Abstract:
A method of producing a valve includes the steps of: providing a mold comprising a pair of mating mold halves, with each of the mold halves including a mold cavity; providing a valve member-stem unit comprising a valve member of substantially circular cross-section attached to a stem, with the valve member including a passageway extending therethrough in a direction generally normal to the stem; inserting a mold core into the passageway of the valve member-stem unit to form a mold insert assembly; positioning the mold insert assembly within the cavity of a first of the mold halves; positioning a second of the mold halves in adjacent contacting relationship with the first mold half such that the mold insert assembly is located within the mold cavities of the first and second mold halves; injecting a polymeric material into the mold half cavities such that a valve casing forms around and captures the valve member-stem unit; and removing the valve casing, the valve member-stem unit and the mold core from the mold halves. With this method, the casing of the valve can be formed around the ball-stem unit during molding so that the product of the molding steps is ready for use.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to valves, and more particularly to configurations of polymeric valves and methods for constructing them. 
     BACKGROUND OF THE INVENTION 
     Valves are common components of almost any piping system. Although they can be constructed in many different configurations and sizes, a typical valve will include a few basic elements. These include: a valve body that houses internal components within an internal cavity; inlet and outlet pipes leading to and from the valve body; and a valve member that is positioned within the cavity of the valve body. These components are attached such that fluid entering the valve through the inlet pipe is either allowed by the valve member to flow therethrough to the outlet pipe or prevented from such flow based on the position and/or orientation of the valve member within to the valve body. 
     In many instances, the valve member of a valve is a rotatable structure, such as a ball or frustoconical plug, that includes a passageway through which fluid can flow. Rotation of the valve member moves the passageway from an orientation aligned with the inlet and outlet pipes (in which fluid can pass through along a flow axis) and an orientation perpendicular to the flow axis (in which fluid flow is blocked). Often valves that employ a rotating valve member include structures on the valve member (or a component attached thereto, such as the valve stem or adapter) and the body that interact to control the degree of rotation of the valve member. For example, many valves are designed to rotate through only 90 degrees between the open and closed positions, with further rotation being prevented by stops located on the upper portion of the body and the lower surface of the adapter. 
     Valves can be formed of a variety of materials, including both metallic and polymeric materials. Valves formed of polymeric materials can be advantageous in many pipeline environments; they do not rust or corrode, they are typically lighter weight than metal valves, they can be quickly welded into place when the pipelines are also formed of a polymeric material, and often the pieces of the valve (and in particular the valve body) can be molded in an injection or compression molding process rather than requiring extensive machining. 
     Although they enjoy the foregoing advantages, polymeric valves typically require several assembly steps. Of course, the configuration of components formed of polymeric materials is limited by the practicalities of the molding process. As a consequence, if the valve body is injection or compression molded, it is generally molded in two or three separate pieces that are joined in a subsequent welding or fusion operation. The valve member and accompanying stem and adapter (which facilitate rotation of the valve member) are typically formed of separate pieces that are assembled in a subsequent operation (usually after the valve member has been placed inside the valve body pieces and they have been fused). All of these post-molding assembly steps can add cost to the finished valve. Also, it may be desirable that the valve include structure that halts rotation of the valve in desired positions; if so, these structures are also subject to the practical limitations of the molding process. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, it is an object of the present invention to provide a method of constructing a polymeric valve with reduced labor steps and cost. 
     It is also an object of the present invention to provide such a method that produces a polymeric valve that meets or exceeds the performance of currently produced polymeric valves. 
     It is an additional object of the present invention to provide such a method that produces a polymeric valve with stops that desirably limit rotation of the valve. 
     These and other objects are satisfied by the present invention, which is directed to a polymeric valve that can be produced by an insert-molding method. The method comprises the steps of: providing a mold comprising a pair of mating mold halves, with each of the mold halves including a mold cavity; providing a valve member-stem unit comprising a valve member of substantially circular cross-section attached to a stem, with the valve member including a passageway extending therethrough in a direction generally normal to the stem; inserting a mold core into the passageway of the valve member-stem unit to form a mold insert assembly; positioning the mold insert assembly within the cavity of a first of the mold halves; positioning a second of the mold halves in adjacent contacting relationship with the first mold half such that the mold insert assembly is located within the mold cavities of the first and second mold halves; injecting a polymeric material into the mold half cavities such that a valve casing forms around and captures the valve member-stem unit; and removing the valve casing, the valve member-stem unit and the mold core from the mold halves. With this method, the casing of the valve can be formed around the ball-stem unit during molding so that the product of the molding steps is ready for use. 
