to nozzle sealing flange NF. Consequently, nozzle assembly NA 1  is subjected to a moment (unequal forces applied to points on opposite sides of the longitudinal center of the nozzle assembly) that tends to tilt nozzle assembly NA 1  relative to the longitudinal centerlines of manifold receiving bore MR and of nozzle well WN, such tilt being represented by angles AA and BB, respectively, of  FIG. 1   b . Such tilt can result in loss of sealing contact between nozzle assembly NA 1  and one or both of manifold block MB and nozzle well WN. 
     In constructions where the extent of thermal expansion driven tilting of nozzle assemblies relative to other mold members can so impair sealing contact that operation is adversely affected, it is known to arrange the manifold and associated nozzle assemblies to permit relative movement therebetween. Such known arrangements rely on abutting contact of the inlet end face of a nozzle assembly with an opposed face of a manifold block so that the manifold block can slide relative to the nozzle assembly while desired sealing contact is maintained. Compressive force holds the nozzle assembly in abutting contact with the manifold block so as to maintain sealing contact under normal operating pressure of material being conveyed from the manifold to the nozzle. The compressive forces are achieved by means that engage only the nozzle assemblies or manifold block rather than by means engaging both the nozzle assemblies and the manifold. A disadvantage of such known constructions arises from the lack of attachment of nozzle assemblies with manifolds negating pre-assembly of such constructions to facilitate installation of the construction in a mold assembly. Hence, there remains a need to provide manifold and nozzle assembly constructions that allow for pre-assembly thereof to facilitate installation in mold members and that permit relative movement of nozzle assemblies and the associated manifold in use. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a clip for retaining a nozzle assembly with a material distributing manifold to facilitate installation of a pre-assembled construction of a manifold and nozzle assembly in a mold assembly component, wherein a pair of clips are located so that respective engagement portions thereof engage opposite sides of a nozzle assembly so as to retain the nozzle assembly with the manifold member in a manner that permits relative movement of the manifold and nozzle assembly. 
     It is a further object of the present invention to provide a clip for retaining a nozzle assembly with a material distributing manifold to facilitate installation of a pre-assembled construction of a manifold and nozzle assembly in a mold assembly component wherein the clip comprises an attachment portion and an engagement portion oblique to the attachment portion and at least the engagement portion is sufficiently resilient so that with a pair of clips attached to a manifold member so as to engage opposite sides of a nozzle assembly, elastic displacement of the engagement portions to accommodate the nozzle assembly therebetween produces sufficient force to retain the nozzle assembly with the manifold member. 
     It is a further object of the present invention to provide an apparatus for injection molding comprising a material distributing manifold, at least one nozzle assembly and at least one pair of nozzle retaining clips for retaining at least one nozzle assembly with the manifold, a nozzle assembly being held in abutting contact with the manifold by the pair of nozzle retaining clips so that the nozzle assembly and manifold can move relative to each other while abutted and while the pair of clips continue to engage the nozzle assembly. 
     Further objects and advantages of the invention shall be made apparent from the accompanying drawings and the following description thereof. 
     In accordance with the aforesaid objects the present invention provides a nozzle retaining clip for retaining a nozzle assembly with a material distributing manifold to facilitate installation of a pre-assembled construction of a manifold and nozzle assembly in a mold assembly component, the manifold comprising a manifold member comprising a manifold passage for conveying material in a flowable condition, each nozzle assembly comprising a nozzle passage there-through for conveying material from the manifold passage to a mold cavity, the nozzle retaining clip comprising an attachment portion by which the clip is attached to the manifold member, an engagement portion for engaging a nozzle assembly abutted to the manifold member and at least one locating tab for contacting a surface of the manifold member so as to restrain movement of the attachment portion relative to the manifold member, wherein a pair of nozzle retaining clips are locatable so that the respective engagement portions thereof engage opposite sides of a nozzle assembly abutted to the manifold member so as to allow the manifold member and nozzle assembly to move relative to one another while the engagement portions of the clips remain engaged with the nozzle assembly. Alternative designs for nozzle retaining clips in accordance with the invention contemplate engagement of the clips and a nozzle assembly by surface contact alone and, alternatively, by protrusion of a segment of the periphery of a nozzle assembly through the clips. An apparatus for injection molding comprises a manifold and nozzle assembly construction comprising clips in accordance with the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1   a  and  1   b  illustrate known manifold and nozzle assembly constructions where nozzle assemblies are attached to a manifold by treaded connections. 