     As another aspect of the present invention, a preferred valve that can be formed by the aforementioned method comprises: a casing including a body having an internal cavity, an inlet attached to the body and an outlet attached to the body opposite the inlet; and a valve member being positioned at least partially within the cavity and having an outer surface of substantially circular cross-section. The valve member includes a passageway extending diametrically across its substantially circular cross-section and has an axis of rotation extending substantially normal to the passageway. The valve member further includes a slot extending inwardly toward the passageway from the outer surface, the slot being defined by slot surfaces and being configured to receive a projection extending from a valve casing when said valve member is placed within a valve body and rotated about the axis of rotation. The slot is further configured such that a stop portion of at least one of the slot walls acts as a stop for halting rotation of the valve member relative to the valve body in a first rotative direction. The valve also comprises a stem attached to the valve member that extends away from the valve member along the axis of rotation. In this configuration, the valve member includes stops that interact with the projection of the casing to desirably limit rotation of the valve member, and can be formed with the method set forth hereinabove. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a valve of the present invention. 
     FIG. 2 is a front view of the valve of FIG.  1 . 
     FIG. 3 is a front section view of the valve of FIG.  1 . 
     FIG. 4 is a front right perspective section view of the casing of the valve of FIG.  1 . 
     FIG. 5 is a front left perspective section view of the casing of the valve of FIG.  1 . 
     FIG. 6 is a bottom right rear perspective view of the ball-stem unit of the valve of FIG.  1 . 
     FIG. 7 is a front view of the ball-stem unit of FIG. 6 with the seat unit shown in exploded form. 
     FIG. 8 is a right side view of the ball-stem unit of FIG.  6 . 
     FIG. 9 is a rear view of the ball-stem unit of FIG. 6 with the seat unit shown in exploded form. 
     FIG. 10 is a left side view of the ball-stem unit of FIG.  6 . 
     FIG. 11 is a top section view of the ball-stem unit taken along lines  11 — 11  of FIG.  6 . 
     FIG. 11A is a schematic illustration of the configuration of the passageway and slot of the ball-stem unit illustrated in FIG.  11 . 
     FIG. 12 is a top section view of the ball-stem unit of FIG. 11 interacting with the stop member of the casing of FIG. 4 with the ball-stem unit in the open position. 
     FIG. 12A is a schematic illustration of the configuration of the passageway and slot of the ball-stem unit of FIG. 12 showing the interaction between the slot and the stop member of the casing. 
     FIG. 13 is a top section view of the ball-stem unit and casing of FIG. 12 with the ball-stem unit rotated 45 degrees clockwise to the partially closed position. 
     FIG. 13A is a schematic illustration of the configuration of the passageway and slot of the ball-stem unit of FIG. 13 interacting with the stop member of the casing. 
     FIG. 14 is a top section view of the ball-stem unit and casing of FIG. 12 with the ball-stem unit rotated 90 degrees clockwise from its position in FIG. 12 to a fully closed position. 
     FIG. 14A is a schematic illustration of the interaction between the passageway and slot of the ball-stem unit and the stop member of the casing in the closed position of FIG.  14 . 
     FIG. 15 is a front view showing the insertion of a mold core into the ball-stem unit of FIG. 6 prior to molding. 
     FIG. 16 is a front view of the ball-stem unit of FIG. 15 with one mold core fully inserted and a small mold insert being inserted. 
     FIG. 17 is a front view of the ball-stem unit, the seat unit and mold core of FIG. 16 with one mold core and the small mold insert fully inserted and a second mold core being inserted. 
     FIG. 18 is a front section view of the ball-stem unit, seat unit, mold cores and small mold insert of FIG. 17 positioned between two separated mold cavities. 
     FIG. 19 is a front section view of the molding operation of FIG. 18 with the mold cavities in a closed position. 
     FIG. 20 is a front section view of the closed mold cavities of FIG. 19 illustrating the injection of molten polymeric material into the mold cavities. 
     FIG. 21 is a front view of the molds of FIG. 20, wherein the mold cavities have been completely filled and the mold halves have separated. 
     FIG. 22 is a front section view of the valve molded in FIG. 21 showing the removal of one mold core from the valve. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
     Referring now to the figures, a ball valve, designated broadly at  20 , is shown in FIGS. 1 through 3. The valve  20  generally includes a casing  22 , a ball-stem unit  50 , and a seat unit  80 . These components are described in greater detail below. 
     The casing  22 , seen best in FIGS. 3 through 5, includes a body  24  comprising a generally spherical wall  25 , a inlet pipe  28 , and an outlet pipe  30 . The body wall  25  has an internal surface  25   a  that, along with an attached floor  27 , defines an internal valve cavity  26 . The inlet pipe  28  is hollow and is attached at one end to the wall  25  such that the lumen  28   a  of the inlet pipe  28  is in fluid communication with the cavity  26  via an inlet  29 . Similarly, the outlet pipe  30  is hollow and is attached at one end to the wall  25  such that the lumen  30   a  of the outlet pipe  30  is in fluid communication with the cavity  26  via an outlet  31 . Together, the inlet and outlet pipes  28 ,  30  define a flow axis F for fluid flow. The inlet  29  and outlet  31  are located at generally opposite positions from one another across the cavity  26  and are typically of approximately the same diameter. A circular recess  44  is located in the floor  27 . A stem aperture  46  is located above the cavity  26 ; two grooves  47  encircle the portions of the wall  25  that define the stem aperture  46 . 
     Referring now to FIGS. 4 and 5, a stop member  34  projects from the internal surface  25   a  of the wall  25 . The stop member  34  is generally T-shaped and includes a generally horizontal trunk  36  that extends from the outlet  31  toward the inlet  29 . The trunk  36  includes horizontal surfaces  36   a  (only one of which is illustrated herein) and a vertical surface  36   b  that merges smoothly with the inner surface of the inlet pipe  30 . Two ears  38  extend vertically in opposite directions from the end of the trunk member  36  located away from the outlet  31 . The ears  38  include horizontal surfaces  38   a  (only one of which is shown herein), vertical contact surfaces  40   a ,  40   b  that extend between the horizontal surfaces  38   a  and the horizontal surfaces  36   a  of the trunk  36  and generally face the outlet  31 , an arcuate, generally vertically disposed contact surface  42  that extends between the horizontal surfaces  38   a  and generally faces the inlet  29 , and a vertical surface  41  that merges with the vertical surface  36   b.    
     As will be discussed in greater detail hereinbelow, preferably the casing  22  is formed of a polymeric material, such as polyethylene, polypropylene or the like. It is also preferred that the casing  22  be formed in an injection molding process, and that the stop member  34  be formed simultaneously with the remainder of the casing  22  as an integral unit. 
     Referring now to FIGS. 6 through 10, the ball-stem unit  50 , which resides within and extends above the casing cavity  26 , includes a ball  52 , a stem  66 , and an adapter  70 . The ball  52  is generally spherical; it includes a knob  53  at its lower end that fits within the recess  44  of the casing floor  27 , and it is attached to the stem  66  at its upper end. A passageway  54  extends horizontally and diametrically through the ball  52 . The passageway  54  is illustratively and preferably approximately the same diameter as the inlet  29  and outlet  31 . 
     A generally horizontal slot  56  is included in the ball  52  that begins at one lateral edge of the passageway  54  and extends outwardly therefrom to the outer surface  52   a  of the ball  52 , such that the passageway  54  is open from that side. The slot  56  includes a narrow portion  58  and an adjacent wide portion  60 . The narrow portion  58  is defined by opposed horizontal surfaces  58   a  (only one of which is expressly illustrated in FIG. 6) and terminates on one end at the passageway  54  and at the other end at vertical step surfaces  62 . The wide portion  60  is defined by opposed horizontal surfaces  60   a  (only one of which is expressly illustrated in FIG. 6) and terminates at one end at the passageway  54  and at the other end at the vertical step surfaces  62 . 
     Preferably, the outer surface  52   a  of the ball  52  is sized to fit snugly within the inner surface  25   a  of the casing wall  25 . The knob  53  should be sized to fit and rotate within the recess  44 . The passageway  54  should have a diameter larger than the width of the wide portion  60  of the slot  56  (wherein the width is measured between the horizontal surfaces  60   a  of the wide portion  60 ). The wide portion  60  should be at least as wide as the distance between the horizontal surfaces  38   a  of the stop member ears  38 . The narrow portion  58  should be at least as wide as the trunk  36  of the stop member  34 , but should not be as wide as the distance between the horizontal surfaces  38   a  of the ears  38  (as with the wide portion  60 , the width of the narrow portion  58  is measured between the horizontal surfaces  58   a ). 