         FIG. 2  is a partial cross sectional view of an injection molding clamp and injection unit for molding articles from material supplied from the injection unit to cavities defined by members of a mold assembly. 
         FIG. 3  is a three dimensional view of a manifold and nozzle assembly construction in accordance with the invention. 
         FIGS. 4   a  and  4   b  are partial cross sectional views depicting an arrangement of a manifold, nozzle assembly and retention device in accordance with the invention. 
         FIGS. 5   a  and  5   b  illustrate a first alternative nozzle retaining clip in accordance with the invention and its engagement with the head end of a nozzle assembly. 
         FIGS. 6   a  and  6   b  illustrate a second alternative nozzle retaining clip in accordance with the invention and its engagement with the head end of a nozzle assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention shall be illustrated with reference to preferred embodiments which shall be described in detail. It is not the intention of applicants that the invention be limited to the preferred embodiments. 
     Referring to  FIG. 2 , a mold assembly  10  comprises a primary core component  12  and a primary cavity component  14 . Primary core component  12  is supported by movable platen  16 , and primary cavity component  14  is supported by stationary platen  18 . Mold assembly  10  has parting plane (illustrated by line  20 ) and the primary cavity component  14  and primary core component  12  define at least one mold cavity (not shown) when the mold components are engaged, i.e., when the mold assembly is “closed” so that components  12  and  14  abut at the parting plane. Articles are produced by: (i) filling the mold cavities with material in flowable condition, so-called “melt”; (ii) allowing the melt to solidify; and, (iii) with the mold components separated, i.e., “open”, removing the molded articles. Movable platen  16  and stationary platen  18  comprise a press unit of an injection molding machine. Movable platen  16  is moved to open and close mold assembly  10 , an open position of movable platen  16  being shown in phantom (dashed line) in  FIG. 2 . Melt is injected to mold assembly  10  from a nozzle such as nozzle  19  of an injection unit  22 , the nozzle passing through an opening of stationary platen  18  as illustrated by the cross-section thereof shown in  FIG. 2 . Distribution of melt to the mold cavities is advantageously effected by a configuration of conduits and nozzles (not shown in  FIG. 2 ) receiving melt from nozzle  19  and conveying melt through the nozzles to the mold cavities. Primary core component  12  may advantageously comprise a sub-assembly of members providing support for a core mold die as well as a mechanism and components to dislodge molded articles from the core mold die. Primary cavity component  14  may advantageously comprise a sub-assembly of members providing support for a cavity mold die as well as constructions for conveying melt from injection unit  22  to the mold cavities. Such constructions may advantageously comprise one or more manifold and nozzle assembly constructions effective to distribute melt in a flowable condition at pressures adequate to achieve expeditious and complete filling of the mold cavities. 
     A portion of a manifold and nozzle assembly construction  30  in accordance with the invention is shown in  FIGS. 3 and 4   a . Advantageously, manifold and nozzle assembly construction  30  is received within a mold assembly component such as mold assembly component  14  of  FIG. 2 . As illustrated in  FIG. 4   a , the mold assembly component comprises members including a manifold retainer plate  32 , a nozzle retainer plate  34 , a mold die retainer plate  37  and a mold die block  39 . Manifold and nozzle assembly construction  30  comprises a manifold member such as manifold block  36 , and at least one nozzle assembly such as nozzle assembly  38 . Manifold and nozzle assembly construction  30  is received in the mold assembly component so that manifold block  36  is supported between manifold retainer plate  32  and nozzle retainer plate  34  so as to minimize contact between manifold block  36  and plates  32  and  34 . Nozzle assemblies associated with manifold block  36 , such as nozzle assembly  38 , are supported in nozzle retainer plate  32  to minimize contact of each nozzle assembly with nozzle retainer plate  32 . The outlet of each nozzle assembly is received in an opening, a so-called “well”,  39   a  in a mold die block such mold die block  39 . Well  39   a  is in fluid communication with a mold cavity space such as cavity space MC. Advantageously, heating elements (not shown) are fitted to manifold block  36  to supply heat required to maintain material within manifold block  36  in a flowable condition. Likewise, a heating element such as heater  52  comprising nozzle assembly  38  is effective to maintain melt within nozzle assembly  38  in a flowable condition. 