     Those skilled in this art will appreciate that, although the illustrated ball configuration is preferred, other configurations for the valve member  52  of the valve  20  may also be used. For example, the present invention can encompass frustoconical, conical, or cylindrical plugs or other valve members of substantially circular cross-section (such as ovoid and semi-ovoid configurations), as the principles behind the present invention are equally applicable to these and other additional configurations. 
     The stem  66  is circular in cross-section, is fixed to the upper end of the ball  52  opposite the knob  53 , and extends upwardly from the ball  52  through the stem aperture  46 . The stem  66  is sized to fit snugly and rotate within the stem aperture  46 . The stem  66  and knob  53  define an axis of rotation A for the ball-stem unit  50  that is substantially normal to the flow axis F. The stem  66  includes two circular ridges  68  between which an O-ring  69  resides; these ridges  68  fit within the grooves  47  of the stem aperture  46 . 
     The adapter  70  is fixed to the upper end of the stem  66 . As illustrated herein, the adapter  70  includes a square block  72  and an upper rib  74 . An adapter of this configuration enables an operator to use either a square wrench or a T-wrench to turn the adapter  70  (and, in turn, the ball  52 ) to open or close the valve  70 . This adapter is described in greater detail in co-pending and co-assigned U.S. patent application Ser. No. 09/316,819 filed concurrently and entitled VALVE INCLUDING VALVE ADAPTER AND STOP ASSEMBLY the disclosure of which is hereby incorporated herein by reference in its entirety. Those skilled in this art will recognize that, although the illustrated adapter configuration is preferred, any other adapter configuration that enables an operator to rotate the ball  52  between open and closed positions can also be employed with the present invention. 
     Illustratively and preferably, the ball-stem unit  50  is formed as an integral unit, although multiple pieces may be employed. It is also preferred that the ball stem-unit  50  be formed of a polymeric material, such as polypropylene, acetal, and the like, and that it be injection molded. It is further preferred that the ball-stem unit so be formed of a material that does not deform at the molding temperatures of the material of the casing  22 . 
     Referring to FIGS. 3,  7  and  9 , the seat unit  80  comprises a ring-shaped seat retainer  82  and a seat layer  84 . The seat retainer  82  is sized and positioned such that its opening encircles the inlet  31 . The seat layer  84 , which should be formed of a compressible material, overlies the surface of the seat retainer  82  that rests upon the outer surface  52   a  of the ball  52 . The seat layer  84  may be formed as a separate component for the seat retainer  82 , in the manner of a gasket, or may be a layer of material that is adhered to the seat retainer  82  in the manner of a coating. The interaction between the seat layer  84  and the ball  52  provides a fluid-tight seal between these components when the ball  52  is in the closed position. 
     Like the ball-stem unit  50 , it is preferred that, if the casing  22  is injection molded of a polymeric material, the seat retainer  82  and the seat layer  84  be formed of a material that does not deform at the molding temperature of the material of the casing  22 . For example, if the casing  22  is formed of polyethylene, the seat retainer  82  may be formed of acetal or polypropylene, and the seat layer  84  may be formed of Buna N or Viton®. 
     In operation, the valve  20  can be moved between an open position (see, for example, FIGS. 2 and 12) and a closed position (see, for example, FIG. 14) through rotation of the adapter  70  relative to the casing  22 . In the open position, the passageway  54  of the ball  52  is oriented such that it is substantially parallel with the flow axis F defined by the inlet and outlet pipes  28 ,  30 . As shown in FIGS. 12 and 12A, the slot  56  of the ball  52  is positioned such that it surrounds the stop member  34  of the casing  22 , with the horizontal surfaces  58   a  of the narrow portion  58  in adjacent relationship with the horizontal surfaces  36   a  of the trunk  36 , and with the horizontal surfaces  60   a  of the wide portion  60  of the slot  56  in adjacent relationship with the horizontal surfaces  38   a  of the ears  38 . The relationship of these components is illustrated in two-dimensional schematic form in FIG. 12A, which represents the passageway  54  and slot  56  interacting with the stop member  34 . The contact surfaces  40   a  of the ears  38  contact the step surfaces  62  of the slot  56 , thereby preventing the ball  52  from additional rotation in the counterclockwise direction as seen in FIG.  12 . 