     Continuing with reference to  FIGS. 3 and 4   a , nozzle assemblies such as nozzle assembly  38  are held in abutting contact with manifold block  36  by compressive forces applied through, advantageously, a collar such as collar  70  that surrounds a portion of the head end of the nozzle assembly and engages an inlet end flange thereof such as flange  51 . As best seen in  FIGS. 4   a  and  4   b  an anti-rotation clip  72  is interposed between collar  70  and manifold block  36 . Anti-rotation clip  72  engages a flat formed in the head end of nozzle body  50  so that rotation of nozzle body  50  around the longitudinal axis thereof rotates anti-rotation clip  72 . A projection of anti-rotation clip  72  engages a dowel attached to manifold block  36  such as dowel  74  ( FIG. 4   b ). By virtue of engagement of anti-rotation clip  72  with dowel  74 , rotation of nozzle assembly  38  is prevented. Anti-rotation clip  72  facilitates installation and removal of threadably connected nozzle tips into nozzle assembly  38  with the nozzle assembly installed in a manifold and nozzle assembly construction such as construction  30 . Anti-rotation clip  72  is shown interposed between collar  70  and inlet end flange  51  of nozzle body  50 . Alternatively, where a nozzle body has an inlet end flange spaced from the inlet end face, an anti-rotation clip may be interposed between that inlet end flange and manifold block  36 . As seen in  FIGS. 3 and 4   b , a locating dowel such as locating dowel  76  is attached to manifold block  36  to establish a locating limit for placement of a nozzle assembly relative to the outlet of the manifold passage. Locating dowel  76  is an aid for assembly of a manifold and nozzle assembly construction. As will be understood from the showing of  FIG. 4   b , locating dowel  76  will be displaced away from nozzle assembly  38  with thermal expansion of manifold block  36  (change of position shown in phantom (dashed lines) in  FIG. 4   b ). 
     Continuing with references to  FIGS. 3 ,  4   a  and  4   b , collar  70  is illustrated as a removable collar. Collars such as collar  70  may, alternatively, comprise an integrated element of the head end of a nozzle body. As seen in  FIGS. 3 ,  4   a  and  4   b , collar  70  is received in a stepped bore  35  through nozzle retainer plate  34  and abuts an internal shoulder thereof. By virtue of spacing between the interior step of bore  35  and the opposed face of manifold block  36 , collar  70  is elastically compressed in consequence of abutment of nozzle assembly  38  with manifold block  36 . Collar  70  exerts a compressive force on nozzle assembly  38  in the direction of manifold block  36  according to the extent of elastic compression of collar  70 . That force is sufficient to maintain sealing contact between the inlet end face of nozzle assembly  38  and the abutting face of manifold block  36  under normal operating conditions. The longitudinal centerline of each stepped bore  35  is substantially aligned with the longitudinal centerline of a well  39   a  so that the longitudinal centerline of each nozzle assembly supported by nozzle retainer plate  32  is substantially aligned with the longitudinal centerline of a well  39   a . Advantageously, collar  70  locates nozzle body  50  within bore  35  so that nozzle body  50  is spaced from the internal sidewalls of bore  35 , whereby there is no direct contact between nozzle body  50  and the interior of bore  35 . Such spacing reduces heat transfer from nozzle assembly  38  to nozzle retainer plate  34  aiding maintenance of a flowable condition of material within nozzle assembly  38 . 
     Manifold block  36  receives melt from injection unit  22  and conveys melt through one or more internal manifold passages such as manifold passage  40  in fluid communication with nozzle assemblies abutted to manifold block  36 . In constructions where more than one nozzle assembly is associated with a single manifold passage  40 , communicating passages, such as communicating passage  42  convey melt from the manifold passage through a communicating passage outlet  42   a  to a nozzle assembly inlet. Nozzle assembly  38  advantageously comprises an elongated cylindrical body such as nozzle body  50  through which a melt passage such as nozzle passage  54  communicates with a nozzle inlet  56  and a nozzle outlet  58 . As a further advantage, an exit tip such as needle tip  60  is fitted to the outlet end of nozzle body  50  and comprises a tip passage  62  in fluid communication with nozzle passage  54  and tip outlet  64 . Advantageously, needle tip  60  is retained in the outlet end of nozzle body  50  by a tip retainer such as tip retaining nut  66  threadably engaged with nozzle body  50 . Alternative tip arrangements are known, including tip members that are directly threadably connected to nozzle bodies. Melt flows from the nozzle assemblies such as nozzle assembly  38  through mold cavity opening  39   b , a so called “gate”, into cavity space MC. Sealing contact is maintained between the forward end of nozzle assembly  38  and sidewalls of well  39   a  to prevent material from escaping from well  39   a . As illustrated in  FIG. 4   a , that sealing contact is effected by contact of a protruding flange  66   a  of tip retaining nut  66  with sidewalls of well  39   a.    
     To facilitate pre-installation assembly of a manifold and nozzle assembly construction that permits relative movement of the nozzle assemblies and associated manifold with expected thermal expansion, the invention provides retaining means for retaining nozzle assemblies with a manifold member such as manifold block  36 . In particular, a pair of nozzle retaining clips, such as retaining clips  57  and  59  are attached to manifold block  36  and located to engage the head end of a nozzle assembly such as nozzle assembly  38 . The clips  57  and  59  need not be effective for maintaining sealing contact between a manifold block and nozzle assembly at normal operating pressures since sealing contact is expected to be maintained by compressive force effected by, for example, a collar such as collar  70 . Conversely, clips  57  and  59  do not interfere with intended operation of manifold and nozzle assembly construction  30  in any manner or with relative movement of a manifold block and abutted nozzle assemblies with thermal expansion. Therefore, clips  57  and  59  are left in place after installation of manifold and nozzle assembly construction  30  in a mold component. 
     Permitted relative movement of a manifold member and associated nozzle assemblies accommodated by nozzle retaining clips in accordance with the invention shall be described with reference to  FIG. 4   b . Nozzle assembly  38  is held in a fixed position relative to die block  39  in consequence of contact between flange  66   a  of tip retainer  66  and the sidewall of nozzle well  39   a . The inlet end of nozzle assembly  38  is held in abutting contact with manifold block  36  by compressive forces exerted on nozzle assembly  38  by collar  70 . Thermal expansion occurs in all directions according to the coefficient of thermal expansion of the material of manifold block  36 . In an arrangement where communicating passages  42  are located in the center of width of manifold block  36 , thermal expansion of manifold block  36  will not alter the position of communicating passages  42  relative to that center of width. Conversely, with communicating passages spaced along the length of manifold block  36 , thermal expansion of the length of manifold block  36  will effect a change of position of communicating passages as indicated in phantom (dashed lines) in  FIG. 4   b . The magnitude of the change of position is designated “Δp” as represented by the change of position of the longitudinal centerline of communicating passage  42  in  FIG. 4   b . It is to be expected that any change of position of nozzle wells  39   a  with thermal expansion of other members of a mold assembly component will not be of magnitude Δp. Consequently, with nozzle assembly  38  fixed in location in nozzle well  39   a , thermal expansion of manifold block  36  will result in movement of manifold block  36 , and communicating passage  42 , relative to nozzle assembly  38 . 
     To accommodate expected changes of position of communicating passages relative to nozzle assemblies, manifold and nozzle assembly construction  30  is pre-assembled to locate the longitudinal axes of nozzle assemblies to be aligned with the longitudinal centerlines of wells  39   a . Locating dowels such as locating dowel  76  facilitate correct location of nozzle assemblies along the length of manifold block  36 . The longitudinal axes of the nozzle assemblies are spaced apart from the longitudinal centerlines of communicating passages  42  at the temperature of pre-assembly by approximately the anticipated change of position Δp upon thermal expansion. When installed, nozzle assemblies of manifold and nozzle assembly construction  30  will be precisely located within stepped bores  35  of nozzle retainer plate  34  and within wells  39   a  of mold die  39 . Upon manifold and nozzle assembly construction  30  reaching operating temperature, the position of communicating passages  42  will have changed to align the longitudinal centerlines thereof with the longitudinal centerlines of wells  39   a . Because nozzle assemblies are held in fixed location relative to wells  39   a , the longitudinal centerlines of the nozzle assemblies will remain substantially aligned with the longitudinal centerlines of wells  39   a , whereby, at operating temperature, the inlets  56  ( FIG. 4   a ) of nozzle passages  54  will be substantially concentric with the outlets of communicating passages  42 . The contemplated relative movement is effected by sliding of the face of manifold block  36  against the abutting inlet end faces of nozzle assemblies. 
     A first alternative design for retaining clips such as retaining clips  57  and  59  shall be described with reference to  FIGS. 5   a  and  5   b . It is to be born in mind that both clips of each pair of retaining clips will conform to a single design. Referring to  FIG. 5   a , retainer clip member  80  comprises attachment portion  82 , engagement portion  84  and transition region  86  joining attachment portion  82  with engagement portion  84 . Attachment portion  82  advantageously comprises a hole such as through-hole  82   a  through which the shank of a fastener passes to attach clip member  80  to a side of a manifold block such as manifold block  36  (shown in phantom (dashed) in  FIG. 5   b ). Engagement portion  84  comprises convex contact segment  83  establishing a line (LC) for contact with the head end of a nozzle assembly. Engagement portion  84  is oblique to attachment portion  82 , the angle of inclination CC between engagement portion  84  and attachment portion  82  being established by transition region  86 . A locating tab  86   a  is located in transition region  86  so as to abut the lower face of a manifold block when clip member  80  is attached to a manifold block side. When so abutted, locating tab  86   a  is effective to prevent rotation of clip  80  around the longitudinal centerline of a fastener shank passing through hole  82   a . The angle of inclination CC of engagement portion  84  to attachment portion  82  together with the length LA of engagement portion  84  determines the location of contact line LC relative to the location of locating tab  86   a  and hence relative to the lower face of a manifold block. As best seen in  FIG. 5   b , contact segment  83  of the clip design of  FIG. 5   a  contacts collar  70  of a nozzle assembly in a transition region between a top cylindrical segment abutting a flange  51  of a nozzle body and a tapered segment terminating proximate the lower end of collar  70 . As contact segment  83  presents a convex surface facing a nozzle assembly, contact line LC determines the location of contact of contact segment  83  with, for example, collar  70 . As best seen in  FIG. 5   b , the aforesaid transition region of collar  70  presents a curved contour facing contact segment  83 . In consequence of contact of the facing curved surfaces of the retainer clip member and collar, point contact is established between contact segment  83  and collar  70 . Advantageously, clip member  80  is somewhat resilient so that with a pair of retaining clips engaging a nozzle assembly and attached to opposite sides of a manifold block, the engagement portions  84  are elastically displaced and exert sufficient force on a nozzle assembly at opposed points of contact to overcome gravitational force acting on a nozzle assembly so that the forces exerted solely by the clips are effective to retain the nozzle assembly with the manifold block. 
     A second alternative design for retaining clips such as retaining clips  57  and  59  shall be described with reference to  FIGS. 6   a  and  6   b . Common elements of the designs depicted in  FIGS. 5   a  and  6   a  are designated by the same reference numbers. Referring to  FIG. 6   a , a pair of locating tabs  86   b  and  86   c  are located at clip peripheral edges of the transition region  86  and abut the lower face of a manifold block when clip member  80  of  FIG. 6   a  is attached to a manifold block side. Locating tabs  86   b  and  86   c  function in the same manner as locating tab  86   a  of  FIG. 5   a  to prevent rotation of clip  80 . An open slot  83   a  through contact segment  83  permits protrusion of a portion of a periphery of a mold assembly head end as best illustrated in  FIG. 6   b . By virtue of the magnitude of angle of inclination CC and the length LA of engagement portion  84 , open slot  83   a  is advantageously located relative to locating tabs  86   b  and  86   c  (and hence, to the lower face of a manifold block) so as to engage a peripheral portion of a top cylindrical segment of a collar  70  of a nozzle assembly. With a pair of retaining clips  80  of  FIG. 6   a  engaging a nozzle assembly, the head end is “captured” by open slots  83   a  to resist displacement of the nozzle assembly relative to the manifold block across the width of the retaining clips. Hence, use of retaining clips in accordance with the design of  FIG. 6   a  provides increased resistance to displacement of nozzle assemblies of a manifold and nozzle assembly construction as might otherwise occur in the course of handling and installation of that construction. 
     Although the preferred embodiments illustrate nozzle assemblies comprising separate collars, an integral collar element comprising the so-called “head” of a nozzle body is recognized as an alternative construction suitable for use with clips in accordance with the invention. It is only necessary that the head end of a nozzle assembly comprise external surfaces suitable for engagement by a pair of nozzle retaining clips disposed to engage opposite sides of the nozzle assembly so as to be effective to retain the nozzle assembly with a manifold member.