     Those skilled in the art will appreciate that other projection and slot configurations can also be employed with the present invention. For example, the stop member  34  may include only a single ear  38 , with the wide position  60  of the slot  56  being narrowed in a corresponding manner. It is also contemplated that the slot  56  may not be contiguous with the passageway  54 . Further, the trunk  36  may be omitted altogether; in that instance, the narrow portion  58  of the slot  56  may also be omitted. Irrespective of the configuration selected, it is preferred that the interaction between the slot of the valve member and the projection on the casing limit rotation of the valve member within a range of 75 to 105 degrees, with a rotative range of about 90 degrees being more preferred. 
     To move the ball  52  to the closed position from the open position, the operator rotates the adapter  70  relative to the casing  22  (in a clockwise direction as viewed from above, as in FIGS.  12  through  14 ), which in turn rotates the stem  66  and the ball  52  clockwise about the axis A (see FIGS. 13 and 13A, which show the ball  52  in a partially open position). Rotation ceases as the ball  52  reaches the closed position, in which the passageway  54  is oriented to be substantially perpendicular to the flow axis F (see FIGS.  14  and  14 A). In the closed position, a contact surface  64  located on an interior edge portion of the passageway  54  opposite the wide portion  60  of the slot  56  is in contact with the contact surface  42  of the stop member  34 , thereby preventing further rotation of the ball  52 , stem  66  and adapter  70  in the clockwise direction. The relative movement of the stop member  34 , the passageway  54  and the slot  56  as they move toward and to the closed position is schematically illustrated in two dimensions in FIGS. 13A and 14A. 
     Although the ball  52  is generally spherical, it is preferred that the ball  52  be slightly greater in diameter in the horizontal dimension normal to the passageway  54  than in the horizontal dimension parallel to the passageway  54 . In such a configuration, the ball  52  can press against the seat layer  84  with greater pressure in the closed position than in the open position, thus creating a tighter seal in the closed position (when the integrity of the seal is more important). 
     FIGS. 15 through 22 illustrate a method of constructing the valve  20  through an injection molding process. First, a cylindrical mold core  92   a  is inserted through the seat unit  80  and the passageway  54  of the ball  52 . (FIG.  15 ). The mold core  92   a  fills the passageway  54 , but does not fill the slot  56 . The mold core  92   a  can be formed of any material typically used in the injection molding of polymeric materials, but is preferably steel. A small mold insert  92   b  is then inserted in the wide portion  60  of the slot  56  (FIG.  16 ). The seat unit  80  is then placed in contact with the ball  52 , and a second mold core  92   a  is inserted into the seat retainer  82  to form a mold insert assembly  91  (FIG.  17 ). The mold insert assembly  91  is then positioned within a cavity  90   a  of a mold half  90 , with the adapter  70  fitting flush against the walls of the cavity  90   a  (FIG. 18) and the ends of the mold cores  92   a ,  92   b  fitting within recesses in the mold half  90 . A mating mold half  93  having a cavity  93   a  is then positioned opposite the mold half  90  and brought into contact with the mold half  90  such that the cavities  90   a ,  93   a  are contiguous (FIG.  19 ). Molten polymeric material  97  is injected through a sprue  95  that is in fluid communication with the mold cavity  93   a , and the polymeric material  97  fills the portions of the cavities  90   a ,  93   a  that are not occupied by the insert assembly  91  to form the casing  22  (FIG.  20 ). Thus, the wall  25 , the floor  27 , the inlet pipe  28 , the outlet pipe  30 , and the stop member  34  are formed by the injected polymeric material  97  as it flows around the mold insert assembly  91 . Once the unoccupied space has been filled and the polymeric material  97  has solidified sufficiently for handling, the mold half  93  retracts (FIG.  21 ), and the finished valve  20  and the mold core  92  are removed from the valve  20  (FIG.  22 ). The finished valve  20  is then ready for use. 
     Notably, and as demonstrated by the foregoing discussion, the valve  20  can be constructed in an injection molding process that requires no post-molding assembly steps to enable the valve to operate. The ball-stem unit can be formed as an integral component, then included in the valve without additional steps to assemble separate portions of the casing. Further, the injection molding of the valve with the ball-stem insert can produce stops for the ball to halt rotation of the ball at desired points. As such, the valve and construction method of the present invention solves problems presented by prior art valves. 
     The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. The invention is defined by the following claims, with equivalents of the claims to be included therein. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures.